File: cons.bat

package info (click to toggle)
cons 2.3.0.1%2B2.2.0-2
  • links: PTS
  • area: main
  • in suites: stretch
  • size: 604 kB
  • sloc: perl: 2,307; makefile: 28
file content (5750 lines) | stat: -rwxr-xr-x 189,165 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
@rem = '--*-PERL-*--';
@rem = '';
@rem = 'Copyright (C) 1996-2000 Free Software Foundation, Inc.';
@rem = '';
@rem = 'This program is free software; you can redistribute it and/or modify';
@rem = 'it under the terms of the GNU General Public License as published by';
@rem = 'the Free Software Foundation; either version 2 of the License, or';
@rem = '(at your option) any later version.';
@rem = '';
@rem = 'This program is distributed in the hope that it will be useful,';
@rem = 'but WITHOUT ANY WARRANTY; without even the implied warranty of';
@rem = 'MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the';
@rem = 'GNU General Public License for more details.';
@rem = '';
@rem = 'You should have received a copy of the GNU General Public License';
@rem = 'along with this program; see the file COPYING.  If not, write to';
@rem = 'the Free Software Foundation, Inc., 59 Temple Place - Suite 330,';
@rem = 'Boston, MA 02111-1307, USA.';
@rem = '
@echo off
rem setlocal
set ARGS=
:loop
if .%1==. goto endloop
set ARGS=%ARGS% %1
shift
goto loop
:endloop
rem ***** This assumes PERL is in the PATH *****
rem $Id: cons.bat.proto,v 1.4 2000/06/14 22:33:01 rv Exp $
perl.exe -S cons.bat %ARGS%
goto endofperl
@rem ';

#!/usr/bin/env perl

# NOTE:  Cons intentionally does not use the "perl -w" option or
# "use strict."  Because Cons "configuration files" are actually
# Perl scripts, enabling those restrictions here would force them
# on every user's config files, wanted or not.  Would users write
# "better" Construct and Conscript files if we forced "use strict"
# on them?  Probably.  But we want people to use Cons to get work
# done, not force everyone to become a Perl guru to use it, so we
# don't insist.
#
# That said, Cons' code is both "perl -w" and "use strict" clean.
# Regression tests keep the code honest by checking for warnings
# and "use strict" failures.

# $Id: cons.pl,v 1.129 2000/11/16 12:22:37 knight Exp $

use vars qw( $ver_num $ver_rev $version );

$ver_num = "2.2";
$ver_rev = ".0";
$version = sprintf "This is Cons %s%s " .
	    '($Id: cons.pl,v 1.129 2000/11/16 12:22:37 knight Exp $)'. "\n",
	    $ver_num, $ver_rev;

# Cons: A Software Construction Tool.
# Copyright (c) 1996-2000 Free Software Foundation, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; see the file COPYING.  If not, write to
# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.

require 5.002;
# See the NOTE above about why Cons doesn't "use strict".
use integer;
use Cwd;
use File::Copy;

use vars qw( $_WIN32 $_a $_exe $_o $_so );

#------------------------------------------------------------------
# Determine if running on win32 platform - either Windows NT or 95
#------------------------------------------------------------------

use vars qw( $PATH_SEPARATOR $iswin32 $_WIN32 $usage $indent @targets );

BEGIN {
    use Config;

    # if the version is 5.003, we can check $^O
    if ($] <  5.003) {
	eval("require Win32");
	$_WIN32 = (!$@);
    } else {
	$_WIN32 = ($^O eq "MSWin32") ? 1 : 0;
    }

    # Fetch the PATH separator from Config;
    # provide our old defaults in case it's not set.
    $PATH_SEPARATOR = $Config{path_sep};
    $PATH_SEPARATOR = $_WIN32 ? ';' : ':' if ! defined $PATH_SEPARATOR;

    # Fetch file suffixes from Config,
    # accomodating differences in the Config variables
    # used by different Perl versions.
    $_exe = $Config{_exe};
    $_exe = $Config{exe_ext} if ! defined $_exe;
    $_exe = $_WIN32 ? '.exe' : '' if ! defined $_exe;
    $_o = $Config{_o};
    $_o = $Config{obj_ext}  if ! defined $_o;
    $_o = $_WIN32 ? '.obj' : '.o' if ! defined $_o;
    $_a = $Config{_a};
    $_a = $Config{lib_ext} if ! defined $_a;
    $_a = $_WIN32 ? '.lib' : '.a' if ! defined $_a;
    $_so = ".$Config{so}";
    $_so = $_WIN32 ? '.dll' : '.so' if ! defined $_so;
}

# Flush stdout each time.
$| = 1;

# Seed random number generator.
srand(time . $$); # this works better than time ^ $$ in perlfunc manpage.

$usage = q(
Usage: cons <arguments> -- <construct-args>

Arguments can be any of the following, in any order:

  <targets>	Build the specified targets. If <target> is a directory
		recursively build everything within that directory.

  +<pattern>	Limit the cons scripts considered to just those that
		match <pattern>. Multiple + arguments are accepted.

  <name>=<val>	Sets <name> to value <val> in the ARG hash passed to the
		top-level Construct file.

  -cc           Show command that would have been executed, when
		retrieving from cache. No indication that the file
		has been retrieved is given; this is useful for
		generating build logs that can be compared with
		real build logs.

  -cd           Disable all caching. Do not retrieve from cache nor
		flush to cache.

  -cr           Build dependencies in random order. This is useful when
		building multiple similar trees with caching enabled.

  -cs           Synchronize existing build targets that are found to be
		up-to-date with cache. This is useful if caching has
		been disabled with -cc or just recently enabled with
		UseCache.

  -d            Enable dependency debugging.

  -f <file>	Use the specified file instead of "Construct" (but first
		change to containing directory of <file>).

  -h            Show a help message local to the current build if
		one such is defined,  and exit.

  -k		Keep going as far as possible after errors.

  -o <file>	Read override file <file>.

  -p		Show construction products in specified trees.
  -pa		Show construction products and associated actions.
  -pw		Show products and where they are defined.

  -q		Be quiet about Installing and Removing targets.

  -r		Remove construction products associated with <targets>

  -R <repos>	Search for files in <repos>.  Multiple -R <repos>
		directories are searched in the order specified.

  -t            Traverse up the directory hierarchy looking for a
		Construct file, if none exists in the current directory.
		(Targets will be modified to be relative to the
		Construct file.)

  -v		Show cons version and continue processing.
  -V            Show cons version and exit.

  -wf <file>    Write all filenames considered into <file>.

  -x		Show this message and exit.


   Please report any suggestions through the cons-discuss@gnu.org mailing
   list.

   To subscribe, send mail to cons-discuss-request@gnu.org with body
   'subscribe'.

   If you find a bug, please report it through the bug-cons@gnu.org
   mailing list.

   Information about CONS can be obtained from the official cons web site
   http://www.dsmit.com/cons/ or its mirrors (listed there).

   The cons maintainers can be contacted by email at cons-maintainers@gnu.org

   User documentation of cons is contained in cons and can be obtained
   by doing 'perldoc /path/to/cons'.

);

# Simplify program name, if it is a path.
{
    my ($vol, $dir, $file) = File::Spec->splitpath(File::Spec->canonpath($0));
    $0 = $file;
}

# Default parameters.
$param::topfile = 'Construct';	# Top-level construction file.
$param::install = 1;		# Show installations
$param::build = 1;		# Build targets
### $param::show = 1;		# Show building of targets.
$param::sigpro = 'md5';		# Signature protocol.
$param::depfile = '';		# Write all deps out to this file
$param::salt = '';		# Salt derived file signatures with this.
$param::rep_sig_times_ok = 1;	# Repository .consign times are in sync
				#   w/files.
$param::conscript_chdir = 0;	# Change dir to Conscript directory
$param::quiet = 0;		# should we show the command being executed.

#
$indent = '';

# Display a command while executing or otherwise. This
# should be called by command builder action methods.
sub showcom {
    print($indent . $_[0] . "\n");
}

# Default environment.
# This contains only the completely platform-independent information
# we can figure out.  Platform-specific information (UNIX, Win32)
# gets added below.
@param::defaults = (
     'SUFEXE'	    => $_exe,				# '' on UNIX systems
     'SUFLIB'	    => $_a,				# '.a' on UNIX systems
     'SUFLIBS'      => "$_so:$_a",			# '.so:.a' on UNIX
     'SUFOBJ'	    => $_o,				# '.o' on UNIX systems
     'SUFMAP'       => {
	 '.c'  => 'build::command::cc',
	 '.s'  => 'build::command::cc',
	 '.S'  => 'build::command::cc',
	 '.C'  => 'build::command::cxx',
	 '.cc' => 'build::command::cxx',
	 '.cxx'=> 'build::command::cxx',
	 '.cpp'=> 'build::command::cxx',
	 '.c++'=> 'build::command::cxx',
	 '.C++'=> 'build::command::cxx',
     },
);

if ($_WIN32) {
    # Defaults for Win32.
    # Defined for VC++ 6.0 by Greg Spencer <greg_spencer@acm.org>.
    # Your mileage may vary.
    my @win = (
	'CC'             => 'cl',
	'CFLAGS'         => '/nologo',
	'CCCOM'          => '%CC %CFLAGS %_IFLAGS /c %< /Fo%>',
	'CXX'            => '%CC',
	'CXXFLAGS'       => '%CFLAGS',
	'CXXCOM'         => '%CXX %CXXFLAGS %_IFLAGS /c %< /Fo%>',
	'INCDIRPREFIX'   => '/I',
	'LINK'           => 'link',
	'LINKCOM'        => '%LINK %LDFLAGS /out:%> %< %_LDIRS %LIBS',
	'LINKMODULECOM'  => '%LD /r /o %> %<',
	'LIBDIRPREFIX'   => '/LIBPATH:',
	'AR'             => 'lib',
	'ARFLAGS'        => '/nologo ',
	'ARCOM'          => "%AR %ARFLAGS /out:%> %<",
	'RANLIB'         => '',
	'LD'             => 'link',
	'LDFLAGS'        => '/nologo ',
	'PREFLIB'        => '',
    );
    push(@param::defaults, @win);
} else {
    # Defaults for a typical (?) UNIX platform.
    # Your mileage may vary.
    my @unix = (
	'CC'             => 'cc',
	'CFLAGS'         => '',
	'CCCOM'          => '%CC %CFLAGS %_IFLAGS -c %< -o %>',
	'CXX'            => '%CC',
	'CXXFLAGS'       => '%CFLAGS',
	'CXXCOM'         => '%CXX %CXXFLAGS %_IFLAGS -c %< -o %>',
	'INCDIRPREFIX'   => '-I',
	'LINK'           => '%CXX',
	'LINKCOM'        => '%LINK %LDFLAGS -o %> %< %_LDIRS %LIBS',
	'LINKMODULECOM'  => '%LD -r -o %> %<',
	'LIBDIRPREFIX'   => '-L',
	'AR'             => 'ar',
	'ARFLAGS'        => 'r', # rs?
	'ARCOM'          => "%AR %ARFLAGS %> %<\n%RANLIB %>",
	'RANLIB'         => 'ranlib',
	'AS'             => 'as',
	'ASFLAGS'        => '',
	'ASCOM'          => '%AS %ASFLAGS %< -o %>',
	'LD'             => 'ld',
	'LDFLAGS'        => '',
	'PREFLIB'        => 'lib',
	'ENV'            => { 'PATH' => '/bin:/usr/bin' },
    );
    push(@param::defaults, @unix);
}

# Handle command line arguments.
while (@ARGV) {
    $_ = shift @ARGV;
    last if /^--$/;		# Argument passing to Construct.
    &option, next			if s/^-//;
    push (@param::include, $_), next	if s/^\+//;
    &equate, next			if /=/;
    push (@targets, $_), next;
}

sub option {
    my %opt = (
		    'cc' =>   sub { $param::cachecom = 1; },
		    'cd' =>   sub { $param::cachedisable = 1; },
		    'cr' =>   sub { $param::random = 1; },
		    'cs' =>   sub { $param::cachesync = 1; },
		    'd' =>    sub { $param::depends = 1; },
		    'h' =>    sub { $param::localhelp = 1; },
		    'k' =>    sub { $param::kflag = 1; },
		    'p' =>    sub { $param::pflag = 1;
				    $param::build = 0; },
		    'pa' =>   sub { $param::pflag = 1;
				    $param::aflag = 1;
				    $indent = "... ";
				    $param::build = 0; },
		    'pw' =>   sub { $param::pflag = 1;
				    $param::wflag = 1;
				    $param::build = 0; },
		    'q' =>    sub { $param::quiet = 1; },
		    'r' =>    sub { $param::rflag = 1;
				    $param::build = 0; },
		    't' =>    sub { $param::traverse = 1; },
		    'v' =>    sub { print($version); },
		    'V' =>    sub { print($version), exit(0); },
		    'x' =>    sub { print($usage), exit 0; },
		);

    my %opt_arg = (
		    'f' =>    sub { $param::topfile = $_[0]; },
		    'o' =>    sub { $param::overfile = $_[0]; },
		    'R' =>    sub { script::Repository($_[0]); },
		    'wf' =>   sub { $param::depfile = $_[0]; },
		);

    if (defined $opt{$_}) {
	&{$opt{$_}}();
	return;
    }
    $_  =~ m/(.)(.*)/;
    if (defined $opt_arg{$1}) {
	if (! $2) {
	    $_ = shift @ARGV;
	    die("$0: -$1 option requires an argument.\n") if ! $_;
	}
	&{$opt_arg{$1}}($2 || $_);
	return;
    }
    $_  =~ m/(..)(.*)/;
    if (defined $opt_arg{$1}) {
	if (! $2) {
	    $_ = shift @ARGV;
	    die("$0: -$1 option requires an argument.\n") if ! $_;
	}
	&{$opt_arg{$1}}($2 || $_);
	return;
    }
    if ($_) {
	die qq($0: unrecognized option "-$_".  Use -x for a usage message.\n);
    }
}

# Process an equate argument (var=val).
sub equate {
    my($var, $val) = /([^=]*)=(.*)/;
    $script::ARG{$var} = $val;
}

# Define file signature protocol.
'sig'->select($param::sigpro);

# Cleanup after an interrupt.
$SIG{INT} = $SIG{QUIT} = $SIG{TERM} = sub {
    $SIG{PIPE} = $SIG{INT} = $SIG{QUIT} = $SIG{TERM} = 'IGNORE';
    $SIG{HUP} = $SIG{INT} if ! $main::_WIN32;
    warn("\n$0: killed\n");
    # Call this first, to make sure that this processing
    # occurs even if a child process does not die (and we
    # hang on the wait).
    sig::hash::END();
    wait();
    exit(1);
};
$SIG{HUP} = $SIG{INT} if ! $main::_WIN32;

# Cleanup after a broken pipe (someone piped our stdout?)
$SIG{PIPE} = sub {
    $SIG{PIPE} = $SIG{HUP} = $SIG{INT} = $SIG{QUIT} = $SIG{TERM} = 'IGNORE';
    warn("\n$0: broken pipe\n");
    sig::hash::END();
    wait();
    exit(1);
};

if ($param::depfile) {
  open (main::DEPFILE, ">".$param::depfile) ||
    die ("$0: couldn't open $param::depfile ($!)\n");
}

# If the supplied top-level Conscript file is not in the
# current directory, then change to that directory.
{
    my ($vol, $dir, $file) = File::Spec->splitpath(File::Spec->canonpath($param::topfile));
    if ($vol || $dir) {
	my($cd) = File::Spec->catpath($vol, $dir, undef);
	chdir($cd) || die("$0: couldn't change to directory $cd ($!)\n");
	$param::topfile = $file;
    }
}

# Walk up the directory hierarchy looking for a Conscript file (if -t set).
my($target_top);
my(@targetdir) = ();
if ($param::traverse && ! -f $param::topfile) {
    my($vol, $dirs, $file) = File::Spec->splitpath(cwd());
    my(@dirs) = (File::Spec->splitdir($dirs), $file);
    while (! -f File::Spec->catpath($vol, File::Spec->catdir(@dirs), $param::topfile)) {
	die("$0: unable to find $param::topfile.\n") if ! @dirs;
	unshift(@targetdir, pop(@dirs));
    }
    my($cwd) = File::Spec->catpath($vol, File::Spec->catdir(@dirs), '');
    print "$0: Entering directory `$cwd'\n";
    chdir($cwd);
    @targets = map {File::Spec->catdir(@targetdir, $_)} @targets;
}

# Set up $dir::top and $dir::cwd, now that we are in the right directory.
dir::init();

#
if (@targetdir) {
    $target_top = $dir::top->lookupdir(File::Spec->catdir(@targetdir));
}

# Now handle override file.
package override;
if ($param::overfile) {
    my($ov) = $param::overfile;
    die qq($0: can\'t read override file "$ov" ($!)\n) if ! -f $ov; #'
    do $ov;
    if ($@) {
	chop($@);
	die qq($0: errors in override file "$ov" ($@)\n);
    }
}

# Provide this to user to setup override patterns.
sub Override {
    my($re, @env) = @_;
    return if $param::overrides{$re}; # if identical, first will win.
    $param::overrides = 1;
    $param::overrides{$re} = \@env;
    push(@param::overrides, $re);
}

package main;

use vars qw( %priority $errors );

# Check script inclusion regexps
my $re;
for $re (@param::include) {
    if (! defined eval {"" =~ /$re/}) {
	my($err) = $@;
	$err =~ s/in regexp at .*$//;
	die("$0: error in regexp $err");
    }
}

# Read the top-level construct file and its included scripts.
doscripts($param::topfile);

# Status priorities. This lets us aggregate status for directories
# and print an appropriate message (at the top-level).
%priority =
    ('none' => 1, 'handled' => 2, 'built' => 3, 'unknown' => 4, 'errors' => 5);

# If no targets were specified, supply default targets (if any).
@targets = @param::default_targets if ! @targets;

$errors = 0;

# Build the supplied target patterns.
my $tgt;
for $tgt (map($dir::top->lookup($_), @targets)) {
    if ($target_top && ! $tgt->is_under($target_top)) {
	# A -t option was used, and this target is not underneath
	# the directory where we were invoked via -t.
	# If the target is a directory and the -t directory
	# is underneath it, then build the -t directory.
	if (ref $tgt ne "dir" || ! $target_top->is_under($tgt)) {
	    next;
	}
	$tgt = $target_top;
    }
    buildtoptarget($tgt);
}

exit 0 + ($errors != 0);

sub buildtoptarget {
    my($tgt) = @_;
    return if ! $tgt;
    my($status) = buildtarget($tgt);
    if ($status ne 'built') {
	my($path) = $tgt->path;
	if ($status eq "errors") {
	    print qq($0: "$path" not remade because of errors.\n);
	    $errors++;
	} elsif ($status eq "handled") {
	    print qq($0: "$path" is up-to-date.\n);
	} elsif ($status eq "unknown") {
	    # cons error already reported.
	    $errors++;
	} elsif ($status eq "none") {
	    # search for targets that may be linked to the given path.
	    my @linked = dir::linked_targets($tgt) if $target_top;
	    if (@linked) {
		my @names = map($_->path, @linked);
		print "Linked targets: @names\n" unless ($param::quiet);
		map(buildtoptarget($_), @linked);
	    } else {
		print qq($0: nothing to be built in "$path".\n) if $param::build;
	    }
	} else {
	    print qq($0: don\'t know how to construct "$path".\n); #'
	    $errors++;
	}
    }
}

# Build the supplied target directory or files. Return aggregated status.
sub buildtarget {
    my($tgt) = @_;
    if (ref($tgt) eq "dir") {
	my($result) = "none";
	my($priority) = $priority{$result};
	if (exists $tgt->{member}) {
	    my($members) = $tgt->{member};
	    my $entry;
	    for $entry (sort keys %$members) {
		next if $entry eq $dir::CURDIR || $entry eq $dir::UPDIR;
		my($tgt) = $members->{$entry};
		next if ref($tgt) ne "dir" && !exists($tgt->{builder});
		my($stat) = buildtarget($members->{$entry});
		my($pri) = $priority{$stat};
		if ($pri > $priority) {
		    $priority = $pri;
		    $result = $stat;
		}
	    }
	}
	return $result;
    }
    if ($param::depends) {
	my($path) = $tgt->path;
	if ($tgt->{builder}) {
	    my(@dep) = (@{$tgt->{dep}}, @{$tgt->{sources}});
	    my($dep) = join(' ',map($_->path, @dep));
	    print("Target $path: $dep\n");
	} else {
	    print("Target $path: not a derived file\n");
	}
    }
    if ($param::build) {
	return build $tgt;
    } elsif ($param::pflag || $param::wflag || $param::aflag) {
	if ($tgt->{builder}) {
	    if ($param::wflag) {
		print qq(${\$tgt->path}: $tgt->{script}\n);
	    } elsif ($param::pflag) {
		print qq(${\$tgt->path}:\n) if $param::aflag;
		print qq(${\$tgt->path}\n) if !$param::aflag;
	    }
	    if ($param::aflag) {
		$tgt->{builder}->action($tgt);
	    }
	}
    } elsif ($param::rflag && $tgt->{builder}) {
	my($path) = $tgt->path;
	if (-f $path) {
	    if (unlink($path)) {
		print("Removed $path\n") unless ($param::quiet);
	    } else {
		warn("$0: couldn't remove $path\n");
	    }
	}
    }

    return "none";
}

package NameSpace;

# Return a hash that maps the name of symbols in a namespace to an
# array of refs for all types for which the name has a defined value.
# A list of symbols may be specified; default is all symbols in the
# name space.
sub save {
    my $package = shift;
    my(%namerefs, $var, $type);
    no strict 'refs';
    @_ = keys %{$package."::"} if ! @_;
    foreach $var (@_) {
	$namerefs{$var} = [];
	my $fqvar = $package."::".$var;
	# If the scalar for this variable name doesn't already
	# exist, *foo{SCALAR} will autovivify the reference
	# instead of returning undef, so unlike the other types,
	# we have to dereference to find out if it exists.
	push(@{$namerefs{$var}}, *{$fqvar}{SCALAR})
		    if defined ${*{$fqvar}{SCALAR}};
	foreach $type (qw(ARRAY HASH CODE IO)) {
	    push(@{$namerefs{$var}}, *{$fqvar}{$type})
			  if defined *{$fqvar}{$type};
	}
    }
    return \%namerefs;
}

# Remove the specified symbols from the namespace.
# Default is to remove all.
sub remove {
    my $package = shift;
    my(%namerefs, $var);
    no strict 'refs';
    @_ = keys %{$package."::"} if ! @_;
    foreach $var (@_) {
	delete ${$package."::"}{$var};
    }
}

# Restore values to symbols specified in a hash as returned
# by NameSpace::save.
sub restore {
    my($package, $namerefs) = @_;
    my($var, $ref);
    no strict 'refs';
    foreach $var (keys %$namerefs) {
	my $fqvar = $package."::".$var;
	foreach $ref (@{$namerefs->{$var}}) {
	    *{$fqvar} = $ref;
	}
    }
}

# Support for "building" scripts, importing and exporting variables.
# With the exception of the top-level routine here (invoked from the
# main package by cons), these are all invoked by user scripts.
package script;

use vars qw( $ARG $caller_dir_path %special_var );

BEGIN {
    # We can't Export or Import the following variables because Perl always
    # treats them as part of the "main::" package (see perlvar(1)).
    %special_var = map {$_ => 1} qw(ENV INC ARGV ARGVOUT SIG
				    STDIN STDOUT STDERR);
}

# This is called from main to interpret/run the top-level Construct
# file, passed in as the single argument.
sub main::doscripts {
    my($script) = @_;
    Build($script);
    # Now set up the includes/excludes (after the Construct file is read).
    $param::include = join('|', @param::include);

    # Save the original variable names from the script package.
    # These will stay intact, but any other "script::" variables
    # defined in a Conscript file will get saved, deleted,
    # and (when necessary) restored.
    my(%orig_script_var) = map {$_ => 1} keys %script::;
    $caller_dir_path = undef;
    my $cwd = Cwd::cwd();
    my(@scripts) = pop(@priv::scripts);
    while ($priv::self = shift(@scripts)) {
	my($path) = $priv::self->{script}->rsrcpath;
	if (-f $path) {
	    $dir::cwd = $priv::self->{script}->{dir};
	    # Handle chdir to the Conscript file directory, if necessary.
	    my ($vol, $dir, $file);
	    if ($param::conscript_chdir) {
		($vol, $dir, $file) = File::Spec->splitpath(File::Spec->canonpath($path));
		if ($vol ne '' || $dir ne '') {
		    $caller_dir_path = File::Spec->catpath($vol, $dir, undef);
		    chdir($caller_dir_path) ||
			die "Could not chdir to $caller_dir_path: $!\n";
		}
	    } else {
		$file = $path;
	    }
	    # Actually process the Conscript file.
	    do $file;
	    # Save any variables defined by the Conscript file
	    # so we can restore them later, if needed;
	    # then delete them from the script:: namespace.
	    my(@del) = grep(! $orig_script_var{$_}, keys %script::);
	    if (@del) {
		$priv::self->{script}->{pkgvars} =
						NameSpace::save('script', @del);
		NameSpace::remove('script', @del);
	    }
	    if ($caller_dir_path) {
		chdir($cwd);
		$caller_dir_path = undef;
	    }
	    if ($@) {
		chomp($@);
		my $err = ($@ =~ /\n/ms) ? ":\n$@" : " ($@)";
		print qq($0: error in file "$path"$err\n);
		$run::errors++;
	    } else {
		# Only process subsidiary scripts if no errors in parent.
		unshift(@scripts, @priv::scripts);
	    }
	    undef @priv::scripts;
	} else {
	    my $where = '';
	    my $cref = $priv::self->{script}->creator;
	    if (defined $cref) {
		my($_foo, $script, $line, $sub) = @$cref;
		$where = " ($sub in $script, line $line)";
	    }
	    warn qq(Ignoring missing script "$path"$where);
	}
    }
    die("$0: script errors encountered: construction aborted\n")
	if $run::errors;
}

# Return caller info about the method being invoked.
# This is everything from the Perl "caller" builtin function,
# including which Construct/Conscript file, line number,
# subroutine name, etc.
sub caller_info {
    my($lev) = 1;
    my(@frame);
    do {
	@frame = caller ++$lev;
	if (defined($frame[3]) && $frame[3] eq '(eval)') {
	    @frame = caller --$lev;
	    if ($caller_dir_path) {
		$frame[1] = File::Spec->catfile($caller_dir_path, $frame[1]);
	    }
	    return @frame;
	}
    } while ($frame[3]);
    return;
}

# Link a directory to another. This simply means set up the *source*
# for the directory to be the other directory.
sub Link {
    dir::link(@_);
}

# Add directories to the repository search path for files.
# We're careful about stripping our current directory from
# the list, which we do by comparing the `pwd` results from
# the current directory and the specified directory.  This
# is cumbersome, but assures that the paths will be reported
# the same regardless of symbolic links.
sub Repository {
    my($my_dir) = Cwd::cwd();
    my $dir;
    foreach $dir (@_) {
	my($d) = `$^X -e "use Cwd; chdir('$dir') && print cwd"`;
	next if ! $d || ! -d $d || $d eq $my_dir;
	# We know we can get away with passing undef to lookupdir
	# as the directory because $dir is an absolute path.
	push(@param::rpath, dir::lookupdir(undef, $dir));
	push @INC, $d;
    }
}

# Return the list of Repository directories specified.
sub Repository_List {
    map($_->path, @param::rpath);
}

# Specify whether the .consign signature times in repository files are,
# in fact, consistent with the times on the files themselves.
sub Repository_Sig_Times_OK {
    $param::rep_sig_times_ok = shift;
}

# Specify whether we should chdir to the containing directories
# of Conscript files.
sub Conscript_chdir {
    $param::conscript_chdir = shift;
}

# Specify files/targets that must be present and built locally,
# even if they exist already-built in a Repository.
sub Local {
    my(@files) = map($dir::cwd->lookupfile($_), @_);
    map($_->local(1), @files);
}

# Export variables to any scripts invoked from this one.
sub Export {
    my(@illegal) = grep($special_var{$_}, @_);
    if (@illegal) {
	die qq($0: cannot Export special Perl variables: @illegal\n);
    }
    @{$priv::self->{exports}} = grep(! defined $special_var{$_}, @_);
}

# Import variables from the export list of the caller
# of the current script.
sub Import {
    my(@illegal) = grep($special_var{$_}, @_);
    if (@illegal) {
	die qq($0: cannot Import special Perl variables: @illegal\n");
    }
    my($parent) = $priv::self->{parent};
    my($imports) = $priv::self->{imports};
    @{$priv::self->{exports}} = keys %$imports;
    my($var);
    foreach $var (grep(! defined $special_var{$_}, @_)) {
	if (!exists $imports->{$var}) {
	    my($path) = $parent->{script}->path;
	    die qq($0: variable "$var" not exported by file "$path"\n);
	}
	if (!defined $imports->{$var}) {
	    my $path = $parent->{script}->path;
	    my $err = "$0: variable \"$var\" exported but not " .
		      "defined by file \"$path\"\n";
	    die $err;
	}
	${"script::$var"} = $imports->{$var};
    }
}

# Build an inferior script. That is, arrange to read and execute
# the specified script, passing to it any exported variables from
# the current script.
sub Build {
    my(@files) = map($dir::cwd->lookupfile($_), @_);
    my(%imports) = map {$_ => ${"script::$_"}} @{$priv::self->{exports}};
    my $file;
    for $file (@files) {
	next if $param::include && $file->path !~ /$param::include/o;
	my($self) = {'script' => $file,
		     'parent' => $priv::self,
		     'imports' => \%imports};
	bless $self;  # may want to bless into class of parent in future
	push(@priv::scripts, $self);
    }
}

# Set up regexps dependencies to ignore. Should only be called once.
sub Ignore {
    die("Ignore called more than once\n") if $param::ignore;
    $param::ignore = join("|", map("($_)", @_)) if @_;
}

# Specification of default targets.
sub Default {
    push(@param::default_targets, map($dir::cwd->lookup($_)->path, @_));
}

# Local Help.  Should only be called once.
sub Help {
    if ($param::localhelp) {
	print "@_\n";
	exit 2;
    }
}

# Return the build name(s) of a file or file list.
sub FilePath {
    wantarray
	? map($dir::cwd->lookupfile($_)->path, @_)
	: $dir::cwd->lookupfile($_[0])->path;
}

# Return the build name(s) of a directory or directory list.
sub DirPath {
    wantarray
	? map($dir::cwd->lookupdir($_)->path, @_)
	: $dir::cwd->lookupdir($_[0])->path;
}

# Split the search path provided into components. Look each up
# relative to the current directory.
# The usual path separator problems abound; for now we'll use :
sub SplitPath {
    my($dirs) = @_;
    if (ref($dirs) ne "ARRAY") {
	$dirs = [ split(/$main::PATH_SEPARATOR/o, $dirs) ];
    }
    map { DirPath($_) } @$dirs;
}

# Return true if the supplied path is available as a source file
# or is buildable (by rules seen to-date in the build).
sub ConsPath {
    my($path) = @_;
    my($file) = $dir::cwd->lookup($path);
    return $file->accessible;
}

# Return the source path of the supplied path.
sub SourcePath {
    wantarray
	? map($dir::cwd->lookupfile($_)->rsrcpath, @_)
	: $dir::cwd->lookupfile($_[0])->rsrcpath;
}

# Search up the tree for the specified cache directory, starting with
# the current directory. Returns undef if not found, 1 otherwise.
# If the directory is found, then caching is enabled. The directory
# must be readable and writable. If the argument "mixtargets" is provided,
# then targets may be mixed in the cache (two targets may share the same
# cache file--not recommended).
sub UseCache($@) {
    my($dir, @args) = @_;
    # NOTE: it's important to process arguments here regardless of whether
    # the cache is disabled temporarily, since the mixtargets option affects
    # the salt for derived signatures.
    for (@args) {
	if ($_ eq "mixtargets") {
	    # When mixtargets is enabled, we salt the target signatures.
	    # This is done purely to avoid a scenario whereby if
	    # mixtargets is turned on or off after doing builds, and
	    # if cache synchronization with -cs is used, then
	    # cache files may be shared in the cache itself (linked
	    # under more than one name in the cache). This is not bad,
	    # per se, but simply would mean that a cache cleaning algorithm
	    # that looked for a link count of 1 would never find those
	    # particular files; they would always appear to be in use.
	    $param::salt = 'M' . $param::salt;
	    $param::mixtargets = 1;
	} else {
	    die qq($0: UseCache unrecognized option "$_"\n);
	}
    }
    if ($param::cachedisable) {
	warn("Note: caching disabled by -cd flag\n");
	return 1;
    }
    my($depth) = 15;
    while ($depth-- && ! -d $dir) {
	$dir = File::Spec->catdir($dir::UPDIR, $dir);
    }
    if (-d $dir) {
	$param::cache = $dir;
	return 1;
    }
    return undef;
}

# Salt the signature generator. The salt (a number of string) is added
# into the signature of each derived file. Changing the salt will
# force recompilation of all derived files.
sub Salt($) {
    # We append the value, so that UseCache and Salt may be used
    # in either order without changing the signature calculation.
    $param::salt .= $_[0];
}

# Mark files (or directories) to not be removed before building.
sub Precious {
    map($_->{precious} = 1, map($dir::cwd->lookup($_), @_));
}


# These methods are callable from Conscript files, via a cons
# object. Procs beginning with _ are intended for internal use.
package cons;

use vars qw( %envcache );

# This is passed the name of the base environment to instantiate.
# Overrides to the base environment may also be passed in
# as key/value pairs.
sub new {
    my($package) = shift;
    my ($env) = {@param::defaults, @_};
    @{$env->{_envcopy}} = %$env; # Note: we never change PATH
    $env->{_cwd} = $dir::cwd; # Save directory of environment for
    bless $env, $package;	# any deferred name interpretation.
}

# Clone an environment.
# Note that the working directory will be the initial directory
# of the original environment.
sub clone {
    my($env) = shift;
    my $clone = {@{$env->{_envcopy}}, @_};
    @{$clone->{_envcopy}} = %$clone; # Note: we never change PATH
    $clone->{_cwd} = $env->{_cwd};
    bless $clone, ref $env;
}

# Create a flattened hash representing the environment.
# It also contains a copy of the PATH, so that the path
# may be modified if it is converted back to a hash.
sub copy {
    my($env) = shift;
    (@{$env->{_envcopy}}, 'ENV' => {%{$env->{ENV}}}, @_)
}

# Resolve which environment to actually use for a given
# target. This is just used for simple overrides.
sub _resolve {
    return $_[0] if !$param::overrides;
    my($env, $tgt) = @_;
    my($path) = $tgt->path;
    my $re;
    for $re (@param::overrides) {
	next if $path !~ /$re/;
	# Found one. Return a combination of the original environment
	# and the override.
	my($ovr) = $param::overrides{$re};
	return $envcache{$env,$re} if $envcache{$env,$re};
	my($newenv) = {@{$env->{_envcopy}}, @$ovr};
	@{$newenv->{_envcopy}} = %$env;
	$newenv->{_cwd} = $env->{_cwd};
	return $envcache{$env,$re} = bless $newenv, ref $env;
    }
    return $env;
}

# Substitute construction environment variables into a string.
# Internal function/method.
sub _subst {
    my($env, $str) = @_;
    if (! defined $str) {
	return undef;
    } elsif (ref($str) eq "ARRAY") {
	return [ map($env->_subst($_), @$str) ];
    } else {
	# % expansion.  %% gets converted to % later, so expand any
	# %keyword construction that doesn't have a % in front of it,
	# modulo multiple %% pairs in between.
	# In Perl 5.005 and later, we could actually do this in one regex
	# using a conditional expression as follows,
	#	while ($str =~ s/($pre)\%(\{)?([_a-zA-Z]\w*)(?(2)\})/"$1".$env->{$3}/ge) {}
	# The following two-step approach is backwards-compatible
	# to (at least) Perl5.003.
	my $pre = '^|[^\%](?:\%\%)*';
	while (($str =~ s/($pre)\%([_a-zA-Z]\w*)/$1.($env->{$2}||'')/ge) ||
	       ($str =~ s/($pre)\%\{([_a-zA-Z]\w*)\}/$1.($env->{$2}||'')/ge)) {}
	return $str;
    }
}

sub Install {
    my($env) = shift;
    my($tgtdir) = $dir::cwd->lookupdir($env->_subst(shift));
    my $file;
    for $file (map($dir::cwd->lookupfile($env->_subst($_)), @_)) {
	my($tgt) = $tgtdir->lookupfile($file->{entry});
	$tgt->bind(find build::install, $file);
    }
}

sub InstallAs {
    my $env = shift;
    my $tgt = shift;
    my $src = shift;
    my @sources = ();
    my @targets = ();

    if (ref $tgt) {
	die "InstallAs: Source is a file and target is a list!\n"
	    if (!ref($src));
	@sources = @$src;
	@targets = @$tgt;
    } elsif (ref $src) {
	die "InstallAs: Target is a file and source is a list!\n";
    } else {
	push @sources, $src;
	push @targets, $tgt;
    }

    if ($#sources != $#targets) {
	my $tn = $#targets+1;
	my $sn = $#sources+1;
	die "InstallAs: Source file list ($sn) and target file list ($tn) " .
	    "are inconsistent in length!\n";
    } else {
	foreach (0..$#sources) {
	    my $tfile = $dir::cwd->lookupfile($env->_subst($targets[$_]));
	    my $sfile = $dir::cwd->lookupfile($env->_subst($sources[$_]));
	    $tfile->bind(find build::install, $sfile);
	}
    }
}

# Installation in a local build directory,
# copying from the repository if it's already built there.
# Functionally equivalent to:
#	Install $env $dir, $file;
#	Local "$dir/$file";
sub Install_Local {
    my($env) = shift;
    my($tgtdir) = $dir::cwd->lookupdir($env->_subst(shift));
    my $file;
    for $file (map($dir::cwd->lookupfile($env->_subst($_)), @_)) {
	my($tgt) = $tgtdir->lookupfile($file->{entry});
	$tgt->bind(find build::install, $file);
	$tgt->local(1);
    }
}

sub Objects {
    my($env) = shift;
    map($dir::cwd->relpath($_),
	_Objects($env, map($dir::cwd->lookupfile($env->_subst($_)), @_)))
}

# Called with multiple source file references (or object files).
# Returns corresponding object files references.
sub _Objects {
    my($env) = shift;
    my($suffix) = $env->{SUFOBJ};
    map(_Object($env, $_, $_->{dir}->lookupfile($_->base_suf($suffix))), @_);
}

# Called with an object and source reference.  If no object reference
# is supplied, then the object file is determined implicitly from the
# source file's extension. Sets up the appropriate rules for creating
# the object from the source.  Returns the object reference.
sub _Object {
    my($env, $src, $obj) = @_;
    return $obj if $src eq $obj; # don't need to build self from self.
    my($objenv) = $env->_resolve($obj);
    my($suffix) = $src->suffix;

    my($builder) = $env->{SUFMAP}{$suffix};

    if ($builder) {
	$obj->bind((find $builder($objenv)), $src);
    } else {
	die("don't know how to construct ${\$obj->path} from " .
	    "${\$src->path}.\n");
    }
    $obj
}

sub Program {
    my($env) = shift;
    my($tgt) = $dir::cwd->lookupfile(file::addsuffix($env->_subst(shift),
						 $env->{SUFEXE}));
    my($progenv) = $env->_resolve($tgt);
    $tgt->bind(find build::command::link($progenv, $progenv->{LINKCOM}),
	       $env->_Objects(map($dir::cwd->lookupfile($env->_subst($_)), @_)));
}

sub Module {
    my($env) = shift;
    my($tgt) = $dir::cwd->lookupfile($env->_subst(shift));
    my($modenv) = $env->_resolve($tgt);
    my($com) = pop(@_);
    $tgt->bind(find build::command::link($modenv, $com),
	       $env->_Objects(map($dir::cwd->lookupfile($env->_subst($_)), @_)));
}

sub LinkedModule {
    my($env) = shift;
    my($tgt) = $dir::cwd->lookupfile($env->_subst(shift));
    my($progenv) = $env->_resolve($tgt);
    $tgt->bind(find build::command::linkedmodule
	       ($progenv, $progenv->{LINKMODULECOM}),
	       $env->_Objects(map($dir::cwd->lookupfile($env->_subst($_)), @_)));
}

sub Library {
    my($env) = shift;
    my($lib) = $dir::cwd->lookupfile(file::addsuffix($env->_subst(shift),
						 $env->{SUFLIB}));
    my($libenv) = $env->_resolve($lib);
    $lib->bind(find build::command::library($libenv),
	       $env->_Objects(map($dir::cwd->lookupfile($env->_subst($_)), @_)));
}

# Simple derivation: you provide target, source(s), command.
# Special variables substitute into the rule.
# Target may be a reference, in which case it is taken
# to be a multiple target (all targets built at once).
sub Command {
    my($env) = shift;
    my($tgt) = $env->_subst(shift);
    my($com) = pop(@_);
    my(@sources) = map($dir::cwd->lookupfile($env->_subst($_)), @_);
    if (ref($tgt)) {
	# A multi-target command.
	my(@tgts) = map($dir::cwd->lookupfile($_), @$tgt);
	die("empty target list in multi-target command\n") if !@tgts;
	$env = $env->_resolve($tgts[0]);
	my $builder = find build::command::user($env, $com, 'script');
	my($multi) = build::multiple->new($builder, \@tgts);
	for $tgt (@tgts) {
	    $tgt->bind($multi, @sources);
	}
    } else {
	$tgt = $dir::cwd->lookupfile($tgt);
	$env = $env->_resolve($tgt);
	my $builder = find build::command::user($env, $com, 'script');
	$tgt->bind($builder, @sources);
    }
}

sub Depends {
    my($env) = shift;
    my($tgt) = $env->_subst(shift);
    my(@deps) = map($dir::cwd->lookup($env->_subst($_)), @_);
    if (! ref($tgt)) {
	$tgt = [ $tgt ];
    }
    my($t);
    foreach $t (map($dir::cwd->lookupfile($_), @$tgt)) {
	push(@{$t->{dep}}, @deps);
    }
}

# Setup a quick scanner for the specified input file, for the
# associated environment. Any use of the input file will cause the
# scanner to be invoked, once only. The scanner sees just one line at
# a time of the file, and is expected to return a list of
# dependencies.
sub QuickScan {
    my($env, $code, $file, $path) = @_;
    $dir::cwd->lookup($env->_subst($file))->{'srcscan',$env} =
	find scan::quickscan($code, $env, $env->_subst($path));
}

# Generic builder module. Just a few default methods.  Every derivable
# file must have a builder object of some sort attached.  Usually
# builder objects are shared.
package build;

# Null signature for dynamic includes.
sub includes { () }

# Null signature for build script.
sub script { () }

# Not compatible with any other builder, by default.
sub compatible { 0 }


# Builder module for the Install command.
package build::install;

use vars qw( @ISA $installer );

BEGIN {
    @ISA = qw(build);
    bless $installer = {}    # handle for this class.
}

sub find {
    $installer
}

# Caching not supported for Install: generally install is trivial anyway,
# and we don't want to clutter the cache.
sub cachin { undef }
sub cachout { }

# Do the installation.
sub action {
    my($self, $tgt) = @_;
    my($src) = $tgt->{sources}[0];
    main::showcom("Install ${\$src->rpath} as ${\$tgt->path}")
	if ($param::install && !$param::quiet);
    return unless $param::build;
    futil::install($src->rpath, $tgt);
    return 1;
}


# Builder module for generic UNIX commands.
package build::command;

use vars qw( @ISA %com );

BEGIN { @ISA = qw(build) }

sub find {
    my ($class, $env, $com, $package) = @_;
    $com = $env->_subst($com);
    $package ||= '';
    $com{$env,$com,$package} || do {
	# Remove unwanted bits from signature -- those bracketed by %( ... %)
	my $comsig = $com;
	$comsig =~ s/^\@\s*//mg;
	while ($comsig =~ s/%\(([^%]|%[^\(])*?%\)//g) { }
	my $self = { env => $env, com => $com, 'package' => $package,
		     comsig => $comsig };
	$com{$env,$com,$package} = bless $self, $class;
    }
}

# Default cache in function.
sub cachin {
    my($self, $tgt, $sig) = @_;
    if (cache::in($tgt, $sig)) {
	if ($param::cachecom) {
	    map { if (! s/^\@\s*//) { main::showcom($_) } } $self->getcoms($tgt);
	} else {
	    printf("Retrieved %s from cache\n", $tgt->path)
		unless ($param::quiet);
	}
	return 1;
    }
    return undef;
}

# Default cache out function.
sub cachout {
    my($self, $tgt, $sig) = @_;
    cache::out($tgt, $sig);
}

# internal routine to process variable options.
# f: return file part
# F: return file part, but strip any suffix
# d: return directory part
# b: return full path, but strip any suffix (a.k.a. return basename)
# s: return only the suffix (or an empty string, if no suffix is there)
# a: return the absolute path to the file
# no option: return full path to file
sub _variant {
    my($opt, $file) = @_;
    $opt = '' if ! defined $opt;
    if ($opt eq 'f') { return $file->{entry}; }
    elsif ($opt eq 'd') { return $file->{dir}->path; }
    elsif ($opt eq 'F') {
	my $subst = $file->{entry};
	$subst =~ s/\.[^\.]+$//;
	return $subst;
    }
    elsif ($opt eq 'b') {
	my $subst = $file->path;
	$subst =~ s/\.[^\.]+$//;
	return $subst;
    }
    elsif ($opt eq 's') {
	my $subst = $file->{entry};
	$subst =~ m/(\.[^\.]+)$/;
	return $1;
    }
    elsif ($opt eq 'a') {
	my $path = $file->path;
	if (! File::Spec->file_name_is_absolute($path)) {
	    $path = File::Spec->catfile(Cwd::cwd(), $path);
	}
	return $path;
    }
    else { return $file->path; }
}

# For the signature of a basic command, we don't bother
# including the command itself. This is not strictly correct,
# and if we wanted to be rigorous, we might want to insist
# that the command was checked for all the basic commands
# like gcc, etc. For this reason we don't have an includes
# method.

# Call this to get the command line script: an array of
# fully substituted commands.
sub getcoms {
    my($self, $tgt) = @_;
    my(@coms);
    my $com;
    for $com (split(/\n/, $self->{com})) {
	my(@src) = (undef, @{$tgt->{sources}});
	my(@src1) = @src;

	next if $com =~ /^\s*$/;

	# NOTE: we used to have a more elegant s//.../e solution
	# for the items below, but this caused a bus error...

	# Remove %( and %) -- those are only used to bracket parts
	# of the command that we don't depend on.
	$com =~ s/%[()]//g;

	# Deal with %n, n=1,9 and variants.
	while ($com =~ /%([1-9])(:([fdbsFa]?))?/) {
	    my($match) = $&;
	    my($src) = $src1[$1];
	    my($subst) = _variant($3, $src1[$1]->rfile);
	    undef $src[$1];
	    $com =~ s/$match/$subst/;
	}

	# Deal with %0 aka %> and variants.
	while ($com =~ /%[0>](:([fdbsFa]?))?/) {
	    my($match) = $&;
	    my($subst) = _variant($2, $tgt);
	    $com =~ s/$match/$subst/;
	}

	# Deal with %< (all sources except %n's already used)
	while ($com =~ /%<(:([fdbsFa]?))?/) {
	    my($match) = $&;
	    my @list = ();
	    foreach (@src) {
		push(@list, _variant($2, $_->rfile)) if $_;
	    }
	    my($subst) = join(' ', @list);
	    $com =~ s/$match/$subst/;
	}

	# Deal with %[ %].
	$com =~ s{%\[(.*?)%\]}{
	    my($func, @args) = grep { $_ ne '' } split(/\s+/, $1);
	    die("$0: \"$func\" is not defined.\n")
		unless ($self->{env}->{$func});
	    &{$self->{env}->{$func}}(@args);
	}gex;

	# Convert left-over %% into %.
	$com =~ s/%%/%/g;

	# White space cleanup. XXX NO WAY FOR USER TO HAVE QUOTED SPACES
	$com = join(' ', split(' ', $com));
	next if $com =~ /^:/ && $com !~ /^:\S/;
	push(@coms, $com);
    }
    @coms
}

# Build the target using the previously specified commands.
sub action {
    my($self, $tgt) = @_;
    my($env) = $self->{env};

    if ($param::build) {
	futil::mkdir($tgt->{dir});
	unlink($tgt->path) if ! $tgt->precious;
    }

    # Set environment.
    map(delete $ENV{$_}, keys %ENV);
    %ENV = %{$env->{ENV}};

    # Handle multi-line commands.
    my $com;
    for $com ($self->getcoms($tgt)) {
	if ($com !~ s/^\@\s*//) {
	    main::showcom($com);
	}
	if ($param::build) {

	  if ($com =~ /^\[perl\]\s*/) {
	    my $perlcmd = $';
	    my $status;
	    {
	      # Restore the script package variables that were defined
	      # in the Conscript file that defined this [perl] build,
	      # so the code executes with the expected variables.
	      my($package) = $self->{'package'};
	      my($pkgvars) = $tgt->{conscript}->{pkgvars};
	      NameSpace::restore($package, $pkgvars) if $pkgvars;
	      # Actually execute the [perl] command to build the target.
	      $status = eval "package $package; $perlcmd";
	      # Clean up the namespace by deleting the package variables
	      # we just restored.
	      NameSpace::remove($package, keys %$pkgvars) if $pkgvars;
	    }
	    if (!defined($status)) {
		warn "$0: *** Error during perl command eval: $@.\n";
		return undef;
	    } elsif ($status == 0) {
		warn "$0: *** Perl command returned $status (this indicates an error).\n";
		return undef;
	    }
	    next;
	  }
	  #---------------------
	  # Can't fork on Win32
	  #---------------------
	  if ($main::_WIN32) {
	    system($com);
	    if ($?) {
	      my ($b0, $b1) = ($? & 0xFF, $? >> 8);
	      my $err = $b1 || $?;
	      my $path = $tgt->path;
	      my $warn = qq($0: *** [$path] Error $err);
	      $warn .= " (executable not found in path?)" if $b1 == 0xFF;
	      warn "$warn\n";
	      return undef;
	    }
	  } else {
	    my($pid) = fork();
	    die("$0: unable to fork child process ($!)\n") if !defined $pid;
	    if (!$pid) {
	      # This is the child.  We eval the command to suppress -w
	      # warnings about not reaching the statements afterwards.
	      eval 'exec($com)';
	      $com =~ s/\s.*//;
	      die qq($0: failed to execute "$com" ($!). )
		. qq(Is this an executable on path "$ENV{PATH}"?\n);
	    }
	    for (;;) {
	      do {} until wait() == $pid;
	      my ($b0, $b1) = ($? & 0xFF, $? >> 8);
	      # Don't actually see 0177 on stopped process; is this necessary?
	      next if $b0 == 0177; # process stopped; we can wait.
	      if ($b0) {
		my($core, $sig) = ($b0 & 0200, $b0 & 0177);
		my($coremsg) = $core ? "; core dumped" : "";
		$com =~ s/\s.*//;
		my $path = $tgt->path;
		my $err = "$0: *** \[$path\] $com terminated by signal " .
			  "$sig$coremsg\n";
		warn $err;
		return undef;
	      }
	      if ($b1) {
		my($path) = $tgt->path;
		warn qq($0: *** [$path] Error $b1\n); # trying to be like make.
		return undef;
	      }
	      last;
	    }
	  }
	}
    }

    # success.
    return 1;
}

# Return script signature.
sub script {
    $_[0]->{comsig}
}


# Create a linked module.
package build::command::link;

use vars qw( @ISA );

BEGIN { @ISA = qw(build::command) }

# Find an appropriate linker.
sub find {
    my($class, $env, $command) = @_;
    if (!exists $env->{_LDIRS}) {
	my($ldirs) = '';
	my($wd) = $env->{_cwd};
	my($pdirs) = $env->{LIBPATH};
	if (! defined $pdirs) {
	    $pdirs = [ ];
	} elsif (ref($pdirs) ne 'ARRAY') {
	    $pdirs = [ split(/$main::PATH_SEPARATOR/o, $pdirs) ];
	}
	my $dir;
	for $dir (map($wd->lookupdir($env->_subst($_)), @$pdirs)) {
	    my($dpath) = $dir->path;
	    $ldirs .= " ".$env->{LIBDIRPREFIX}.$dpath;
	    next if File::Spec->file_name_is_absolute($dpath);
	    if (@param::rpath) {
		my $d;
		if ($dpath eq $dir::CURDIR) {
		    foreach $d (map($_->path, @param::rpath)) {
			$ldirs .= " ".$env->{LIBDIRPREFIX}.$d;
		    }
		} else {
		    foreach $d (map($_->path, @param::rpath)) {
			$ldirs .= " ".$env->{LIBDIRPREFIX}.File::Spec->catfile($d, $dpath);
		    }
		}
	    }
	}
	$env->{_LDIRS} = "%($ldirs%)";
    }

    # Introduce a new magic _LIBS symbol which allows to use the
    # Unix-style -lNAME syntax for Win32 only. -lNAME will be replaced
    # with %{PREFLIB}NAME%{SUFLIB}. <schwarze@isa.de> 1998-06-18

    if ($main::_WIN32 && !exists $env->{_LIBS}) {
	my $libs;
	my $name;
	for $name (split(' ', $env->_subst($env->{LIBS} || ''))) {
	    if ($name =~ /^-l(.*)/) {
		$name = "$env->{PREFLIB}$1$env->{SUFLIB}";
	    }
	    $libs .= ' ' . $name;
	}
	$env->{_LIBS} = $libs ? "%($libs%)" : '';
    }
    bless find build::command($env, $command);
}

# Called from file::build. Make sure any libraries needed by the
# environment are built, and return the collected signatures
# of the libraries in the path.
sub includes {
    return $_[0]->{sig} if exists $_[0]->{sig};
    my($self, $tgt) = @_;
    my($env) = $self->{env};
    my($ewd) = $env->{_cwd};
    my $ldirs = $env->{LIBPATH};
    if (! defined $ldirs) {
	$ldirs = [ ];
    } elsif (ref($ldirs) ne 'ARRAY') {
	$ldirs = [ split(/$main::PATH_SEPARATOR/o, $ldirs) ];
    }
    my @lpath = map($ewd->lookupdir($_), @$ldirs);
    my(@sigs);
    my(@names);

    if ($main::_WIN32) {
	# Pass %LIBS symbol through %-substituition
	# <schwarze@isa.de> 1998-06-18
	@names = split(' ', $env->_subst($env->{LIBS} || ''));
    } else {
	@names = split(' ', $env->{LIBS} || '');
    }
    my $name;
    for $name (@names) {
	my ($lpath, @allnames);
	if ($name =~ /^-l(.*)/) {
	    # -l style names are looked up on LIBPATH, using all
	    # possible lib suffixes in the same search order the
	    # linker uses (according to SUFLIBS).
	    # Recognize new PREFLIB symbol, which should be 'lib' on
	    # Unix, and empty on Win32. TODO: What about shared
	    # library suffixes?  <schwarze@isa.de> 1998-05-13
	   @allnames = map("$env->{PREFLIB}$1$_",
			   split(/:/, $env->{SUFLIBS}));
	    $lpath = \@lpath;
	} else {
	    @allnames = ($name);
	    # On Win32, all library names are looked up in LIBPATH
	    # <schwarze@isa.de> 1998-05-13
	    if ($main::_WIN32) {
		$lpath = [$dir::top, @lpath];
	    }
	    else {
		$lpath = [$dir::top];
	    }
	}
	my $dir;
	DIR: for $dir (@$lpath) {
	    my $n;
	    for $n (@allnames) {
		my($lib) = $dir->lookup_accessible($n);
		if ($lib) {
		    last DIR if $lib->ignore;
		    if ((build $lib) eq 'errors') {
			$tgt->{status} = 'errors';
			return undef;
		    }
		    push(@sigs, 'sig'->signature($lib));
		    last DIR;
		}
	    }
	}
    }
    $self->{sig} = 'sig'->collect(@sigs);
}

# Always compatible with other such builders, so the user
# can define a single program or module from multiple places.
sub compatible {
    my($self, $other) = @_;
    ref($other) eq "build::command::link";
}

# Link a program.
package build::command::linkedmodule;

use vars qw( @ISA );

BEGIN { @ISA = qw(build::command) }

# Always compatible with other such builders, so the user
# can define a single linked module from multiple places.
sub compatible {
    my($self, $other) = @_;
    ref($other) eq "build::command::linkedmodule";
}

# Builder for a C module
package build::command::cc;

use vars qw( @ISA );

BEGIN { @ISA = qw(build::command) }

sub find {
    $_[1]->{_cc} || do {
	my($class, $env) = @_;
	my($cpppath) = $env->_subst($env->{CPPPATH});
	my($cscanner) = find scan::cpp($env->{_cwd}, $cpppath);
	$env->{_IFLAGS} = "%(" . $cscanner->iflags($env) . "%)";
	my($self) = find build::command($env, $env->{CCCOM});
	$self->{scanner} = $cscanner;
	bless $env->{_cc} = $self;
    }
}

# Invoke the associated	 C scanner to get signature of included files.
sub includes {
    my($self, $tgt) = @_;
    $self->{scanner}->includes($tgt, $tgt->{sources}[0]);
}

# Builder for a C++ module
package build::command::cxx;

use vars qw( @ISA );

BEGIN { @ISA = qw(build::command) }

sub find {
    $_[1]->{_cxx} || do {
	my($class, $env) = @_;
	my($cpppath) = $env->_subst($env->{CPPPATH});
	my($cscanner) = find scan::cpp($env->{_cwd}, $cpppath);
	$env->{_IFLAGS} = "%(" . $cscanner->iflags($env) . "%)";
	my($self) = find build::command($env, $env->{CXXCOM});
	$self->{scanner} = $cscanner;
	bless $env->{_cxx} = $self;
    }
}

# Invoke the associated	 C scanner to get signature of included files.
sub includes {
    my($self, $tgt) = @_;
    $self->{scanner}->includes($tgt, $tgt->{sources}[0]);
}

# Builder for a user command (cons::Command).  We assume that a user
# command might be built and implement the appropriate dependencies on
# the command itself (actually, just on the first word of the command
# line).
package build::command::user;

use vars qw( @ISA );

BEGIN { @ISA = qw(build::command) }

# XXX Optimize this to not use ignored paths.
sub comsig {
    return $_[0]->{_comsig} if exists $_[0]->{_comsig};
    my($self, $tgt) = @_;
    my($env) = $self->{env};
    $self->{_comsig} = '';
    my $com;
  com:
    for $com (split(/[\n;]/, $self->script)) {
	# Isolate command word.
	$com =~ s/^\s*//;
	$com =~ s/\s.*//;
	next if !$com; # blank line
	my($pdirs) = $env->{ENV}->{PATH};
	if (! defined $pdirs) {
	    $pdirs = [ ];
	} elsif (ref($pdirs) ne 'ARRAY') {
	    $pdirs = [ split(/$main::PATH_SEPARATOR/o, $pdirs) ];
	}
	my $dir;
	for $dir (map($dir::top->lookupdir($_), @$pdirs)) {
	    my($prog) = $dir->lookup_accessible($com);
	    if ($prog) { # XXX Not checking execute permission.
		if ((build $prog) eq 'errors') {
		    $tgt->{status} = 'errors';
		    return undef;
		}
		next com if $prog->ignore;
		$self->{_comsig} .= 'sig'->signature($prog);
		next com;
	    }
	}
	# Not found: let shell give an error.
    }
    $self->{_comsig}
}

sub includes {
    my($self, $tgt) = @_;
    my($sig) = '';

    # Check for any quick scanners attached to source files.
    my $dep;
    for $dep (@{$tgt->{dep}}, @{$tgt->{sources}}) {
	my($scanner) = $dep->{'srcscan',$self->{env}};
	if ($scanner) {
	    $sig .= $scanner->includes($tgt, $dep);
	}
    }

    # Add the command signature.
    return &comsig . $sig;
}


# Builder for a library module (archive).
# We assume that a user command might be built and implement the
# appropriate dependencies on the command itself.
package build::command::library;

use vars qw( @ISA );

BEGIN { @ISA = qw(build::command) }

sub find {
    my($class, $env) = @_;
    bless find build::command($env, $env->{ARCOM})
}

# Always compatible with other library builders, so the user
# can define a single library from multiple places.
sub compatible {
    my($self, $other) = @_;
    ref($other) eq "build::command::library";
}

# A multi-target builder.
# This allows multiple targets to be associated with a single build
# script, without forcing all the code to be aware of multiple targets.
package build::multiple;

sub new {
    my($class, $builder, $tgts) = @_;
    bless { 'builder' => $builder, 'tgts' => $tgts };
}

sub script {
    my($self, $tgt) = @_;
    $self->{builder}->script($tgt);
}

sub includes {
    my($self, $tgt) = @_;
    $self->{builder}->includes($tgt);
}

sub compatible {
    my($self, $tgt) = @_;
    $self->{builder}->compatible($tgt);
}

sub cachin {
    my($self, $tgt, $sig) = @_;
    $self->{builder}->cachin($tgt, $sig);
}

sub cachout {
    my($self, $tgt, $sig) = @_;
    $self->{builder}->cachout($tgt, $sig);
}

sub action {
    my($self, $invoked_tgt) = @_;
    return $self->{built} if exists $self->{built};

    # Make sure all targets in the group are unlinked before building any.
    my($tgts) = $self->{tgts};
    my $tgt;
    for $tgt (@$tgts) {
	futil::mkdir($tgt->{dir});
	unlink($tgt->path) if ! $tgt->precious;
    }

    # Now do the action to build all the targets. For consistency
    # we always call the action on the first target, just so that
    # $> is deterministic.
    $self->{built} = $self->{builder}->action($tgts->[0]);

    # Now "build" all the other targets (except for the one
    # we were called with). This guarantees that the signature
    # of each target is updated appropriately. We force the
    # targets to be built even if they have been previously
    # considered and found to be OK; the only effect this
    # has is to make sure that signature files are updated
    # correctly.
    for $tgt (@$tgts) {
	if ($tgt ne $invoked_tgt) {
	    delete $tgt->{status};
	    'sig'->invalidate($tgt);
	    build $tgt;
	}
    }

    # Status of action.
    $self->{built};
}


# Generic scanning module.
package scan;

# Returns the signature of files included by the specified files on
# behalf of the associated target. Any errors in handling the included
# files are propagated to the target on whose behalf this processing
# is being done. Signatures are cached for each unique file/scanner
# pair.
sub includes {
    my($self, $tgt, @files) = @_;
    my(%files, $file);
    my($inc) = $self->{includes} || ($self->{includes} = {});
    while ($file = pop @files) {
	next if exists $files{$file};
	if ($inc->{$file}) {
	    push(@files, @{$inc->{$file}});
	    $files{$file} = 'sig'->signature($file->rfile);
	} else {
	    if ((build $file) eq 'errors') {
		$tgt->{status} = 'errors'; # tgt inherits build status
		return ();
	    }
	    $files{$file} = 'sig'->signature($file->rfile);
	    my(@includes) = $self->scan($file);
	    $inc->{$file} = \@includes;
	    push(@files, @includes);
	}
    }
    'sig'->collect(sort values %files)
}


# A simple scanner. This is used by the QuickScanfunction, to setup
# one-time target and environment-independent scanning for a source
# file. Only used for commands run by the Command method.
package scan::quickscan;

use vars qw( @ISA %scanner );

BEGIN { @ISA = qw(scan) }

sub find {
    my($class, $code, $env, $pdirs) = @_;
    if (! defined $pdirs) {
	$pdirs = [ ] ;
    } elsif (ref($pdirs) ne 'ARRAY') {
	$pdirs = [ split(/$main::PATH_SEPARATOR/o, $pdirs) ];
    }
    my(@path) = map { $dir::cwd->lookupdir($_) } @$pdirs;
    my($spath) = "@path";
    $scanner{$code,$env,$spath} || do {
	my($self) = { code => $code, env => $env, path => \@path };
	$scanner{$code,$env,$spath} = bless $self;
    }
}

# Scan the specified file for included file names.
sub scan {
    my($self, $file) = @_;
    my($code) = $self->{code};
    my(@includes);
    # File should have been built by now. If not, we'll ignore it.
    return () unless open(SCAN, $file->rpath);
    while(<SCAN>) {
	push(@includes, grep($_ ne '', &$code));
    }
    close(SCAN);
    my($wd) = $file->{dir};
    my(@files);
    my $name;
    for $name (@includes) {
	my $dir;
	for $dir ($file->{dir}, @{$self->{path}}) {
	    my($include) = $dir->lookup_accessible($name);
	    if ($include) {
		push(@files, $include) unless $include->ignore;
		last;
	    }
	}
    }
    @files
}


# CPP (C preprocessor) scanning module
package scan::cpp;

use vars qw( @ISA %scanner );

BEGIN { @ISA = qw(scan) }

# For this constructor, provide the include path argument (colon
# separated). Each path is taken relative to the provided directory.

# Note: a particular scanning object is assumed to always return the
# same result for the same input. This is why the search path is a
# parameter to the constructor for a CPP scanning object. We go to
# some pains to make sure that we return the same scanner object
# for the same path: otherwise we will unecessarily scan files.
sub find {
    my($class, $dir, $pdirs) = @_;
    if (! defined $pdirs) {
	$pdirs = [ ];
    } elsif (ref($pdirs) ne 'ARRAY') {
	$pdirs = [ split(/$main::PATH_SEPARATOR/o, $pdirs) ];
    }
    my @path = map($dir->lookupdir($_), @$pdirs);
    my($spath) = "@path";
    $scanner{$spath} || do {
	my($self) = {'path' => \@path};
	$scanner{$spath} = bless $self;
    }
}

# Scan the specified file for include lines.
sub scan {
    my($self, $file) = @_;
    my($angles, $quotes);

    if (exists $file->{angles}) {
	$angles = $file->{angles};
	$quotes = $file->{quotes};
    } else {
	my(@anglenames, @quotenames);
	return () unless open(SCAN, $file->rpath);
	while (<SCAN>) {
	    next unless /^\s*#/;
	    if (/^\s*#\s*include\s*([<"])(.*?)[>"]/) {
		if ($1 eq "<") {
		    push(@anglenames, $2);
		} else {
		    push(@quotenames, $2);
		}
	    }
	}
	close(SCAN);
	$angles = $file->{angles} = \@anglenames;
	$quotes = $file->{quotes} = \@quotenames;
    }


    my(@shortpath) = @{$self->{path}};	  # path for <> style includes
    my(@longpath) = ($file->{dir}, @shortpath); # path for "" style includes

    my(@includes);

    my $name;
    for $name (@$angles) {
	my $dir;
	for $dir (@shortpath) {
	    my($include) = $dir->lookup_accessible($name);
	    if ($include) {
		push(@includes, $include) unless $include->ignore;
		last;
	    }
	}
    }

    for $name (@$quotes) {
	my $dir;
	for $dir(@longpath) {
	    my($include) = $dir->lookup_accessible($name);
	    if ($include) {
		push(@includes, $include) unless $include->ignore;
		last;
	    }
	}
    }

    return @includes
}

# Return the include flags that would be used for a C Compile.
sub iflags {
    my($self, $env) = @_;
    my($iflags) = '';
    my($dpath);
    for $dpath (map($_->path, @{$self->{path}})) {
	$iflags .= " ".$env->{INCDIRPREFIX}.$dpath;
	next if File::Spec->file_name_is_absolute($dpath);
	if (@param::rpath) {
	    my $d;
	    if ($dpath eq $dir::CURDIR) {
		foreach $d (map($_->path, @param::rpath)) {
		    $iflags .= " ".$env->{INCDIRPREFIX}.$d;
		}
	    } else {
		foreach $d (map($_->path, @param::rpath)) {
		    $iflags .= " ".$env->{INCDIRPREFIX}.File::Spec->catfile($d, $dpath);
		}
	    }
	}
    }
    $iflags
}

package File::Spec;

use vars qw( $_SEP $_MATCH_SEP $_MATCH_VOL );

# Cons is migrating to using File::Spec for portable path name
# manipulation.  This is the right long-term direction, but there are
# some problems with making the transition:
#
#	For multi-volume support, we need to use newer interfaces
#	(splitpath, catpath, splitdir) that are only available in
#	File::Spec 0.8.
#
#	File::Spec 0.8 doesn't work with Perl 5.00[34] due to
#	regular expression incompatibilities (use of \z).
#
#	Forcing people to use a new version of a module is painful
#	because (in the workplace) their administrators aren't
#	always going to agree to install it everywhere.
#
# As a middle ground, we provide our own versions of all the File::Spec
# methods we use, supporting both UNIX and Win32.  Some of these methods
# are home brew, some are cut-and-pasted from the real File::Spec methods.
# This way, we're not reinventing the whole wheel, at least.
#
# We can (and should) get rid of this class whenever 5.00[34] and
# versions of File::Spec prior to 0.9 (?) have faded sufficiently.
# We also may need to revisit whenever someone first wants to use
# Cons on some platform other than UNIX or Win32.

BEGIN {
    if ($main::_WIN32) {
	$_SEP = '\\';
	$_MATCH_SEP = "[\Q/$_SEP\E]";
	$_MATCH_VOL = "([a-z]:)?$_MATCH_SEP";
    } else {
	$_SEP = '/';
	$_MATCH_SEP = "\Q$_SEP\E";
	$_MATCH_VOL = $_MATCH_SEP;
    }
}

sub canonpath {
    my ($self, $path) = @_;
    if ($main::_WIN32) {
	$path =~ s/^([a-z]:)/\u$1/s;
	$path =~ s|/|\\|g;
	$path =~ s|([^\\])\\+|$1\\|g;                  # xx////xx  -> xx/xx
	$path =~ s|(\\\.)+\\|\\|g;                     # xx/././xx -> xx/xx
	$path =~ s|^(\.\\)+||s unless $path eq ".\\";  # ./xx      -> xx
	$path =~ s|\\$||
		 unless $path =~ m#^([A-Z]:)?\\$#s;   # xx/       -> xx
    } else {
	$path =~ s|/+|/|g unless($^O eq 'cygwin');     # xx////xx  -> xx/xx
	$path =~ s|(/\.)+/|/|g;                        # xx/././xx -> xx/xx
	$path =~ s|^(\./)+||s unless $path eq "./";    # ./xx      -> xx
	$path =~ s|^/(\.\./)+|/|s;                     # /../../xx -> xx
	$path =~ s|/$|| unless $path eq "/";          # xx/       -> xx
    }
    return $path;
}

sub catdir {
    my $self = shift;
    my @args = @_;
    foreach (@args) {
	# append a slash to each argument unless it has one there
	$_ .= $_SEP if $_ eq '' || substr($_,-1) ne $_SEP;
    }
    return $self->canonpath(join('', @args));
}

sub catfile {
    my $self = shift;
    my $file = pop @_;
    return $file unless @_;
    my $dir = $self->catdir(@_);
    $dir .= $_SEP unless substr($dir,-1) eq $_SEP;
    $file = '' if ! defined($file);
    return $dir.$file;
}

sub catpath {
    my $path = $_[1] . $_[0]->catfile(@_[2..$#_]);
    $path =~ s/(.)$_MATCH_SEP*$/$1/;
    $path;
}

sub curdir {
    '.'
}

sub file_name_is_absolute {
    my ($self, $file) = @_;
    return scalar($file =~ m{^$_MATCH_VOL}is);
}

sub splitdir {
    my @dirs = split(/$_MATCH_SEP/, $_[1], -1);
    push(@dirs, '') if $dirs[$#dirs];
    @dirs;
}

sub splitpath {
    my ($self, $path) = @_;
    my $vol = '';
    my $sep = $_SEP;
    if ($main::_WIN32) {
	if ($path =~ s#^([A-Za-z]:|(?:\\\\|//)[^\\/]+[\\/][^\\/]+)([\\/])#$2#) {
	    $vol = $1;
	    $sep = $2;
	}
    }
    my(@path) = split(/$_MATCH_SEP/, $path, -1);
    my $file = pop @path;
    my $dirs = join($sep, @path, '');
    return ($vol, $dirs, $file);
}

sub updir {
    '..'
}

sub case_tolerant {
    return $main::_WIN32;
}

# Directory and file handling. Files/dirs are represented by objects.
# Other packages are welcome to add component-specific attributes.
package dir;

use vars qw( $SEPARATOR $MATCH_SEPARATOR $CURDIR $UPDIR
	     $cwd_vol %root $top $cwd );

BEGIN {
    # A portable way of determing our directory separator.
    $SEPARATOR = File::Spec->catdir('', '');
    # A fast-path regular expression to match a directory separator
    # anywhere in a path name.
    if ($SEPARATOR eq '/') {
	$MATCH_SEPARATOR = "\Q$SEPARATOR\E";
    } else {
	$MATCH_SEPARATOR = "[\Q/$SEPARATOR\E]";
    }
    # Cache these values so we don't have to make a method call
    # every time we need them.
    $CURDIR = File::Spec->curdir;	# '.' on UNIX
    $UPDIR = File::Spec->updir;	# '..' on UNIX
    #
    $cwd_vol = '';
}

# Annotate a node (file or directory) with info about the
# method that created it.
sub creator {
    my($self, @frame) = @_;
    $self->{'creator'} = \@frame if @frame;
    $self->{'creator'};
}

# Handle a file|dir type exception.  We only die if we find we were
# invoked by something in a Conscript/Construct file, because
# dependencies created directly by Cons' analysis shouldn't cause
# an error.
sub _type_exception {
    my($e) = @_;
    my($line, $sub);
    (undef, undef, $line, $sub) = script::caller_info;
    if (defined $line) {
	my $err = "\"${\$e->path}\" already in use as a " . ref($e) . " before $sub on line $line";
	if ($e->{'creator'}) {
	    my $script;
	    (undef, $script, $line, $sub) = @{$e->{'creator'}};
	    $err = "\t" . $err . ",\n\t\tdefined by $sub in $script, line $line";
	}
	$err .= "\n";
	die $err;
    }
}

# This wraps up all the common File::Spec logic that we use for parsing
# directory separators in a path and turning it into individual
# subdirectories that we must create, as well as creation of root
# nodes for any new file system volumes we find.  File::Spec doesn't have
# intuitively obvious interfaces, so this is heavily commented.
#
# Note:  This is NOT an object or class method;
# it's just a utility subroutine.
sub _parse_path {
    my($dir, $path) = @_;

    # Convert all slashes to the native directory separator.
    # This allows Construct files to always be written with good
    # old POSIX path names, regardless of what we're running on.
    $path = File::Spec->canonpath($path);

    # File::Spec doesn't understand the Cons convention of
    # an initial '#' for top-relative files.  Strip it.
    my($toprel) = $path =~ s/^#//;

    # Let File::Spec do the heavy lifting of parsing the path name.
    my($vol, $directories, $entry) = File::Spec->splitpath($path);
    my @dirs = File::Spec->splitdir($directories);

    # If there was a file entry on the end of the path, then the
    # last @dirs element is '' and we don't need it.  If there
    # wasn't a file entry on the end (File::Spec->splitpath() knew
    # the last component was a directory), then the last @dirs
    # element becomes the entry we want to look up.
    my($e) = pop @dirs;
    $entry = $e if $entry eq '';

    if (File::Spec->file_name_is_absolute($path)) {
	# An absolute path name.  If no volume was supplied,
	# use the volume of our current directory.
	$vol = $cwd_vol if $vol eq '';
	$vol = uc($vol) if File::Spec->case_tolerant;
	if (! defined $root{$vol}) {
	    # This is our first time looking up a path name
	    # on this volume, so create a root node for it.
	    # (On UNIX systems, $vol is always '', so '/'
	    # always maps to the $root{''} node.)
	    $root{$vol} = {path => $vol.$SEPARATOR,
			prefix => $vol.$SEPARATOR,
			srcpath => $vol.$SEPARATOR,
			'exists' => 1 };
	    $root{$vol}->{'srcdir'} = $root{$vol};
	    bless $root{$vol};
	}
	# We're at the top, so strip the blank entry from the front of
	# the @dirs array since the initial '/' it represents will now
	# be supplied by the root node we return.
	shift @dirs;
	$dir = $root{$vol};
    } elsif ($toprel) {
	$dir = $dir::top;
    }
    ($dir, \@dirs, $entry);
}

# Common subroutine for creating directory nodes.
sub _create_dirs {
    my ($dir, @dirs) = @_;
    my $e;
    foreach $e (@dirs) {
	my $d = $dir->{member}->{$e};
	if (! defined $d) {
	    bless $d = { 'entry' => $e, 'dir' => $dir, }, 'dir';
	    $d->creator(script::caller_info);
	    $d->{member}->{$dir::CURDIR} = $d;
	    $d->{member}->{$dir::UPDIR} = $dir;
	    $dir->{member}->{$e} = $d;
	} elsif (ref $d eq 'entry') {
	    bless $d, 'dir';
	    $d->{member}->{$dir::CURDIR} = $d;
	    $d->{member}->{$dir::UPDIR} = $dir;
	} elsif (ref $d eq 'file') {
	    # This clause is to supply backwards compatibility,
	    # with a warning, for anyone that's used FilePath
	    # to refer to a directory.  After people have using
	    # 1.8 have had time to adjust (sometime in version
	    # 1.9 or later), we should remove this entire clause.
	    my($script, $line, $sub);
	    (undef, $script, $line, $sub) = @{$d->{'creator'}};
	    if ($sub eq 'script::FilePath') {
		print STDERR "$0:  Warning:  $sub used to refer to a directory\n"
			. "\tat line $line of $script.  Use DirPath instead.\n";
		bless $d, 'dir';
	    } else {
		_type_exception($d);
	    }
	} elsif (ref $d ne 'dir') {
	    _type_exception($d);
	}
	$dir = $d;
    }
    $dir;
}

# Look up an entry in a directory.  This method is for when we don't
# care whether a file or directory is returned, so if the entry already
# exists, it will simply be returned.  If not, we create it as a
# generic "entry" which can be later turned into a file or directory
# by a more-specific lookup.
#
# The file entry may be specified as relative, absolute (starts with /),
# or top-relative (starts with #).
sub lookup {
    my($dir, $entry) = @_;

    if ($entry !~ m#$MATCH_SEPARATOR#o) {
	# Fast path: simple entry name in a known directory.
	if ($entry =~ s/^#//) {
	    # Top-relative names begin with #.
	    $dir = $dir::top;
	}
    } else {
	my $dirsref;
	($dir, $dirsref, $entry) = _parse_path($dir, $entry);
	$dir = _create_dirs($dir, @$dirsref) if @$dirsref;
	return if ! defined $dir;
	return $dir if $entry eq '';
    }

    my $e = $dir->{member}->{$entry};
    if (! defined $e) {
	bless $e = { 'entry' => $entry, 'dir' => $dir, }, 'entry';
	$e->creator(script::caller_info);
	$dir->{member}->{$entry} = $e;
    }

    $e;
}

# Look up a file entry in a directory.
#
# The file entry may be specified as relative, absolute (starts with /),
# or top-relative (starts with #).
sub lookupfile {
    my($dir, $entry) = @_;

    if ($entry !~ m#$MATCH_SEPARATOR#o) {
	# Fast path: simple entry name in a known directory.
	if ($entry =~ s/^#//) {
	    # Top-relative names begin with #.
	    $dir = $dir::top;
	}
    } else {
	my $dirsref;
	($dir, $dirsref, $entry) = _parse_path($dir, $entry);
	$dir = _create_dirs($dir, @$dirsref) if @$dirsref;
	return undef if $entry eq '';
    }

    my $f = $dir->{member}->{$entry};
    if (! defined $f) {
	bless $f = { 'entry' => $entry, 'dir' => $dir, }, 'file';
	$f->creator(script::caller_info);
	$dir->{member}->{$entry} = $f;
    } elsif (ref $f eq 'entry') {
	bless $f, 'file';
    } elsif (ref $f ne 'file') {
	_type_exception($f);
    }

    $f;
}

# Look up a (sub-)directory entry in a directory.
#
# The (sub-)directory entry may be specified as relative, absolute
# (starts with /), or top-relative (starts with #).
sub lookupdir {
    my($dir, $entry) = @_;

    my $dirsref;
    if ($entry !~ m#$MATCH_SEPARATOR#o) {
	# Fast path: simple entry name in a known directory.
	if ($entry =~ s/^#//) {
	    # Top-relative names begin with #.
	    $dir = $dir::top;
	}
    } else {
	($dir, $dirsref, $entry) = _parse_path($dir, $entry);
    }
    _create_dirs($dir, @$dirsref, $entry);
}

# Look up a file entry and return it if it's accessible.
sub lookup_accessible {
    my $file = $_[0]->lookupfile($_[1]);
    return ($file && $file->accessible) ? $file : undef;
}

# Return the parent directory without doing a lookupdir,
# which would create a parent if it doesn't already exist.
# A return value of undef (! $dir->up) indicates a root directory.
sub up {
    $_[0]->{member}->{$dir::UPDIR};
}

# Return whether this is an entry somewhere underneath the
# specified directory.
sub is_under {
    my $dir = $_[0];
    while ($dir) {
	return 1 if $_[1] == $dir;
	$dir = $dir->up;
    }
    return undef;
}

# Return the relative path from the calling directory ($_[1])
# to the object.  If the object is not under the directory, then
# we return it as a top-relative or absolute path name.
sub relpath {
    my ($dir, $obj) = @_;
    my @dirs;
    my $o = $obj;
    while ($o) {
	if ($dir == $o) {
	    if (@dirs < 2) {
		return $dirs[0] || '';
	    } else {
		return File::Spec->catdir(@dirs);
	    }
	}
	unshift(@dirs, $o->{entry});
	$o = $o->up;
    }
    # The object was not underneath the specified directory.
    # Use the node's cached path, which is either top-relative
    # (in which case we append '#' to the beginning) or
    # absolute.
    my $p = $obj->path;
    $p = '#' . $p if ! File::Spec->file_name_is_absolute($p);
    return $p;
}

# Return the path of the directory (file paths implemented
# separately, below).
sub path {
    $_[0]->{path} ||
	($_[0]->{path} = $_[0]->{dir}->prefix . $_[0]->{entry});
}

# Return the pathname as a prefix to be concatenated with an entry.
sub prefix {
    return $_[0]->{prefix} if exists $_[0]->{prefix};
    $_[0]->{prefix} = $_[0]->path . $SEPARATOR;
}

# Return the related source path prefix.
sub srcprefix {
    return $_[0]->{srcprefix} if exists $_[0]->{srcprefix};
    my($srcdir) = $_[0]->srcdir;
    $srcdir->{srcprefix} = $srcdir eq $_[0] ? $srcdir->prefix
					    : $srcdir->srcprefix;
}

# Return the related source directory.
sub srcdir {
    $_[0]->{'srcdir'} ||
	($_[0]->{'srcdir'} = $_[0]->{dir}->srcdir->lookupdir($_[0]->{entry}))
}

# Return if the directory is linked to a separate source directory.
sub is_linked {
    return $_[0]->{is_linked} if defined $_[0]->{is_linked};
    $_[0]->{is_linked} = $_[0]->path ne $_[0]->srcdir->path;
}

sub link {
    my(@paths) = @_;
    my($srcdir) = $dir::cwd->lookupdir(pop @paths)->srcdir;
    map($dir::cwd->lookupdir($_)->{'srcdir'} = $srcdir, @paths);

    # make a reverse lookup for the link.
    $srcdir->{links} = [] if ! $srcdir->{links};
    push @{$srcdir->{links}}, @paths;
}

use vars qw( @tail ); # TODO: Why global ????

sub linked_targets {
    my $tgt = shift;
    my @targets = ();
    my $dir;
    if (ref $tgt eq 'dir') {
	$dir = $tgt;
    } else {
	push @tail, $tgt;
	$dir = $tgt->{dir};
    }
    while ($dir) {
	if (defined $dir->{links} && @{$dir->{links}}) {
	    push(@targets, map(File::Spec->catdir($_, @tail), @{$dir->{links}}));
	    #print STDERR "Found Link: ${\$dir->path} -> @{\$dir->{links}}\n";
	}
	unshift @tail, $dir->{entry};
	$dir = $dir->up;
    }

    return map($dir::top->lookupdir($_), @targets);
}

sub accessible {
    my $path = $_[0]->path;
    my $err = "$0: you have attempted to use path \"$path\" both as a file " .
	      "and as a directory!\n";
    die $err;
}

sub init {
    my $path = Cwd::cwd();

    # We know we can get away with passing undef to lookupdir
    # as the directory because $dir is an absolute path.
    $top = lookupdir(undef, $path);
    $top->{'path'} = $top->{srcpath} = $dir::CURDIR;
    $top->{'prefix'} = '';
    $top->{'srcdir'} = $top;

    $cwd = $top;

    ($cwd_vol, undef, undef) = File::Spec->splitpath($path);
    $cwd_vol = '' if ! defined $cwd_vol;
    $cwd_vol = uc($cwd_vol) if File::Spec->case_tolerant;
}

package file;

use vars qw( @ISA $level );

BEGIN { @ISA = qw(dir); $level = 0 }

# Return the pathname of the file.
# Define this separately from dir::path because we don't want to
# cache all file pathnames (just directory pathnames).
sub path {
    $_[0]->{dir}->prefix . $_[0]->{entry}
}

# Return the related source file path.
sub srcpath {
    $_[0]->{dir}->srcprefix . $_[0]->{entry}
}

# Return if the file is (should be) linked to a separate source file.
sub is_linked {
    $_[0]->{dir}->is_linked
}

# Repository file search.  If the local file exists, that wins.
# Otherwise, return the first existing same-named file under a
# Repository directory.  If there isn't anything with the same name
# under a Repository directory, return the local file name anyway
# so that some higher layer can try to construct it.
sub rfile {
    return $_[0]->{rfile} if exists $_[0]->{rfile};
    my($self) = @_;
    my($rfile) = $self;
    if (@param::rpath) {
	my($path) = $self->path;
	if (! File::Spec->file_name_is_absolute($path) && ! -f $path) {
	    my($dir);
	    foreach $dir (@param::rpath) {
		my($t) = $dir->prefix . $path;
		if (-f $t) {
		    $rfile = $_[0]->lookupfile($t);
		    $rfile->{is_on_rpath} = 1;
		    last;
		}
	    }
	}
    }
    $self->{rfile} = $rfile;
}

# returns the "precious" status of this file.
sub precious {
    return $_[0]->{precious};
}

# "Erase" reference to a Repository file,
# making this a completely local file object
# by pointing it back to itself.
sub no_rfile {
    $_[0]->{'rfile'} = $_[0];
}

# Return a path to the first existing file under a Repository directory,
# implicitly returning the current file's path if there isn't a
# same-named file under a Repository directory.
sub rpath {
    $_[0]->{rpath} ||
	($_[0]->{rpath} = $_[0]->rfile->path)
}

# Return a path to the first linked srcpath file under a Repositoy
# directory, implicitly returning the current file's srcpath if there
# isn't a same-named file under a Repository directory.
sub rsrcpath {
    return $_[0]->{rsrcpath} if exists $_[0]->{rsrcpath};
    my($self) = @_;
    my($path) = $self->{rsrcpath} = $self->srcpath;
    if (@param::rpath && ! File::Spec->file_name_is_absolute($path) && ! -f $path) {
	my($dir);
	foreach $dir (@param::rpath) {
	    my($t) = $dir->prefix . $path;
	    if (-f $t) {
		$self->{rsrcpath} = $t;
		last;
	    }
	}
    }
    $self->{rsrcpath};
}

# Return if a same-named file source file exists.
# This handles the interaction of Link and Repository logic.
# As a side effect, it will link a source file from its Linked
# directory (preferably local, but maybe in a repository)
# into a build directory from its proper Linked directory.
sub source_exists {
    return $_[0]->{source_exists} if defined $_[0]->{source_exists};
    my($self) = @_;
    my($path) = $self->path;
    my($time) = (stat($path))[9];
    if ($self->is_linked) {
	# Linked directory, local logic.
	my($srcpath) = $self->srcpath;
	my($srctime) = (stat($srcpath))[9];
	if ($srctime) {
	    if (! $time || $srctime != $time) {
		futil::install($srcpath, $self);
	    }
	    return $self->{source_exists} = 1;
	}
	# Linked directory, repository logic.
	if (@param::rpath) {
	    if ($self != $self->rfile) {
		return $self->{source_exists} = 1;
	    }
	    my($rsrcpath) = $self->rsrcpath;
	    if ($path ne $rsrcpath) {
		my($rsrctime) = (stat($rsrcpath))[9];
		if ($rsrctime) {
		    if (! $time || $rsrctime != $time) {
			futil::install($rsrcpath, $self);
		    }
		    return $self->{source_exists} = 1;
		}
	    }
	}
	# There was no source file in any Linked directory
	# under any Repository.  If there's one in the local
	# build directory, it no longer belongs there.
	if ($time) {
	    unlink($path) || die("$0: couldn't unlink $path ($!)\n");
	}
	return $self->{source_exists} = '';
    } else {
	if ($time) {
	    return $self->{source_exists} = 1;
	}
	if (@param::rpath && $self != $self->rfile) {
	    return $self->{source_exists} = 1;
	}
	return $self->{source_exists} = '';
    }
}

# Return if a same-named derived file exists under a Repository directory.
sub derived_exists {
    $_[0]->{derived_exists} ||
	($_[0]->{derived_exists} = ($_[0] != $_[0]->rfile));
}

# Return if this file is somewhere under a Repository directory.
sub is_on_rpath {
    $_[0]->{is_on_rpath};
}

sub local {
    my($self, $arg) = @_;
    if (defined $arg) {
	$self->{'local'} = $arg;
    }
    $self->{'local'};
}

# Return the entry name of the specified file with the specified
# suffix appended.  Leave it untouched if the suffix is already there.
# Differs from the addsuffix function, below, in that this strips
# the existing suffix (if any) before appending the desired one.
sub base_suf {
    my($entry) = $_[0]->{entry};
    if ($entry !~ m/$_[1]$/) {
	$entry =~ s/\.[^\.]*$//;
	$entry .= $_[1];
    }
    $entry;
}

# Return the suffix of the file, for up to a 3 character
# suffix. Anything less returns nothing.
sub suffix {
  if (! $main::_WIN32) {
    $_[0]->{entry} =~ /\.[^\.\/]{0,3}$/;
    $&
  } else {
    my @pieces = split(/\./, $_[0]->{entry});
    my $suffix = pop(@pieces);
    return ".$suffix";
  }
}

# Called as a simple function file::addsuffix(name, suffix)
sub addsuffix {
    my($name, $suffix) = @_;

    if ($suffix && substr($name, -length($suffix)) ne $suffix) {
	return $name .= $suffix;
    }
    $name;
}

# Return true if the file is (or will be) accessible.
# That is, if we can build it, or if it is already present.
sub accessible {
    (exists $_[0]->{builder}) || ($_[0]->source_exists);
}

# Return true if the file should be ignored for the purpose
# of computing dependency information (should not be considered
# as a dependency and, further, should not be scanned for
# dependencies).
sub ignore {
    return 0 if !$param::ignore;
    return $_[0]->{ignore} if exists $_[0]->{ignore};
    $_[0]->{ignore} = $_[0]->path =~ /$param::ignore/o;
}

# Build the file, if necessary.
sub build {
    $_[0]->{status} || &file::_build;
}

sub _build {
    my($self) = @_;
    print main::DEPFILE $self->path, "\n" if $param::depfile;
    print((' ' x $level), "Checking ", $self->path, "\n") if $param::depends;
    if (!exists $self->{builder}) {
	# We don't know how to build the file. This is OK, if
	# the file is present as a source file, under either the
	# local tree or a Repository.
	if ($self->source_exists) {
	    return $self->{status} = 'handled';
	} else {
	    my($name) = $self->path;
	    print("$0: don't know how to construct \"$name\"\n");
	    exit(1) unless $param::kflag;
	    return $self->{status} = 'errors'; # xxx used to be 'unknown'
	}
    }

    # An associated build object exists, so we know how to build
    # the file. We first compute the signature of the file, based
    # on its dependendencies, then only rebuild the file if the
    # signature has changed.
    my($builder) = $self->{builder};
    $level += 2;

    my(@deps) = (@{$self->{dep}}, @{$self->{sources}});
    my($rdeps) = \@deps;

    if ($param::random) {
	# If requested, build in a random order, instead of the
	# order that the dependencies were listed.
	my(%rdeps);
	map { $rdeps{$_,'*' x int(rand 10)} = $_ } @deps;
	$rdeps = [values(%rdeps)];
    }

    $self->{status} = '';

    my $dep;
    for $dep (@$rdeps) {
	if ((build $dep) eq 'errors') {
	    # Propagate dependent errors to target.
	    # but try to build all dependents regardless of errors.
	    $self->{status} = 'errors';
	}
    }

    # If any dependents had errors, then we abort.
    if ($self->{status} eq 'errors') {
	$level -= 2;
	return 'errors';
    }

    # Compute the final signature of the file, based on
    # the static dependencies (in order), dynamic dependencies,
    # output path name, and (non-substituted) build script.
    my($sig) = 'sig'->collect(map('sig'->signature($_->rfile), @deps),
			    $builder->includes($self),
			    $builder->script);

    # May have gotten errors during computation of dynamic
    # dependency signature, above.
    $level -= 2;
    return 'errors' if $self->{status} eq 'errors';

    if (@param::rpath && $self->derived_exists) {
	# There is no local file of this name, but there is one
	# under a Repository directory.

	if ('sig'->current($self->rfile, $sig)) {
	    # The Repository copy is current (its signature matches
	    # our calculated signature).
	    if ($self->local) {
		# ...but they want a local copy, so provide it.
		main::showcom("Local copy of ${\$self->path} from " .
			      "${\$self->rpath}");
		futil::install($self->rpath, $self);
		'sig'->set($self, $sig);
	    }
	    return $self->{status} = 'handled';
	}

	# The signatures don't match, implicitly because something
	# on which we depend exists locally.  Get rid of the reference
	# to the Repository file; we'll build this (and anything that
	# depends on it) locally.
	$self->no_rfile;
    }

    # Then check for currency.
    if (! 'sig'->current($self, $sig)) {
	# We have to build/derive the file.
	print((' ' x $level), "Rebuilding ", $self->path, ": out of date.\n")
		if $param::depends;
	# First check to see if the built file is cached.
	if ($builder->cachin($self, $sig)) {
	    'sig'->set($self, $sig);
	    return $self->{status} = 'built';
	} elsif ($builder->action($self)) {
	    $builder->cachout($self, $sig);
	    'sig'->set($self, $sig);
	    return $self->{status} = 'built';
	} else {
	    die("$0: errors constructing ${\$self->path}\n")
		unless $param::kflag;
	    return $self->{status} = 'errors';
	}
    } else {
	# Push this out to the cache if we've been asked to (-C option).
	# Don't normally do this because it slows us down.
	# In a fully built system, no accesses to the cache directory
	# are required to check any files. This is a win if cache is
	# heavily shared. Enabling this option puts the directory in the
	# loop. Useful only when you wish to recreate a cache from a build.
	if ($param::cachesync) {
	    $builder->cachout($self, $sig);
	    'sig'->set($self, $sig);
	}
	return $self->{status} = 'handled';
    }
}

# Bind an action to a file, with the specified sources. No return value.
sub bind {
    my($self, $builder, @sources) = @_;
    if ($self->{builder} && !$self->{builder}->compatible($builder)) {
	# Even if not "compatible", we can still check to see if the
	# derivation is identical. It should be identical if the builder is
	# the same and the sources are the same.
	if ("$self->{builder} @{$self->{sources}}" ne "$builder @sources") {
	    $main::errors++;
	    my($_foo1, $script1, $line1, $sub1) = @{$self->creator};
	    my($_foo2, $script2, $line2, $sub2) = script::caller_info;
	    my $err = "\t${\$self->path}\n" .
		      "\tbuilt (at least) two different ways:\n" .
		      "\t\t$script1, line $line1:  $sub1\n" .
		      "\t\t$script2, line $line2:  $sub2\n";
	    die $err;
	}
	return;
    }
    if ($param::wflag) {
	my($script, $line, $sub);
	(undef, $script, $line, $sub) = script::caller_info;
	$self->{script} = '' if ! defined $self->{script};
	$self->{script} .= "; " if $self->{script};
	$self->{script} .= qq($sub in "$script", line $line);
    }
    $self->{builder} = $builder;
    push(@{$self->{sources}}, @sources);
    @{$self->{dep}} = () if ! defined $self->{dep};
    $self->{conscript} = $priv::self->{script};
}

sub is_under {
    $_[0]->{dir}->is_under($_[1]);
}

sub relpath {
    my $dirpath = $_[0]->relpath($_[1]->{dir});
    if (! $dirpath) {
	return $_[1]->{entry};
    } else {
	File::Spec->catfile($dirpath, $_[1]->{entry});
    }
}

# Generic entry (file or directory) handling.
# This is an empty subclass for nodes that haven't
# quite decided whether they're files or dirs.
# Use file methods until someone blesses them one way or the other.
package entry;

use vars qw( @ISA );

BEGIN { @ISA = qw(file) }

# File utilities
package futil;

# Install one file as another.
# Links them if possible (hard link), otherwise copies.
# Don't ask why, but the source is a path, the tgt is a file obj.
sub install {
    my($sp, $tgt) = @_;
    my($tp) = $tgt->path;
    return 1 if $tp eq $sp;
    return 1 if eval { link($sp, $tp) };
    unlink($tp);
    if (! futil::mkdir($tgt->{dir})) {
	return undef;
    }
    return 1 if eval { link($sp, $tp) };
    futil::copy($sp, $tp);
}

# Copy one file to another. Arguments are actual file names.
# Returns undef on failure. Preserves mtime and mode.
sub copy {
    my ($sp, $tp) = @_;
    my ($mode, $length, $atime, $mtime) = (stat($sp))[2,7,8,9];

    # Use Perl standard library module for file copying, which handles
    # binary copies. <schwarze@isa.de> 1998-06-18
    if (! File::Copy::copy($sp, $tp)) {
	warn qq($0: can\'t install "$sp" to "$tp" ($!)\n); #'
	return undef;
    }
    # The file has been created, so try both the chmod and utime,
    # first making sure the copy is writable (because permissions
    # affect the ability to modify file times on some operating
    # systems), and then changing permissions back if necessary.
    my $ret = 1;
    my $wmode = $mode | 0700;
    if (! chmod $wmode, $tp) {
	warn qq($0: can\'t set mode $wmode on file "$tp" ($!)\n); #'
	$ret = undef;
    }
    if (! utime $atime, $mtime, $tp) {
	warn qq($0: can\'t set modification time for file "$tp" ($!)\n); #'
	$ret = undef;
    }
    if ($mode !=  $wmode && ! chmod $mode, $tp) {
	warn qq($0: can\'t set mode $mode on file "$tp" ($!)\n); #'
	$ret = undef;
    }
    return $ret;
}

# Ensure that the specified directory exists.
# Aborts on failure.
sub mkdir {
    return 1 if $_[0]->{'exists'};
    if (! futil::mkdir($_[0]->{dir})) { # Recursively make parent.
	return undef;
    }
    my($path) = $_[0]->path;
    if (!-d $path && !mkdir($path, 0777)) {
	warn qq($0: can't create directory $path ($!).\n); #'
	return undef;
    }
    $_[0]->{'exists'} = 1;
}


# Signature package.
package sig::hash;

use vars qw( $called );

sub init {
    my($dir) = @_;
    my($consign) = $dir->prefix . ".consign";
    my($dhash) = $dir->{consign} = {};
    if (-f $consign) {
	open(CONSIGN, $consign) || die("$0: can't open $consign ($!)\n");
	while(<CONSIGN>) {
	    chop;
	    my ($file, $sig) = split(/:/,$_);
	    $dhash->{$file} = $sig;
	}
	close(CONSIGN);
    }
    $dhash
}

# Read the hash entry for a particular file.
sub in {
    my($dir) = $_[0]->{dir};
    ($dir->{consign} || init($dir))->{$_[0]->{entry}}
}

# Write the hash entry for a particular file.
sub out {
    my($file, $sig) = @_;
    my($dir) = $file->{dir};
    ($dir->{consign} || init($dir))->{$file->{entry}} = $sig;
    $sig::hash::dirty{$dir} = $dir;
}

# Flush hash entries. Called at end or via ^C interrupt.
sub END {
    return if $called++; # May be called twice.
    close(CONSIGN); # in case this came in via ^C.
    my $dir;
    for $dir (values %sig::hash::dirty) {
	my($consign) = $dir->prefix . ".consign";
	my($constemp) = $consign . ".$$";
	if (! open(CONSIGN, ">$constemp")) {
	    die("$0: can't create $constemp ($!)\n");
	}
	my($entry, $sig);
	while (($entry, $sig) = each %{$dir->{consign}}) {
	    if (! print CONSIGN "$entry:$sig\n") {
		die("$0: error writing to $constemp ($!)\n");
	    }
	}
	close(CONSIGN);
	if (! rename($constemp, $consign)) {
	    if (futil::copy($constemp, $consign)) {
		unlink($constemp);
	    } else {
		die("$0: couldn't rename or copy $constemp to $consign " .
		    "($!)\n");
	    }
	}
    }
}


# Derived file caching.
package cache;

# Find a file in the cache. Return non-null if the file is in the cache.
sub in {
    return undef unless $param::cache;
    my($file, $sig) = @_;
    # Add the path to the signature, to make it unique.
    $sig = 'sig'->collect($sig, $file->path) unless $param::mixtargets;
    my($dir) = substr($sig, 0, 1);
    my($cp) = File::Spec->catfile($param::cache, $dir, $sig);
    return -f $cp && futil::install($cp, $file);
}

# Try to flush a file to the cache, if not already there.
# If it doesn't make it out, due to an error, then that doesn't
# really matter.
sub out {
    return unless $param::cache;
    my($file, $sig) = @_;
    # Add the path to the signature, to make it unique.
    $sig = 'sig'->collect($sig, $file->path) unless $param::mixtargets;
    my($dir) = substr($sig, 0, 1);
    my($sp) = $file->path;
    my($cp) = File::Spec->catfile($param::cache, $dir, $sig);
    my($cdir) = File::Spec->catfile($param::cache, $dir);
    if (! -d $cdir) {
	mkdir($cdir, 0777) ||
	    die("$0: can't create cache directory $cdir ($!).\n");
    } elsif (-f $cp) {
	# Already cached: try to use that instead, to save space.
	# This can happen if the -cs option is used on a previously
	# uncached build, or if two builds occur simultaneously.
	my($lp) = ".$sig";
	unlink($lp);
	return if ! eval { link($cp, $lp) };
	rename($lp, $sp);
	# Unix98 says, "If the old argument and the new argument both
	# [refer] to the same existing file, the rename() function
	# returns successfully and performs no other action."  So, if
	# $lp and $sp are links (i.e., $cp and $sp are links), $lp is
	# left, and we must unlink it ourselves.  If the rename failed
	# for any reason, it is also good form to unlink the temporary
	# $lp.  Otherwise $lp no longer exists and, barring some race,
	# the unlink fails silently.
	unlink($lp);
	return;
    }

    return if eval { link($sp, $cp) };
    return if ! -f $sp; # if nothing to cache.
    if (futil::copy($sp, "$cp.new")) {
	rename("$cp.new", $cp);
    }
}


# Generic signature handling
package sig;

use vars qw( @ISA );

sub select {
    my($package, $subclass) = @_;
    @ISA = ($package . "::" . $subclass);
};


# MD5-based signature package.
package sig::md5;

use vars qw( $md5 );

BEGIN {
    my $module;
    my @md5_modules = qw(Digest::MD5 MD5);
    for (@md5_modules) {
	eval "use $_";
	if (! $@) {
	    $module = $_;
	    last;
	}
    }
    die "Cannot find any MD5 module from:  @md5_modules" if $@;

    $md5 = new $module;
}

# Invalidate a cache entry.
sub invalidate {
    delete $_[1]->{sig}
}

# Determine the current signature of an already-existing or
# non-existant file.
sub signature {
    if (defined $_[1]->{sig}) {
	return $_[1]->{sig};
    }
    my ($self, $file) = @_;
    my($path) = $file->path;
    my($time) = (stat($path))[9];
    if ($time) {
	my($sigtime) = sig::hash::in($file);
	if ($file->is_on_rpath) {
	    if ($sigtime) {
		my ($htime, $hsig) = split(' ',$sigtime);
		if (! $hsig) {
		    # There was no separate $htime recorded in
		    # the .consign file, which implies that this
		    # is a source file in the repository.
		    # (Source file .consign entries don't record
		    # $htime.)  Just return the signature that
		    # someone else conveniently calculated for us.
		    return $htime;	# actually the signature
		} else {
		    if (! $param::rep_sig_times_ok || $htime == $time) {
			return $file->{sig} = $hsig;
		    }
		}
	    }
	    return $file->{sig} = $file->path . $time;
	}
	if ($sigtime) {
	    my ($htime, $hsig) = split(' ',$sigtime);
	    if ($htime eq $time) {
		return $file->{sig} = $hsig;
	    }
	}
	if (! File::Spec->file_name_is_absolute($path)) {
	    # A file in the local build directory. Assume we can write
	    # a signature file for it, and compute the actual source
	    # signature. We compute the file based on the build path,
	    # not source path, only because there might be parallel
	    # builds going on... In principle, we could use the source
	    # path and only compute this once.
	    my($sig) = srcsig($path);
	    sig::hash::out($file, $sig);
	    return $file->{sig} = $sig;
	} else {
	    return $file->{sig} = $file->{entry} . $time;
	}
    }
    $file->{sig} = '';
}

# Is the provided signature equal to the signature of the current
# instantiation of the target (and does the target exist)?
sub current {
    my($self, $file, $sig) = @_;
    # Uncomment this to debug checks for signature currency.
    # <knight@baldmt.com> 1998-10-29
    # my $fsig = $self->signature($file);
    # print STDOUT "\$self->signature(${\$file->path})
    #    '$fsig' eq \$sig '$sig'\n";
    # return $fsig eq $sig;
    $self->signature($file) eq $sig;
}

# Store the signature for a file.
sub set {
    my($self, $file, $sig) = @_;
    my($time) = (stat($file->path))[9];
    sig::hash::out($file, "$time $sig");
    $file->{sig} = $sig
}

# Return an aggregate signature
sub collect {
    my($self, @sigs) = @_;
    # The following sequence is faster than calling the hex interface.
    $md5->reset();
    $md5->add(join('', $param::salt, @sigs));

    # Uncomment this to debug dependency signatures.
    # <schwarze@isa.de> 1998-05-08
    # my $buf = join(', ', $param::salt, @sigs);
    # print STDOUT "sigbuf=|$buf|\n";
    # Uncomment this to print the result of dependency signature calculation.
    # <knight@baldmt.com> 1998-10-13
    # $buf = unpack("H*", $md5->digest());
    # print STDOUT "\t=>|$buf|\n";
    # return $buf;

    unpack("H*", $md5->digest());
}

# Directly compute a file signature as the MD5 checksum of the
# bytes in the file.
sub srcsig {
    my($path) = @_;
    $md5->reset();
    open(FILE, $path) || return '';
    binmode(FILE);
    $md5->addfile(\*FILE);
    close(FILE);
    # Uncomment this to print the result of file signature calculation.
    # <knight@baldmt.com> 1998-10-13
    # my $buf = unpack("H*", $md5->digest());
    # print STDOUT "$path=|$buf|\n";
    # return $buf;
    unpack("H*", $md5->digest());
}

__END__;

=head1 NAME

Cons - A Software Construction System

=head1 DESCRIPTION

A guide and reference for version 2.2.0

Copyright (c) 1996-2000 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.

=head1 Introduction

B<Cons> is a system for constructing, primarily, software, but is quite
different from previous software construction systems. Cons was designed
from the ground up to deal easily with the construction of software spread
over multiple source directories. Cons makes it easy to create build scripts
that are simple, understandable and maintainable. Cons ensures that complex
software is easily and accurately reproducible.

Cons uses a number of techniques to accomplish all of this. Construction
scripts are just Perl scripts, making them both easy to comprehend and very
flexible. Global scoping of variables is replaced with an import/export
mechanism for sharing information between scripts, significantly improving
the readability and maintainability of each script. B<Construction
environments> are introduced: these are Perl objects that capture the
information required for controlling the build process. Multiple
environments are used when different semantics are required for generating
products in the build tree. Cons implements automatic dependency analysis
and uses this to globally sequence the entire build. Variant builds are
easily produced from a single source tree. Intelligent build subsetting is
possible, when working on localized changes. Overrides can be setup to
easily override build instructions without modifying any scripts. MD5
cryptographic B<signatures> are associated with derived files, and are used
to accurately determine whether a given file needs to be rebuilt.

While offering all of the above, and more, Cons remains simple and easy to
use. This will, hopefully, become clear as you read the remainder of this
document.


=head1 Why Cons? Why not Make?

Cons is a B<make> replacement. In the following paragraphs, we look at a few
of the undesirable characteristics of make--and typical build environments
based on make--that motivated the development of Cons.

=head2 Build complexity

Traditional make-based systems of any size tend to become quite complex. The
original make utility and its derivatives have contributed to this tendency
in a number of ways. Make is not good at dealing with systems that are
spread over multiple directories. Various work-arounds are used to overcome
this difficulty; the usual choice is for make to invoke itself recursively
for each sub-directory of a build. This leads to complicated code, in which
it is often unclear how a variable is set, or what effect the setting of a
variable will have on the build as a whole. The make scripting language has
gradually been extended to provide more possibilities, but these have
largely served to clutter an already overextended language. Often, builds
are done in multiple passes in order to provide appropriate products from
one directory to another directory. This represents a further increase in
build complexity.


=head2 Build reproducibility

The bane of all makes has always been the correct handling of
dependencies. Most often, an attempt is made to do a reasonable job of
dependencies within a single directory, but no serious attempt is made to do
the job between directories. Even when dependencies are working correctly,
make's reliance on a simple time stamp comparison to determine whether a
file is out of date with respect to its dependents is not, in general,
adequate for determining when a file should be rederived. If an external
library, for example, is rebuilt and then ``snapped'' into place, the
timestamps on its newly created files may well be earlier than the last
local build, since it was built before it became visible.


=head2 Variant builds

Make provides only limited facilities for handling variant builds. With the
proliferation of hardware platforms and the need for debuggable
vs. optimized code, the ability to easily create these variants is
essential. More importantly, if variants are created, it is important to
either be able to separate the variants or to be able to reproduce the
original or variant at will. With make it is very difficult to separate the
builds into multiple build directories, separate from the source. And if
this technique isn't used, it's also virtually impossible to guarantee at
any given time which variant is present in the tree, without resorting to a
complete rebuild.


=head2 Repositories

Make provides only limited support for building software from code that
exists in a central repository directory structure.  The VPATH feature of
GNU make (and some other make implementations) is intended to provide this,
but doesn't work as expected: it changes the path of target file to the
VPATH name too early in its analysis, and therefore searches for all
dependencies in the VPATH directory.  To ensure correct development builds,
it is important to be able to create a file in a local build directory and
have any files in a code repository (a VPATH directory, in make terms) that
depend on the local file get rebuilt properly.  This isn't possible with
VPATH, without coding a lot of complex repository knowledge directly into
the makefiles.


=head1 Keeping it simple

A few of the difficulties with make have been cited above. In this and
subsequent sections, we shall introduce Cons and show how these issues are
addressed.

=head2 Perl scripts

Cons is Perl-based. That is, Cons scripts--F<Conscript> and F<Construct>
files, the equivalent to F<Makefile> or F<makefile>--are all written in
Perl. This provides an immediate benefit: the language for writing scripts
is a familiar one. Even if you don't happen to be a Perl programmer, it
helps to know that Perl is basically just a simple declarative language,
with a well-defined flow of control, and familiar semantics. It has
variables that behave basically the way you would expect them to,
subroutines, flow of control, and so on. There is no special syntax
introduced for Cons. The use of Perl as a scripting language simplifies
the task of expressing the appropriate solution to the often complex
requirements of a build.


=head2 Hello, World!

To ground the following discussion, here's how you could build the B<Hello,
World!> C application with Cons:



  $env = new cons();
  Program $env 'hello', 'hello.c';

If you install this script in a directory, naming the script F<Construct>,
and create the F<hello.c> source file in the same directory, then you can
type C<cons hello> to build the application:



  % cons hello
  cc -c hello.c -o hello.o
  cc -o hello hello.o


=head2 Construction environments

A key simplification of Cons is the idea of a B<construction environment>. A
construction environment is an B<object> characterized by a set of key/value
pairs and a set of B<methods. >In order to tell Cons how to build something,
you invoke the appropriate method via an appropriate construction
environment. Consider the following example:



  $env = new cons(
	CC	=>	'gcc',
	LIBS	=>	'libworld.a'
  );

  Program $env 'hello', 'hello.c';

In this case, rather than using the default construction environment, as is,
we have overridden the value of C<CC> so that the GNU C Compiler equivalent
is used, instead. Since this version of B<Hello, World!> requires a library,
F<libworld.a>, we have specified that any program linked in this environment
should be linked with that library. If the library exists already, well and
good, but if not, then we'll also have to include the statement:



  Library $env 'libworld', 'world.c';

Now if you type C<cons hello>, the library will be built before the program
is linked, and, of course, C<gcc> will be used to compile both modules:



  % cons hello
  gcc -c hello.c -o hello.o
  gcc -c world.c -o world.o
  ar r libworld.a world.o
  ar: creating libworld.a
  ranlib libworld.a
  gcc -o hello hello.o libworld.a


=head2 Automatic and complete dependency analysis

With Cons, dependencies are handled automatically. Continuing the previous
example, note that when we modify F<world.c>, F<world.o> is recompiled,
F<libworld.a> recreated, and F<hello> relinked:



  % vi world.c
    [EDIT]
  % cons hello
  gcc -c world.c -o world.o
  ar r libworld.a world.o
  ar: creating libworld.a
  ranlib libworld.a
  gcc -o hello hello.o libworld.a

This is a relatively simple example: Cons ``knows'' F<world.o> depends upon
F<world.c>, because the dependency is explicitly set up by the C<Library>
method. It also knows that F<libworld.a> depends upon F<world.o> and that
F<hello> depends upon F<libworld.a>, all for similar reasons.

Now it turns out that F<hello.c> also includes the interface definition
file, F<world.h>:



  % emacs world.h
    [EDIT]
  % cons hello
  gcc -c hello.c -o hello.o
  gcc -o hello hello.o libworld.a

How does Cons know that F<hello.c> includes F<world.h>, and that F<hello.o>
must therefore be recompiled? For now, suffice it to say that when
considering whether or not F<hello.o> is up-to-date, Cons invokes a scanner
for its dependency, F<hello.c>. This scanner enumerates the files included
by F<hello.c> to come up with a list of further dependencies, beyond those
made explicit by the Cons script. This process is recursive: any files
included by included files will also be scanned.

Isn't this expensive? The answer is--it depends. If you do a full build of a
large system, the scanning time is insignificant. If you do a rebuild of a
large system, then Cons will spend a fair amount of time thinking about it
before it decides that nothing has to be done (although not necessarily more
time than make!). The good news is that Cons makes it very easy to
intelligently subset your build, when you are working on localized changes.


=head2 Automatic global build sequencing

Because Cons does full and accurate dependency analysis, and does this
globally, for the entire build, Cons is able to use this information to take
full control of the B<sequencing> of the build. This sequencing is evident
in the above examples, and is equivalent to what you would expect for make,
given a full set of dependencies. With Cons, this extends trivially to
larger, multi-directory builds. As a result, all of the complexity involved
in making sure that a build is organized correctly--including multi-pass
hierarchical builds--is eliminated. We'll discuss this further in the next
sections.

=head1 Building large trees--still just as simple


=head2 A hierarchy of build scripts

A larger build, in Cons, is organized by creating a hierarchy of B<build
scripts>. At the top of the tree is a script called F<Construct>. The rest
of the scripts, by convention, are each called F<Conscript>. These scripts
are connected together, very simply, by the C<Build>, C<Export>, and
C<Import> commands.


=head2 The Build command

The C<Build> command takes a list of F<Conscript> file names, and arranges
for them to be included in the build. For example:

  Build qw(
	drivers/display/Conscript
	drivers/mouse/Conscript
	parser/Conscript
	utilities/Conscript
  );

This is a simple two-level hierarchy of build scripts: all the subsidiary
F<Conscript> files are mentioned in the top-level F<Construct> file. Notice
that not all directories in the tree necessarily have build scripts
associated with them.

This could also be written as a multi-level script. For example, the
F<Construct> file might contain this command:

  Build qw(
	parser/Conscript
	drivers/Conscript
	utilities/Conscript
  );

and the F<Conscript> file in the F<drivers> directory might contain this:

  Build qw(
	display/Conscript
	mouse/Conscript
  );

Experience has shown that the former model is a little easier to understand,
since the whole construction tree is laid out in front of you, at the
top-level. Hybrid schemes are also possible. A separately maintained
component that needs to be incorporated into a build tree, for example,
might hook into the build tree in one place, but define its own construction
hierarchy.

By default, Cons does not change its working directory to the directory
containing a subsidiary F<Conscript> file it is including.  This behavior
can be enabled for a build by specifying, in the top-level F<Construct>
file:

  Conscript_chdir 1;

When enabled, Cons will change to the subsidiary F<Conscript> file's
containing directory while reading in that file, and then change back
to the top-level directory once the file has been processed.

It is expected that this behavior will become the default in some future
version of Cons.  To prepare for this transition, builds that expect
Cons to remain at the top of the build while it reads in a subsidiary
F<Conscript> file should explicitly disable this feature as follows:

  Conscript_chdir 0;


=head2 Relative, top-relative, and absolute file names

You may have noticed that the file names specified to the Build command are
relative to the location of the script it is invoked from. This is generally
true for other filename arguments to other commands, too, although we might
as well mention here that if you begin a file name with a hash mark, ``#'',
then that file is interpreted relative to the top-level directory (where the
F<Construct> file resides). And, not surprisingly, if you begin it with ``/'',
then it is considered to be an absolute pathname. This is true even on
systems which use a back slash rather than a forward slash to name absolute
paths.


=head2 Using modules in build scripts

You may pull modules into each F<Conscript> file using the normal Perl
C<use> or C<require> statements:

  use English;
  require My::Module;

Each C<use> or C<require> only affects the one F<Conscript> file in which
it appears.  To use a module in multiple F<Conscript> files, you must
put a C<use> or C<require> statement in each one that needs the module.


=head2 Scope of variables

The top-level F<Construct> file and all F<Conscript> files begin life in
a common, separate Perl package.  B<Cons> controls the symbol table for
the package so that, the symbol table for each script is empty, except
for the F<Construct> file, which gets some of the command line arguments.
All of the variables that are set or used, therefore, are set by the
script itself--not by some external script.

Variables can be explicitly B<imported> by a script from its parent
script. To import a variable, it must have been B<exported> by the parent
and initialized (otherwise an error will occur).


=head2 The Export command

The C<Export> command is used as in the following example:

  $env = new cons();
  $INCLUDE = "#export/include";
  $LIB = "#export/lib";
  Export qw( env INCLUDE LIB );
  Build qw( util/Conscript );

The values of the simple variables mentioned in the C<Export> list will be
squirreled away by any subsequent C<Build> commands. The C<Export> command
will only export Perl B<scalar> variables, that is, variables whose name
begins with C<$>. Other variables, objects, etc. can be exported by
reference--but all scripts will refer to the same object, and this object
should be considered to be read-only by the subsidiary scripts and by the
original exporting script. It's acceptable, however, to assign a new value
to the exported scalar variable--that won't change the underlying variable
referenced. This sequence, for example, is OK:

  $env = new cons();
  Export qw( env INCLUDE LIB );
  Build qw( util/Conscript );
  $env = new cons(CFLAGS => '-O');
  Build qw( other/Conscript );

It doesn't matter whether the variable is set before or after the C<Export>
command. The important thing is the value of the variable at the time the
C<Build> command is executed. This is what gets squirreled away. Any
subsequent C<Export> commands, by the way, invalidate the first: you must
mention all the variables you wish to export on each C<Export> command.


=head2 The Import command

Variables exported by the C<Export> command can be imported into subsidiary
scripts by the C<Import> command. The subsidiary script always imports
variables directly from the superior script. Consider this example:

  Import qw( env INCLUDE );

This is only legal if the parent script exported both C<$env> and
C<$INCLUDE>. It also must have given each of these variables values. It is
OK for the subsidiary script to only import a subset of the exported
variables (in this example, C<$LIB>, which was exported by the previous
example, is not imported).

All the imported variables are automatically re-exported, so the sequence:

  Import qw ( env INCLUDE );
  Build qw ( beneath-me/Conscript );

will supply both C<$env> and C<$INCLUDE> to the subsidiary file. If only
C<$env> is to be exported, then the following will suffice:

  Import qw ( env INCLUDE );
  Export qw ( env );
  Build qw ( beneath-me/Conscript );

Needless to say, the variables may be modified locally before invoking
C<Build> on the subsidiary script.


=head2 Build script evaluation order

The only constraint on the ordering of build scripts is that superior
scripts are evaluated before their inferior scripts. The top-level
F<Construct> file, for instance, is evaluated first, followed by any
inferior scripts. This is all you really need to know about the evaluation
order, since order is generally irrelevant. Consider the following C<Build>
command:

  Build qw(
	drivers/display/Conscript
	drivers/mouse/Conscript
	parser/Conscript
	utilities/Conscript
  );

We've chosen to put the script names in alphabetical order, simply because
that's the most convenient for maintenance purposes. Changing the order will
make no difference to the build.


=head1 A Model for sharing files


=head2 Some simple conventions

In any complex software system, a method for sharing build products needs to
be established. We propose a simple set of conventions which are trivial to
implement with Cons, but very effective.

The basic rule is to require that all build products which need to be shared
between directories are shared via an intermediate directory. We have
typically called this F<export>, and, in a C environment, provided
conventional sub-directories of this directory, such as F<include>, F<lib>,
F<bin>, etc.

These directories are defined by the top-level F<Construct> file. A simple
F<Construct> file for a B<Hello, World!> application, organized using
multiple directories, might look like this:

  # Construct file for Hello, World!

  # Where to put all our shared products.
  $EXPORT = '#export';

  Export qw( CONS INCLUDE LIB BIN );

  # Standard directories for sharing products.
  $INCLUDE = "$EXPORT/include";
  $LIB = "$EXPORT/lib";
  $BIN = "$EXPORT/bin";

  # A standard construction environment.
  $CONS = new cons (
	CPPPATH => $INCLUDE,	# Include path for C Compilations
	LIBPATH => $LIB,	# Library path for linking programs
	LIBS => '-lworld',	# List of standard libraries
  );

  Build qw(
	hello/Conscript
	world/Conscript
  );

The F<world> directory's F<Conscript> file looks like this:

  # Conscript file for directory world
  Import qw( CONS INCLUDE LIB );

  # Install the products of this directory
  Install $CONS $LIB, 'libworld.a';
  Install $CONS $INCLUDE, 'world.h';

  # Internal products
  Library $CONS 'libworld.a', 'world.c';

and the F<hello> directory's F<Conscript> file looks like this:

  # Conscript file for directory hello
  Import qw( CONS BIN );

  # Exported products
  Install $CONS $BIN, 'hello';

  # Internal products
  Program $CONS 'hello', 'hello.c';

To construct a B<Hello, World!> program with this directory structure, go to
the top-level directory, and invoke C<cons> with the appropriate
arguments. In the following example, we tell Cons to build the directory
F<export>. To build a directory, Cons recursively builds all known products
within that directory (only if they need rebuilding, of course). If any of
those products depend upon other products in other directories, then those
will be built, too.

  % cons export
  Install world/world.h as export/include/world.h
  cc -Iexport/include -c hello/hello.c -o hello/hello.o
  cc -Iexport/include -c world/world.c -o world/world.o
  ar r world/libworld.a world/world.o
  ar: creating world/libworld.a
  ranlib world/libworld.a
  Install world/libworld.a as export/lib/libworld.a
  cc -o hello/hello hello/hello.o -Lexport/lib -lworld
  Install hello/hello as export/bin/hello


=head2 Clean, understandable, location-independent scripts

You'll note that the two F<Conscript> files are very clean and
to-the-point. They simply specify products of the directory and how to build
those products. The build instructions are minimal: they specify which
construction environment to use, the name of the product, and the name of
the inputs. Note also that the scripts are location-independent: if you wish
to reorganize your source tree, you are free to do so: you only have to
change the F<Construct> file (in this example), to specify the new locations
of the F<Conscript> files. The use of an export tree makes this goal easy.

Note, too, how Cons takes care of little details for you. All the F<export>
directories, for example, were made automatically. And the installed files
were really hard-linked into the respective export directories, to save
space and time. This attention to detail saves considerable work, and makes
it even easier to produce simple, maintainable scripts.


=head1 Separating source and build trees

It's often desirable to keep any derived files from the build completely
separate from the source files. This makes it much easier to keep track of
just what is a source file, and also makes it simpler to handle B<variant>
builds, especially if you want the variant builds to co-exist.


=head2 Separating build and source directories using the Link command

Cons provides a simple mechanism that handles all of these requirements. The
C<Link> command is invoked as in this example:

  Link 'build' => 'src';

The specified directories are ``linked'' to the specified source
directory. Let's suppose that you setup a source directory, F<src>, with the
sub-directories F<world> and F<hello> below it, as in the previous
example. You could then substitute for the original build lines the
following:

  Build qw(
	build/world/Conscript
	build/hello/Conscript
  );

Notice that you treat the F<Conscript> file as if it existed in the build
directory. Now if you type the same command as before, you will get the
following results:

  % cons export
  Install build/world/world.h as export/include/world.h
  cc -Iexport/include -c build/hello/hello.c -o build/hello/hello.o
  cc -Iexport/include -c build/world/world.c -o build/world/world.o
  ar r build/world/libworld.a build/world/world.o
  ar: creating build/world/libworld.a
  ranlib build/world/libworld.a
  Install build/world/libworld.a as export/lib/libworld.a
  cc -o build/hello/hello build/hello/hello.o -Lexport/lib -lworld
  Install build/hello/hello as export/bin/hello

Again, Cons has taken care of the details for you. In particular, you will
notice that all the builds are done using source files and object files from
the build directory. For example, F<build/world/world.o> is compiled from
F<build/world/world.c>, and F<export/include/world.h> is installed from
F<build/world/world.h>. This is accomplished on most systems by the simple
expedient of ``hard'' linking the required files from each source directory
into the appropriate build directory.

The links are maintained correctly by Cons, no matter what you do to the
source directory. If you modify a source file, your editor may do this ``in
place'' or it may rename it first and create a new file. In the latter case,
any hard link will be lost. Cons will detect this condition the next time
the source file is needed, and will relink it appropriately.

You'll also notice, by the way, that B<no> changes were required to the
underlying F<Conscript> files. And we can go further, as we shall see in the
next section.


=head1 Variant builds


=head2 Hello, World! for baNaNa and peAcH OS's

Variant builds require just another simple extension. Let's take as an
example a requirement to allow builds for both the baNaNa and peAcH
operating systems. In this case, we are using a distributed file system,
such as NFS to access the particular system, and only one or the other of
the systems has to be compiled for any given invocation of C<cons>. Here's
one way we could set up the F<Construct> file for our B<Hello, World!>
application:

  # Construct file for Hello, World!

  die qq(OS must be specified) unless $OS = $ARG{OS};
  die qq(OS must be "peach" or "banana")
	if $OS ne "peach" && $OS ne "banana";

  # Where to put all our shared products.
  $EXPORT = "#export/$OS";

  Export qw( CONS INCLUDE LIB BIN );

  # Standard directories for sharing products.
  $INCLUDE = "$EXPORT/include";
  $LIB = "$EXPORT/lib";
  $BIN = "$EXPORT/bin";

  # A standard construction environment.
  $CONS = new cons (
	CPPPATH => $INCLUDE,	# Include path for C Compilations
	LIBPATH => $LIB,	# Library path for linking programs
	LIBS => '-lworld',	# List of standard libraries
  );

  # $BUILD is where we will derive everything.
  $BUILD = "#build/$OS";

  # Tell cons where the source files for $BUILD are.
  Link $BUILD => 'src';

  Build (
	"$BUILD/hello/Conscript",
	"$BUILD/world/Conscript",
  );

Now if we login to a peAcH system, we can build our B<Hello, World!>
application for that platform:

  % cons export OS=peach
  Install build/peach/world/world.h as export/peach/include/world.h
  cc -Iexport/peach/include -c build/peach/hello/hello.c -o build/peach/hello/hello.o
  cc -Iexport/peach/include -c build/peach/world/world.c -o build/peach/world/world.o
  ar r build/peach/world/libworld.a build/peach/world/world.o
  ar: creating build/peach/world/libworld.a
  ranlib build/peach/world/libworld.a
  Install build/peach/world/libworld.a as export/peach/lib/libworld.a
  cc -o build/peach/hello/hello build/peach/hello/hello.o -Lexport/peach/lib -lworld
  Install build/peach/hello/hello as export/peach/bin/hello


=head2 Variations on a theme

Other variations of this model are possible. For example, you might decide
that you want to separate out your include files into platform dependent and
platform independent files. In this case, you'd have to define an
alternative to C<$INCLUDE> for platform-dependent files. Most F<Conscript>
files, generating purely platform-independent include files, would not have
to change.

You might also want to be able to compile your whole system with debugging
or profiling, for example, enabled. You could do this with appropriate
command line options, such as C<DEBUG=on>. This would then be translated
into the appropriate platform-specific requirements to enable debugging
(this might include turning off optimization, for example). You could
optionally vary the name space for these different types of systems, but, as
we'll see in the next section, it's not B<essential> to do this, since Cons
is pretty smart about rebuilding things when you change options.


=head1 Signatures


=head2 MD5 cryptographic signatures

Whenever Cons creates a derived file, it stores a B<signature> for that
file. The signature is stored in a separate file, one per directory. After
the previous example was compiled, the F<.consign> file in the
F<build/peach/world> directory looked like this:

  world.o:834179303 23844c0b102ecdc0b4548d1cd1cbd8c6
  libworld.a:834179304 9bf6587fa06ec49d864811a105222c00

The first number is a timestamp--for a UNIX systems, this is typically the
number of seconds since January 1st, 1970. The second value is an MD5
checksum. The B<Message Digest Algorithm> is an algorithm that, given an
input string, computes a strong cryptographic signature for that string. The
MD5 checksum stored in the F<.consign> file is, in effect, a digest of all
the dependency information for the specified file. So, for example, for the
F<world.o> file, this includes at least the F<world.c> file, and also any
header files that Cons knows about that are included, directly or indirectly
by F<world.c>. Not only that, but the actual command line that was used to
generate F<world.o> is also fed into the computation of the
signature. Similarly, F<libworld.a> gets a signature which ``includes'' all
the signatures of its constituents (and hence, transitively, the signatures
of B<their> constituents), as well as the command line that created the
file.

The signature of a non-derived file is computed, by default, by taking the
current modification time of the file and the file's entry name (unless
there happens to be a current F<.consign> entry for that file, in which case
that signature is used).

Notice that there is no need for a derived file to depend upon any
particular F<Construct> or F<Conscript> file--if changes to these files
affect the file in question, then this will be automatically reflected in
its signature, since relevant parts of the command line are included in the
signature. Unrelated changes will have no effect.

When Cons considers whether to derive a particular file, then, it first
computes the expected signature of the file. It then compares the file's
last modification time with the time recorded in the F<.consign> entry, if
one exists. If these times match, then the signature stored in the
F<.consign> file is considered to be accurate. If the file's previous
signature does not match the new, expected signature, then the file must be
rederived.

Notice that a file will be rederived whenever anything about a dependent
file changes. In particular, notice that B<any> change to the modification
time of a dependent (forward or backwards in time) will force recompilation
of the derived file.

The use of these signatures is an extremely simple, efficient, and effective
method of improving--dramatically--the reproducibility of a system.

We'll demonstrate this with a simple example:

  # Simple "Hello, World!" Construct file
  $CFLAGS = '-g' if $ARG{DEBUG} eq 'on';
  $CONS = new cons(CFLAGS => $CFLAGS);
  Program $CONS 'hello', 'hello.c';

Notice how Cons recompiles at the appropriate times:

  % cons hello
  cc -c hello.c -o hello.o
  cc -o hello hello.o
  % cons hello
  cons: "hello" is up-to-date.
  % cons DEBUG=on hello
  cc -g -c hello.c -o hello.o
  cc -o hello hello.o
  % cons DEBUG=on hello
  cons: "hello" is up-to-date.
  % cons hello
  cc -c hello.c -o hello.o
  cc -o hello hello.o


=head1 Code Repositories

Many software development organizations will have one or more central
repository directory trees containing the current source code for one or
more projects, as well as the derived object files, libraries, and
executables.  In order to reduce unnecessary recompilation, it is useful to
use files from the repository to build development software--assuming, of
course, that no newer dependency file exists in the local build tree.


=head2 Repository

Cons provides a mechanism to specify a list of code repositories that will
be searched, in-order, for source files and derived files not found in the
local build directory tree.

The following lines in a F<Construct> file will instruct Cons to look first
under the F</usr/experiment/repository> directory and then under the
F</usr/product/repository> directory:

  Repository qw (
	/usr/experiment/repository
	/usr/product/repository
  );

The repository directories specified may contain source files, derived files
(objects, libraries and executables), or both.  If there is no local file
(source or derived) under the directory in which Cons is executed, then the
first copy of a same-named file found under a repository directory will be
used to build any local derived files.

Cons maintains one global list of repositories directories.  Cons will
eliminate the current directory, and any non-existent directories, from the
list.


=head2 Finding the Construct file in a Repository

Cons will also search for F<Construct> and F<Conscript> files in the
repository tree or trees.  This leads to a chicken-and-egg situation,
though: how do you look in a repository tree for a F<Construct> file if the
F<Construct> file tells you where the repository is?  To get around this,
repositories may be specified via C<-R> options on the command line:

  % cons -R /usr/experiment/repository -R /usr/product/repository .

Any repository directories specified in the F<Construct> or F<Conscript>
files will be appended to the repository directories specified by
command-line C<-R> options.

=head2 Repository source files

If the source code (include the F<Conscript> file) for the library version
of the I<Hello, World!> C application is in a repository (with no derived
files), Cons will use the repository source files to create the local object
files and executable file:

  % cons -R /usr/src_only/repository hello
  gcc -c /usr/src_only/repository/hello.c -o hello.o
  gcc -c /usr/src_only/repository/world.c -o world.o
  ar r libworld.a world.o
  ar: creating libworld.a
  ranlib libworld.a
  gcc -o hello hello.o libworld.a

Creating a local source file will cause Cons to rebuild the appropriate
derived file or files:

  % pico world.c
    [EDIT]
  % cons -R /usr/src_only/repository hello
  gcc -c world.c -o world.o
  ar r libworld.a world.o
  ar: creating libworld.a
  ranlib libworld.a
  gcc -o hello hello.o libworld.a

And removing the local source file will cause Cons to revert back to
building the derived files from the repository source:

  % rm world.c
  % cons -R /usr/src_only/repository hello
  gcc -c /usr/src_only/repository/world.c -o world.o
  ar r libworld.a world.o
  ar: creating libworld.a
  ranlib libworld.a
  gcc -o hello hello.o libworld.a


=head2 Repository derived files

If a repository tree contains derived files (usually object files,
libraries, or executables), Cons will perform its normal signature
calculation to decide whether the repository file is up-to-date or a derived
file must be built locally.  This means that, in order to ensure correct
signature calculation, a repository tree must also contain the F<.consign>
files that were created by Cons when generating the derived files.

This would usually be accomplished by building the software in the
repository (or, alternatively, in a build directory, and then copying the
result to the repository):

  % cd /usr/all/repository
  % cons hello
  gcc -c hello.c -o hello.o
  gcc -c world.c -o world.o
  ar r libworld.a world.o
  ar: creating libworld.a
  ranlib libworld.a
  gcc -o hello hello.o libworld.a

(This is safe even if the F<Construct> file lists the F</usr/all/repository>
directory in a C<Repository> command because Cons will remove the current
directory from the repository list.)

Now if we want to build a copy of the application with our own F<hello.c>
file, we only need to create the one necessary source file, and use the
C<-R> option to have Cons use other files from the repository:

  % mkdir $HOME/build1
  % cd $HOME/build1
  % ed hello.c
    [EDIT]
  % cons -R /usr/all/repository hello
  gcc -c hello.c -o hello.o
  gcc -o hello hello.o /usr/all/repository/libworld.a

Notice that Cons has not bothered to recreate a local F<libworld.a> library
(or recompile the F<world.o> module), but instead uses the already-compiled
version from the repository.

Because the MD5 signatures that Cons puts in the F<.consign> file contain
timestamps for the derived files, the signature timestamps must match the
file timestamps for a signature to be considered valid.

Some software systems may alter the timestamps on repository files (by
copying them, e.g.), in which case Cons will, by default, assume the
repository signatures are invalid and rebuild files unnecessarily.  This
behavior may be altered by specifying:

  Repository_Sig_Times_OK 0;

This tells Cons to ignore timestamps when deciding whether a signature is
valid.  (Note that avoiding this sanity check means there must be proper
control over the repository tree to ensure that the derived files cannot be
modified without updating the F<.consign> signature.)


=head2 Local copies of files

If the repository tree contains the complete results of a build, and we try
to build from the repository without any files in our local tree, something
moderately surprising happens:

  % mkdir $HOME/build2
  % cd $HOME/build2
  % cons -R /usr/all/repository hello
  cons: "hello" is up-to-date.

Why does Cons say that the F<hello> program is up-to-date when there is no
F<hello> program in the local build directory?  Because the repository (not
the local directory) contains the up-to-date F<hello> program, and Cons
correctly determines that nothing needs to be done to rebuild this
up-to-date copy of the file.

There are, however, many times in which it is appropriate to ensure that a
local copy of a file always exists.  A packaging or testing script, for
example, may assume that certain generated files exist locally.  Instead of
making these subsidiary scripts aware of the repository directory, the
C<Local> command may be added to a F<Construct> or F<Conscript> file to
specify that a certain file or files must appear in the local build
directory:

  Local qw(
	hello
  );

Then, if we re-run the same command, Cons will make a local copy of the
program from the repository copy (telling you that it is doing so):

  % cons -R /usr/all/repository hello
  Local copy of hello from /usr/all/repository/hello
  cons: "hello" is up-to-date.

Notice that, because the act of making the local copy is not considered a
"build" of the F<hello> file, Cons still reports that it is up-to-date.

Creating local copies is most useful for files that are being installed into
an intermediate directory (for sharing with other directories) via the
C<Install> command.  Accompanying the C<Install> command for a file with a
companion C<Local> command is so common that Cons provides a
C<Install_Local> command as a convenient way to do both:

  Install_Local $env, '#export', 'hello';

is exactly equivalent to:

  Install $env '#export', 'hello';
  Local '#export/hello';

Both the C<Local> and C<Install_Local> commands update the local F<.consign>
file with the appropriate file signatures, so that future builds are
performed correctly.


=head2 Repository dependency analysis

Due to its built-in scanning, Cons will search the specified repository
trees for included F<.h> files.  Unless the compiler also knows about the
repository trees, though, it will be unable to find F<.h> files that only
exist in a repository.  If, for example, the F<hello.c> file includes the
F<hello.h> file in its current directory:

  % cons -R /usr/all/repository hello
  gcc -c /usr/all/repository/hello.c -o hello.o
  /usr/all/repository/hello.c:1: hello.h: No such file or directory

Solving this problem forces some requirements onto the way construction
environments are defined and onto the way the C C<#include> preprocessor
directive is used to include files.

In order to inform the compiler about the repository trees, Cons will add
appropriate C<-I> flags to the compilation commands.  This means that the
C<CPPPATH> variable in the construct environment must explicitly specify all
subdirectories which are to be searched for included files, including the
current directory.  Consequently, we can fix the above example by changing
the environment creation in the F<Construct> file as follows:

  $env = new cons(
	CC	=> 'gcc',
	CPPPATH	=> '.',
	LIBS	=> 'libworld.a',
  );

Due to the definition of the C<CPPPATH> variable, this yields, when we
re-execute the command:

  % cons -R /usr/all/repository hello
  gcc -c -I. -I/usr/all/repository /usr/all/repository/hello.c -o hello.o
  gcc -o hello hello.o /usr/all/repository/libworld.a

The order of the C<-I> flags replicates, for the C preprocessor, the same
repository-directory search path that Cons uses for its own dependency
analysis.  If there are multiple repositories and multiple C<CPPPATH>
directories, Cons will append the repository directories to the beginning of
each C<CPPPATH> directory, rapidly multiplying the number of C<-I> flags.
As an extreme example, a F<Construct> file containing:

  Repository qw(
	/u1
	/u2
  );

  $env = new cons(
	CPPPATH	=> 'a:b:c',
  );

Would yield a compilation command of:

  cc -Ia -I/u1/a -I/u2/a -Ib -I/u1/b -I/u2/b -Ic -I/u1/c -I/u2/c -c hello.c -o hello.o

Because Cons relies on the compiler's C<-I> flags to communicate the order
in which repository directories must be searched, Cons' handling of
repository directories is fundamentally incompatible with using
double-quotes on the C<#include> directives in your C source code:

  #include "file.h"	/* DON'T USE DOUBLE-QUOTES LIKE THIS */

This is because most C preprocessors, when faced with such a directive, will
always first search the directory containing the source file.  This
undermines the elaborate C<-I> options that Cons constructs to make the
preprocessor conform to its preferred search path.

Consequently, when using repository trees in Cons,
B<always> use angle-brackets for included files:

  #include <file.h>	/* USE ANGLE-BRACKETS INSTEAD */


=head2 Repository_List

Cons provides a C<Repository_List> command to return a list of all
repository directories in their current search order.  This can be used for
debugging, or to do more complex Perl stuff:

  @list = Repository_List;
  print join(' ', @list), "\n";


=head2 Repository interaction with other Cons features

Cons' handling of repository trees interacts correctly with other Cons
features--which is to say, it generally does what you would expect.

Most notably, repository trees interact correctly, and rather powerfully,
with the 'Link' command.  A repository tree may contain one or more
subdirectories for version builds established via C<Link> to a source
subdirectory.  Cons will search for derived files in the appropriate build
subdirectories under the repository tree.


=head1 Default targets

Until now, we've demonstrated invoking Cons with an explicit target
to build:

  % cons hello

Normally, Cons does not build anything unless a target is specified,
but specifying '.' (the current directory) will build everything:

  % cons		# does not build anything

  % cons .		# builds everything under the top-level directory

Adding the C<Default> method to any F<Construct> or F<Conscript> file will add
the specified targets to a list of default targets.  Cons will build
these defaults if there are no targets specified on the command line.
So adding the following line to the top-level F<Construct> file will mimic
Make's typical behavior of building everything by default:

  Default '.';

The following would add the F<hello> and F<goodbye> commands (in the
same directory as the F<Construct> or F<Conscript> file) to the default list:

  Default qw(
	hello
	goodbye
  );

The C<Default> method may be used more than once to add targets to the
default list.

=head1 Selective builds

Cons provides two methods for reducing the size of given build. The first is
by specifying targets on the command line, and the second is a method for
pruning the build tree. We'll consider target specification first.


=head2 Selective targeting

Like make, Cons allows the specification of ``targets'' on the command
line. Cons targets may be either files or directories. When a directory is
specified, this is simply a short-hand notation for every derivable
product--that Cons knows about--in the specified directory and below. For
example:

  % cons build/hello/hello.o

means build F<hello.o> and everything that F<hello.o> might need. This is
from a previous version of the B<Hello, World!> program in which F<hello.o>
depended upon F<export/include/world.h>. If that file is not up-to-date
(because someone modified F<src/world/world.h)>, then it will be rebuilt,
even though it is in a directory remote from F<build/hello>.

In this example:

  % cons build

Everything in the F<build> directory is built, if necessary. Again, this may
cause more files to be built. In particular, both F<export/include/world.h>
and F<export/lib/libworld.a> are required by the F<build/hello> directory,
and so they will be built if they are out-of-date.

If we do, instead:

  % cons export

then only the files that should be installed in the export directory will be
rebuilt, if necessary, and then installed there. Note that C<cons build>
might build files that C<cons export> doesn't build, and vice-versa.


=head2 No ``special'' targets

With Cons, make-style ``special'' targets are not required. The simplest
analog with Cons is to use special F<export> directories, instead. Let's
suppose, for example, that you have a whole series of unit tests that are
associated with your code. The tests live in the source directory near the
code. Normally, however, you don't want to build these tests. One solution
is to provide all the build instructions for creating the tests, and then to
install the tests into a separate part of the tree. If we install the tests
in a top-level directory called F<tests>, then:

  % cons tests

will build all the tests.

  % cons export

will build the production version of the system (but not the tests), and:

  % cons build

should probably be avoided (since it will compile tests unecessarily).

If you want to build just a single test, then you could explicitly name the
test (in either the F<tests> directory or the F<build> directory). You could
also aggregate the tests into a convenient hierarchy within the tests
directory. This hierarchy need not necessarily match the source hierarchy,
in much the same manner that the include hierarchy probably doesn't match
the source hierarchy (the include hierarchy is unlikely to be more than two
levels deep, for C programs).

If you want to build absolutely everything in the tree (subject to whatever
options you select), you can use:

  % cons .

This is not particularly efficient, since it will redundantly walk all the
trees, including the source tree. The source tree, of course, may have
buildable objects in it--nothing stops you from doing this, even if you
normally build in a separate build tree.


=head1 Build Pruning

In conjunction with target selection, B<build pruning> can be used to reduce
the scope of the build. In the previous peAcH and baNaNa example, we have
already seen how script-driven build pruning can be used to make only half
of the potential build available for any given invocation of C<cons>. Cons
also provides, as a convenience, a command line convention that allows you
to specify which F<Conscript> files actually get ``built''--that is,
incorporated into the build tree. For example:

  % cons build +world

The C<+> argument introduces a Perl regular expression. This must, of
course, be quoted at the shell level if there are any shell meta-characters
within the expression. The expression is matched against each F<Conscript>
file which has been mentioned in a C<Build> statement, and only those
scripts with matching names are actually incorporated into the build
tree. Multiple such arguments are allowed, in which case a match against any
of them is sufficient to cause a script to be included.

In the example, above, the F<hello> program will not be built, since Cons
will have no knowledge of the script F<hello/Conscript>. The F<libworld.a>
archive will be built, however, if need be.

There are a couple of uses for build pruning via the command line. Perhaps
the most useful is the ability to make local changes, and then, with
sufficient knowledge of the consequences of those changes, restrict the size
of the build tree in order to speed up the rebuild time. A second use for
build pruning is to actively prevent the recompilation of certain files that
you know will recompile due to, for example, a modified header file. You may
know that either the changes to the header file are immaterial, or that the
changes may be safely ignored for most of the tree, for testing
purposes.With Cons, the view is that it is pragmatic to admit this type of
behavior, with the understanding that on the next full build everything that
needs to be rebuilt will be. There is no equivalent to a ``make touch''
command, to mark files as permanently up-to-date. So any risk that is
incurred by build pruning is mitigated. For release quality work, obviously,
we recommend that you do not use build pruning (it's perfectly OK to use
during integration, however, for checking compilation, etc. Just be sure to
do an unconstrained build before committing the integration).


=head1 Temporary overrides

Cons provides a very simple mechanism for overriding aspects of a build. The
essence is that you write an override file containing one or more
C<Override> commands, and you specify this on the command line, when you run
C<cons>:

  % cons -o over export

will build the F<export> directory, with all derived files subject to the
overrides present in the F<over> file. If you leave out the C<-o> option,
then everything necessary to remove all overrides will be rebuilt.


=head2 Overriding environment variables

The override file can contain two types of overrides. The first is incoming
environment variables. These are normally accessible by the F<Construct>
file from the C<%ENV> hash variable. These can trivially be overridden in
the override file by setting the appropriate elements of C<%ENV> (these
could also be overridden in the user's environment, of course).


=head2 The Override command

The second type of override is accomplished with the C<Override> command,
which looks like this:

  Override <regexp>, <var1> => <value1>, <var2> => <value2>, ...;

The regular expression I<regexp> is matched against every derived file that
is a candidate for the build. If the derived file matches, then the
variable/value pairs are used to override the values in the construction
environment associated with the derived file.

Let's suppose that we have a construction environment like this:

  $CONS = new cons(
	COPT => '',
	CDBG => '-g',
	CFLAGS => '%COPT %CDBG',
  );

Then if we have an override file F<over> containing this command:

  Override '\.o$', COPT => '-O', CDBG => '';

then any C<cons> invocation with C<-o over> that creates F<.o> files via
this environment will cause them to be compiled with C<-O >and no C<-g>. The
override could, of course, be restricted to a single directory by the
appropriate selection of a regular expression.

Here's the original version of the Hello, World! program, built with this
environment. Note that Cons rebuilds the appropriate pieces when the
override is applied or removed:

  % cons hello
  cc -g -c hello.c -o hello.o
  cc -o hello hello.o
  % cons -o over hello
  cc -O -c hello.c -o hello.o
  cc -o hello hello.o
  % cons -o over hello
  cons: "hello" is up-to-date.
  % cons hello
  cc -g -c hello.c -o hello.o
  cc -o hello hello.o

It's important that the C<Override> command only be used for temporary,
on-the-fly overrides necessary for development because the overrides are not
platform independent and because they rely too much on intimate knowledge of
the workings of the scripts. For temporary use, however, they are exactly
what you want.

Note that it is still useful to provide, say, the ability to create a fully
optimized version of a system for production use--from the F<Construct> and
F<Conscript> files. This way you can tailor the optimized system to the
platform. Where optimizer trade-offs need to be made (particular files may
not be compiled with full optimization, for example), then these can be
recorded for posterity (and reproducibility) directly in the scripts.


=head1 More on construction environments

=head2 Default construction variables

We have mentioned, and used, the concept of a B<construction environment>,
many times in the preceding pages. Now it's time to make this a little more
concrete. With the following statement:

  $env = new cons();

a reference to a new, default construction environment is created. This
contains a number of construction variables and some methods. At the present
writing, the default list of construction variables is defined as follows:

  CC		=> 'cc',
  CFLAGS	=> '',
  CCCOM		=> '%CC %CFLAGS %_IFLAGS -c %< -o %>',
  INCDIRPREFIX  => '-I',
  CXX		=> '%CC',
  CXXFLAGS	=> '%CFLAGS',
  CXXCOM	=> '%CXX %CXXFLAGS %_IFLAGS -c %< -o %>',
  LINK		=> '%CXX',
  LINKCOM	=> '%LINK %LDFLAGS -o %> %< %_LDIRS %LIBS',
  LINKMODULECOM	=> '%LD -r -o %> %<',
  LIBDIRPREFIX  => '-L',
  AR		=> 'ar',
  ARFLAGS	=> 'r',
  ARCOM		=> "%AR %ARFLAGS %> %<\n%RANLIB %>",
  RANLIB	=> 'ranlib',
  AS		=> 'as',
  ASFLAGS	=> '',
  ASCOM		=> '%AS %ASFLAGS %< -o %>',
  LD		=> 'ld',
  LDFLAGS	=> '',
  PREFLIB	=> 'lib',
  SUFLIB	=> '.a',
  SUFLIBS	=> '.so:.a',
  SUFOBJ	=> '.o',
  ENV		=> { 'PATH' => '/bin:/usr/bin' },


On Win32 systems (Windows NT), the following construction variables
are overridden in the default:

  CC		=> 'cl',
  CFLAGS	=> '/nologo',
  CCCOM		=> '%CC %CFLAGS %_IFLAGS /c %< /Fo%>',
  CXXCOM        => '%CXX %CXXFLAGS %_IFLAGS /c %< /Fo%>',
  INCDIRPREFIX  => '/I',
  LINK		=> 'link',
  LINKCOM	=> '%LINK %LDFLAGS /out:%> %< %_LDIRS %LIBS',
  LINKMODULECOM	=> '%LD /r /o %> %<',
  LIBDIRPREFIX  => '/LIBPATH:',
  AR		=> 'lib',
  ARFLAGS	=> '/nologo ',
  ARCOM		=> "%AR %ARFLAGS /out:%> %<",
  RANLIB	=> '',
  LD		=> 'link',
  LDFLAGS	=> '/nologo ',
  PREFLIB	=> '',
  SUFEXE	=> '.exe',
  SUFLIB	=> '.lib',
  SUFLIBS	=> '.dll:.lib',
  SUFOBJ	=> '.obj',

These variables are used by the various methods associated with the
environment, in particular any method that ultimately invokes an external
command will substitute these variables into the final command, as
appropriate. For example, the C<Objects> method takes a number of source
files and arranges to derive, if necessary, the corresponding object
files. For example:

  Objects $env 'foo.c', 'bar.c';

This will arrange to produce, if necessary, F<foo.o> and F<bar.o>. The
command invoked is simply C<%CCCOM>, which expands through substitution, to
the appropriate external command required to build each object. We will
explore the substitution rules further under the C<Command> method, below.

The construction variables are also used for other purposes. For example,
C<CPPPATH> is used to specify a colon-separated path of include
directories. These are intended to be passed to the C preprocessor and are
also used by the C-file scanning machinery to determine the dependencies
involved in a C Compilation. Variables beginning with underscore, are
created by various methods, and should normally be considered ``internal''
variables. For example, when a method is called which calls for the creation
of an object from a C source, the variable C<_IFLAGS> is created: this
corresponds to the C<-I> switches required by the C compiler to represent
the directories specified by C<CPPPATH>.

Note that, for any particular environment, the value of a variable is set
once, and then never reset (to change a variable, you must create a new
environment. Methods are provided for copying existing environments for this
purpose). Some internal variables, such as C<_IFLAGS> are created on demand,
but once set, they remain fixed for the life of the environment.

The C<CFLAGS>, C<LDFLAGS>, and C<ARFLAGS> variables all supply a place
for passing options to the compiler, loader, and archiver, respectively.
Less obviously, the C<INCDIRPREFIX> variable specifies the option string
to be appended to the beginning of each include directory so that the
compiler knows where to find F<.h> files.  Similarly, the C<LIBDIRPREFIX>
variable specifies the option string to be appended to the beginning of
each directory that the linker should search for libraries.

Another variable, C<ENV>, is used to determine the system environment during
the execution of an external command. By default, the only environment
variable that is set is C<PATH>, which is the execution path for a UNIX
command. For the utmost reproducibility, you should really arrange to set
your own execution path, in your top-level F<Construct> file (or perhaps by
importing an appropriate construction package with the Perl C<use>
command). The default variables are intended to get you off the ground.

=head2 Interpolating construction variables

Construction environment variables may be interpolated in the source and
target file names by prefixing the construction variable name with C<%>.

  $env = new cons(
	DESTDIR	=>	'programs',
	SRCDIR	=>	'src',
  );
  Program $env '%DESTDIR/hello', '%SRCDIR/hello.c';

Expansion of construction variables is recursive--that is, the file
name(s) will be re-expanded until no more substitutions can be made. If
a construction variable is not defined in the environment, then the null
string will be substituted.

=head1 Default construction methods

The list of default construction methods includes the following:


=head2 The C<new> constructor

The C<new> method is a Perl object constructor. That is, it is not invoked
via a reference to an existing construction environment B<reference>, but,
rather statically, using the name of the Perl B<package> where the
constructor is defined. The method is invoked like this:

  $env = new cons(<overrides>);

The environment you get back is blessed into the package C<cons>, which
means that it will have associated with it the default methods described
below. Individual construction variables can be overridden by providing
name/value pairs in an override list. Note that to override any command
environment variable (i.e. anything under C<ENV>), you will have to override
all of them. You can get around this difficulty by using the C<copy> method
on an existing construction environment.


=head2 The C<clone> method

The C<clone> method creates a clone of an existing construction environment,
and can be called as in the following example:

  $env2 = $env1->clone(<overrides>);

You can provide overrides in the usual manner to create a different
environment from the original. If you just want a new name for the same
environment (which may be helpful when exporting environments to existing
components), you can just use simple assignment.


=head2 The C<copy> method

The C<copy> method extracts the externally defined construction variables
from an environment and returns them as a list of name/value
pairs. Overrides can also be provided, in which case, the overridden values
will be returned, as appropriate. The returned list can be assigned to a
hash, as shown in the prototype, below, but it can also be manipulated in
other ways:

  %env = $env1->copy(<overrides>);

The value of C<ENV>, which is itself a hash, is also copied to a new hash,
so this may be changed without fear of affecting the original
environment. So, for example, if you really want to override just the
C<PATH> variable in the default environment, you could do the following:

  %cons = new cons()->copy();
  $cons{ENV}{PATH} = "<your path here>";
  $cons = new cons(%cons);

This will leave anything else that might be in the default execution
environment undisturbed.


=head2 The C<Install> method

The C<Install> method arranges for the specified files to be installed in
the specified directory. The installation is optimized: the file is not
copied if it can be linked. If this is not the desired behavior, you will
need to use a different method to install the file. It is called as follows:

  Install $env <directory>, <names>;

Note that, while the files to be installed may be arbitrarily named,
only the last component of each name is used for the installed target
name. So, for example, if you arrange to install F<foo/bar> in F<baz>,
this will create a F<bar> file in the F<baz> directory (not F<foo/bar>).


=head2 The C<InstallAs> method

The C<InstallAs> method arranges for the specified source file(s) to be
installed as the specified target file(s). Multiple files should be
specified as a file list. The installation is optimized: the file is not
copied if it can be linked. If this is not the desired behavior, you will
need to use a different method to install the file. It is called as follows:

C<InstallAs> works in two ways:

Single file install:

  InstallAs $env TgtFile, SrcFile;

Multiple file install:

  InstallAs $env ['tgt1', 'tgt2'], ['src1', 'src2'];

Or, even as:

  @srcs = qw(src1 src2 src3);
  @tgts = qw(tgt1 tgt2 tgt3);
  InstallAs $env [@tgts], [@srcs];

Both the target and the sources lists should be of the same length.

=head2 The C<Precious> method

The C<Precious> method asks cons not to delete the specified file or
list of files before building them again.  It is invoked as:

  Precious <files>;

This is especially useful for allowing incremental updates to libraries
or debug information files which are updated rather than rebuilt anew each
time.  Cons will still delete the files when the C<-r> flag is specified.

=head2 The C<Command> method

The C<Command> method is a catchall method which can be used to arrange for
any external command to be called to update the target. For this command, a
target file and list of inputs is provided. In addition a construction
command line, or lines, is provided as a string (this string may have
multiple commands embedded within it, separated by new lines). C<Command> is
called as follows:

  Command $env <target>, <inputs>, <construction command>;

The target is made dependent upon the list of input files specified, and the
inputs must be built successfully or Cons will not attempt to build the
target.

Within the construction command, any variable from the construction
environment may be introduced by prefixing the name of the construction
variable with C<%>. This is recursive: the command is expanded until no more
substitutions can be made. If a construction variable is not defined in the
environment, then the null string will be substituted.  A doubled C<%%>
will be replaced by a single C<%> in the construction command.

There are several pseudo variables which will also be expanded:

=over 10

=item %>

The target file name (in a multi-target command, this is always the first
target mentioned).

=item %0

Same as C<%E<gt>>.

=item %1, %2, ..., %9

These refer to the first through ninth input file, respectively.

=item %E<lt>

The full set of inputs. If any of these have been used anywhere else in the
current command line (via C<%1>, C<%2>, etc.), then those will be deleted
from the list provided by C<%E<lt>>. Consider the following command found in a
F<Conscript> file in the F<test> directory:

  Command $env 'tgt', qw(foo bar baz), qq(
	echo %< -i %1 > %>
	echo %< -i %2 >> %>
	echo %< -i %3 >> %>
  );

If F<tgt> needed to be updated, then this would result in the execution of
the following commands, assuming that no remapping has been established for
the F<test> directory:

  echo test/bar test/baz -i test/foo > test/tgt
  echo test/foo test/baz -i test/bar >> test/tgt
  echo test/foo test/bar -i test/baz >> test/tgt

=back

Any of the above pseudo variables may be followed immediately by one of
the following suffixes to select a portion of the expanded path name:

  :a    the absolute path to the file name
  :b    the directory plus the file name stripped of any suffix
  :d    the directory
  :f    the file name
  :s    the file name suffix
  :F    the file name stripped of any suffix

Continuing with the above example, C<%<:f> would expand to C<foo bar baz>,
and C<%>:d> would expand to C<test>.

It is possible to programmatically rewrite part of the command by
enclosing part of it between C<%[> and C<%]>.  This will call the
construction variable named as the first word enclosed in the brackets
as a Perl code reference; the results of this call will be used to
replace the contents of the brackets in the command line.  For example,
given an existing input file named F<tgt.in>:

  @keywords = qw(foo bar baz);
  $env = new cons(X_COMMA => sub { join(",", @_) });
  Command $env 'tgt', 'tgt.in', qq(
	echo '# Keywords: %[X_COMMA @keywords %]' > %>
	cat %< >> %>
  );

This will execute:

  echo '# Keywords: foo,bar,baz' > tgt
  cat tgt.in >> tgt

After substitution occurs, strings of white space are converted into single
blanks, and leading and trailing white space is eliminated. It is therefore
not possible to introduce variable length white space in strings passed into
a command, without resorting to some sort of shell quoting.

If a multi-line command string is provided, the commands are executed
sequentially. If any of the commands fails, then none of the rest are
executed, and the target is not marked as updated, i.e. a new signature is
not stored for the target.

Normally, if all the commands succeed, and return a zero status (or whatever
platform-specific indication of success is required), then a new signature
is stored for the target. If a command erroneously reports success even
after a failure, then Cons will assume that the target file created by that
command is accurate and up-to-date.

The first word of each command string, after expansion, is assumed to be an
executable command looked up on the C<PATH> environment variable (which is,
in turn, specified by the C<ENV> construction variable). If this command is
found on the path, then the target will depend upon it: the command will
therefore be automatically built, as necessary. It's possible to write
multi-part commands to some shells, separated by semi-colons. Only the first
command word will be depended upon, however, so if you write your command
strings this way, you must either explicitly set up a dependency (with the
C<Depends> method), or be sure that the command you are using is a system
command which is expected to be available. If it isn't available, you will,
of course, get an error.

If any command (even one within a multi-line command) begins with
C<[perl]>, the remainder of that command line will be evaluated by the
running Perl instead of being forked by the shell.  If an error occurs
in parsing the Perl or if the Perl expression returns 0 or undef, the
command will be considered to have failed.  For example, here is a simple
command which creates a file C<foo> directly from Perl:

  $env = new cons();
  Command $env 'foo',
    qq([perl] open(FOO,'>foo');print FOO "hi\\n"; close(FOO); 1);

Note that when the command is executed, you are in the same package as
when the F<Construct> or F<Conscript> file was read, so you can call
Perl functions you've defined in the same F<Construct> or F<Conscript>
file in which the C<Command> appears:

  $env = new cons();
  sub create_file {
	my $file = shift;
	open(FILE, ">$file");
	print FILE "hi\n";
	close(FILE);
	return 1;
  }
  Command $env 'foo', "[perl] &create_file('%>')";

The Perl string will be used to generate the signature for the derived
file, so if you change the string, the file will be rebuilt.  The contents
of any subroutines you call, however, are not part of the signature,
so if you modify a called subroutine such as C<create_file> above,
the target will I<not> be rebuilt.  Caveat user.

Cons normally prints a command before executing it.  This behavior is
suppressed if the first character of the command is C<@>.  Note that
you may need to separate the C<@> from the command name or escape it to
prevent C<@cmd> from looking like an array to Perl quote operators that
perform interpolation:

  # The first command line is incorrect,
  # because "@cp" looks like an array
  # to the Perl qq// function.
  # Use the second form instead.
  Command $env 'foo', 'foo.in', qq(
	@cp %< tempfile
	@ cp tempfile %>
  );

If there are shell meta characters anywhere in the expanded command line,
such as C<E<lt>>, C<E<gt>>, quotes, or semi-colon, then the command
will actually be executed by invoking a shell. This means that a command
such as:

  cd foo

alone will typically fail, since there is no command C<cd> on the path. But
the command string:

  cd $<:d; tar cf $>:f $<:f

when expanded will still contain the shell meta character semi-colon, and a
shell will be invoked to interpret the command. Since C<cd> is interpreted
by this sub-shell, the command will execute as expected.

To specify a command with multiple targets, you can specify a reference to a
list of targets. In Perl, a list reference can be created by enclosing a
list in square brackets. Hence the following command:

  Command $env ['foo.h', 'foo.c'], 'foo.template', q(
	gen %1
  );

could be used in a case where the command C<gen> creates two files, both
F<foo.h> and F<foo.c>.


=head2 The C<Objects> method

The C<Objects> method arranges to create the object files that correspond to
the specified source files. It is invoked as shown below:

  @files = Objects $env <source or object files>;

Under Unix, source files ending in F<.s> and F<.c> are currently
supported, and will be compiled into a name of the same file ending
in F<.o>. By default, all files are created by invoking the external
command which results from expanding the C<CCCOM> construction
variable, with C<%E<lt>> and C<%E<gt>> set to the source and object
files, respectively (see the C<Command> method for expansion details).
The variable C<CPPPATH> is also used when scanning source files for
dependencies. This is a colon separated list of pathnames, and is also
used to create the construction variable C<_IFLAGS,> which will contain
the appropriate list of -C<I> options for the compilation. Any relative
pathnames in C<CPPPATH> is interpreted relative to the directory in
which the associated construction environment was created (absolute
and top-relative names may also be used). This variable is used by
C<CCCOM>. The behavior of this command can be modified by changing any
of the variables which are interpolated into C<CCCOM>, such as C<CC>,
C<CFLAGS>, and, indirectly, C<CPPPATH>. It's also possible to replace
the value of C<CCCOM>, itself. As a convenience, this file returns the
list of object filenames.


=head2 The C<Program> method

The C<Program> method arranges to link the specified program with the
specified object files. It is invoked in the following manner:

  Program $env <program name>, <source or object files>;

The program name will have the value of the C<SUFEXE> construction
variable appended (by default, C<.exe> on Win32 systems, nothing on Unix
systems) if the suffix is not already present.

Source files may be specified in place of objects files--the C<Objects>
method will be invoked to arrange the conversion of all the files into
object files, and hence all the observations about the C<Objects> method,
above, apply to this method also.

The actual linking of the program will be handled by an external command
which results from expanding the C<LINKCOM> construction variable, with
C<%E<lt>> set to the object files to be linked (in the order presented),
and C<%E<gt>> set to the target (see the C<Command> method for expansion
details). The user may set additional variables in the construction
environment, including C<LINK>, to define which program to use for
linking, C<LIBPATH>, a colon-separated list of library search paths,
for use with library specifications of the form I<-llib>, and C<LIBS>,
specifying the list of libraries to link against (in either I<-llib>
form or just as pathnames. Relative pathnames in both C<LIBPATH> and
C<LIBS> are interpreted relative to the directory in which the associated
construction environment is created (absolute and top-relative names may
also be used). Cons automatically sets up dependencies on any libraries
mentioned in C<LIBS>: those libraries will be built before the command
is linked.


=head2 The C<Library> method

The C<Library> method arranges to create the specified library from the
specified object files. It is invoked as follows:

  Library $env <library name>, <source or object files>;

The library name will have the value of the C<SUFLIB> construction
variable appended (by default, C<.lib> on Win32 systems, C<.a> on Unix
systems) if the suffix is not already present.

Source files may be specified in place of objects files--the C<Objects>
method will be invoked to arrange the conversion of all the files into
object files, and hence all the observations about the C<Objects> method,
above, apply to this method also.

The actual creation of the library will be handled by an external
command which results from expanding the C<ARCOM> construction variable,
with C<%E<lt>> set to the library members (in the order presented),
and C<%E<gt>> to the library to be created (see the C<Command> method
for expansion details). The user may set variables in the construction
environment which will affect the operation of the command. These
include C<AR>, the archive program to use, C<ARFLAGS>, which can be
used to modify the flags given to the program specified by C<AR>, and
C<RANLIB>, the name of a archive index generation program, if needed
(if the particular need does not require the latter functionality,
then C<ARCOM> must be redefined to not reference C<RANLIB>).

The C<Library> method allows the same library to be specified in multiple
method invocations. All of the contributing objects from all the invocations
(which may be from different directories) are combined and generated by a
single archive command. Note, however, that if you prune a build so that
only part of a library is specified, then only that part of the library will
be generated (the rest will disappear!).


=head2 The C<Module> method

The C<Module> method is a combination of the C<Program> and C<Command>
methods. Rather than generating an executable program directly, this command
allows you to specify your own command to actually generate a module. The
method is invoked as follows:

  Module $env <module name>, <source or object files>, <construction command>;

This command is useful in instances where you wish to create, for example,
dynamically loaded modules, or statically linked code libraries.


=head2 The C<Depends> method

The C<Depends> method allows you to specify additional dependencies for a
target.  It is invoked as follows:

  Depends $env <target>, <dependencies>;

This may be occasionally useful, especially in cases where no scanner exists
(or is writable) for particular types of files. Normally, dependencies are
calculated automatically from a combination of the explicit dependencies set
up by the method invocation or by scanning source files.

A set of identical dependencies for multiple targets may be specified
using a reference to a list of targets. In Perl, a list reference can
be created by enclosing a list in square brackets. Hence the following
command:

  Depends $env ['foo', 'bar'], 'input_file_1', 'input_file_2';

specifies that both the F<foo> and F<bar> files depend on the listed
input files.


=head2 The C<Ignore> method

The C<Ignore> method allows you to ignore explicitly dependencies that
Cons infers on its own.  It is invoked as follows:

  Ignore <patterns>;

This can be used to avoid recompilations due to changes in system header
files or utilities that are known to not affect the generated targets.

If, for example, a program is built in an NFS-mounted directory on
multiple systems that have different copies of F<stdio.h>, the differences
will affect the signatures of all derived targets built from source files
that C<#include E<lt>stdio.hE<gt>>.  This will cause all those targets to
be rebuilt when changing systems.  If this is not desirable behavior, then
the following line will remove the dependencies on the F<stdio.h> file:

  Ignore '^/usr/include/stdio\.h$';

Note that the arguments to the C<Ignore> method are regular expressions,
so special characters must be escaped and you may wish to anchor the
beginning or end of the expression with C<^> or C<$> characters.


=head2 The C<Salt> method

The C<Salt> method adds a constant value to the signature calculation
for every derived file.  It is invoked as follows:

  Salt $string;

Changing the Salt value will force a complete rebuild of every derived
file.  This can be used to force rebuilds in certain desired
circumstances.  For example,

  Salt `uname -s`;

Would force a complete rebuild of every derived file whenever the
operating system on which the build is performed (as reported by C<uname
-s>) changes.


=head2 The C<UseCache> method

The C<UseCache> method instructs Cons to maintain a cache of derived
files, to be shared among separate build trees of the same project.

  UseCache("cache/<buildname>") || warn("cache directory not found");


=head2 The C<SourcePath> method

The C<SourcePath> mathod returns the real source path name of a file,
as opposted to the path name within a build directory.  It is invoked
as follows:

  $path = SourcePath <buildpath>;


=head2 The C<ConsPath> method

The C<ConsPath> method returns true if the supplied path is a derivable
file, and returns undef (false) otherwise.
It is invoked as follows:

  $result = ConsPath <path>;


=head2 The C<SplitPath> method

The C<SplitPath> method looks up multiple path names in a string separated
by the default path separator for the operating system (':' on UNIX
systems, ';' on Windows NT), and returns the fully-qualified names.
It is invoked as follows:

  @paths = SplitPath <pathlist>;

The C<SplitPath> method will convert  names prefixed '#' to the
appropriate top-level build name (without the '#') and will convert
relative names to top-level names.


=head2 The C<DirPath> method

The C<DirPath> method returns the build path name(s) of a directory or
list of directories.  It is invoked as follows:

  $cwd = DirPath <paths>;

The most common use for the C<DirPath> method is:

  $cwd = DirPath '.';

to fetch the path to the current directory of a subsidiary F<Conscript>
file.


=head2 The C<FilePath> method

The C<FilePath> method returns the build path name(s) of a file or
list of files.  It is invoked as follows:

  $file = FilePath <path>;


=head2 The C<Help> method

The C<Help> method specifies help text that will be displayed when the
user invokes C<cons -h>.  This can be used to provide documentation
of specific targets, values, build options, etc. for the build tree.
It is invoked as follows:

  Help <helptext>;

The C<Help> method may only be called once, and should typically be
specified in the top-level F<Construct> file.


=head1 Extending Cons


=head2 Overriding construction variables

There are several ways of extending Cons, which vary in degree of
difficulty. The simplest method is to define your own construction
environment, based on the default environment, but modified to reflect your
particular needs. This will often suffice for C-based applications. You can
use the C<new> constructor, and the C<clone> and C<copy> methods to create
hybrid environments. These changes can be entirely transparent to the
underlying F<Conscript> files.


=head2 Adding new methods

For slightly more demanding changes, you may wish to add new methods to the
C<cons> package. Here's an example of a very simple extension,
C<InstallScript>, which installs a tcl script in a requested location, but
edits the script first to reflect a platform-dependent path that needs to be
installed in the script:

  # cons::InstallScript - Create a platform dependent version of a shell
  # script by replacing string ``#!your-path-here'' with platform specific
  # path $BIN_DIR.

  sub cons::InstallScript {
	my ($env, $dst, $src) = @_;
	Command $env $dst, $src, qq(
		sed s+your-path-here+$BIN_DIR+ %< > %>
		chmod oug+x %>
	);
  }

Notice that this method is defined directly in the C<cons> package (by
prefixing the name with C<cons::>). A change made in this manner will be
globally visible to all environments, and could be called as in the
following example:

  InstallScript $env "$BIN/foo", "foo.tcl";

For a small improvement in generality, the C<BINDIR> variable could be
passed in as an argument or taken from the construction environment--as
C<%BINDIR>.


=head2 Overriding methods

Instead of adding the method to the C<cons> name space, you could define a
new package which inherits existing methods from the C<cons> package and
overrides or adds others. This can be done using Perl's inheritance
mechanisms.

The following example defines a new package C<cons::switch> which overrides the
standard C<Library> method. The overridden method builds linked library
modules, rather than library archives. A new constructor is
provided. Environments created with this constructor will have the new
library method; others won't.

  package cons::switch;
  BEGIN {@ISA = 'cons'}

  sub new {
	shift;
	bless new cons(@_);
  }

  sub Library {
	my($env) = shift;
	my($lib) = shift;
	my(@objs) = Objects $env @_;
	Command $env $lib, @objs, q(
		%LD -r %LDFLAGS %< -o %>
	);
  }

This functionality could be invoked as in the following example:

  $env = new cons::switch(@overrides);
  ...
  Library $env 'lib.o', 'foo.c', 'bar.c';


=head1 Invoking Cons

The C<cons> command is usually invoked from the root of the build tree. A
F<Construct> file must exist in that directory. If the C<-f> argument is
used, then an alternate F<Construct> file may be used (and, possibly, an
alternate root, since C<cons> will cd to F<Construct> file's containing
directory).

If C<cons> is invoked from a child of the root of the build tree with
the C<-t> argument, it will walk up the directory hierarchy looking for a
F<Construct> file.  (An alternate name may still be specified with C<-f>.)
The targets supplied on the command line will be modified to be relative
to the discovered F<Construct> file.  For example, from a directory
containing a top-level F<Construct> file, the following invocation:

  % cd libfoo/subdir
  % cons -t target

is exactly equivalent to:

  % cons libfoo/subdir/target

If there are any C<Default> targets specified in the directory hierarchy's
F<Construct> or F<Conscript> files, only the default targets at or below
the directory from which C<cons -t> was invoked will be built.

The command is invoked as follows:

  cons <arguments> -- <construct-args>

where I<arguments> can be any of the following, in any order:

=over 10

=item I<target>

Build the specified target. If I<target> is a directory, then recursively
build everything within that directory.

=item I<+pattern>

Limit the F<Conscript> files considered to just those that match I<pattern>,
which is a Perl regular expression. Multiple C<+> arguments are accepted.

=item I<name>=<val>

Sets I<name> to value I<val> in the C<ARG> hash passed to the top-level
F<Construct> file.

=item C<-cc>

Show command that would have been executed, when retrieving from cache. No
indication that the file has been retrieved is given; this is useful for
generating build logs that can be compared with real build logs.

=item C<-cd>

Disable all caching. Do not retrieve from cache nor flush to cache.

=item C<-cr>

Build dependencies in random order. This is useful when building multiple
similar trees with caching enabled.

=item C<-cs>

Synchronize existing build targets that are found to be up-to-date with
cache. This is useful if caching has been disabled with -cc or just recently
enabled with UseCache.

=item C<-d>

Enable dependency debugging.

=item C<-f> <file>

Use the specified file instead of F<Construct> (but first change to
containing directory of I<file>).

=item C<-h>

Show a help message local to the current build if one such is defined, and
exit.

=item C<-k>

Keep going as far as possible after errors.

=item C<-o> <file>

Read override file I<file>.

=item C<-p>

Show construction products in specified trees. No build is attempted.

=item C<-pa>

Show construction products and associated actions. No build is attempted.

=item C<-pw>

Show products and where they are defined. No build is attempted.

=item C<-q>

Don't be verbose about Installing and Removing targets.

=item C<-r>

Remove construction products associated with <targets>. No build is
attempted.

=item C<-R> <repos>

Search for files in I<repos>.  Multiple B<-R> I<repos> directories are
searched in the order specified.

=item C<-t>

Traverse up the directory hierarchy looking for a F<Construct> file, if
none exists in the current directory.  Targets will be modified to be
relative to the F<Construct> file.

=item C<-v>

Show C<cons> version and continue processing.

=item C<-V>

Show C<cons> version and exit.

=item C<-wf> <file>

Write all filenames considered into I<file>.

=item C<-x>

Show a help message similar to this one, and exit.

=back

And I<construct-args> can be any arguments that you wish to process in the
F<Construct> file. Note that there should be a B<--> separating the arguments
to cons and the arguments that you wish to process in the F<Construct> file.

Processing of I<construct-args> can be done by any standard package like
B<Getopt> or its variants, or any user defined package. B<cons> will pass in
the I<construct-args> as B<@ARGV> and will not attempt to interpret anything
after the B<-->.

  % cons -R /usr/local/repository -d os=solaris +driver -- -c test -f DEBUG

would pass the following to cons

  -R /usr/local/repository -d os=solaris +driver

and the following, to the top level F<Construct> file as B<@ARGV>

  -c test -f DEBUG

Note that C<cons -r .> is equivalent to a full recursive C<make clean>,
but requires no support in the F<Construct> file or any F<Conscript>
files. This is most useful if you are compiling files into source
directories (if you separate the F<build> and F<export> directories,
then you can just remove the directories).

The options C<-p>, C<-pa>, and C<-pw> are extremely useful for use as an aid
in reading scripts or debugging them. If you want to know what script
installs F<export/include/foo.h>, for example, just type:

  % cons -pw export/include/foo.h


=head1 Using and writing dependency scanners

QuickScan allows simple target-independent scanners to be set up for source
files. Only one QuickScan scanner may be associated with any given source
file and environment.

QuickScan is invoked as follows:

  QuickScan CONSENV CODEREF, FILENAME [, PATH]

The subroutine referenced by CODEREF is expected to return a list of
filenames included directly by FILE. These filenames will, in turn, be
scanned. The optional PATH argument supplies a lookup path for finding
FILENAME and/or files returned by the user-supplied subroutine.  The PATH
may be a reference to an array of lookup-directory names, or a string of
names separated by the system's separator character (':' on UNIX systems,
';' on Windows NT).

The subroutine is called once for each line in the file, with $_ set to the
current line. If the subroutine needs to look at additional lines, or, for
that matter, the entire file, then it may read them itself, from the
filehandle SCAN. It may also terminate the loop, if it knows that no further
include information is available, by closing the filehandle.

Whether or not a lookup path is provided, QuickScan first tries to lookup
the file relative to the current directory (for the top-level file supplied
directly to QuickScan), or from the directory containing the file which
referenced the file. This is not very general, but seems good
enough--especially if you have the luxury of writing your own utilities and
can control the use of the search path in a standard way. Finally, the
search path is, currently, colon separated. This may not make the NT camp
happy.

Here's a real example, taken from a F<Construct> file here:

  sub cons::SMFgen {
      my($env, @tables) = @_;
      foreach $t (@tables) {
	  $env->QuickScan(sub { /\b\S*?\.smf\b/g }, "$t.smf",
			  $env->{SMF_INCLUDE_PATH});
	  $env->Command(
	      ["$t.smdb.cc","$t.smdb.h","$t.snmp.cc","$t.ami.cc", "$t.http.cc"],
	      "$t.smf",
	      q(
		smfgen %( %SMF_INCLUDE_OPT %) %<
	      )
	  );
      }
  }

[NOTE that the form C<$env-E<gt>QuickScan ...>  and C<$env-E<gt>Command
...> should not be necessary, but, for some reason, is required
for this particular invocation. This appears to be a bug in Perl or
a misunderstanding on my part; this invocation style does not always
appear to be necessary.]

This finds all names of the form <name>.smf in the file. It will return the
names even if they're found within comments, but that's OK (the mechanism is
forgiving of extra files; they're just ignored on the assumption that the
missing file will be noticed when the program, in this example, smfgen, is
actually invoked).

A scanner is only invoked for a given source file if it is needed by some
target in the tree. It is only ever invoked once for a given source file.

Here is another way to build the same scanner. This one uses an
explicit code reference, and also (unecessarily, in this case) reads
the whole file itself:

  sub myscan {
      my(@includes);
      do {
	  push(@includes, /\b\S*?\.smf\b/g);
      } while <SCAN>;
      @includes
  }

Note that the order of the loop is reversed, with the loop test at the
end. This is because the first line is already read for you. This scanner
can be attached to a source file by:

    QuickScan $env \myscan, "$_.smf";

=head1 SUPPORT AND SUGGESTIONS

Cons is maintained by the user community.  To subscribe, send mail to
B<cons-discuss-request@gnu.org> with body B<subscribe>.

Please report any suggestions through the B<cons-discuss@gnu.org> mailing
list.

=head1 BUGS

Sure to be some. Please report any bugs through the B<bug-cons@gnu.org>
mailing list.

=head1 INFORMATION ABOUT CONS

Information about CONS can be obtained from the official cons web site
B<http://www.dsmit.com/cons/> or its mirrors listed there.

The cons maintainers can be contacted by email at
B<cons-maintainers@gnu.org>

=head1 AUTHORS

Originally by Bob Sidebotham. Then significantly enriched by the members
of the Cons community B<cons-discuss@gnu.org>.

The Cons community would like to thank Ulrich Pfeifer for the original pod
documentation derived from the F<cons.html> file. Cons documentation is now
a part of the program itself.

=cut


#:endofperl