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
|
<HTML>
<!--
***********************************************************************
FUNNELWEB MANUAL WEB PAGE
=========================
Copyright (c) Ross N. Williams 1992,1999. All rights reserved.
Permission is granted to redistribute and use this manual in
any medium, with or without modification, provided that all
notices (including, without limitation, the copyright
notice, this permission notice, any record of modification,
and all legal notices) are preserved on all copies, that all
modifications are clearly marked, and that modified versions
are not represented as the original version unless all the
modifications since the manual's original release by Ross N.
Williams (www.ross.net) consist of translations or other
transformations that alter only the manual's form, not its
content. THIS MANUAL IS PROVIDED "AS IS" AND WITHOUT ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND
FITNESS FOR A PARTICULAR PURPOSE. TO THE EXTENT PERMITTED BY
LAW THERE IS ABSOLUTELY NO WARRANTY.
***********************************************************************
-->
<HEAD>
<TITLE>3.2 Special Sequences</TITLE>
<STYLE TYPE="text/css"> <!-- A {text-decoration: none} // --> </STYLE>
</HEAD>
<BODY BACKGROUND="binary/background.gif"
BGCOLOR="#FFFFFF"
TEXT="#000000"
VLINK="#660000"
LINK="#FF0000"
ALINK="#CC0000">
<TABLE WIDTH="490">
<TR>
<TD WIDTH="130" VALIGN="top">
<IMG SRC="binary/d_clear.gif" ALT="" WIDTH="130" HEIGHT="1"><BR>
<FONT SIZE="2">
<BR>
<A HREF="http://www.ross.net/"
TARGET="rosshome"
onClick="window.open('','rosshome','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
>
<IMG SRC="binary/rossnet_logo.gif"
WIDTH="64" HEIGHT="32"
BORDER="0" ALT="RossNet"
HSPACE="0" VSPACE="1"></A><BR>
<BR>
<A HREF="../index.shtml"
TARGET="funnelweb"
onClick="window.open('','funnelweb','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
>
<IMG SRC="binary/linklogo.gif"
WIDTH="64" HEIGHT="32"
BORDER="0" ALT="FunnelWeb"
HSPACE="0" VSPACE="1"></A><BR>
<BR>
<TABLE CELLSPACING=0 CELLPADDING=0 BORDER=0><TR><TD BGCOLOR="#000000">
<A HREF="../tutorial/index.html"
TARGET="funnelwebtutorial"
onClick="window.open('','funnelwebtutorial','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
><FONT COLOR="#FFFFFF"><B>Tutorial</B></FONT></A><BR>
<BR>
<A HREF="../developer/index.html"
TARGET="funnelwebdeveloper"
onClick="window.open('','funnelwebdeveloper','location,status,menubar,scrollbars,resizable',false).focus(); return true;"
><FONT COLOR="#FFFFFF"><B>Developer</B></FONT></A><BR>
<BR>
<A HREF="index.html"><FONT COLOR="#FFFFFF"><B>Reference</B></FONT></A><BR>
<A HREF="intro.html"><FONT COLOR="#FFFFFF">1 Introduction</FONT></A><BR>
<A HREF="interface.html"><FONT COLOR="#FFFFFF">2 Interface</FONT></A><BR>
<A HREF="scanner.html"><FONT COLOR="#FFFFFF">3 Scanner</FONT></A><BR>
<A HREF="parser.html"><FONT COLOR="#FFFFFF">4 Parser</FONT></A><BR>
<A HREF="analyser.html"><FONT COLOR="#FFFFFF">5 Analyser</FONT></A><BR>
<A HREF="tangle.html"><FONT COLOR="#FFFFFF">6 Tangle</FONT></A><BR>
<A HREF="weave.html"><FONT COLOR="#FFFFFF">7 Weave</FONT></A><BR>
<A HREF="shell.html"><FONT COLOR="#FFFFFF">8 Shell</FONT></A><BR>
<A HREF="commands.html"><FONT COLOR="#FFFFFF">9 Commands</FONT></A><BR>
<A HREF="glossary.html"><FONT COLOR="#FFFFFF">10 Glossary</FONT></A><BR>
<A HREF="references.html"><FONT COLOR="#FFFFFF">11 References</FONT></A><BR>
<BR>
<A HREF="search.html"><FONT COLOR="#FFFFFF"><B>SEARCH</B></FONT></A><BR>
</FONT>
</TD></TR></TABLE>
</TD>
<TD WIDTH="360" VALIGN="top">
<FONT SIZE="3">
<A HREF="index.html"><IMG SRC="binary/title.gif"
WIDTH="316" HEIGHT="24"
BORDER="0" ALT="FunnelWeb Reference Manual"
HSPACE="0" VSPACE="0"></A>
<P><FONT SIZE="5">3.2 Special Sequences</FONT><BR>
<P>The scanner scans the input file from top to bottom,
left to right, treating the input as ordinary text (to be
handed directly to the parser as a text token) unless it
encounters the <STRONG>special character</STRONG> which
introduces a <STRONG>special sequence</STRONG>. Thus, the
scanner partitions the input file into ordinary text and
special sequences. (Note: This sort of character is often
referred to as the "escape character" or the
"control character" in other systems. However, as
there is great potential to confuse these names with the
"escape" character (ASCII 27) and ASCII
"control" characters, the term "special" has
been chosen instead. This results in the terms
<I>special character</I> and <I>special sequence</I> .
<P>
<PRE>
input_file = { ordinary_text | special_sequence }
</PRE>
<P>Upon startup, the special
character is
<SAMP>@</SAMP>, but it can be changed using the
<special><SAMP>=</SAMP><new_special> special sequence.
Rather than using <special> whenever the special
character appears, this document uses the default special
character "<TT>@</TT>" to represent the current special
character. More importantly, FunnelWeb's error messages all
use the default special character in examples,
even if the special character has been changed.
<P>An occurrence of the special character in the input
file introduces a special sequence. The kind of special
sequence is determined by the character following the
special character. Only printable characters can follow the
special character.
<P>The following list gives all the possible characters
that can follow the special character, and the legality of
each sequence. The first column gives the ASCII number of
each ASCII character. The second column gives the special
sequence for that character. The next column contains one of
three characters: "<TT>-</TT>" means that the sequence is
illegal. "<TT>S</TT>" indicates that the sequence is a
<STRONG>simple sequence</STRONG> (with no attributes or side
effects) that appears exactly as shown and is converted
directly into a token and fed to the parser. Finally,
"<TT>C</TT>" indicates that the special sequence is complex,
possibly having a following syntax or producing funny side
effects.
<P>
<PRE>
ASC SEQ COMMENT
-----------------
000 \
016 | Unprintable chars (illegal specials).
031 /
032 @ - Illegal (space).
033 @! C Comment.
034 @" S Parameter delimeter.
035 @# C Short name sequence.
036 @$ S Start of macro definition.
037 @% - Illegal.
038 @& - Illegal.
039 @' - Illegal.
040 @( S Open parameter list.
041 @) S Close parameter list.
042 @* - Illegal.
043 @+ C Insert newline.
044 @, S Parameter separator.
045 @- C Suppress end of line marker.
046 @. - Illegal.
047 @/ S Open or close emphasised text.
048 @0 - Illegal.
049 @1 S Formal parameter 1.
050 @2 S Formal parameter 2.
051 @3 S Formal parameter 3.
052 @4 S Formal parameter 4.
053 @5 S Formal parameter 5.
054 @6 S Formal parameter 6.
055 @7 S Formal parameter 7.
056 @8 S Formal parameter 8.
057 @9 S Formal parameter 9.
058 @: - Illegal.
059 @; - Illegal.
060 @< S Open macro name.
061 @= C Set special character.
062 @> S Close macro name.
063 @? - Illegal. Reserved for future use.
064 @@ C Insert special character into text.
065 @A S New section (level 1).
066 @B S New section (level 2).
067 @C S New section (level 3).
068 @D S New section (level 4).
069 @E S New section (level 5).
070 @F - Illegal.
071 @G - Illegal.
072 @H - Illegal.
073 @I C Include file.
074 @J - Illegal.
075 @K - Illegal.
076 @L S Macro is library macro.
077 @M S Macro may be called many times.
078 @N - Illegal.
079 @O S Macro is attached to product file.
080 @P C Pragma.
081 @Q - Illegal.
082 @R - Illegal.
083 @S - Illegal.
084 @T C Typesetter directive.
085 @U - Illegal.
086 @V - Illegal.
087 @W - Illegal.
088 @X - Illegal.
089 @Y - Illegal.
090 @Z S Macro may be called zero times.
091 @[ - Illegal. Reserved for future use.
092 @\ - Illegal.
093 @] - Illegal. Reserved for future use.
094 @^ C Insert control character into text
095 @_ - Illegal.
096 @` - Illegal.
097 @a \
109 @m | Identical to @A..@Z.
122 @z /
123 @{ S Open macro body/Open literal directive.
124 @| - Illegal.
125 @} S Close macro body/Close literal directive.
126 @~ - Illegal.
127 to 255 - Illegal specials (as non-standard ASCII).
</PRE>
<P>The most important thing to remember about the scanner
is that <I>nothing happens unless the special character
is seen.</I> There are no funny sequences that will cause
strange things to happen. The best way to view a FunnelWeb
document at the scanner level is as a body of text
punctuated by special sequences that serve to structure the
text at a higher level.
<P>The remaining description of the scanner consists of a
detailed description of the effect of each complex special
sequence.
<P>
<TABLE WIDTH="100%">
<TR>
<TD ALIGN="left" VALIGN="bottom"><A HREF="scanner_basic.html"><IMG SRC="binary/fw_left.gif" HEIGHT="32" WIDTH="32" BORDER="0" ALT="Prev"></A></TD>
<TD ALIGN="center" VALIGN="bottom"><A HREF="scanner.html"><IMG SRC="binary/fw_up.gif" HEIGHT="32" WIDTH="32" BORDER="0" ALT="Up"></A></TD>
<TD ALIGN="right" VALIGN="bottom"><A HREF="scanner_special_set.html"><IMG SRC="binary/fw_right.gif" HEIGHT="32" WIDTH="32" BORDER="0" ALT="Next"></A></TD>
</TR>
</TABLE>
<P>
<HR>
<FONT SIZE="2">
<A HREF="mailto:webmaster@ross.net">Webmaster</A>
<A HREF="copyright.html">Copyright © Ross N. Williams 1992,1999. All rights reserved.</A><BR>
</FONT>
</FONT>
</TD>
</TR>
</TABLE>
</FONT>
</BODY>
<!-- *********************************************************************** -->
<!-- End Of A FunnelWeb Manual Web Page (www.ross.net/funnelweb/) -->
<!-- *********************************************************************** -->
</HTML>
|
