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
|
<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>3.11 Pragmas</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">3.11 Pragmas</FONT><BR>
<P>Most tools have to support some essential, but rather
inelegant features. In FunnelWeb these messy bits have all
been stuffed into the scanner's <STRONG>pragma</STRONG> (for
<I>pragma</I> tic) construct.
<P>A pragma consists of a single line of input (including
the EOL) commencing with <SAMP>@p</SAMP>. This must be followed
by a single space, and then the pragma verb. This must be
followed by a sequence of zero or more arguments separated
by one or more spaces. Four pragmas are available
<P>
<PRE>
pragma = pragma_ident | pragma_mill |
pragma_moll | pragma_typesetter
</PRE>
The following syntax definitions assist in defining the pragmas.
<P>
<PRE>
s = {" "}+
ps = ("@p" | "@P") " "
number = { decimal_digit }+
numorinf = number | "infinity"
</PRE>
<P>The arguments to pragmas are case-sensitive and must be
specified in lower case.
<P>Pragmas are processed and consumed entirely by the
scanner. The parser never sees them and so they can play no
part in the parser level syntax. As a result, pragma lines
can appear anywhere in the entire input file regardless of
the surrounding context (e.g. even in the middle of a macro
definition). The sole effect of a pragma is to modify some
internal parameter of FunnelWeb.
<P>The following sections describe the four FunnelWeb pragmas.
<P>
<TABLE WIDTH="100%">
<TR>
<TD ALIGN="left" VALIGN="bottom"><A HREF="scanner_include.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_prag_ind.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>
|
