Mercurial > ~dholland > hg > ag > index.cgi

annotate doc/misc/html/examples/mpp/ex.html @ 21:1c9dac05d040

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add lint-style FALLTHROUGH annotations to fallthrough cases. (in the parse engine and thus the output code) Document this, because the old output causes warnings with gcc10.
author David A. Holland
date Mon, 13 Jun 2022 00:04:38 -0400
parents 13d2b8934445
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
0
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
2 <HTML>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
3 <HEAD>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
4 <TITLE>Expression Evaluator - Macro preprocessor and C Parser </TITLE>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
5 </HEAD>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
6
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
7
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
8 <BODY BGCOLOR="#ffffff" BACKGROUND="tilbl6h.gif"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
9 TEXT="#000000" LINK="#0033CC"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
10 VLINK="#CC0033" ALINK="#CC0099">
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
11
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
12 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
13 <IMG ALIGN="right" SRC="../../images/agrsl6c.gif" ALT="AnaGram"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
14 WIDTH=124 HEIGHT=30 >
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
15 <BR CLEAR="all">
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
16 Back to :
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
17 <A HREF="../../index.html">Index</A> |
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
18 <A HREF="index.html">Macro preprocessor overview</A>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
19 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
20
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
21
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
22 <IMG ALIGN="bottom" SRC="../../images/rbline6j.gif" ALT="----------------------"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
23 WIDTH=1010 HEIGHT=2 >
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
24 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
25 <H1> Expression Evaluator - Macro preprocessor and C Parser </H1>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
26
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
27 <IMG ALIGN="bottom" SRC="../../images/rbline6j.gif" ALT="----------------------"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
28 WIDTH=1010 HEIGHT=2 >
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
29 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
30 <BR>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
31
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
32 <H2>Introduction</H2>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
33 <P> The Expression Evaluator module, <tt>ex.syn</tt>, exists only to
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
34 evaluate the conditional expressions in <tt>#if</tt> and
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
35 <tt>#elif</tt>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
36 statements. The syntax for these expressions has been
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
37 extracted from a full C syntax and reduced to that which is
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
38 necessary for this purpose.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
39 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
40 The rules for the evaluation of constant expressions are
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
41 given in Kernighan and Ritchie, sections A7.19 and A12.5
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
42 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
43 <BR>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
44
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
45 <H2>Theory of Operation</H2>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
46 The only unusual feature of this grammar is the
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
47 interposition of a token called "nonzero" to avoid division
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
48 by zero. Otherwise the grammar is a conventional expression
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
49 grammar.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
50 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
51 The parser is implemented as an event driven parser. The
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
52 initializer is <tt>init_ex()</tt>. The parser itself is
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
53 <tt>ex()</tt>. The
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
54 parser has been interfaced to the rest of the program by a
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
55 class definition, <tt>expression_evaluator</tt>.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
56 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
57 The class definition for <tt>expression_evaluator</tt> is given in
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
58 <tt>mpp.h</tt>. Each instance of the class has its own parser control
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
59 block. Therefore the parser makes all of its references
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
60 indirectly through a pointer, <tt>ex_pcb</tt>. Whenever it is
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
61 necessary to invoke <tt>init_ex()</tt> or <tt>ex()</tt>,
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
62 therefore, it is
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
63 necessary first to make sure <tt>ex_pcb</tt> is correctly set.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
64 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
65 Input to the parser consists of tokens as defined in
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
66 <tt>token.h</tt>. Since the input does not consist of simple
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
67 characters, the <b>input values</b> switch is set. The input
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
68 procedures store the full token into the input_value field
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
69 of the pcb and the id field into input_code.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
70
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
71 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
72
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
73 <BR>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
74
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
75
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
76 <IMG ALIGN="bottom" SRC="../../images/rbline6j.gif" ALT="----------------------"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
77 WIDTH=1010 HEIGHT=2 >
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
78 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
79 <IMG ALIGN="right" SRC="../../images/pslrb6d.gif" ALT="Parsifal Software"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
80 WIDTH=181 HEIGHT=25>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
81 <BR CLEAR="right">
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
82
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
83 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
84 Back to :
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
85 <A HREF="../../index.html">Index</A> |
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
86 <A HREF="index.html">Macro preprocessor overview</A>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
87
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
88 <P>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
89 <ADDRESS><FONT SIZE="-1">
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
90 AnaGram parser generator - examples<BR>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
91 Expression Evaluator - Macro preprocessor and C Parser <BR>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
92 Copyright &copy; 1993-1999, Parsifal Software. <BR>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
93 All Rights Reserved.<BR>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
94 </FONT></ADDRESS>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
95
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
96 </BODY>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
97 </HTML>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
98
13d2b8934445 Import AnaGram (near-)release tree into Mercurial.
David A. Holland
parents:
diff changeset
99