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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/cpp/Traditional-lexical-analysis.html | |
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diff --git a/share/doc/cpp/Traditional-lexical-analysis.html b/share/doc/cpp/Traditional-lexical-analysis.html new file mode 100644 index 0000000..b4e4ccb --- /dev/null +++ b/share/doc/cpp/Traditional-lexical-analysis.html @@ -0,0 +1,155 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1987-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation. A copy of +the license is included in the +section entitled "GNU Free Documentation License". + +This manual contains no Invariant Sections. The Front-Cover Texts are +(a) (see below), and the Back-Cover Texts are (b) (see below). + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>The C Preprocessor: Traditional lexical analysis</title> + +<meta name="description" content="The C Preprocessor: Traditional lexical analysis"> +<meta name="keywords" content="The C Preprocessor: Traditional lexical analysis"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Index-of-Directives.html#Index-of-Directives" rel="index" title="Index of Directives"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Traditional-Mode.html#Traditional-Mode" rel="up" title="Traditional Mode"> +<link href="Traditional-macros.html#Traditional-macros" rel="next" title="Traditional macros"> +<link href="Traditional-Mode.html#Traditional-Mode" rel="previous" title="Traditional Mode"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Traditional-lexical-analysis"></a> +<div class="header"> +<p> +Next: <a href="Traditional-macros.html#Traditional-macros" accesskey="n" rel="next">Traditional macros</a>, Up: <a href="Traditional-Mode.html#Traditional-Mode" accesskey="u" rel="up">Traditional Mode</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Traditional-lexical-analysis-1"></a> +<h3 class="section">10.1 Traditional lexical analysis</h3> + +<p>The traditional preprocessor does not decompose its input into tokens +the same way a standards-conforming preprocessor does. The input is +simply treated as a stream of text with minimal internal form. +</p> +<p>This implementation does not treat trigraphs (see <a href="Initial-processing.html#trigraphs">trigraphs</a>) +specially since they were an invention of the standards committee. It +handles arbitrarily-positioned escaped newlines properly and splices +the lines as you would expect; many traditional preprocessors did not +do this. +</p> +<p>The form of horizontal whitespace in the input file is preserved in +the output. In particular, hard tabs remain hard tabs. This can be +useful if, for example, you are preprocessing a Makefile. +</p> +<p>Traditional CPP only recognizes C-style block comments, and treats the +‘<samp>/*</samp>’ sequence as introducing a comment only if it lies outside +quoted text. Quoted text is introduced by the usual single and double +quotes, and also by an initial ‘<samp><</samp>’ in a <code>#include</code> +directive. +</p> +<p>Traditionally, comments are completely removed and are not replaced +with a space. Since a traditional compiler does its own tokenization +of the output of the preprocessor, this means that comments can +effectively be used as token paste operators. However, comments +behave like separators for text handled by the preprocessor itself, +since it doesn’t re-lex its input. For example, in +</p> +<div class="smallexample"> +<pre class="smallexample">#if foo/**/bar +</pre></div> + +<p>‘<samp>foo</samp>’ and ‘<samp>bar</samp>’ are distinct identifiers and expanded +separately if they happen to be macros. In other words, this +directive is equivalent to +</p> +<div class="smallexample"> +<pre class="smallexample">#if foo bar +</pre></div> + +<p>rather than +</p> +<div class="smallexample"> +<pre class="smallexample">#if foobar +</pre></div> + +<p>Generally speaking, in traditional mode an opening quote need not have +a matching closing quote. In particular, a macro may be defined with +replacement text that contains an unmatched quote. Of course, if you +attempt to compile preprocessed output containing an unmatched quote +you will get a syntax error. +</p> +<p>However, all preprocessing directives other than <code>#define</code> +require matching quotes. For example: +</p> +<div class="smallexample"> +<pre class="smallexample">#define m This macro's fine and has an unmatched quote +"/* This is not a comment. */ +/* <span class="roman">This is a comment. The following #include directive + is ill-formed.</span> */ +#include <stdio.h +</pre></div> + +<p>Just as for the ISO preprocessor, what would be a closing quote can be +escaped with a backslash to prevent the quoted text from closing. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Traditional-macros.html#Traditional-macros" accesskey="n" rel="next">Traditional macros</a>, Up: <a href="Traditional-Mode.html#Traditional-Mode" accesskey="u" rel="up">Traditional Mode</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |