95 lines
4.3 KiB
HTML
95 lines
4.3 KiB
HTML
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<!DOCTYPE html>
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<html>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<!-- This manual documents Guile version 3.0.10.
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Inc.
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
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copy of the license is included in the section entitled "GNU Free
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Documentation License." -->
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<title>PEG Parsing (Guile Reference Manual)</title>
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<meta name="description" content="PEG Parsing (Guile Reference Manual)">
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<link href="index.html" rel="start" title="Top">
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="API-Reference.html" rel="up" title="API Reference">
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<link href="Read_002fLoad_002fEval_002fCompile.html" rel="next" title="Read/Load/Eval/Compile">
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<link href="LALR_00281_0029-Parsing.html" rel="prev" title="LALR(1) Parsing">
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</head>
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<body lang="en">
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<div class="section-level-extent" id="PEG-Parsing">
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<div class="nav-panel">
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<p>
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Next: <a href="Read_002fLoad_002fEval_002fCompile.html" accesskey="n" rel="next">Reading and Evaluating Scheme Code</a>, Previous: <a href="LALR_00281_0029-Parsing.html" accesskey="p" rel="prev">LALR(1) Parsing</a>, Up: <a href="API-Reference.html" accesskey="u" rel="up">API Reference</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<h3 class="section" id="PEG-Parsing-1"><span>6.15 PEG Parsing<a class="copiable-link" href="#PEG-Parsing-1"> ¶</a></span></h3>
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<p>Parsing Expression Grammars (PEGs) are a way of specifying formal
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languages for text processing. They can be used either for matching
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(like regular expressions) or for building recursive descent parsers
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(like lex/yacc). Guile uses a superset of PEG syntax that allows more
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control over what information is preserved during parsing.
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</p>
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<p>Wikipedia has a clear and concise introduction to PEGs if you want to
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familiarize yourself with the syntax:
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<a class="url" href="http://en.wikipedia.org/wiki/Parsing_expression_grammar">http://en.wikipedia.org/wiki/Parsing_expression_grammar</a>.
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</p>
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<p>The <code class="code">(ice-9 peg)</code> module works by compiling PEGs down to lambda
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expressions. These can either be stored in variables at compile-time by
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the define macros (<code class="code">define-peg-pattern</code> and
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<code class="code">define-peg-string-patterns</code>) or calculated explicitly at runtime
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with the compile functions (<code class="code">compile-peg-pattern</code> and
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<code class="code">peg-string-compile</code>).
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</p>
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<p>They can then be used for either parsing (<code class="code">match-pattern</code>) or searching
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(<code class="code">search-for-pattern</code>). For convenience, <code class="code">search-for-pattern</code>
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also takes pattern literals in case you want to inline a simple search
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(people often use regular expressions this way).
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</p>
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<p>The rest of this documentation consists of a syntax reference, an API
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reference, and a tutorial.
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</p>
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<ul class="mini-toc">
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<li><a href="PEG-Syntax-Reference.html" accesskey="1">PEG Syntax Reference</a></li>
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<li><a href="PEG-API-Reference.html" accesskey="2">PEG API Reference</a></li>
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<li><a href="PEG-Tutorial.html" accesskey="3">PEG Tutorial</a></li>
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<li><a href="PEG-Internals.html" accesskey="4">PEG Internals</a></li>
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</ul>
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</div>
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</body>
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</html>
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