1Pegex::Compiler(3) User Contributed Perl Documentation Pegex::Compiler(3)
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6 Pegex::Compiler - Pegex Compiler
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9 use Pegex::Compiler;
10 my $grammar_text = '... grammar text ...';
11 my $pegex_compiler = Pegex::Compiler->new();
12 my $grammar_tree = $pegex_compiler->compile($grammar_text)->tree;
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14 or:
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16 perl -Ilib -MYourGrammarModule=compile
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19 The Pegex::Compiler transforms a Pegex grammar string (or file) into a
20 compiled form. The compiled form is known as a grammar tree, which is
21 simply a nested data structure.
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23 The grammar tree can be serialized to YAML, JSON, Perl, or any other
24 programming language. This makes it extremely portable. Pegex::Grammar
25 has methods for serializing to all these forms.
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27 NOTE: Unless you are developing Pegex based modules, you can safely
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29 this module. Even if you are you probably won't use it directly.
30 See [In
31 Place Compilation] below.
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34 The following public methods are available:
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36 "$compiler = Pegex::Compiler->new();"
37 Return a new Pegex::Compiler object.
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39 "$grammar_tree = $compiler->compile($grammar_input);"
40 Compile a grammar text into a grammar tree that can be used by a
41 Pegex::Parser. This method is calls the "parse" and "combinate"
42 methods and returns the resulting tree.
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44 Input can be a string, a string ref, a file path, a file handle, or
45 a Pegex::Input object. Return $self so you can chain it to other
46 methods.
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48 "$compiler->parse($grammar_text)"
49 The first step of a "compile" is "parse". This applies the Pegex
50 language grammar to your grammar text and produces an unoptimized
51 tree.
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53 This method returns $self so you can chain it to other methods.
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55 "$compiler->combinate()"
56 Before a Pegex grammar tree can be used to parse things, it needs
57 to be combinated. This process turns the regex tokens into real
58 regexes. It also combines some rules together and eliminates rules
59 that are not needed or have been combinated. The result is a Pegex
60 grammar tree that can be used by a Pegex::Parser.
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62 NOTE: While the parse phase of a compile is always the same for
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64 programming languages, the combinate phase takes into
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66 special needs of the target language. Pegex::Compiler only
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68 for Perl, although this is often sufficient in similar
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70 Ruby or Python (PCRE based regexes). Languages like Java
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72 to use their own combinators.
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74 "$compiler->tree()"
75 Return the current state of the grammar tree (as a hash ref).
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77 "$compiler->to_yaml()"
78 Serialize the current grammar tree to YAML.
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80 "$compiler->to_json()"
81 Serialize the current grammar tree to JSON.
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83 "$compiler->to_perl()"
84 Serialize the current grammar tree to Perl.
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87 When you write a Pegex based module you will want to precompile your
88 grammar into Perl so that it has no load penalty. Pegex::Grammar
89 provides a special mechanism for this. Say you have a class like this:
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91 package MyThing::Grammar;
92 use Pegex::Base;
93 extends 'Pegex::Grammar';
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95 use constant file => '../mything-grammar-repo/mything.pgx';
96 sub make_tree {
97 }
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99 Simply use this command:
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101 perl -Ilib -MMyThing::Grammar=compile
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103 and Pegex::Grammar will call Pegex::Compile to put your compiled
104 grammar inside your "tree" subroutine. It will actually write the text
105 into your module. This makes it trivial to update your grammar module
106 after making changes to the grammar file.
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108 See Pegex::JSON for an example.
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111 Ingy döt Net <ingy@cpan.org>
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114 Copyright 2010-2018. Ingy döt Net.
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116 This program is free software; you can redistribute it and/or modify it
117 under the same terms as Perl itself.
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119 See <http://www.perl.com/perl/misc/Artistic.html>
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123perl v5.28.1 2018-11-12 Pegex::Compiler(3)