Parsing with Perl 6 Regexes and Grammars by Moritz Lenz

Author:Moritz Lenz
Language: eng
Format: epub
Publisher: Apress, Berkeley, CA

Here the implicit <.ws> between a and b doesn’t match, so the rule as a whole does not match either.

8.3 8.3 Grammars

Named regexes offer a first level of abstraction, but we often want more than one level. Most high-level programming languages have modules, namespaces, classes, or even all three to manage reuse of functions and methods.

Perl 6 offers these higher-level abstractions too, and makes them available to regexes. A grammar is a class that offers some tools for invoking regexes. Regexes are then methods in this grammar:

grammar IPv4Address {

token byte {

\d ** 1..3

<?{ $/.Int <= 255 }>

}

token TOP {

<byte> ** 4 % '.'

}

}

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