Parse::RecDescent 1.94

Parse::RecDescent is a Perl module to generate Recursive-Descent Parsers.
SYNOPSIS
use Parse::RecDescent;
# Generate a parser from the specification in $grammar:
$parser = new Parse::RecDescent ($grammar);
# Generate a parser from the specification in $othergrammar
$anotherparser = new Parse::RecDescent ($othergrammar);
# Parse $text using rule startrule (which must be
# defined in $grammar):
$parser->startrule($text);
# Parse $text using rule otherrule (which must also
# be defined in $grammar):
$parser->otherrule($text);
# Change the universal token prefix pattern
# (the default is: s*):
$Parse::RecDescent::skip = [ t]+;
# Replace productions of existing rules (or create new ones)
# with the productions defined in $newgrammar:
$parser->Replace($newgrammar);
# Extend existing rules (or create new ones)
# by adding extra productions defined in $moregrammar:
$parser->Extend($moregrammar);
# Global flags (useful as command line arguments under -s):
$::RD_ERRORS # unless undefined, report fatal errors
$::RD_WARN # unless undefined, also report non-fatal problems
$::RD_HINT # if defined, also suggestion remedies
$::RD_TRACE # if defined, also trace parsers behaviour
$::RD_AUTOSTUB # if defined, generates "stubs" for undefined rules
$::RD_AUTOACTION # if defined, appends specified action to productions
Parse::RecDescent incrementally generates top-down recursive-descent text parsers from simple yacc-like grammar specifications.
Main features:
- Regular expressions or literal strings as terminals (tokens),
- Multiple (non-contiguous) productions for any rule,
- Repeated and optional subrules within productions,
- Full access to Perl within actions specified as part of the grammar,
- Simple automated error reporting during parser generation and parsing,
- The ability to commit to, uncommit to, or reject particular productions during a parse,
- The ability to pass data up and down the parse tree ("down" via subrule argument lists, "up" via subrule return values)
- Incremental extension of the parsing grammar (even during a parse),
- Precompilation of parser objects,
- User-definable reduce-reduce conflict resolution via "scoring" of matching productions.