NAME
MarpaX::ESLIF::Grammar - MarpaX::ESLIF's grammar
VERSION
version 2.0.7
SYNOPSIS
use MarpaX::ESLIF;
my $eslif = MarpaX::ESLIF->new();
my $data = do { local $/; <DATA> };
my $eslifGrammar = MarpaX::ESLIF::Grammar->new($eslif, $data);
__DATA__
#
# This is an example of a calculator grammar
#
:start ::= Expression
:default ::= action => do_op
symbol-action => do_symbol
free-action => do_free # Supported but useless
:desc ::= 'Calculator'
:discard ::= whitespaces event => discard_whitespaces$
:discard ::= comment event => discard_comment$
event ^Number = predicted Number
event Number$ = completed Number
Number ::= NUMBER action => ::shift
event Expression$ = completed Expression
event ^Expression = predicted Expression
Expression ::=
Number action => do_int
| '(' Expression ')' assoc => group action => ::copy[1]
|| Expression '**' Expression assoc => right
|| Expression '*' Expression
| Expression '/' Expression
|| Expression '+' Expression
| Expression '-' Expression
whitespaces ::= WHITESPACES
comment ::= /(?:(?:(?:\/\/)(?:[^\n]*)(?:\n|\z))|(?:(?:\/\*)(?:(?:[^\*]+|\*(?!\/))*)(?:\*\/)))/u
:lexeme ::= NUMBER pause => before event => ^NUMBER
:lexeme ::= NUMBER pause => after event => NUMBER$
:desc ~ 'Calculator Tokens'
NUMBER ~ /[\d]+/ name => 'NUMBER Lexeme'
WHITESPACES ~ [\s]+ name => 'WHITESPACES Lexeme'As many grammars as wanted can be created using the same MarpaX::ESLIF parent. After creating a MarpaX::ESLIF::Grammar instance, the user can use the parse() method to have an immediate parse value, or create a MarpaX::ESLIF::Recognizer instance to control the parse.
DESCRIPTION
MarpaX::ESLIF::Grammar is the second step after getting a MarpaX::ESLIF instance.
METHODS
MarpaX::ESLIF::Grammar->new($eslif, $grammar, $encoding)
my $eslifGrammar = MarpaX::ESLIF::Grammar->new($eslif, $data);Returns a grammar instance, noted $eslifGrammar later. Parameters are:
$eslif-
MarpaX::ESLIF object instance. Required.
$grammar-
A scalar containing the grammar. Required.
$encoding-
A scalar containing the grammar encoding. Optional.
Encoding will always be guessed if not given.
$eslifGrammar->ngrammar()
printf "Number of sub-grammars: %d\n", $eslifGrammar->ngrammar;Return the number of sub-grammars.
A grammar can have multiple sub-grammars, identified by a level. Internally this is a sparse array of grammars, and it is legal that a level is not defined.
$eslifGrammar->currentLevel()
printf "Current indice: %d\n", $eslifGrammar->currentLevel;Return the current level, which is always the first indice that have a defined sub-grammar.
$eslifGrammar->currentDescription()
printf "Current description: %s\n", $eslifGrammar->currentDescription;Return the description of the current level, with the same encoding as found in the grammar. This correspong to the :desc meta-symbol in a grammar.
$eslifGrammar->descriptionByLevel($level)
printf "Level 1 description: %s\n", $eslifGrammar->descriptionByLevel(1);Return the description of the grammar at indice $level, with the same encoding as found in the grammar.
$eslifGrammar->currentRuleIds
printf "Current Rule Ids: %s\n", join(' ', @{$eslifGrammar->currentRuleIds});Return the list of rule identifiers of the current grammar, as a reference to an array of integers.
Rule identifiers are integers that uniquely identify a rule.
$eslifGrammar->ruleIdsByLevel($level)
printf "Level 1 Rule Ids: %s\n", join(' ', @{$eslifGrammar->ruleIdsByLevel(1)});Return the list of rule identifiers at indice $level, as a reference to an array of integers.
$eslifGrammar->ruleDisplay($ruleId)
printf "Rules names:\n\t%s\n", join("\n\t", map { $eslifGrammar->ruleDisplay($_) } @{$eslifGrammar->currentRuleIds});Return the name of a rule identified by its rule ID $ruleId.
$eslifGrammar->ruleShow($ruleId)
printf "Rules shows:\n\t%s\n", join("\n\t", map { $eslifGrammar->ruleShow($_) } @{$eslifGrammar->currentRuleIds});Return the description of a rule identified by its rule ID $ruleId.
$eslifGrammar->ruleDisplayByLevel($level, $ruleId)
printf "Level 1 Rule names 1:\n\t%s\n", join("\n\t", map { $eslifGrammar->ruleDisplayByLevel(1, $_) } @{$eslifGrammar->ruleIdsByLevel(1)});Return the name of a rule at a specificed indice $level identified by its rule ID $ruleId. This correspond to the name adverb, if present, else a default naming applies.
$eslifGrammar->ruleShowByLevel($level, $ruleId)
printf "Level 1 Rules shows:\n\t%s\n", join("\n\t", map { $eslifGrammar->ruleShowByLevel(1, $_) } @{$eslifGrammar->ruleIdsByLevel(1)});Return the description of a rule at a specified indice $level, identified by its rule ID $ruleId.
$eslifGrammar->show()
printf "Description of current grammar: %s\n", $eslifGrammar->show();Return the description of current grammar.
$eslifGrammar->showByLevel($level)
printf "Level 1 grammar description: %s\n", $eslifGrammar->showByLevel(1);Return the description of the grammar at indice $level.
$eslifGrammar->parse($recognizerInterface, $valueInterface)
my $recognizerInterface = MyRecognizer->new();
my $valueInterface = MyValue->new();
if ($eslifGrammar->parse($recognizerInterface, $valueInterface)) {
printf "Parse result: %s\n", $valueInterface->getResult;
}Short version of input validation and valuation, that will never give back control to the user until the end or a failure. No event is possible when using this method. If this method returns true, then it is guaranteed that the result is in $valueInterface-getResult()>.
Please refer to MarpaX::ESLIF::Recognizer::Interface and MarpaX::ESLIF::Value::Interface for the $recognizerInterface and $valueInterface required parameters.
SEE ALSO
MarpaX::ESLIF::Recognizer::Interface, MarpaX::ESLIF::Recognizer::Interface, MarpaX::ESLIF::Value::Interface
AUTHOR
Jean-Damien Durand <jeandamiendurand@free.fr>
COPYRIGHT AND LICENSE
This software is copyright (c) 2017 by Jean-Damien Durand.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.