Class: Citrus::Choice

Inherits:
Object show all
Includes:
Nonterminal
Defined in:
lib/citrus.rb

Overview

A Choice is a Nonterminal where only one rule must match. The Citrus notation is two or more expressions separated by a vertical bar, e.g.:

expr | expr

Instance Attribute Summary

Attributes included from Nonterminal

#rules

Attributes included from Rule

#extension, #grammar, #label, #name

Instance Method Summary collapse

Methods included from Nonterminal

#grammar=, #initialize

Methods included from Rule

#==, #===, #default_options, #extend_match, for, #inspect, #needs_paren?, #parse, #terminal?, #test, #to_embedded_s, #to_s

Instance Method Details

#elide? ⇒ Boolean

Returns true if this rule should extend a match but should not appear in its event stream.

Returns:

  • (Boolean) 


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# File 'lib/citrus.rb', line 1260

def elide? # :nodoc:
  true
end

#exec(input, events = []) ⇒ Object

Returns an array of events for this rule on the given input.



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# File 'lib/citrus.rb', line 1237

def exec(input, events=[])
  events << self

  index = events.size
  n = 0
  m = rules.length

  while n < m && input.exec(rules[n], events).size == index
    n += 1
  end

  if index < events.size
    events << CLOSE
    events << events[-2]
  else
    events.pop
  end

  events
end

#to_citrus ⇒ Object

Returns the Citrus notation of this rule as a string.



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# File 'lib/citrus.rb', line 1265

def to_citrus # :nodoc:
  rules.map {|r| r.to_embedded_s }.join(' | ')
end