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# An exploration of two ideas:
# a) Constructing a whole parser inline, without the artificial class around
# it.
# and:
# b) Constructing non-greedy or non-blind parsers by transforming the
# grammar.
$:.unshift File.dirname(__FILE__) + "/../lib"
require 'parslet'
include Parslet
a = str('a').repeat >> str('aa')
# E1% E2
# S = E2 | E1 S
def this(name, &block); return, &block) end
def epsilon; any.absent? end
# Traditional repetition will try as long as the pattern can be matched and
# then give up. This is greedy and blind.
a = str('a').as(:e) >> this('a') { a }.as(:rec) | epsilon
# Here's a pattern match that is greedy and non-blind. The first pattern
# 'a'* will be tried as many times as possible, while still matching the
# end pattern 'aa'.
b = str('aa').as(:e2) >> epsilon | str('a').as(:e1) >> this('b') { b }.as(:rec)
p a.parse('aaaa')
p b
p b.parse('aaaa')