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Contents
# frozen_string_literal: true
require_relative '../lang/zenlish_grammar'
module Zenlish
class ZParser
# @!attribute [r] engine
# @return [Rley::Engine] Facade object of Rley library
attr_reader(:engine)
def initialize
# Create a Rley facade object
@engine = Rley::Engine.new do |config|
config.diagnose = true
end
# Step 1. Load Zenlish grammar
@engine.use_grammar(ZenlishGrammar)
end
# Parse the sequence of words into a parse tree.
# @raise [StandardError] Fails when the parse is ambiguous.
# @return [Rley::PTree;;ParseTree] the resulting parse tree.
def parse(tokenSeq)
result = earley_parse(tokenSeq)
# Convert into a parse tree
engine.to_ptree(result)
end
alias to_ptree parse
# Parse the sequence of words into a parse forest.
# Parse forests are needed when dealing with ambiguous input.
# @return [Rley::SPPF::ParseForest] the resulting parse forest.
def to_pforest(tokenSeq)
result = earley_parse(tokenSeq)
# puts result
# Convert into a parse forest
engine.to_pforest(result)
end
private
def earley_parse(tokenSeq)
result = engine.parse(tokenSeq)
unless result.success?
# Stop if the parse failed...
line1 = "Parsing failed\n"
line2 = "Reason: #{result.failure_reason.message}"
raise StandardError, line1 + line2
end
result
end
end # class
end # module
Version data entries
17 entries across 17 versions & 1 rubygems