Class: Yaparc::Seq

Inherits:
Object
  • Object
show all
Includes:
Parsable
Defined in:
lib/yaparc.rb

Constant Summary

Constants included from Parsable

Parsable::IS_ALPHANUM, Parsable::IS_CR, Parsable::IS_DIGIT, Parsable::IS_LOWER, Parsable::IS_SPACE, Parsable::IS_WHITESPACE

Instance Attribute Summary

Attributes included from Parsable

#tree

Instance Method Summary collapse

Methods included from Parsable

#parse

Constructor Details

#initialize(*parsers, &block) ⇒ Seq

Returns a new instance of Seq.



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# File 'lib/yaparc.rb', line 148

def initialize(*parsers, &block)
  @parser = lambda do |input|
    args = []
    initial_result = Result::OK.new(:input => input)
    final_result = parsers.inject(initial_result) do |subsequent, parser|
      result = parser.parse(subsequent.input)
      if result.instance_of?(Result::Fail)
        break Result::Fail.new(:input => subsequent.input)
      else
        args << result.value
        result
      end
    end

    case final_result
    when Result::Fail
      Result::Fail.new(:input => final_result.input)
    when Result::OK
      final_value = if block_given?
                      yield(*args)
                    else
                      args.last
                    end
      Result::OK.new(:value => final_value, :input => final_result.input)
    else
      raise
    end
  end
end