module Treetop
  module Runtime
    class CompiledParser
      include Treetop::Runtime
      
      attr_reader :input, :index, :terminal_failures, :max_terminal_failure_index
      attr_writer :root
      attr_accessor :consume_all_input
      alias :consume_all_input? :consume_all_input
      
      def initialize
        self.consume_all_input = true
      end

      def parse(input, options = {})
        prepare_to_parse(input)
        @index = options[:index] if options[:index]
        result = send("_nt_#{root}")
        return nil if (consume_all_input? && index != input.size)
        return result
      end

      def failure_index
        max_terminal_failure_index
      end

      def failure_line
        terminal_failures && input.line_of(failure_index)
      end

      def failure_column
        terminal_failures && input.column_of(failure_index)
      end

      def failure_reason
        return nil unless (tf = terminal_failures) && tf.size > 0
	"Expected " +
	  (tf.size == 1 ?
	   tf[0].expected_string :
           "one of #{tf.map{|f| f.expected_string}.uniq*', '}"
	  ) +
          " at line #{failure_line}, column #{failure_column} (byte #{failure_index+1})" +
          " after #{input[index...failure_index]}"
      end


      protected
      
      attr_reader :node_cache, :input_length
      attr_writer :index
              
      def prepare_to_parse(input)
        @input = input
        @input_length = input.length
        reset_index
        @node_cache = Hash.new {|hash, key| hash[key] = Hash.new}
        @terminal_failures = []
        @max_terminal_failure_index = 0
      end
      
      def reset_index
        @index = 0
      end
      
      def parse_anything(node_class = SyntaxNode, inline_module = nil)
        if index < input.length
          result = node_class.new(input, index...(index + 1))
          result.extend(inline_module) if inline_module
          @index += 1
          result
        else
          terminal_parse_failure("any character")
        end
      end
    
      def terminal_parse_failure(expected_string)
        return nil if index < max_terminal_failure_index
        if index > max_terminal_failure_index
          @max_terminal_failure_index = index
          @terminal_failures = []
        end
        terminal_failures << TerminalParseFailure.new(index, expected_string)
        return nil
      end
    end
  end
end