class Treetop::Runtime::CompiledParser

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

def failure_index
  max_terminal_failure_index
end

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

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

def forget_failures_to_here
  @terminal_failures = []
  @max_terminal_failure_index = -1
end

def has_terminal?(terminal, mode, index)
  case mode
  when :regexp    # A Regexp has been passed in, either a character class or a literel regex 'foo'r
    (terminal =~ input[index..-1]) == 0 && $&.length
  when false      # The terminal is a string which must match exactly
    input[index, terminal.size] == terminal && terminal.size
  when :insens    # The terminal is a downcased string which must match input downcased
    input[index, terminal.size].downcase == terminal && terminal.size
  when true       # Only occurs with old compiled grammars, for character classes
    rx = @regexps[terminal] ||= Regexp.new(terminal)
    input.index(rx, index) == index && $&.length
  end
end

def initialize
  self.consume_all_input = true
end

def instantiate_node(node_type,*args)
  if node_type.respond_to? :new
    node_type.new(*args)
  else
    SyntaxNode.new(*args).extend(node_type)
  end
end

def parse(input, options = {})
  prepare_to_parse(input)
  @index = options[:index] if options[:index]
  result = send("_nt_#{options[:root] || root}")
  should_consume_all = options.include?(:consume_all_input) ? options[:consume_all_input] : consume_all_input?
  if (should_consume_all && index != input.size)
    if index > max_terminal_failure_index # Otherwise the failure is already explained
      terminal_parse_failure('<END OF INPUT>', true)
    end
    return nil
  end
  return SyntaxNode.new(input, index...(index + 1)) if result == true
  return result
end

def parse_anything(node_class = SyntaxNode, inline_module = nil)
  if index < input.length
    result = instantiate_node(node_class,input, index...(index + 1))
    result.extend(inline_module) if inline_module
    @index += 1
    result
  else
    terminal_parse_failure("any character")
  end
end

def prepare_to_parse(input)
  @input = input
  @input_length = input.length
  reset_index
  @node_cache = Hash.new {|hash, key| hash[key] = Hash.new}
  @regexps = {}
  @terminal_failures = []
  @max_terminal_failure_index = 0
end

def reset_index
  @index = 0
end

def terminal_failures
  if @terminal_failures.empty? || @terminal_failures[-1].is_a?(TerminalParseFailure)
    @terminal_failures
  else
    @terminal_failures.map! {|tf_ary| tf_ary.is_a?(TerminalParseFailure) ? tf_ary : TerminalParseFailure.new(*tf_ary) }
  end
end

def terminal_parse_failure(expected_string, unexpected = false)
  if @max_terminal_failure_index == -1
    @max_terminal_failure_index = 0
    return nil
  end
  return nil if index < max_terminal_failure_index
  if index > max_terminal_failure_index
    @max_terminal_failure_index = index
    @terminal_failures = []
  end
  @terminal_failures << [index, expected_string, unexpected]
  # It's very slow, but this shows the last 5 nested rules:
  # caller.reject{|l| l =~ /`loop'|`block in /}[0..5].reverse.map{|l| l.sub(/[^`]*`_nt_/,'').sub(/'/,'')}
  terminal_failures
  return nil
end