Class: KPeg::CodeGenerator

Inherits:
Object
  • Object
show all
Defined in:
lib/kpeg/code_generator.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, gram, debug = false) ⇒ CodeGenerator

Returns a new instance of CodeGenerator.



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# File 'lib/kpeg/code_generator.rb', line 6

def initialize(name, gram, debug=false)
  @name = name
  @grammar = gram
  @debug = debug
  @saves = 0
  @output = nil
  @standalone = false
end

Instance Attribute Details

#standalone ⇒ Object

Returns the value of attribute standalone.



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# File 'lib/kpeg/code_generator.rb', line 15

def standalone
  @standalone
end

Instance Method Details

#handle_ast(code) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 59

def handle_ast(code)
  output_node = false

  root = @grammar.variables["ast-location"] || "AST"

  methods = []

  vars = @grammar.variables.keys.sort

  vars.each do |name|
    val = @grammar.variables[name]

    if val.index("ast ") == 0
      unless output_node
        code << "\n"
        code << "  module #{root}\n"
        code << "    class Node; end\n"
        output_node = true
      end
      if m = output_ast(name, code, val[4..-1])
        methods << m
      end
    end
  end

  if output_node
    code << "  end\n"
    code << "  module #{root}Construction\n"
    methods.each do |short, name, attrs|
      code << "    def #{short}(#{attrs.join(', ')})\n"
      code << "      #{root}::#{name}.new(#{attrs.join(', ')})\n"
      code << "    end\n"
    end
    code << "  end\n"
    code << "  include #{root}Construction\n"
  end
end

#indentify(code, indent) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 97

def indentify(code, indent)
  "#{"  " * indent}#{code}"
end

#make(str) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 472

def make(str)
  m = Module.new
  m.module_eval output, "(kpeg parser #{@name})"

  cls = m.const_get(@name)
  cls.new(str)
end

#method_name(name) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 17

def method_name(name)
  name = name.gsub("-","_hyphen_")
  "_#{name}"
end

#output ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 335

def output
  return @output if @output

  code = []

  output_header(code)
  output_grammar(code)
  output_footer(code)

  @output = code.join
end

#output_ast(short, code, description) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 37

def output_ast(short, code, description)
  parser = FormatParser.new description

  # just skip it if it's bad.
  return unless parser.parse "ast_root"

  name, attrs = parser.result

  code << "    class #{name} < Node\n"
  code << "      def initialize(#{attrs.join(', ')})\n"
  attrs.each do |at|
    code << "        @#{at} = #{at}\n"
  end
  code << "      end\n"
  attrs.each do |at|
    code << "      attr_reader :#{at}\n"
  end
  code << "    end\n"

  [short, name, attrs]
end

#output_footer(code) ⇒ Object

Output of class end and footer



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# File 'lib/kpeg/code_generator.rb', line 350

def output_footer(code)
  code << "end\n"

  if footer = @grammar.directives['footer']
    code << footer.action
  end
end

#output_grammar(code) ⇒ Object

Output of grammar and rules



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# File 'lib/kpeg/code_generator.rb', line 361

def output_grammar(code)
  code << "  # :stopdoc:\n"
  handle_ast(code)

  fg = @grammar.foreign_grammars

  if fg.empty?
    if @standalone
      code << "  def setup_foreign_grammar; end\n"
    end
  else
    code << "  def setup_foreign_grammar\n"
    @grammar.foreign_grammars.each do |name, gram|
      code << "    @_grammar_#{name} = #{gram}.new(nil)\n"
    end
    code << "  end\n"
  end

  render = GrammarRenderer.new(@grammar)

  renderings = {}

  @grammar.rule_order.each do |name|
    reset_saves

    rule = @grammar.rules[name]
    io = StringIO.new
    render.render_op io, rule.op

    rend = io.string
    rend.gsub! "\n", " "

    renderings[name] = rend

    code << "\n"
    code << "  # #{name} = #{rend}\n"

    if rule.arguments
      code << "  def #{method_name name}(#{rule.arguments.join(',')})\n"
    else
      code << "  def #{method_name name}\n"
    end

    if @debug
      code << "    puts \"START #{name} @ \#{show_pos}\\n\"\n"
    end

    output_op code, rule.op
    if @debug
      code << "    if _tmp\n"
      code << "      puts \"   OK #{name} @ \#{show_pos}\\n\"\n"
      code << "    else\n"
      code << "      puts \" FAIL #{name} @ \#{show_pos}\\n\"\n"
      code << "    end\n"
    end

    code << "    set_failed_rule :#{method_name name} unless _tmp\n"
    code << "    return _tmp\n"
    code << "  end\n"
  end

  code << "\n  Rules = {}\n"
  @grammar.rule_order.each do |name|
    rend = GrammarRenderer.escape renderings[name], true
    code << "  Rules[:#{method_name name}] = rule_info(\"#{name}\", \"#{rend}\")\n"
  end

  code << "  # :startdoc:\n"
end

#output_header(code) ⇒ Object

Output up to the user-defined setup actions



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# File 'lib/kpeg/code_generator.rb', line 434

def output_header(code)
  if header = @grammar.directives['header']
    code << header.action.strip
    code << "\n"
  end

  pre_class = @grammar.directives['pre-class']

  if @standalone
    if pre_class
      code << pre_class.action.strip
      code << "\n"
    end
    code << "class #{@name}\n"

    cp  = standalone_region("compiled_parser.rb")
    cpi = standalone_region("compiled_parser.rb", "INITIALIZE")
    pp  = standalone_region("position.rb")

    cp.gsub!(/^\s*include Position/, pp)
    code << "  # :stopdoc:\n"
    code << cpi << "\n" unless @grammar.variables['custom_initialize']
    code << cp  << "\n"
    code << "  # :startdoc:\n"
  else
    code << "require 'kpeg/compiled_parser'\n\n"
    if pre_class
      code << pre_class.action.strip
      code << "\n"
    end
    code << "class #{@name} < KPeg::CompiledParser\n"
  end

  @grammar.setup_actions.each do |act|
    code << "\n#{act.action}\n\n"
  end
end

#output_op(code, op, indent = 2) ⇒ Object

Default indent is 4 spaces (indent=2)



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# File 'lib/kpeg/code_generator.rb', line 102

def output_op(code, op, indent=2)
  case op
  when Dot
    code << indentify("_tmp = get_byte\n", indent)
  when LiteralString
    code << indentify("_tmp = match_string(#{op.string.dump})\n", indent)
  when LiteralRegexp
    if op.regexp.respond_to?(:kcode)
      lang = op.regexp.kcode.to_s[0,1]
    else
      # Let default ruby string handling figure it out
      lang = ""
    end
    code << indentify("_tmp = scan(/\\G#{op.regexp}/#{lang})\n", indent)
  when CharRange
    ss = save()
    if op.start.bytesize == 1 and op.fin.bytesize == 1
      code << indentify("#{ss} = self.pos\n", indent)
      code << indentify("_tmp = get_byte\n", indent)
      code << indentify("if _tmp\n", indent)

      if op.start.respond_to? :getbyte
        left  = op.start.getbyte 0
        right = op.fin.getbyte 0
      else
        left  = op.start[0]
        right = op.fin[0]
      end

      code << indentify("  unless _tmp >= #{left} and _tmp <= #{right}\n", indent)
      code << indentify("    self.pos = #{ss}\n", indent)
      code << indentify("    _tmp = nil\n", indent)
      code << indentify("  end\n", indent)
      code << indentify("end\n", indent)
    else
      raise "Unsupported char range - #{op.inspect}"
    end
  when Choice
    ss = save()
    code << "\n"
    code << indentify("#{ss} = self.pos\n", indent)
    code << indentify("while true # choice\n", indent)
    op.ops.each_with_index do |n,idx|
      output_op code, n, (indent+1)

      code << indentify("  break if _tmp\n", indent)
      code << indentify("  self.pos = #{ss}\n", indent)
      if idx == op.ops.size - 1
        code << indentify("  break\n", indent)
      end
    end
    code << indentify("end # end choice\n\n", indent)
  when Multiple
    ss = save()
    if op.min == 0 and op.max == 1
      code << indentify("#{ss} = self.pos\n", indent)
      output_op code, op.op, indent
      if op.save_values
        code << indentify("@result = nil unless _tmp\n", indent)
      end
      code << indentify("unless _tmp\n", indent)
      code << indentify("  _tmp = true\n", indent)
      code << indentify("  self.pos = #{ss}\n", indent)
      code << indentify("end\n", indent)
    elsif op.min == 0 and !op.max
      if op.save_values
        code << indentify("_ary = []\n", indent)
      end

      code << indentify("while true\n", indent)
      output_op code, op.op, (indent+1)
      if op.save_values
        code << indentify("  _ary << @result if _tmp\n", indent)
      end
      code << indentify("  break unless _tmp\n", indent)
      code << indentify("end\n", indent)
      code << indentify("_tmp = true\n", indent)

      if op.save_values
        code << indentify("@result = _ary\n", indent)
      end

    elsif op.min == 1 and !op.max
      code << indentify("#{ss} = self.pos\n", indent)
      if op.save_values
        code << indentify("_ary = []\n", indent)
      end
      output_op code, op.op, indent
      code << indentify("if _tmp\n", indent)
      if op.save_values
        code << indentify("  _ary << @result\n", indent)
      end
      code << indentify("  while true\n", indent)
      output_op code, op.op, (indent+2)
      if op.save_values
        code << indentify("    _ary << @result if _tmp\n", indent)
      end
      code << indentify("    break unless _tmp\n", indent)
      code << indentify("  end\n", indent)
      code << indentify("  _tmp = true\n", indent)
      if op.save_values
        code << indentify("  @result = _ary\n", indent)
      end
      code << indentify("else\n", indent)
      code << indentify("  self.pos = #{ss}\n", indent)
      code << indentify("end\n", indent)
    else
      code << indentify("#{ss} = self.pos\n", indent)
      code << indentify("_count = 0\n", indent)
      code << indentify("while true\n", indent)
      output_op code, op.op, (indent+1)
      code << indentify("  if _tmp\n", indent)
      code << indentify("    _count += 1\n", indent)
      code << indentify("    break if _count == #{op.max}\n", indent)
      code << indentify("  else\n", indent)
      code << indentify("    break\n", indent)
      code << indentify("  end\n", indent)
      code << indentify("end\n", indent)
      code << indentify("if _count >= #{op.min}\n", indent)
      code << indentify("  _tmp = true\n", indent)
      code << indentify("else\n", indent)
      code << indentify("  self.pos = #{ss}\n", indent)
      code << indentify("  _tmp = nil\n", indent)
      code << indentify("end\n", indent)
    end

  when Sequence
    ss = save()
    code << "\n"
    code << indentify("#{ss} = self.pos\n", indent)
    code << indentify("while true # sequence\n", indent)
    op.ops.each_with_index do |n, idx|
      output_op code, n, (indent+1)

      if idx == op.ops.size - 1
        code << indentify("  unless _tmp\n", indent)
        code << indentify("    self.pos = #{ss}\n", indent)
        code << indentify("  end\n", indent)
        code << indentify("  break\n", indent)
      else
        code << indentify("  unless _tmp\n", indent)
        code << indentify("    self.pos = #{ss}\n", indent)
        code << indentify("    break\n", indent)
        code << indentify("  end\n", indent)
      end
    end
    code << indentify("end # end sequence\n\n", indent)
  when AndPredicate
    ss = save()
    code << indentify("#{ss} = self.pos\n", indent)
    if op.op.kind_of? Action
      code << indentify("_tmp = begin; #{op.op.action}; end\n", indent)
    else
      output_op code, op.op, indent
    end
    code << indentify("self.pos = #{ss}\n", indent)
  when NotPredicate
    ss = save()
    code << indentify("#{ss} = self.pos\n", indent)
    if op.op.kind_of? Action
      code << indentify("_tmp = begin; #{op.op.action}; end\n", indent)
    else
      output_op code, op.op, indent
    end
    code << indentify("_tmp = _tmp ? nil : true\n", indent)
    code << indentify("self.pos = #{ss}\n", indent)
  when RuleReference
    if op.arguments
      code << indentify("_tmp = apply_with_args(:#{method_name op.rule_name}, #{op.arguments[1..-2]})\n", indent)
    else
      code << indentify("_tmp = apply(:#{method_name op.rule_name})\n", indent)
    end
  when InvokeRule
    if op.arguments
      code << indentify("_tmp = #{method_name op.rule_name}#{op.arguments}\n", indent)
    else
      code << indentify("_tmp = #{method_name op.rule_name}()\n", indent)
    end
  when ForeignInvokeRule
    if op.arguments
      code << indentify("_tmp = @_grammar_#{op.grammar_name}.external_invoke(self, :#{method_name op.rule_name}, #{op.arguments[1..-2]})\n", indent)
    else
      code << indentify("_tmp = @_grammar_#{op.grammar_name}.external_invoke(self, :#{method_name op.rule_name})\n", indent)
    end
  when Tag
    if op.tag_name and !op.tag_name.empty?
      output_op code, op.op, indent
      code << indentify("#{op.tag_name} = @result\n", indent)
    else
      output_op code, op.op, indent
    end
  when Action
    code << indentify("@result = begin; ", indent)
    code << op.action << "; end\n"
    if @debug
      code << indentify("puts \"   => \" #{op.action.dump} \" => \#{@result.inspect} \\n\"\n", indent)
    end
    code << indentify("_tmp = true\n", indent)
  when Collect
    code << indentify("_text_start = self.pos\n", indent)
    output_op code, op.op, indent
    code << indentify("if _tmp\n", indent)
    code << indentify("  text = get_text(_text_start)\n", indent)
    code << indentify("end\n", indent)
  when Bounds
    code << indentify("_bounds_start = self.pos\n", indent)
    output_op code, op.op, indent
    code << indentify("if _tmp\n", indent)
    code << indentify("  bounds = [_bounds_start, self.pos]\n", indent)
    code << indentify("end\n", indent)
  else
    raise "Unknown op - #{op.class}"
  end
end

#parse(str) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 480

def parse(str)
  make(str).parse
end

#reset_saves ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 33

def reset_saves
  @saves = 0
end

#save ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 22

def save
  if @saves == 0
    str = "_save"
  else
    str = "_save#{@saves}"
  end

  @saves += 1
  str
end

#standalone_region(path, marker = "STANDALONE") ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 317

def standalone_region(path, marker = "STANDALONE")
  expanded_path = File.expand_path("../#{path}", __FILE__)
  cp = File.read(expanded_path)

  start_marker = "# #{marker} START"
  end_marker   = /^\s*# #{Regexp.escape marker} END/

  start = cp.index(start_marker) + start_marker.length + 1 # \n
  fin   = cp.index(end_marker)

  unless start and fin
    abort("#{marker} boundaries in #{path} missing " \
          "for standalone generation")
  end

  cp[start..fin]
end