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

#make(str) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 343

def make(str)
  m = Module.new
  m.module_eval output

  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 246

def output
  return @output if @output
  if @standalone
    code = "class #{@name}\n"

    unless cp = standalone_region(
                File.expand_path("../compiled_parser.rb", __FILE__))

      puts "Standalone failure. Check compiler_parser.rb for proper boundary comments"
      exit 1
    end

    unless pp = standalone_region(
                File.expand_path("../position.rb", __FILE__))
      puts "Standalone failure. Check position.rb for proper boundary comments"
    end

    cp.gsub!(/include Position/, pp)
    code << cp << "\n"
  else
    code =  "require 'kpeg/compiled_parser'\n\n"
    code << "class #{@name} < KPeg::CompiledParser\n"
  end

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

  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|
    rule = @grammar.rules[name]

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

  code << "end\n"
  @output = code
end

#output_op(code, op) ⇒ Object 



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

def output_op(code, op)
  case op
  when Dot
    code << "    _tmp = get_byte\n"
  when LiteralString
    code << "    _tmp = match_string(#{op.string.dump})\n"
  when LiteralRegexp
    code << "    _tmp = scan(/\\A#{op.regexp}/)\n"
  when CharRange
    ss = save()
    if op.start.bytesize == 1 and op.fin.bytesize == 1
      code << "    #{ss} = self.pos\n"
      code << "    _tmp = get_byte\n"
      code << "    if _tmp\n"

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

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

      code << "    while true\n"
      output_op code, op.op
      if op.save_values
        code << "    _ary << @result if _tmp\n"
      end
      code << "    break unless _tmp\n"
      code << "    end\n"
      code << "    _tmp = true\n"

      if op.save_values
        code << "    @result = _ary\n"
      end

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

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

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

end

#parse(str) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 351

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) ⇒ Object 



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# File 'lib/kpeg/code_generator.rb', line 237

def standalone_region(path)
  cp = File.read(path)
  start = cp.index("# STANDALONE START")
  fin = cp.index("# STANDALONE END")

  return nil unless start and fin
  cp[start..fin]
end