Class RubyLex < Object

# File ../ruby/lib/irb/ruby-lex.rb, line 39
def initialize
  lex_init
  set_input(STDIN)

  @seek = 0
  @exp_line_no = @line_no = 1
  @base_char_no = 0
  @char_no = 0
  @rests = []
  @readed = []
  @here_readed = []

  @indent = 0
  @indent_stack = []
  @lex_state = EXPR_BEG
  @space_seen = false
  @here_header = false

  @continue = false
  @line = ""

  @skip_space = false
  @readed_auto_clean_up = false
  @exception_on_syntax_error = true

  @prompt = nil
end

# File ../ruby/lib/irb/ruby-lex.rb, line 33
def debug?
  @debug_level > 0
end

# File ../ruby/lib/irb/ruby-lex.rb, line 226
def each_top_level_statement
  initialize_input
  catch(:TERM_INPUT) do
    loop do
      begin
        @continue = false
        prompt
        unless l = lex
          throw :TERM_INPUT if @line == ''
        else
          @line.concat l
          if @ltype or @continue or @indent > 0
            next
          end
        end
        if @line != "\n"
          @line.force_encoding(@io.encoding)
          yield @line, @exp_line_no
        end
        break unless l
        @line = ''
        @exp_line_no = @line_no

        @indent = 0
        @indent_stack = []
        prompt
      rescue TerminateLineInput
        initialize_input
        prompt
        get_readed
      end
    end
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 131
def eof?
  @io.eof?
end

# File ../ruby/lib/irb/ruby-lex.rb, line 88
def get_readed
  if idx = @readed.reverse.index("\n")
    @base_char_no = idx
  else
    @base_char_no += @readed.size
  end

  readed = @readed.join("")
  @readed = []
  readed
end

# File ../ruby/lib/irb/ruby-lex.rb, line 100
  def getc
    while @rests.empty?
#      return nil unless buf_input
      @rests.push nil unless buf_input
    end
    c = @rests.shift
    if @here_header
      @here_readed.push c
    else
      @readed.push c
    end
    @seek += 1
    if c == "\n"
      @line_no += 1
      @char_no = 0
    else
      @char_no += 1
    end
    c
  end

# File ../ruby/lib/irb/ruby-lex.rb, line 135
def getc_of_rests
  if @rests.empty?
    nil
  else
    getc
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 121
def gets
  l = ""
  while c = getc
    l.concat(c)
    break if c == "\n"
  end
  return nil if l == "" and c.nil?
  l
end

# File ../ruby/lib/irb/ruby-lex.rb, line 1123
  def identify_comment
    @ltype = "#"

    while ch = getc
#      if ch == "\\" #"
#       read_escape
#      end
      if ch == "\n"
        @ltype = nil
        ungetc
        break
      end
    end
    return Token(TkCOMMENT)
  end

# File ../ruby/lib/irb/ruby-lex.rb, line 740
def identify_gvar
  @lex_state = EXPR_END

  case ch = getc
  when /[~_*$?!@\/\;,=:<>".]/   #"
    Token(TkGVAR, "$" + ch)
  when "-"
    Token(TkGVAR, "$-" + getc)
  when "&", "`", "'", "+"
    Token(TkBACK_REF, "$"+ch)
  when /[1-9]/
    while getc =~ /[0-9]/; end
    ungetc
    Token(TkNTH_REF)
  when /\w/
    ungetc
    ungetc
    identify_identifier
  else
    ungetc
    Token("$")
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 873
  def identify_here_document
    ch = getc
#    if lt = PERCENT_LTYPE[ch]
    if ch == "-"
      ch = getc
      indent = true
    end
    if /['"`]/ =~ ch
      lt = ch
      quoted = ""
      while (c = getc) && c != lt
        quoted.concat c
      end
    else
      lt = '"'
      quoted = ch.dup
      while (c = getc) && c =~ /\w/
        quoted.concat c
      end
      ungetc
    end

    ltback, @ltype = @ltype, lt
    reserve = []
    while ch = getc
      reserve.push ch
      if ch == "\\"
        reserve.push ch = getc
      elsif ch == "\n"
        break
      end
    end

    @here_header = false
    while l = gets
      l = l.sub(/(:?\r)?\n\z/, '')
      if (indent ? l.strip : l) == quoted
        break
      end
    end

    @here_header = true
    @here_readed.concat reserve
    while ch = reserve.pop
      ungetc ch
    end

    @ltype = ltback
    @lex_state = EXPR_END
    Token(Ltype2Token[lt])
  end

# File ../ruby/lib/irb/ruby-lex.rb, line 764
  def identify_identifier
    token = ""
    if peek(0) =~ /[$@]/
      token.concat(c = getc)
      if c == "@" and peek(0) == "@"
        token.concat getc
      end
    end

    while (ch = getc) =~ /[^\x00-\/:-@\[-^`{-\x7F]/
      print ":", ch, ":" if RubyLex.debug?
      token.concat ch
    end
    ungetc

    if (ch == "!" || ch == "?") && token[0,1] =~ /\w/ && peek(0) != "="
      token.concat getc
    end

    # almost fix token

    case token
    when /^\$/
      return Token(TkGVAR, token)
    when /^\@\@/
      @lex_state = EXPR_END
      # p Token(TkCVAR, token)
      return Token(TkCVAR, token)
    when /^\@/
      @lex_state = EXPR_END
      return Token(TkIVAR, token)
    end

    if @lex_state != EXPR_DOT
      print token, "\n" if RubyLex.debug?

      token_c, *trans = TkReading2Token[token]
      if token_c
        # reserved word?

        if (@lex_state != EXPR_BEG &&
            @lex_state != EXPR_FNAME &&
            trans[1])
          # modifiers
          token_c = TkSymbol2Token[trans[1]]
          @lex_state = trans[0]
        else
          if @lex_state != EXPR_FNAME
            if ENINDENT_CLAUSE.include?(token)
              # check for ``class = val'' etc.
              valid = true
              case token
              when "class"
                valid = false unless peek_match?(/^\s*(<<|\w|::)/)
              when "def"
                valid = false if peek_match?(/^\s*(([+\-\/*&\|^]|<<|>>|\|\||\&\&)=|\&\&|\|\|)/)
              when "do"
                valid = false if peek_match?(/^\s*([+\-\/*]?=|\*|<|>|\&)/)
              when *ENINDENT_CLAUSE
                valid = false if peek_match?(/^\s*([+\-\/*]?=|\*|<|>|\&|\|)/)
              else
                # no nothing
              end
              if valid
                if token == "do"
                  if ![TkFOR, TkWHILE, TkUNTIL].include?(@indent_stack.last)
                    @indent += 1
                    @indent_stack.push token_c
                  end
                else
                  @indent += 1
                  @indent_stack.push token_c
                end
#               p @indent_stack
              end

            elsif DEINDENT_CLAUSE.include?(token)
              @indent -= 1
              @indent_stack.pop
            end
            @lex_state = trans[0]
          else
            @lex_state = EXPR_END
          end
        end
        return Token(token_c, token)
      end
    end

    if @lex_state == EXPR_FNAME
      @lex_state = EXPR_END
      if peek(0) == '='
        token.concat getc
      end
    elsif @lex_state == EXPR_BEG || @lex_state == EXPR_DOT
      @lex_state = EXPR_ARG
    else
      @lex_state = EXPR_END
    end

    if token[0, 1] =~ /[A-Z]/
      return Token(TkCONSTANT, token)
    elsif token[token.size - 1, 1] =~ /[!?]/
      return Token(TkFID, token)
    else
      return Token(TkIDENTIFIER, token)
    end
  end

# File ../ruby/lib/irb/ruby-lex.rb, line 943
def identify_number
  @lex_state = EXPR_END

  if peek(0) == "0" && peek(1) !~ /[.eE]/
    getc
    case peek(0)
    when /[xX]/
      ch = getc
      match = /[0-9a-fA-F_]/
    when /[bB]/
      ch = getc
      match = /[01_]/
    when /[oO]/
      ch = getc
      match = /[0-7_]/
    when /[dD]/
      ch = getc
      match = /[0-9_]/
    when /[0-7]/
      match = /[0-7_]/
    when /[89]/
      RubyLex.fail SyntaxError, "Invalid octal digit"
    else
      return Token(TkINTEGER)
    end

    len0 = true
    non_digit = false
    while ch = getc
      if match =~ ch
        if ch == "_"
          if non_digit
            RubyLex.fail SyntaxError, "trailing `#{ch}' in number"
          else
            non_digit = ch
          end
        else
          non_digit = false
          len0 = false
        end
      else
        ungetc
        if len0
          RubyLex.fail SyntaxError, "numeric literal without digits"
        end
        if non_digit
          RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
        end
        break
      end
    end
    return Token(TkINTEGER)
  end

  type = TkINTEGER
  allow_point = true
  allow_e = true
  non_digit = false
  while ch = getc
    case ch
    when /[0-9]/
      non_digit = false
    when "_"
      non_digit = ch
    when allow_point && "."
      if non_digit
        RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
      end
      type = TkFLOAT
      if peek(0) !~ /[0-9]/
        type = TkINTEGER
        ungetc
        break
      end
      allow_point = false
    when allow_e && "e", allow_e && "E"
      if non_digit
        RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
      end
      type = TkFLOAT
      if peek(0) =~ /[+-]/
        getc
      end
      allow_e = false
      allow_point = false
      non_digit = ch
    else
      if non_digit
        RubyLex.fail SyntaxError, "trailing `#{non_digit}' in number"
      end
      ungetc
      break
    end
  end
  Token(type)
end

# File ../ruby/lib/irb/ruby-lex.rb, line 925
  def identify_quotation
    ch = getc
    if lt = PERCENT_LTYPE[ch]
      ch = getc
    elsif ch =~ /\W/
      lt = "\""
    else
      RubyLex.fail SyntaxError, "unknown type of %string"
    end
#     if ch !~ /\W/
#       ungetc
#       next
#     end
    #@ltype = lt
    @quoted = ch unless @quoted = PERCENT_PAREN[ch]
    identify_string(lt, @quoted)
  end

# File ../ruby/lib/irb/ruby-lex.rb, line 1040
def identify_string(ltype, quoted = ltype)
  @ltype = ltype
  @quoted = quoted
  subtype = nil
  begin
    nest = 0
    while ch = getc
      if @quoted == ch and nest == 0
        break
      elsif @ltype != "'" && ch == "#" && peek(0) == "{"
        identify_string_dvar
      elsif @ltype != "'" && @ltype != "]" && @ltype != ":" and ch == "#"
        subtype = true
      elsif ch == '\' and @ltype == "'" #'
        case ch = getc
        when "\\", "\n", "'"
        else
          ungetc
        end
      elsif ch == '\' #'
        read_escape
      end
      if PERCENT_PAREN.values.include?(@quoted)
        if PERCENT_PAREN[ch] == @quoted
          nest += 1
        elsif ch == @quoted
          nest -= 1
        end
      end
    end
    if @ltype == "/"
      while /[imxoesun]/ =~ peek(0)
        getc
      end
    end
    if subtype
      Token(DLtype2Token[ltype])
    else
      Token(Ltype2Token[ltype])
    end
  ensure
    @ltype = nil
    @quoted = nil
    @lex_state = EXPR_END
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 1087
def identify_string_dvar
  begin
    getc

    reserve_continue = @continue
    reserve_ltype = @ltype
    reserve_indent = @indent
    reserve_indent_stack = @indent_stack
    reserve_state = @lex_state
    reserve_quoted = @quoted

    @ltype = nil
    @quoted = nil
    @indent = 0
    @indent_stack = []
    @lex_state = EXPR_BEG

    loop do
      @continue = false
      prompt
      tk = token
      if @ltype or @continue or @indent > 0
        next
      end
      break if tk.kind_of?(TkRBRACE)
    end
  ensure
    @continue = reserve_continue
    @ltype = reserve_ltype
    @indent = reserve_indent
    @indent_stack = reserve_indent_stack
    @lex_state = reserve_state
    @quoted = reserve_quoted
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 210
def initialize_input
  @ltype = nil
  @quoted = nil
  @indent = 0
  @indent_stack = []
  @lex_state = EXPR_BEG
  @space_seen = false
  @here_header = false

  @continue = false
  prompt

  @line = ""
  @exp_line_no = @line_no
end

# File ../ruby/lib/irb/ruby-lex.rb, line 261
def lex
  until (((tk = token).kind_of?(TkNL) || tk.kind_of?(TkEND_OF_SCRIPT)) &&
           !@continue or
           tk.nil?)
    #p tk
    #p @lex_state
    #p self
  end
  line = get_readed
  #      print self.inspect
  if line == "" and tk.kind_of?(TkEND_OF_SCRIPT) || tk.nil?
    nil
  else
    line
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 338
def lex_init()
  @OP = IRB::SLex.new
  @OP.def_rules("\0", "\004", "\032") do |op, io|
    Token(TkEND_OF_SCRIPT)
  end

  @OP.def_rules(" ", "\t", "\f", "\r", "\13") do |op, io|
    @space_seen = true
    while getc =~ /[ \t\f\r\13]/; end
    ungetc
    Token(TkSPACE)
  end

  @OP.def_rule("#") do |op, io|
    identify_comment
  end

  @OP.def_rule("=begin",
               proc{|op, io| @prev_char_no == 0 && peek(0) =~ /\s/}) do
    |op, io|
    @ltype = "="
    until getc == "\n"; end
    until peek_equal?("=end") && peek(4) =~ /\s/
      until getc == "\n"; end
    end
    gets
    @ltype = nil
    Token(TkRD_COMMENT)
  end

  @OP.def_rule("\n") do |op, io|
    print "\\n\n" if RubyLex.debug?
    case @lex_state
    when EXPR_BEG, EXPR_FNAME, EXPR_DOT
      @continue = true
    else
      @continue = false
      @lex_state = EXPR_BEG
      until (@indent_stack.empty? ||
             [TkLPAREN, TkLBRACK, TkLBRACE,
               TkfLPAREN, TkfLBRACK, TkfLBRACE].include?(@indent_stack.last))
        @indent_stack.pop
      end
    end
    @here_header = false
    @here_readed = []
    Token(TkNL)
  end

  @OP.def_rules("*", "**",
                "=", "==", "===",
                "=~", "<=>",
                "<", "<=",
                ">", ">=", ">>",
                "!", "!=", "!~") do
    |op, io|
    case @lex_state
    when EXPR_FNAME, EXPR_DOT
      @lex_state = EXPR_ARG
    else
      @lex_state = EXPR_BEG
    end
    Token(op)
  end

  @OP.def_rules("<<") do
    |op, io|
    tk = nil
    if @lex_state != EXPR_END && @lex_state != EXPR_CLASS &&
        (@lex_state != EXPR_ARG || @space_seen)
      c = peek(0)
      if /\S/ =~ c && (/["'`]/ =~ c || /\w/ =~ c || c == "-")
        tk = identify_here_document
      end
    end
    unless tk
      tk = Token(op)
      case @lex_state
      when EXPR_FNAME, EXPR_DOT
        @lex_state = EXPR_ARG
      else
        @lex_state = EXPR_BEG
      end
    end
    tk
  end

  @OP.def_rules("'", '"') do
    |op, io|
    identify_string(op)
  end

  @OP.def_rules("`") do
    |op, io|
    if @lex_state == EXPR_FNAME
      @lex_state = EXPR_END
      Token(op)
    else
      identify_string(op)
    end
  end

  @OP.def_rules('?') do
    |op, io|
    if @lex_state == EXPR_END
      @lex_state = EXPR_BEG
      Token(TkQUESTION)
    else
      ch = getc
      if @lex_state == EXPR_ARG && ch =~ /\s/
        ungetc
        @lex_state = EXPR_BEG;
        Token(TkQUESTION)
      else
        if (ch == '\')
          read_escape
        end
        @lex_state = EXPR_END
        Token(TkINTEGER)
      end
    end
  end

  @OP.def_rules("&", "&&", "|", "||") do
    |op, io|
    @lex_state = EXPR_BEG
    Token(op)
  end

  @OP.def_rules("+=", "-=", "*=", "**=",
                "&=", "|=", "^=", "<<=", ">>=", "||=", "&&=") do
    |op, io|
    @lex_state = EXPR_BEG
    op =~ /^(.*)=$/
    Token(TkOPASGN, $1)
  end

  @OP.def_rule("+@", proc{|op, io| @lex_state == EXPR_FNAME}) do
    |op, io|
    @lex_state = EXPR_ARG
    Token(op)
  end

  @OP.def_rule("-@", proc{|op, io| @lex_state == EXPR_FNAME}) do
    |op, io|
    @lex_state = EXPR_ARG
    Token(op)
  end

  @OP.def_rules("+", "-") do
    |op, io|
    catch(:RET) do
      if @lex_state == EXPR_ARG
        if @space_seen and peek(0) =~ /[0-9]/
          throw :RET, identify_number
        else
          @lex_state = EXPR_BEG
        end
      elsif @lex_state != EXPR_END and peek(0) =~ /[0-9]/
        throw :RET, identify_number
      else
        @lex_state = EXPR_BEG
      end
      Token(op)
    end
  end

  @OP.def_rule(".") do
    |op, io|
    @lex_state = EXPR_BEG
    if peek(0) =~ /[0-9]/
      ungetc
      identify_number
    else
      # for "obj.if" etc.
      @lex_state = EXPR_DOT
      Token(TkDOT)
    end
  end

  @OP.def_rules("..", "...") do
    |op, io|
    @lex_state = EXPR_BEG
    Token(op)
  end

  lex_int2
end

# File ../ruby/lib/irb/ruby-lex.rb, line 527
  def lex_int2
    @OP.def_rules("]", "}", ")") do
      |op, io|
      @lex_state = EXPR_END
      @indent -= 1
      @indent_stack.pop
      Token(op)
    end

    @OP.def_rule(":") do
      |op, io|
      if @lex_state == EXPR_END || peek(0) =~ /\s/
        @lex_state = EXPR_BEG
        Token(TkCOLON)
      else
        @lex_state = EXPR_FNAME;
        Token(TkSYMBEG)
      end
    end

    @OP.def_rule("::") do
       |op, io|
#      p @lex_state.id2name, @space_seen
      if @lex_state == EXPR_BEG or @lex_state == EXPR_ARG && @space_seen
        @lex_state = EXPR_BEG
        Token(TkCOLON3)
      else
        @lex_state = EXPR_DOT
        Token(TkCOLON2)
      end
    end

    @OP.def_rule("/") do
      |op, io|
      if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
        identify_string(op)
      elsif peek(0) == '='
        getc
        @lex_state = EXPR_BEG
        Token(TkOPASGN, "/") #/)
      elsif @lex_state == EXPR_ARG and @space_seen and peek(0) !~ /\s/
        identify_string(op)
      else
        @lex_state = EXPR_BEG
        Token("/") #/)
      end
    end

    @OP.def_rules("^") do
      |op, io|
      @lex_state = EXPR_BEG
      Token("^")
    end

    #       @OP.def_rules("^=") do
    #   @lex_state = EXPR_BEG
    #   Token(OP_ASGN, :^)
    #       end

    @OP.def_rules(",") do
      |op, io|
      @lex_state = EXPR_BEG
      Token(op)
    end

    @OP.def_rules(";") do
      |op, io|
      @lex_state = EXPR_BEG
      until (@indent_stack.empty? ||
             [TkLPAREN, TkLBRACK, TkLBRACE,
               TkfLPAREN, TkfLBRACK, TkfLBRACE].include?(@indent_stack.last))
        @indent_stack.pop
      end
      Token(op)
    end

    @OP.def_rule("~") do
      |op, io|
      @lex_state = EXPR_BEG
      Token("~")
    end

    @OP.def_rule("~@", proc{|op, io| @lex_state == EXPR_FNAME}) do
      |op, io|
      @lex_state = EXPR_BEG
      Token("~")
    end

    @OP.def_rule("(") do
      |op, io|
      @indent += 1
      if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
        @lex_state = EXPR_BEG
        tk_c = TkfLPAREN
      else
        @lex_state = EXPR_BEG
        tk_c = TkLPAREN
      end
      @indent_stack.push tk_c
      Token(tk_c)
    end

    @OP.def_rule("[]", proc{|op, io| @lex_state == EXPR_FNAME}) do
      |op, io|
      @lex_state = EXPR_ARG
      Token("[]")
    end

    @OP.def_rule("[]=", proc{|op, io| @lex_state == EXPR_FNAME}) do
      |op, io|
      @lex_state = EXPR_ARG
      Token("[]=")
    end

    @OP.def_rule("[") do
      |op, io|
      @indent += 1
      if @lex_state == EXPR_FNAME
        tk_c = TkfLBRACK
      else
        if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
          tk_c = TkLBRACK
        elsif @lex_state == EXPR_ARG && @space_seen
          tk_c = TkLBRACK
        else
          tk_c = TkfLBRACK
        end
        @lex_state = EXPR_BEG
      end
      @indent_stack.push tk_c
      Token(tk_c)
    end

    @OP.def_rule("{") do
      |op, io|
      @indent += 1
      if @lex_state != EXPR_END && @lex_state != EXPR_ARG
        tk_c = TkLBRACE
      else
        tk_c = TkfLBRACE
      end
      @lex_state = EXPR_BEG
      @indent_stack.push tk_c
      Token(tk_c)
    end

    @OP.def_rule('\') do
      |op, io|
      if getc == "\n"
        @space_seen = true
        @continue = true
        Token(TkSPACE)
      else
        read_escape
        Token("\\")
      end
    end

    @OP.def_rule('%') do
      |op, io|
      if @lex_state == EXPR_BEG || @lex_state == EXPR_MID
        identify_quotation
      elsif peek(0) == '='
        getc
        Token(TkOPASGN, :%)
      elsif @lex_state == EXPR_ARG and @space_seen and peek(0) !~ /\s/
        identify_quotation
      else
        @lex_state = EXPR_BEG
        Token("%") #))
      end
    end

    @OP.def_rule('$') do
      |op, io|
      identify_gvar
    end

    @OP.def_rule('@') do
      |op, io|
      if peek(0) =~ /[\w@]/
        ungetc
        identify_identifier
      else
        Token("@")
      end
    end

    #       @OP.def_rule("def", proc{|op, io| /\s/ =~ io.peek(0)}) do
    #   |op, io|
    #   @indent += 1
    #   @lex_state = EXPR_FNAME
    # # @lex_state = EXPR_END
    # # until @rests[0] == "\n" or @rests[0] == ";"
    # #   rests.shift
    # # end
    #       end

    @OP.def_rule("") do
      |op, io|
      printf "MATCH: start %s: %s\n", op, io.inspect if RubyLex.debug?
      if peek(0) =~ /[0-9]/
        t = identify_number
      elsif peek(0) =~ /[^\x00-\/:-@\[-^`{-\x7F]/
        t = identify_identifier
      end
      printf "MATCH: end %s: %s\n", op, io.inspect if RubyLex.debug?
      t
    end

    p @OP if RubyLex.debug?
  end

# File ../ruby/lib/irb/ruby-lex.rb, line 179
def peek(i = 0)
  while @rests.size <= i
    return nil unless buf_input
  end
  @rests[i]
end

# File ../ruby/lib/irb/ruby-lex.rb, line 164
def peek_equal?(str)
  chrs = str.split(//)
  until @rests.size >= chrs.size
    return false unless buf_input
  end
  @rests[0, chrs.size] == chrs
end

# File ../ruby/lib/irb/ruby-lex.rb, line 172
def peek_match?(regexp)
  while @rests.empty?
    return false unless buf_input
  end
  regexp =~ @rests.join("")
end

# File ../ruby/lib/irb/ruby-lex.rb, line 204
def prompt
  if @prompt
    @prompt.call(@ltype, @indent, @continue, @line_no)
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 1139
def read_escape
  case ch = getc
  when "\n", "\r", "\f"
  when "\\", "n", "t", "r", "f", "v", "a", "e", "b", "s" #"
  when /[0-7]/
    ungetc ch
    3.times do
      case ch = getc
      when /[0-7]/
      when nil
        break
      else
        ungetc
        break
      end
    end

  when "x"
    2.times do
      case ch = getc
      when /[0-9a-fA-F]/
      when nil
        break
      else
        ungetc
        break
      end
    end

  when "M"
    if (ch = getc) != '-'
      ungetc
    else
      if (ch = getc) == "\\" #"
        read_escape
      end
    end

  when "C", "c" #, "^"
    if ch == "C" and (ch = getc) != "-"
      ungetc
    elsif (ch = getc) == "\\" #"
      read_escape
    end
  else
    # other characters
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 77
def set_input(io, p = nil, &block)
  @io = io
  if p.respond_to?(:call)
    @input = p
  elsif block_given?
    @input = block
  else
    @input = Proc.new{@io.gets}
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 195
def set_prompt(p = nil, &block)
  p = block if block_given?
  if p.respond_to?(:call)
    @prompt = p
  else
    @prompt = Proc.new{print p}
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 278
def token
  #      require "tracer"
  #      Tracer.on
  @prev_seek = @seek
  @prev_line_no = @line_no
  @prev_char_no = @char_no
  begin
    begin
      tk = @OP.match(self)
      @space_seen = tk.kind_of?(TkSPACE)
    rescue SyntaxError
      raise if @exception_on_syntax_error
      tk = TkError.new(@seek, @line_no, @char_no)
    end
  end while @skip_space and tk.kind_of?(TkSPACE)
  if @readed_auto_clean_up
    get_readed
  end
  #      Tracer.off
  tk
end

# File ../ruby/lib/irb/ruby-lex.rb, line 143
def ungetc(c = nil)
  if @here_readed.empty?
    c2 = @readed.pop
  else
    c2 = @here_readed.pop
  end
  c = c2 unless c
  @rests.unshift c #c =
  @seek -= 1
  if c == "\n"
    @line_no -= 1
    if idx = @readed.reverse.index("\n")
      @char_no = @readed.size - idx
    else
      @char_no = @base_char_no + @readed.size
    end
  else
    @char_no -= 1
  end
end

# File ../ruby/lib/irb/ruby-lex.rb, line 186
def buf_input
  prompt
  line = @input.call
  return nil unless line
  @rests.concat line.chars.to_a
  true
end