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Class: RubyLex

Do not use. This class is for internal use only.
Relationships & Source Files
Namespace Children
Exceptions:
Inherits: Object
Defined in: lib/irb/ruby-lex.rb

Constant Summary

Class Method Summary

Instance Method Summary

Constructor Details

.newRubyLex

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 25

def initialize
  @exp_line_no = @line_no = 1
  @indent = 0
  @continue = false
  @line = ""
  @prompt = nil
end

Class Method Details

.compile_with_errors_suppressed(code)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 33

def self.compile_with_errors_suppressed(code)
  line_no = 1
  begin
    result = yield code, line_no
  rescue ArgumentError
    code = ";\n#{code}"
    line_no = 0
    result = yield code, line_no
  end
  result
end

.ripper_lex_without_warning(code)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 132

def self.ripper_lex_without_warning(code)
  verbose, $VERBOSE = $VERBOSE, nil
  tokens = nil
  compile_with_errors_suppressed(code) do |inner_code, line_no|
    lexer = Ripper::Lexer.new(inner_code, '-', line_no)
    if lexer.respond_to?(:scan) # Ruby 2.7+
      tokens = []
      pos_to_index = {}
      lexer.scan.each do |t|
        if pos_to_index.has_key?(t[0])
          index = pos_to_index[t[0]]
          found_tk = tokens[index]
          if ERROR_TOKENS.include?(found_tk[1]) && !ERROR_TOKENS.include?(t[1])
            tokens[index] = t
          end
        else
          pos_to_index[t[0]] = tokens.size
          tokens << t
        end
      end
    else
      tokens = lexer.parse
    end
  end
  tokens
ensure
  $VERBOSE = verbose
end

Instance Method Details

#check_code_block(code, tokens = @tokens)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 302

def check_code_block(code, tokens = @tokens)
  return true if tokens.empty?
  if tokens.last[1] == :on_heredoc_beg
    return true
  end

  begin # check if parser error are available
    verbose, $VERBOSE = $VERBOSE, nil
    case RUBY_ENGINE
    when 'ruby'
      self.class.compile_with_errors_suppressed(code) do |inner_code, line_no|
        RubyVM::InstructionSequence.compile(inner_code, nil, nil, line_no)
      end
    when 'jruby'
      JRuby.compile_ir(code)
    else
      catch(:valid) do
        eval("BEGIN { throw :valid, true }\n#{code}")
        false
      end
    end
  rescue EncodingError
    # This is for a hash with invalid encoding symbol, {"\xAE": 1}
  rescue SyntaxError => e
    case e.message
    when /unterminated (?:string|regexp) meets end of file/
      # "unterminated regexp meets end of file"
      #
      #   example:
      #     /
      #
      # "unterminated string meets end of file"
      #
      #   example:
      #     '
      return true
    when /syntax error, unexpected end-of-input/
      # "syntax error, unexpected end-of-input, expecting keyword_end"
      #
      #   example:
      #     if ture
      #       hoge
      #       if false
      #         fuga
      #       end
      return true
    when /syntax error, unexpected keyword_end/
      # "syntax error, unexpected keyword_end"
      #
      #   example:
      #     if (
      #     end
      #
      #   example:
      #     end
      return false
    when /syntax error, unexpected '\.'/
      # "syntax error, unexpected '.'"
      #
      #   example:
      #     .
      return false
    when /unexpected tREGEXP_BEG/
      # "syntax error, unexpected tREGEXP_BEG, expecting keyword_do or '{' or '('"
      #
      #   example:
      #     method / f /
      return false
    end
  ensure
    $VERBOSE = verbose
  end

  if defined?(Ripper::EXPR_BEG)
    last_lex_state = tokens.last[3]
    if last_lex_state.allbits?(Ripper::EXPR_BEG)
      return false
    elsif last_lex_state.allbits?(Ripper::EXPR_DOT)
      return true
    elsif last_lex_state.allbits?(Ripper::EXPR_CLASS)
      return true
    elsif last_lex_state.allbits?(Ripper::EXPR_FNAME)
      return true
    elsif last_lex_state.allbits?(Ripper::EXPR_VALUE)
      return true
    elsif last_lex_state.allbits?(Ripper::EXPR_ARG)
      return false
    end
  end

  false
end

#check_corresponding_token_depth

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 591

def check_corresponding_token_depth
  corresponding_token_depth = nil
  is_first_spaces_of_line = true
  is_first_printable_of_line = true
  spaces_of_nest = []
  spaces_at_line_head = 0
  open_brace_on_line = 0
  in_oneliner_def = nil
  @tokens.each_with_index do |t, index|
    # detecting one-liner method definition
    if in_oneliner_def.nil?
      if t[3].allbits?(Ripper::EXPR_ENDFN)
        in_oneliner_def = :ENDFN
      end
    else
      if t[3].allbits?(Ripper::EXPR_ENDFN)
        # continuing
      elsif t[3].allbits?(Ripper::EXPR_BEG)
        if t[2] == '='
          in_oneliner_def = :BODY
        end
      else
        if in_oneliner_def == :BODY
          # one-liner method definition
          if is_first_printable_of_line
            corresponding_token_depth = spaces_of_nest.pop
          else
            spaces_of_nest.pop
            corresponding_token_depth = nil
          end
        end
        in_oneliner_def = nil
      end
    end

    case t[1]
    when :on_ignored_nl, :on_nl, :on_comment
      if in_oneliner_def != :BODY
        corresponding_token_depth = nil
        spaces_at_line_head = 0
        is_first_spaces_of_line = true
        is_first_printable_of_line = true
        open_brace_on_line = 0
      end
      next
    when :on_sp
      spaces_at_line_head = t[2].count(' ') if is_first_spaces_of_line
      is_first_spaces_of_line = false
      next
    end
    case t[1]
    when :on_lbracket, :on_lbrace, :on_lparen, :on_tlambeg
      spaces_of_nest.push(spaces_at_line_head + open_brace_on_line * 2)
      open_brace_on_line += 1
    when :on_rbracket, :on_rbrace, :on_rparen
      if is_first_printable_of_line
        corresponding_token_depth = spaces_of_nest.pop
      else
        spaces_of_nest.pop
        corresponding_token_depth = nil
      end
      open_brace_on_line -= 1
    when :on_kw
      next if index > 0 and @tokens[index - 1][3].allbits?(Ripper::EXPR_FNAME)
      case t[2]
      when 'do'
        syntax_of_do = take_corresponding_syntax_to_kw_do(@tokens, index)
        if syntax_of_do == :method_calling
          spaces_of_nest.push(spaces_at_line_head)
        end
      when 'def', 'case', 'for', 'begin', 'class', 'module'
        spaces_of_nest.push(spaces_at_line_head)
      when 'rescue'
        unless t[3].allbits?(Ripper::EXPR_LABEL)
          corresponding_token_depth = spaces_of_nest.last
        end
      when 'if', 'unless', 'while', 'until'
        # postfix if/unless/while/until must be Ripper::EXPR_LABEL
        unless t[3].allbits?(Ripper::EXPR_LABEL)
          spaces_of_nest.push(spaces_at_line_head)
        end
      when 'else', 'elsif', 'ensure', 'when', 'in'
        corresponding_token_depth = spaces_of_nest.last
      when 'end'
        if is_first_printable_of_line
          corresponding_token_depth = spaces_of_nest.pop
        else
          spaces_of_nest.pop
          corresponding_token_depth = nil
        end
      end
    end
    is_first_spaces_of_line = false
    is_first_printable_of_line = false
  end
  corresponding_token_depth
end

#check_newline_depth_difference

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 522

def check_newline_depth_difference
  depth_difference = 0
  open_brace_on_line = 0
  in_oneliner_def = nil
  @tokens.each_with_index do |t, index|
    # detecting one-liner method definition
    if in_oneliner_def.nil?
      if t[3].allbits?(Ripper::EXPR_ENDFN)
        in_oneliner_def = :ENDFN
      end
    else
      if t[3].allbits?(Ripper::EXPR_ENDFN)
        # continuing
      elsif t[3].allbits?(Ripper::EXPR_BEG)
        if t[2] == '='
          in_oneliner_def = :BODY
        end
      else
        if in_oneliner_def == :BODY
          # one-liner method definition
          depth_difference -= 1
        end
        in_oneliner_def = nil
      end
    end

    case t[1]
    when :on_ignored_nl, :on_nl, :on_comment
      if index != (@tokens.size - 1) and in_oneliner_def != :BODY
        depth_difference = 0
        open_brace_on_line = 0
      end
      next
    when :on_sp
      next
    end
    case t[1]
    when :on_lbracket, :on_lbrace, :on_lparen, :on_tlambeg
      depth_difference += 1
      open_brace_on_line += 1
    when :on_rbracket, :on_rbrace, :on_rparen
      depth_difference -= 1 if open_brace_on_line > 0
    when :on_kw
      next if index > 0 and @tokens[index - 1][3].allbits?(Ripper::EXPR_FNAME)
      case t[2]
      when 'do'
        syntax_of_do = take_corresponding_syntax_to_kw_do(@tokens, index)
        depth_difference += 1 if syntax_of_do == :method_calling
      when 'def', 'case', 'for', 'begin', 'class', 'module'
        depth_difference += 1
      when 'if', 'unless', 'while', 'until', 'rescue'
        # postfix if/unless/while/until/rescue must be Ripper::EXPR_LABEL
        unless t[3].allbits?(Ripper::EXPR_LABEL)
          depth_difference += 1
        end
      when 'else', 'elsif', 'ensure', 'when'
        depth_difference += 1
      when 'in'
        unless is_the_in_correspond_to_a_for(@tokens, index)
          depth_difference += 1
        end
      when 'end'
        depth_difference -= 1
      end
    end
  end
  depth_difference
end

#check_state(code, tokens = nil)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 206

def check_state(code, tokens = nil)
  tokens = self.class.ripper_lex_without_warning(code) unless tokens
  ltype = process_literal_type(tokens)
  indent = process_nesting_level(tokens)
  continue = process_continue(tokens)
  code_block_open = check_code_block(code, tokens)
  [ltype, indent, continue, code_block_open]
end

#check_string_literal(tokens)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 689

def check_string_literal(tokens)
  i = 0
  start_token = []
  end_type = []
  while i < tokens.size
    t = tokens[i]
    case t[1]
    when :on_tstring_beg
      start_token << t
      end_type << [:on_tstring_end, :on_label_end]
    when :on_regexp_beg
      start_token << t
      end_type << :on_regexp_end
    when :on_symbeg
      acceptable_single_tokens = %i{on_ident on_const on_op on_cvar on_ivar on_gvar on_kw}
      if (i + 1) < tokens.size and acceptable_single_tokens.all?{ |st| tokens[i + 1][1] != st }
        start_token << t
        end_type << :on_tstring_end
      end
    when :on_backtick
      start_token << t
      end_type << :on_tstring_end
    when :on_qwords_beg, :on_words_beg, :on_qsymbols_beg, :on_symbols_beg
      start_token << t
      end_type << :on_tstring_end
    when :on_heredoc_beg
      start_token << t
      end_type << :on_heredoc_end
    when *end_type.last
      start_token.pop
      end_type.pop
    end
    i += 1
  end
  start_token.last.nil? ? '' : start_token.last
end

#check_termination_in_prev_line(code)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 757

def check_termination_in_prev_line(code)
  tokens = self.class.ripper_lex_without_warning(code)
  past_first_newline = false
  index = tokens.rindex do |t|
    # traverse first token before last line
    if past_first_newline
      if t.tok.include?("\n")
        true
      end
    elsif t.tok.include?("\n")
      past_first_newline = true
      false
    else
      false
    end
  end
  if index
    first_token = nil
    last_line_tokens = tokens[(index + 1)..(tokens.size - 1)]
    last_line_tokens.each do |t|
      unless [:on_sp, :on_ignored_sp, :on_comment].include?(t.event)
        first_token = t
        break
      end
    end
    if first_token.nil?
      return false
    elsif first_token && first_token.state == Ripper::EXPR_DOT
      return false
    else
      tokens_without_last_line = tokens[0..index]
      ltype = process_literal_type(tokens_without_last_line)
      indent = process_nesting_level(tokens_without_last_line)
      continue = process_continue(tokens_without_last_line)
      code_block_open = check_code_block(tokens_without_last_line.map(&:tok).join(''), tokens_without_last_line)
      if ltype or indent > 0 or continue or code_block_open
        return false
      else
        return last_line_tokens.map(&:tok).join('')
      end
    end
  end
  false
end

#each_top_level_statement

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 230

def each_top_level_statement
  initialize_input
  catch(:TERM_INPUT) do
    loop do
      begin
        prompt
        unless l = lex
          throw :TERM_INPUT if @line == ''
        else
          @line_no += l.count("\n")
          if l == "\n"
            @exp_line_no += 1
            next
          end
          @line.concat l
          if @code_block_open or @ltype or @continue or @indent > 0
            next
          end
        end
        if @line != "\n"
          @line.force_encoding(@io.encoding)
          yield @line, @exp_line_no
        end
        raise TerminateLineInput if @io.eof?
        @line = ''
        @exp_line_no = @line_no

        @indent = 0
      rescue TerminateLineInput
        initialize_input
        prompt
      end
    end
  end
end

#find_prev_spaces(line_index)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 161

def find_prev_spaces(line_index)
  return 0 if @tokens.size == 0
  md = @tokens[0][2].match(/(\A +)/)
  prev_spaces = md.nil? ? 0 : md[1].count(' ')
  line_count = 0
  @tokens.each_with_index do |t, i|
    if t[2].include?("\n")
      line_count += t[2].count("\n")
      if line_count >= line_index
        return prev_spaces
      end
      if (@tokens.size - 1) > i
        md = @tokens[i + 1][2].match(/(\A +)/)
        prev_spaces = md.nil? ? 0 : md[1].count(' ')
      end
    end
  end
  prev_spaces
end

#initialize_input

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 221

def initialize_input
  @ltype = nil
  @indent = 0
  @continue = false
  @line = ""
  @exp_line_no = @line_no
  @code_block_open = false
end

#is_method_calling?(tokens, index) ⇒ Boolean

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 445

def is_method_calling?(tokens, index)
  tk = tokens[index]
  if tk[3].anybits?(Ripper::EXPR_CMDARG) and tk[1] == :on_ident
    # The target method call to pass the block with "do".
    return true
  elsif tk[3].anybits?(Ripper::EXPR_ARG) and tk[1] == :on_ident
    non_sp_index = tokens[0..(index - 1)].rindex{ |t| t[1] != :on_sp }
    if non_sp_index
      prev_tk = tokens[non_sp_index]
      if prev_tk[3].anybits?(Ripper::EXPR_DOT) and prev_tk[1] == :on_period
        # The target method call with receiver to pass the block with "do".
        return true
      end
    end
  end
  false
end

#is_the_in_correspond_to_a_for(tokens, index)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 494

def is_the_in_correspond_to_a_for(tokens, index)
  syntax_of_in = nil
  # Finding a syntax correnponding to "do".
  index.downto(0) do |i|
    tk = tokens[i]
    # In "continue", the token isn't the corresponding syntax to "do".
    non_sp_index = tokens[0..(i - 1)].rindex{ |t| t[1] != :on_sp }
    first_in_fomula = false
    if non_sp_index.nil?
      first_in_fomula = true
    elsif [:on_ignored_nl, :on_nl, :on_comment].include?(tokens[non_sp_index][1])
      first_in_fomula = true
    end
    if tk[1] == :on_kw && tk[2] == 'for'
      # A loop syntax in front of "do" found.
      #
      #   while cond do # also "until" or "for"
      #   end
      #
      # This "do" doesn't increment indent because the loop syntax already
      # incremented.
      syntax_of_in = :for
    end
    break if first_in_fomula
  end
  syntax_of_in
end

#lex

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 266

def lex
  line = @input.call
  if @io.respond_to?(:check_termination)
    return line # multiline
  end
  code = @line + (line.nil? ? '' : line)
  code.gsub!(/\s*\z/, '').concat("\n")
  @tokens = self.class.ripper_lex_without_warning(code)
  @continue = process_continue
  @code_block_open = check_code_block(code)
  @indent = process_nesting_level
  @ltype = process_literal_type
  line
end

#process_continue(tokens = @tokens)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 281

def process_continue(tokens = @tokens)
  # last token is always newline
  if tokens.size >= 2 and tokens[-2][1] == :on_regexp_end
    # end of regexp literal
    return false
  elsif tokens.size >= 2 and tokens[-2][1] == :on_semicolon
    return false
  elsif tokens.size >= 2 and tokens[-2][1] == :on_kw and ['begin', 'else', 'ensure'].include?(tokens[-2][2])
    return false
  elsif !tokens.empty? and tokens.last[2] == "\\\n"
    return true
  elsif tokens.size >= 1 and tokens[-1][1] == :on_heredoc_end # "EOH\n"
    return false
  elsif tokens.size >= 2 and defined?(Ripper::EXPR_BEG) and tokens[-2][3].anybits?(Ripper::EXPR_BEG | Ripper::EXPR_FNAME) and tokens[-2][2] !~ /\A\.\.\.?\z/
    # end of literal except for regexp
    # endless range at end of line is not a continue
    return true
  end
  false
end

#process_literal_type(tokens = @tokens)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 726

def process_literal_type(tokens = @tokens)
  start_token = check_string_literal(tokens)
  case start_token[1]
  when :on_tstring_beg
    case start_token[2]
    when ?"      then ?"
    when /^%.$/  then ?"
    when /^%Q.$/ then ?"
    when ?'      then ?'
    when /^%q.$/ then ?'
    end
  when :on_regexp_beg   then ?/
  when :on_symbeg       then ?:
  when :on_backtick     then ?`
  when :on_qwords_beg   then ?]
  when :on_words_beg    then ?]
  when :on_qsymbols_beg then ?]
  when :on_symbols_beg  then ?]
  when :on_heredoc_beg
    start_token[2] =~ /<<[-~]?(['"`])[_a-zA-Z0-9]+\1/
    case $1
    when ?" then ?"
    when ?' then ?'
    when ?` then ?`
    else         ?"
    end
  else
    nil
  end
end

#process_nesting_level(tokens = @tokens)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 395

def process_nesting_level(tokens = @tokens)
  indent = 0
  in_oneliner_def = nil
  tokens.each_with_index { |t, index|
    # detecting one-liner method definition
    if in_oneliner_def.nil?
      if t[3].allbits?(Ripper::EXPR_ENDFN)
        in_oneliner_def = :ENDFN
      end
    else
      if t[3].allbits?(Ripper::EXPR_ENDFN)
        # continuing
      elsif t[3].allbits?(Ripper::EXPR_BEG)
        if t[2] == '='
          in_oneliner_def = :BODY
        end
      else
        if in_oneliner_def == :BODY
          # one-liner method definition
          indent -= 1
        end
        in_oneliner_def = nil
      end
    end

    case t[1]
    when :on_lbracket, :on_lbrace, :on_lparen, :on_tlambeg
      indent += 1
    when :on_rbracket, :on_rbrace, :on_rparen
      indent -= 1
    when :on_kw
      next if index > 0 and tokens[index - 1][3].allbits?(Ripper::EXPR_FNAME)
      case t[2]
      when 'do'
        syntax_of_do = take_corresponding_syntax_to_kw_do(tokens, index)
        indent += 1 if syntax_of_do == :method_calling
      when 'def', 'case', 'for', 'begin', 'class', 'module'
        indent += 1
      when 'if', 'unless', 'while', 'until'
        # postfix if/unless/while/until must be Ripper::EXPR_LABEL
        indent += 1 unless t[3].allbits?(Ripper::EXPR_LABEL)
      when 'end'
        indent -= 1
      end
    end
    # percent literals are not indented
  }
  indent
end

#prompt

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 215

def prompt
  if @prompt
    @prompt.call(@ltype, @indent, @continue, @line_no)
  end
end

#set_auto_indent(context)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 181

def set_auto_indent(context)
  if @io.respond_to?(:auto_indent) and context.auto_indent_mode
    @io.auto_indent do |lines, line_index, byte_pointer, is_newline|
      if is_newline
        @tokens = self.class.ripper_lex_without_warning(lines[0..line_index].join("\n"))
        prev_spaces = find_prev_spaces(line_index)
        depth_difference = check_newline_depth_difference
        depth_difference = 0 if depth_difference < 0
        prev_spaces + depth_difference * 2
      else
        code = line_index.zero? ? '' : lines[0..(line_index - 1)].map{ |l| l + "\n" }.join
        last_line = lines[line_index]&.byteslice(0, byte_pointer)
        code += last_line if last_line
        @tokens = self.class.ripper_lex_without_warning(code)
        corresponding_token_depth = check_corresponding_token_depth
        if corresponding_token_depth
          corresponding_token_depth
        else
          nil
        end
      end
    end
  end
end

#set_input(io, p = nil, &block)

io functions

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 46

def set_input(io, p = nil, &block)
  @io = io
  if @io.respond_to?(:check_termination)
    @io.check_termination do |code|
      if Reline::IOGate.in_pasting?
        lex = RubyLex.new
        rest = lex.check_termination_in_prev_line(code)
        if rest
          Reline.delete_text
          rest.bytes.reverse_each do |c|
            Reline.ungetc(c)
          end
          true
        else
          false
        end
      else
        code.gsub!(/\s*\z/, '').concat("\n")
        ltype, indent, continue, code_block_open = check_state(code)
        if ltype or indent > 0 or continue or code_block_open
          false
        else
          true
        end
      end
    end
  end
  if @io.respond_to?(:dynamic_prompt)
    @io.dynamic_prompt do |lines|
      lines << '' if lines.empty?
      result = []
      tokens = self.class.ripper_lex_without_warning(lines.map{ |l| l + "\n" }.join)
      code = String.new
      partial_tokens = []
      unprocessed_tokens = []
      line_num_offset = 0
      tokens.each do |t|
        partial_tokens << t
        unprocessed_tokens << t
        if t[2].include?("\n")
          t_str = t[2]
          t_str.each_line("\n") do |s|
            code << s << "\n"
            ltype, indent, continue, code_block_open = check_state(code, partial_tokens)
            result << @prompt.call(ltype, indent, continue || code_block_open, @line_no + line_num_offset)
            line_num_offset += 1
          end
          unprocessed_tokens = []
        else
          code << t[2]
        end
      end
      unless unprocessed_tokens.empty?
        ltype, indent, continue, code_block_open = check_state(code, unprocessed_tokens)
        result << @prompt.call(ltype, indent, continue || code_block_open, @line_no + line_num_offset)
      end
      result
    end
  end
  if p.respond_to?(:call)
    @input = p
  elsif block_given?
    @input = block
  else
    @input = Proc.new{@io.gets}
  end
end

#set_prompt(p = nil, &block)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 114

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

#take_corresponding_syntax_to_kw_do(tokens, index)

[ GitHub ]

  
# File 'lib/irb/ruby-lex.rb', line 463

def take_corresponding_syntax_to_kw_do(tokens, index)
  syntax_of_do = nil
  # Finding a syntax correnponding to "do".
  index.downto(0) do |i|
    tk = tokens[i]
    # In "continue", the token isn't the corresponding syntax to "do".
    non_sp_index = tokens[0..(i - 1)].rindex{ |t| t[1] != :on_sp }
    first_in_fomula = false
    if non_sp_index.nil?
      first_in_fomula = true
    elsif [:on_ignored_nl, :on_nl, :on_comment].include?(tokens[non_sp_index][1])
      first_in_fomula = true
    end
    if is_method_calling?(tokens, i)
      syntax_of_do = :method_calling
      break if first_in_fomula
    elsif tk[1] == :on_kw && %w{while until for}.include?(tk[2])
      # A loop syntax in front of "do" found.
      #
      #   while cond do # also "until" or "for"
      #   end
      #
      # This "do" doesn't increment indent because the loop syntax already
      # incremented.
      syntax_of_do = :loop_syntax
      break if first_in_fomula
    end
  end
  syntax_of_do
end