class IRB::Irb - irb: Ruby Standard Library Documentation

# class IRB::Irb

### Constants

CONTROL_CHARACTERS_PATTERN
PROMPT_MAIN_TRUNCATE_LENGTH

  Note: instance and index assignment expressions could also be written like: “foo.bar=(1)” and “foo.[]=(1, bar)”, when expressed that way, the former be parsed as :assign and echo will be suppressed, but the latter is parsed as a :method_add_arg and the output won’t be suppressed

PROMPT_MAIN_TRUNCATE_OMISSION

### Attributes

context[R]

Returns the current context of this irb session

from_binding[R]
scanner[RW]

The lexer used by this irb session

### Public Class Methods

new(workspace = nil, input_method = nil, from_binding: false) click to toggle source

Creates a new irb session

    # File irb.rb, line 940
    def initialize(workspace = nil, input_method = nil, from_binding: false)
      @from_binding = from_binding
      @context = Context.new(self, workspace, input_method)
      @context.workspace.load_helper_methods_to_main
      @signal_status = :IN_IRB
      @scanner = RubyLex.new
      @line_no = 1
    end

### Public Instance Methods

build_statement(code) click to toggle source

    # File irb.rb, line 1130
    def build_statement(code)
      if code.match?(/\A\n*\z/)
        return Statement::EmptyInput.new
      end

      code = code.dup.force_encoding(@context.io.encoding)
      if (command, arg = @context.parse_command(code))
        command_class = Command.load_command(command)
        Statement::Command.new(code, command_class, arg)
      else
        is_assignment_expression = @scanner.assignment_expression?(code, local_variables: @context.local_variables)
        Statement::Expression.new(code, is_assignment_expression)
      end
    end

command?(code) click to toggle source

    # File irb.rb, line 1145
    def command?(code)
      !!@context.parse_command(code)
    end

configure_io() click to toggle source

    # File irb.rb, line 1149
    def configure_io
      if @context.io.respond_to?(:check_termination)
        @context.io.check_termination do |code|
          if Reline::IOGate.in_pasting?
            rest = @scanner.check_termination_in_prev_line(code, local_variables: @context.local_variables)
            if rest
              Reline.delete_text
              rest.bytes.reverse_each do |c|
                Reline.ungetc(c)
              end
              true
            else
              false
            end
          else
            next true if command?(code)

            _tokens, _opens, terminated = @scanner.check_code_state(code, local_variables: @context.local_variables)
            terminated
          end
        end
      end
      if @context.io.respond_to?(:dynamic_prompt)
        @context.io.dynamic_prompt do |lines|
          tokens = RubyLex.ripper_lex_without_warning(lines.map{ |l| l + "\n" }.join, local_variables: @context.local_variables)
          line_results = IRB::NestingParser.parse_by_line(tokens)
          tokens_until_line = []
          line_results.map.with_index do |(line_tokens, _prev_opens, next_opens, _min_depth), line_num_offset|
            line_tokens.each do |token, _s|
              # Avoid appending duplicated token. Tokens that include "n" like multiline
              # tstring_content can exist in multiple lines.
              tokens_until_line << token if token != tokens_until_line.last
            end
            continue = @scanner.should_continue?(tokens_until_line)
            generate_prompt(next_opens, continue, line_num_offset)
          end
        end
      end

      if @context.io.respond_to?(:auto_indent) and @context.auto_indent_mode
        @context.io.auto_indent do |lines, line_index, byte_pointer, is_newline|
          next nil if lines == [nil] # Workaround for exit IRB with CTRL+d
          next nil if !is_newline && lines[line_index]&.byteslice(0, byte_pointer)&.match?(/\A\s*\z/)

          code = lines[0..line_index].map { |l| "#{l}\n" }.join
          tokens = RubyLex.ripper_lex_without_warning(code, local_variables: @context.local_variables)
          @scanner.process_indent_level(tokens, lines, line_index, is_newline)
        end
      end
    end

convert_invalid_byte_sequence(str, enc) click to toggle source

    # File irb.rb, line 1200
    def convert_invalid_byte_sequence(str, enc)
      str.force_encoding(enc)
      str.scrub { |c|
        c.bytes.map{ |b| "\\x#{b.to_s(16).upcase}" }.join
      }
    end

debug_break() click to toggle source

A hook point for `debug` command’s breakpoint after :IRB_EXIT as well as its clean-up

    # File irb.rb, line 951
    def debug_break
      # it means the debug integration has been activated
      if defined?(DEBUGGER__) && DEBUGGER__.respond_to?(:capture_frames_without_irb)
        # after leaving this initial breakpoint, revert the capture_frames patch
        DEBUGGER__.singleton_class.send(:alias_method, :capture_frames, :capture_frames_without_irb)
        # and remove the redundant method
        DEBUGGER__.singleton_class.send(:undef_method, :capture_frames_without_irb)
      end
    end

debug_readline(binding) click to toggle source

    # File irb.rb, line 961
    def debug_readline(binding)
      workspace = IRB::WorkSpace.new(binding)
      context.replace_workspace(workspace)
      context.workspace.load_helper_methods_to_main
      @line_no += 1

      # When users run:
      # 1.  Debugging commands, like `step 2`
      # 2.  Any input that's not irb-command, like `foo = 123`
      #
      #
      # Irb#eval_input will simply return the input, and we need to pass it to the
      # debugger.
      input = nil
      forced_exit = catch(:IRB_EXIT) do
        if History.save_history? && context.io.support_history_saving?
          # Previous IRB session's history has been saved when `Irb#run` is exited We need
          # to make sure the saved history is not saved again by resetting the counter
          context.io.reset_history_counter

          begin
            input = eval_input
          ensure
            context.io.save_history
          end
        else
          input = eval_input
        end
        false
      end

      Kernel.exit if forced_exit

      if input&.include?("\n")
        @line_no += input.count("\n") - 1
      end

      input
    end

each_top_level_statement() { |build_statement(code), line_no| ... } click to toggle source

    # File irb.rb, line 1120
    def each_top_level_statement
      loop do
        code = readmultiline
        break unless code
        yield build_statement(code), @line_no
        @line_no += code.count("\n")
      rescue RubyLex::TerminateLineInput
      end
    end

encode_with_invalid_byte_sequence(str, enc) click to toggle source

    # File irb.rb, line 1207
    def encode_with_invalid_byte_sequence(str, enc)
      conv = Encoding::Converter.new(str.encoding, enc)
      dst = String.new
      begin
        ret = conv.primitive_convert(str, dst)
        case ret
        when :invalid_byte_sequence
          conv.insert_output(conv.primitive_errinfo[3].dump[1..-2])
          redo
        when :undefined_conversion
          c = conv.primitive_errinfo[3].dup.force_encoding(conv.primitive_errinfo[1])
          conv.insert_output(c.dump[1..-2])
          redo
        when :incomplete_input
          conv.insert_output(conv.primitive_errinfo[3].dump[1..-2])
        when :finished
        end
        break
      end while nil
      dst
    end

eval_input() click to toggle source

Evaluates input for this session.

    # File irb.rb, line 1041
    def eval_input
      configure_io

      each_top_level_statement do |statement, line_no|
        signal_status(:IN_EVAL) do
          begin
            # If the integration with debugger is activated, we return certain input if it
            # should be dealt with by debugger
            if @context.with_debugger && statement.should_be_handled_by_debugger?
              return statement.code
            end

            @context.evaluate(statement, line_no)

            if @context.echo? && !statement.suppresses_echo?
              if statement.is_assignment?
                if @context.echo_on_assignment?
                  output_value(@context.echo_on_assignment? == :truncate)
                end
              else
                output_value
              end
            end
          rescue SystemExit, SignalException
            raise
          rescue Interrupt, Exception => exc
            handle_exception(exc)
            @context.workspace.local_variable_set(:_, exc)
          end
        end
      end
    end

handle_exception(exc) click to toggle source

    # File irb.rb, line 1229
    def handle_exception(exc)
      if exc.backtrace[0] =~ /\/irb(2)?(\/.*|-.*|\.rb)?:/ && exc.class.to_s !~ /^IRB/ &&
         !(SyntaxError === exc) && !(EncodingError === exc)
        # The backtrace of invalid encoding hash (ex. {"\xAE": 1}) raises EncodingError without lineno.
        irb_bug = true
      else
        irb_bug = false
        # To support backtrace filtering while utilizing Exception#full_message, we need to clone
        # the exception to avoid modifying the original exception's backtrace.
        exc = exc.clone
        filtered_backtrace = exc.backtrace.map { |l| @context.workspace.filter_backtrace(l) }.compact
        backtrace_filter = IRB.conf[:BACKTRACE_FILTER]

        if backtrace_filter
          if backtrace_filter.respond_to?(:call)
            filtered_backtrace = backtrace_filter.call(filtered_backtrace)
          else
            warn "IRB.conf[:BACKTRACE_FILTER] #{backtrace_filter} should respond to `call` method"
          end
        end

        exc.set_backtrace(filtered_backtrace)
      end

      highlight = Color.colorable?

      order =
        if RUBY_VERSION < '3.0.0'
          STDOUT.tty? ? :bottom : :top
        else # '3.0.0' <= RUBY_VERSION
          :top
        end

      message = exc.full_message(order: order, highlight: highlight)
      message = convert_invalid_byte_sequence(message, exc.message.encoding)
      message = encode_with_invalid_byte_sequence(message, IRB.conf[:LC_MESSAGES].encoding) unless message.encoding.to_s.casecmp?(IRB.conf[:LC_MESSAGES].encoding.to_s)
      message = message.gsub(/((?:^\t.+$\n)+)/) { |m|
        case order
        when :top
          lines = m.split("\n")
        when :bottom
          lines = m.split("\n").reverse
        end
        unless irb_bug
          if lines.size > @context.back_trace_limit
            omit = lines.size - @context.back_trace_limit
            lines = lines[0..(@context.back_trace_limit - 1)]
            lines << "\t... %d levels..." % omit
          end
        end
        lines = lines.reverse if order == :bottom
        lines.map{ |l| l + "\n" }.join
      }
      # The "<top (required)>" in "(irb)" may be the top level of IRB so imitate the main object.
      message = message.gsub(/\(irb\):(?<num>\d+):in (?<open_quote>[`'])<(?<frame>top \(required\))>'/) { "(irb):#{$~[:num]}:in #{$~[:open_quote]}<main>'" }
      puts message
      puts 'Maybe IRB bug!' if irb_bug
    rescue Exception => handler_exc
      begin
        puts exc.inspect
        puts "backtraces are hidden because #{handler_exc} was raised when processing them"
      rescue Exception
        puts 'Uninspectable exception occurred'
      end
    end

inspect() click to toggle source

Outputs the local variables to this current session, including `signal_status` and `context`, using `IRB::Locale`.

    # File irb.rb, line 1410
    def inspect
      ary = []
      for iv in instance_variables
        case (iv = iv.to_s)
        when "@signal_status"
          ary.push format("%s=:%s", iv, @signal_status.id2name)
        when "@context"
          ary.push format("%s=%s", iv, eval(iv).__to_s__)
        else
          ary.push format("%s=%s", iv, eval(iv))
        end
      end
      format("#<%s: %s>", self.class, ary.join(", "))
    end

read_input(prompt) click to toggle source

    # File irb.rb, line 1074
    def read_input(prompt)
      signal_status(:IN_INPUT) do
        @context.io.prompt = prompt
        if l = @context.io.gets
          print l if @context.verbose?
        else
          if @context.ignore_eof? and @context.io.readable_after_eof?
            l = "\n"
            if @context.verbose?
              printf "Use \"exit\" to leave %s\n", @context.ap_name
            end
          else
            print "\n" if @context.prompting?
          end
        end
        l
      end
    end

readmultiline() click to toggle source

    # File irb.rb, line 1093
    def readmultiline
      prompt = generate_prompt([], false, 0)

      # multiline
      return read_input(prompt) if @context.io.respond_to?(:check_termination)

      # nomultiline
      code = +''
      line_offset = 0
      loop do
        line = read_input(prompt)
        unless line
          return code.empty? ? nil : code
        end

        code << line
        return code if command?(code)

        tokens, opens, terminated = @scanner.check_code_state(code, local_variables: @context.local_variables)
        return code if terminated

        line_offset += 1
        continue = @scanner.should_continue?(tokens)
        prompt = generate_prompt(opens, continue, line_offset)
      end
    end

run(conf = IRB.conf) click to toggle source

    # File irb.rb, line 1001
    def run(conf = IRB.conf)
      in_nested_session = !!conf[:MAIN_CONTEXT]
      conf[:IRB_RC].call(context) if conf[:IRB_RC]
      prev_context = conf[:MAIN_CONTEXT]
      conf[:MAIN_CONTEXT] = context

      load_history = !in_nested_session && context.io.support_history_saving?
      save_history = load_history && History.save_history?

      if load_history
        context.io.load_history
      end

      prev_trap = trap("SIGINT") do
        signal_handle
      end

      begin
        if defined?(RubyVM.keep_script_lines)
          keep_script_lines_backup = RubyVM.keep_script_lines
          RubyVM.keep_script_lines = true
        end

        forced_exit = catch(:IRB_EXIT) do
          eval_input
        end
      ensure
        # Do not restore to nil. It will cause IRB crash when used with threads.
        IRB.conf[:MAIN_CONTEXT] = prev_context if prev_context

        RubyVM.keep_script_lines = keep_script_lines_backup if defined?(RubyVM.keep_script_lines)
        trap("SIGINT", prev_trap)
        conf[:AT_EXIT].each{|hook| hook.call}

        context.io.save_history if save_history
        Kernel.exit if forced_exit
      end
    end

signal_handle() click to toggle source

Handler for the signal SIGINT, see Kernel#trap for more information.

    # File irb.rb, line 1337
    def signal_handle
      unless @context.ignore_sigint?
        print "\nabort!\n" if @context.verbose?
        exit
      end

      case @signal_status
      when :IN_INPUT
        print "^C\n"
        raise RubyLex::TerminateLineInput
      when :IN_EVAL
        IRB.irb_abort(self)
      when :IN_LOAD
        IRB.irb_abort(self, LoadAbort)
      when :IN_IRB
        # ignore
      else
        # ignore other cases as well
      end
    end

signal_status(status) { || ... } click to toggle source

Evaluates the given block using the given `status`.

    # File irb.rb, line 1359
    def signal_status(status)
      return yield if @signal_status == :IN_LOAD

      signal_status_back = @signal_status
      @signal_status = status
      begin
        yield
      ensure
        @signal_status = signal_status_back
      end
    end

suspend_input_method(input_method) { |back_io| ... } click to toggle source

Evaluates the given block using the given `input_method` as the `Context#io`.

Used by the irb commands `source` and `irb_load`, see IRB Sessions at `IRB` for more information.

    # File irb.rb, line 1326
    def suspend_input_method(input_method)
      back_io = @context.io
      @context.instance_eval{@io = input_method}
      begin
        yield back_io
      ensure
        @context.instance_eval{@io = back_io}
      end
    end

suspend_name(path = nil, name = nil) { |back_path, back_name| ... } click to toggle source

Evaluates the given block using the given `path` as the `Context#irb_path` and `name` as the `Context#irb_name`.

Used by the irb command `source`, see IRB Sessions at `IRB` for more information.

    # File irb.rb, line 1299
    def suspend_name(path = nil, name = nil)
      @context.irb_path, back_path = path, @context.irb_path if path
      @context.irb_name, back_name = name, @context.irb_name if name
      begin
        yield back_path, back_name
      ensure
        @context.irb_path = back_path if path
        @context.irb_name = back_name if name
      end
    end

suspend_workspace(workspace) { || ... } click to toggle source

Evaluates the given block using the given `workspace` as the `Context#workspace`.

Used by the irb command `irb_load`, see IRB Sessions at `IRB` for more information.

    # File irb.rb, line 1314
    def suspend_workspace(workspace)
      current_workspace = @context.workspace
      @context.replace_workspace(workspace)
      yield
    ensure
      @context.replace_workspace current_workspace
    end

### Private Instance Methods

generate_prompt(opens, continue, line_offset) click to toggle source

    # File irb.rb, line 1427
    def generate_prompt(opens, continue, line_offset)
      ltype = @scanner.ltype_from_open_tokens(opens)
      indent = @scanner.calc_indent_level(opens)
      continue = opens.any? || continue
      line_no = @line_no + line_offset

      if ltype
        f = @context.prompt_s
      elsif continue
        f = @context.prompt_c
      else
        f = @context.prompt_i
      end
      f = "" unless f
      if @context.prompting?
        p = format_prompt(f, ltype, indent, line_no)
      else
        p = ""
      end
      if @context.auto_indent_mode and !@context.io.respond_to?(:auto_indent)
        unless ltype
          prompt_i = @context.prompt_i.nil? ? "" : @context.prompt_i
          ind = format_prompt(prompt_i, ltype, indent, line_no)[/.*\z/].size +
            indent * 2 - p.size
          p += " " * ind if ind > 0
        end
      end
      p
    end