gistfile1.rb

class Pry
  module DefaultCommands
    Cd = Pry::CommandSet.new do
      create_command "cd" do
        group "Context"
        description "Move into a new context (object or scope)."

        banner <<-BANNER
          Usage: cd [OPTIONS] [--help]

          Move into new context (object or scope). As in unix shells use
          `cd ..` to go back, `cd /` to return to Pry top-level and `cd -`
          to toggle between last two scopes).
          Complex syntax (e.g cd ../@x/y) also supported.

          e.g: `cd @x`
          e.g: `cd ..
          e.g: `cd /`
          e.g: `cd -`

          https://github.com/pry/pry/wiki/State-navigation#wiki-Changing_scope
        BANNER

        command_options :old_binding => nil, :append_binding => true

        def process
          # Extract command arguments. Delete blank arguments like " ", but
          # don't delete empty string like "".
          path  = arg_string.split(/\//).delete_if { |a| a =~ /\A\s+\z/ }
          stack = _pry_.binding_stack.dup

          # Save previous command option values for the sake of restoring them
          # them later (for example, when an exception raised).
          old_binding    = command_options[:old_binding]
          append_binding = command_options[:append_binding]

          # Special case when we only get a single "/", return to root.
          if path.empty?
            set_toggle_options(stack.last, true) if old_binding
            stack = [stack.first]
          end

          path.each do |context|
            begin
              case context.chomp
              when ""
                set_toggle_options(stack.last, true)
                stack = [stack.first]
              when "::"
                set_toggle_options(stack.last, false)
                stack.push(TOPLEVEL_BINDING)
              when "."
                next
              when ".."
                unless stack.size == 1
                  set_toggle_options(stack.pop, true)
                end
              when "-"
                if old_binding
                  toggle_old_binding(stack, old_binding, append_binding)
                end
              else
                set_toggle_options(stack.last, false)
                stack.push(Pry.binding_for(stack.last.eval(context)))
              end

            rescue RescuableException => e
              # Restore previous values.
              command_options[:old_binding]    = old_binding
              command_options[:append_binding] = append_binding

              output.puts "Bad object path: #{arg_string.chomp}. Failed trying to resolve: #{context}"
              output.puts e.inspect
              return
            end
          end

          _pry_.binding_stack = stack
        end

        private

        # Toggle old binding value by either appending it to the current stack
        # (when `append_binding` is `true`) or setting the new one (when
        # `append_binding` is `false`).
        #
        # @param [Array<Binding>] The current stack of bindings.
        # @param [Binding] The old binding.
        # @param [Boolean] The append_binding flag.
        #
        # @return [Binding] The new old binding.
        def toggle_old_binding(stack, old_binding, append_binding)
          if append_binding
            stack.push(old_binding)
            old_binding = stack[-2]
          else
            old_binding = stack.pop
          end
          append_binding = !append_binding

          set_toggle_options(old_binding, append_binding)

          old_binding
        end

        # Set new values for command_options (`:old_binding` and
        # `:append_binding`).
        #
        # @param [Binding] The old binding.
        # @param [Boolean] The append_binding flag.
        #
        # @return [void]
        def set_toggle_options(old_binding, append_binding)
          command_options[:old_binding]    = old_binding
          command_options[:append_binding] = append_binding
        end

      end
    end
  end
end