# File lib/rspec/matchers/throw_symbol.rb, line 11
      def matches?(given_proc)
        begin
          if @expected_symbol.nil?
            given_proc.call
          else
            @caught_arg = catch :proc_did_not_throw_anything do
              catch @expected_symbol do
                given_proc.call
                throw :proc_did_not_throw_anything, :nothing_thrown
              end
            end

            if @caught_arg == :nothing_thrown
              @caught_arg = nil
            else
              @caught_symbol = @expected_symbol
            end
          end

        # Ruby 1.8 uses NameError with `symbol'
        # Ruby 1.9 uses ArgumentError with :symbol
        rescue NameError, ArgumentError => e
          unless e.message =~ /uncaught throw (`|\:)([a-zA-Z0-9_]*)(')?/
            other_exception = e
            raise
          end
          @caught_symbol = $2.to_sym
        rescue => other_exception
          raise
        ensure
          unless other_exception
            if @expected_symbol.nil?
              return !@caught_symbol.nil?
            else
              if @expected_arg.nil?
                return @caught_symbol == @expected_symbol
              else
                return (@caught_symbol == @expected_symbol) & (@caught_arg == @expected_arg)
              end
            end
          end
        end
      end