class Spec::Matchers::ThrowSymbol

def args
  @expected_arg.nil? ? "" : " with #{@expected_arg.inspect}"
end

def description
  "throw #{expected}"
end

def expected
  @expected_symbol.nil? ? "a Symbol" : "#{@expected_symbol.inspect}#{args}"
end

def failure_message_for_should
  if @caught_symbol
    "expected #{expected}, got #{@caught_symbol.inspect}"
  else
    "expected #{expected} but nothing was thrown"
  end
end

def failure_message_for_should_not
  if @expected_symbol
    "expected #{expected} not to be thrown"
  else
    "expected no Symbol, got :#{@caught_symbol}"
  end
end

def initialize(expected_symbol = nil, expected_arg=nil)
  @expected_symbol = expected_symbol
  @expected_arg = expected_arg
  @caught_symbol = @caught_arg = nil
end

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