% test the handling of `>>', `<<', unchecked_left_shift
% and unchecked_right_shift.  

:- module shift_test.
:- interface.
:- import_module io.

:- pred main(io__state::di, io__state::uo) is det.

:- implementation.
:- import_module int, list, string.

main -->
	shift_test((<<), "<<", 64, 0, 64),
	shift_test((<<), "<<", 64, 2, 256),
	shift_test((<<), "<<", -64, 2, -256),
	shift_test((<<), "<<", 64, -2, 16),
	shift_test((<<), "<<", -64, -2, -16),
	shift_test((<<), "<<", 64, -256, 0),
	shift_test((<<), "<<", -64, -256, -1),
	shift_test((<<), "<<", 25, 3, 200),
	shift_test((<<), "<<", -25, 3, -200),
	shift_test((<<), "<<", 25, -3, 3),
	shift_test((<<), "<<", -25, -3, -4),

	shift_test((>>), ">>", 64, 0, 64),
	shift_test((>>), ">>", 64, 2, 16),
	shift_test((>>), ">>", -64, 2, -16),
	shift_test((>>), ">>", 64, -2, 256),
	shift_test((>>), ">>", -64, -2, -256),
	shift_test((>>), ">>", 64, 256, 0),
	shift_test((>>), ">>", -64, 256, -1),
	shift_test((>>), ">>", 25, 3, 3),
	shift_test((>>), ">>", -25, 3, -4),
	shift_test((>>), ">>", 25, -3, 200),
	shift_test((>>), ">>", -25, -3, -200),

	shift_test(unchecked_left_shift, "unchecked_left_shift",
		64, 2, 256),
	shift_test(unchecked_right_shift, "unchecked_right_shift",
		-64, 2, -16),

	io__write_string("The following cases test undefined behaviour\n"),
	io__write_string("(they cause overflow):\n"),
	shift_test((<<), "<<", 64, 256, 0),
	shift_test((<<), "<<", -64, 256, 0),
	shift_test((>>), ">>", 64, -256, 0),
	shift_test((>>), ">>", -64, -256, 0).

:- pred shift_test((func(int, int) = int)::(func(in, in) = out is det),
	string::in, int::in, int::in, int::in,
	io__state::di, io__state::uo) is det.

shift_test(Func, FuncName, Left, Right, Result) -->
	io__format("%d %s %d = %d (%d)\n",
		[i(Left), s(FuncName), i(Right),
		i(Func(Left, Right)), i(Result)]).