%%% -*- erlang-indent-level: 2 -*-
%%%-------------------------------------------------------------------
%%% Author: Kostis Sagonas
%%%
%%% Contains tests for correct handling of guards and guard BIFs.
%%%-------------------------------------------------------------------
-module(basic_guards).
-export([test/0]).
test() ->
ok = guard0(4.2),
ok = guard1([foo]),
ok = test_guard2(),
ok = test_guard3(),
ok = test_guard4(),
ok.
%%--------------------------------------------------------------------
guard0(X) when X /= 0, is_float(X) ->
ok.
guard1(X) when is_atom(X) orelse is_float(X) ->
error1;
guard1(X) when is_reference(hd(X)) ->
error2;
guard1(X) when is_integer(hd(X)) ->
error3;
guard1(X) when hd(X) == foo ->
ok.
%%--------------------------------------------------------------------
test_guard2() ->
ok1 = guard2(true),
not_boolean = guard2(42),
ok2 = guard2(false),
ok.
guard2(X) when X -> % gets transformed to: is_boolean(X), X =:= true
ok1;
guard2(X) when X =:= false ->
ok2;
guard2(_) ->
not_boolean.
%%--------------------------------------------------------------------
-define(is_foo(X), (is_atom(X) or (is_tuple(X) and (element(1, X) =:= 'foo')))).
test_guard3() ->
no = f('foo'),
yes = f({'foo', 42}),
no = f(42),
ok.
f(X) when ?is_foo(X) -> yes;
f(_) -> no.
%%--------------------------------------------------------------------
-define(EXT_REF, <<131,114,0,3,100,0,19,114,101,102,95,116,101,115,116,95,98,117,103,64,103,111,114,98,97,103,2,0,0,0,125,0,0,0,0,0,0,0,0>>).
test_guard4() ->
yes = is_ref(make_ref()),
no = is_ref(gazonk),
yes = is_ref(an_external_ref(?EXT_REF)),
ok.
is_ref(Ref) when is_reference(Ref) -> yes;
is_ref(_Ref) -> no.
an_external_ref(Bin) ->
binary_to_term(Bin).
