base/TypeTraits_unittest.cpp

// Copyright 2020 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "aemu/base/TypeTraits.h"

#include <gtest/gtest.h>

#include <array>
#include <functional>
#include <list>
#include <vector>

namespace android {
namespace base {

TEST(TypeTraits, IsCallable) {
    class C;

    auto lambda = [](bool) -> C* { return nullptr; };

    static_assert(is_callable_as<void(), void()>::value, "simple function");
    static_assert(is_callable_as<void(&)(), void()>::value, "function reference");
    static_assert(is_callable_as<void(*)(), void()>::value, "function pointer");
    static_assert(is_callable_as<int(C&, C*), int(C&, C*)>::value,
                  "function with arguments and return type");
    static_assert(is_callable_as<decltype(lambda), C*(bool)>::value, "lambda");
    static_assert(is_callable_as<std::function<bool(int)>, bool(int)>::value,
                  "std::function");

    static_assert(!is_callable_as<int, void()>::value, "int should not be callable");
    static_assert(!is_callable_as<C, void()>::value, "incomplete type");
    static_assert(!is_callable_as<void(), void(int)>::value, "different arguments");
    static_assert(!is_callable_as<int(), void()>::value, "different return types");
    static_assert(!is_callable_as<int(), short()>::value,
                  "slightly different return types");
    static_assert(!is_callable_as<int(int), int(int, int)>::value,
                  "more arguments");
    static_assert(!is_callable_as<int(int, int), int(int)>::value,
                  "less arguments");

    static_assert(!is_callable_as<int(int), int>::value,
                  "bad required signature");


    static_assert(is_callable_with_args<void(), void()>::value, "simple function");
    static_assert(is_callable_with_args<void(&)(), void()>::value, "function reference");
    static_assert(is_callable_with_args<void(*)(), void()>::value, "function pointer");
    static_assert(is_callable_with_args<int(C&, C*), int(C&, C*)>::value,
                  "function with arguments and return type");
    static_assert(is_callable_with_args<decltype(lambda), C*(bool)>::value, "lambda");
    static_assert(is_callable_with_args<std::function<bool(int)>, bool(int)>::value,
                  "std::function");

    static_assert(!is_callable_with_args<int, void()>::value, "int should not be callable");
    static_assert(!is_callable_with_args<C, void()>::value, "incomplete type");
    static_assert(!is_callable_with_args<void(), void(int)>::value, "different arguments");
    static_assert(is_callable_with_args<int(), void()>::value, "different return types are ignored");
    static_assert(is_callable_with_args<int(), short()>::value, "slightly different return types are ignored");
    static_assert(!is_callable_with_args<int(int), int(int, int)>::value,
                  "more arguments");
    static_assert(!is_callable_with_args<int(int, int), int(int)>::value,
                  "less arguments");

    static_assert(!is_callable_with_args<int(int), int>::value,
                  "bad required signature");
}

TEST(TypeTraits, IsTemplateInstantiation) {
    static_assert(!is_template_instantiation_of<int, std::vector>::value,
                  "int is not an instance of vector");
    static_assert(!is_template_instantiation_of<std::list<std::vector<int>>, std::vector>::value,
                  "list is not an instance of vector");

    static_assert(is_template_instantiation_of<std::vector<int>, std::vector>::value,
                  "std::vector<int> is an instance of vector");
    static_assert(is_template_instantiation_of<std::vector<std::vector<std::vector<int>>>, std::vector>::value,
                  "nested std::vector<> is an instance of vector");
}

TEST(TypeTraits, IsRange) {
    static_assert(is_range<std::vector<int>>::value,
                  "vector<> should be detected as a range");
    static_assert(is_range<const std::list<std::function<void()>>>::value,
                  "const list<> should be detected as a range");
    static_assert(is_range<std::array<std::vector<int>, 10>>::value,
                  "array<> should be detected as a range");
    char arr[100];
    static_assert(is_range<decltype(arr)>::value,
                  "C array should be detected as a range");
    static_assert(is_range<decltype("string")>::value,
                  "String literal should be detected as a range");

    static_assert(!is_range<int>::value, "int shouldn't be a range");
    static_assert(!is_range<int*>::value, "int* shouldn't be a range");
    static_assert(!is_range<const int*>::value,
                  "even const int* shouldn't be a range");
}

}  // namespace base
}  // namespace android