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/*
* Copyright (C) 2023 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.
*/
#pragma once
#include <functional>
#include <memory>
namespace android::binder::impl {
template <typename F>
constexpr void assert_small_callable() {
// While this buffer (std::function::__func::__buf_) is an implementation detail generally not
// accessible to users, it's a good bet to assume its size to be around 3 pointers.
constexpr size_t kFunctionBufferSize = 3 * sizeof(void*);
static_assert(sizeof(F) <= kFunctionBufferSize,
"Supplied callable is larger than std::function optimization buffer. "
"Try using std::ref, but make sure lambda lives long enough to be called.");
}
template <typename F>
std::unique_ptr<void, std::function<void(void*)>> make_scope_guard(F&& f) {
assert_small_callable<decltype(std::bind(f))>();
return {reinterpret_cast<void*>(true), std::bind(f)};
}
template <typename T>
class SmallFunction : public std::function<T> {
public:
template <typename F>
SmallFunction(F&& f) : std::function<T>(f) {
assert_small_callable<F>();
}
};
} // namespace android::binder::impl
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