79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
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// Copyright 2017 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_CONTAINERS_UNIQUE_PTR_ADAPTERS_H_
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#define BASE_CONTAINERS_UNIQUE_PTR_ADAPTERS_H_
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#include <memory>
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namespace base {
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// This transparent comparator allows to lookup by raw pointer in
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// a container of unique pointers. This functionality is based on C++14
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// extensions to std::set/std::map interface, and can also be used
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// with base::flat_set/base::flat_map.
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//
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// Example usage:
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// Foo* foo = ...
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// std::set<std::unique_ptr<Foo>, base::UniquePtrComparator> set;
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// set.insert(std::unique_ptr<Foo>(foo));
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// ...
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// auto it = set.find(foo);
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// EXPECT_EQ(foo, it->get());
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//
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// You can find more information about transparent comparisons here:
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// http://en.cppreference.com/w/cpp/utility/functional/less_void
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struct UniquePtrComparator {
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using is_transparent = int;
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template <typename T, class Deleter = std::default_delete<T>>
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bool operator()(const std::unique_ptr<T, Deleter>& lhs,
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const std::unique_ptr<T, Deleter>& rhs) const {
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return lhs < rhs;
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}
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template <typename T, class Deleter = std::default_delete<T>>
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bool operator()(const T* lhs, const std::unique_ptr<T, Deleter>& rhs) const {
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return lhs < rhs.get();
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}
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template <typename T, class Deleter = std::default_delete<T>>
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bool operator()(const std::unique_ptr<T, Deleter>& lhs, const T* rhs) const {
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return lhs.get() < rhs;
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}
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};
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// UniquePtrMatcher is useful for finding an element in a container of
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// unique_ptrs when you have the raw pointer.
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//
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// Example usage:
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// std::vector<std::unique_ptr<Foo>> vector;
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// Foo* element = ...
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// auto iter = std::find_if(vector.begin(), vector.end(),
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// MatchesUniquePtr(element));
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//
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// Example of erasing from container:
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// EraseIf(v, MatchesUniquePtr(element));
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//
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template <class T, class Deleter = std::default_delete<T>>
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struct UniquePtrMatcher {
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explicit UniquePtrMatcher(T* t) : t_(t) {}
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bool operator()(const std::unique_ptr<T, Deleter>& o) {
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return o.get() == t_;
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}
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private:
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T* const t_;
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};
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template <class T, class Deleter = std::default_delete<T>>
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UniquePtrMatcher<T, Deleter> MatchesUniquePtr(T* t) {
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return UniquePtrMatcher<T, Deleter>(t);
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}
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} // namespace base
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#endif // BASE_CONTAINERS_UNIQUE_PTR_ADAPTERS_H_
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