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75 lines
2.2 KiB
75 lines
2.2 KiB
// Copyright 2016 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 THIRD_PARTY_BASE_PTR_UTIL_H_
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#define THIRD_PARTY_BASE_PTR_UTIL_H_
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#include <memory>
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#include <utility>
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namespace pdfium {
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// Helper to transfer ownership of a raw pointer to a std::unique_ptr<T>.
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// Note that std::unique_ptr<T> has very different semantics from
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// std::unique_ptr<T[]>: do not use this helper for array allocations.
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template <typename T>
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std::unique_ptr<T> WrapUnique(T* ptr) {
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return std::unique_ptr<T>(ptr);
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}
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namespace internal {
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template <typename T>
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struct MakeUniqueResult {
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using Scalar = std::unique_ptr<T>;
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};
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template <typename T>
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struct MakeUniqueResult<T[]> {
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using Array = std::unique_ptr<T[]>;
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};
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template <typename T, size_t N>
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struct MakeUniqueResult<T[N]> {
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using Invalid = void;
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};
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} // namespace internal
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// Helper to construct an object wrapped in a std::unique_ptr. This is an
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// implementation of C++14's std::MakeUnique that can be used in Chrome.
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//
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// MakeUnique<T>(args) should be preferred over WrapUnique(new T(args)): bare
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// calls to `new` should be treated with scrutiny.
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//
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// Usage:
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// // ptr is a std::unique_ptr<std::string>
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// auto ptr = MakeUnique<std::string>("hello world!");
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//
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// // arr is a std::unique_ptr<int[]>
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// auto arr = MakeUnique<int[]>(5);
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// Overload for non-array types. Arguments are forwarded to T's constructor.
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template <typename T, typename... Args>
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typename internal::MakeUniqueResult<T>::Scalar MakeUnique(Args&&... args) {
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return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
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}
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// Overload for array types of unknown bound, e.g. T[]. The array is allocated
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// with `new T[n]()` and value-initialized: note that this is distinct from
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// `new T[n]`, which default-initializes.
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template <typename T>
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typename internal::MakeUniqueResult<T>::Array MakeUnique(size_t size) {
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return std::unique_ptr<T>(new typename std::remove_extent<T>::type[size]());
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}
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// Overload to reject array types of known bound, e.g. T[n].
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template <typename T, typename... Args>
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typename internal::MakeUniqueResult<T>::Invalid MakeUnique(Args&&... args) =
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delete;
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} // namespace pdfium
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#endif // THIRD_PARTY_BASE_PTR_UTIL_H_
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