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| 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef PDFIUM_THIRD_PARTY_BASE_PTR_UTIL_H_ |
| 6 #define PDFIUM_THIRD_PARTY_BASE_PTR_UTIL_H_ |
| 7 |
| 8 #include <memory> |
| 9 #include <utility> |
| 10 |
| 11 namespace pdfium { |
| 12 |
| 13 // Helper to transfer ownership of a raw pointer to a std::unique_ptr<T>. |
| 14 // Note that std::unique_ptr<T> has very different semantics from |
| 15 // std::unique_ptr<T[]>: do not use this helper for array allocations. |
| 16 template <typename T> |
| 17 std::unique_ptr<T> WrapUnique(T* ptr) { |
| 18 return std::unique_ptr<T>(ptr); |
| 19 } |
| 20 |
| 21 namespace internal { |
| 22 |
| 23 template <typename T> |
| 24 struct MakeUniqueResult { |
| 25 using Scalar = std::unique_ptr<T>; |
| 26 }; |
| 27 |
| 28 template <typename T> |
| 29 struct MakeUniqueResult<T[]> { |
| 30 using Array = std::unique_ptr<T[]>; |
| 31 }; |
| 32 |
| 33 template <typename T, size_t N> |
| 34 struct MakeUniqueResult<T[N]> { |
| 35 using Invalid = void; |
| 36 }; |
| 37 |
| 38 } // namespace internal |
| 39 |
| 40 // Helper to construct an object wrapped in a std::unique_ptr. This is an |
| 41 // implementation of C++14's std::MakeUnique that can be used in Chrome. |
| 42 // |
| 43 // MakeUnique<T>(args) should be preferred over WrapUnique(new T(args)): bare |
| 44 // calls to `new` should be treated with scrutiny. |
| 45 // |
| 46 // Usage: |
| 47 // // ptr is a std::unique_ptr<std::string> |
| 48 // auto ptr = MakeUnique<std::string>("hello world!"); |
| 49 // |
| 50 // // arr is a std::unique_ptr<int[]> |
| 51 // auto arr = MakeUnique<int[]>(5); |
| 52 |
| 53 // Overload for non-array types. Arguments are forwarded to T's constructor. |
| 54 template <typename T, typename... Args> |
| 55 typename internal::MakeUniqueResult<T>::Scalar MakeUnique(Args&&... args) { |
| 56 return std::unique_ptr<T>(new T(std::forward<Args>(args)...)); |
| 57 } |
| 58 |
| 59 // Overload for array types of unknown bound, e.g. T[]. The array is allocated |
| 60 // with `new T[n]()` and value-initialized: note that this is distinct from |
| 61 // `new T[n]`, which default-initializes. |
| 62 template <typename T> |
| 63 typename internal::MakeUniqueResult<T>::Array MakeUnique(size_t size) { |
| 64 return std::unique_ptr<T>(new typename std::remove_extent<T>::type[size]()); |
| 65 } |
| 66 |
| 67 // Overload to reject array types of known bound, e.g. T[n]. |
| 68 template <typename T, typename... Args> |
| 69 typename internal::MakeUniqueResult<T>::Invalid MakeUnique(Args&&... args) = |
| 70 delete; |
| 71 |
| 72 } // namespace pdfium |
| 73 |
| 74 #endif // PDFIUM_THIRD_PARTY_BASE_PTR_UTIL_H_ |
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