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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_MEMORY_PTR_UTIL_H_
#define BASE_MEMORY_PTR_UTIL_H_
#include <memory>
#include <utility>
namespace base {
// Helper to transfer ownership of a raw pointer to a std::unique_ptr<T>.
// Note that std::unique_ptr<T> has very different semantics from
// std::unique_ptr<T[]>: do not use this helper for array allocations.
template <typename T>
std::unique_ptr<T> WrapUnique(T* ptr) {
return std::unique_ptr<T>(ptr);
}
namespace internal {
template <typename T>
struct MakeUniqueResult {
using Scalar = std::unique_ptr<T>;
};
template <typename T>
struct MakeUniqueResult<T[]> {
using Array = std::unique_ptr<T[]>;
};
template <typename T, size_t N>
struct MakeUniqueResult<T[N]> {
using Invalid = void;
};
} // namespace internal
// Helper to construct an object wrapped in a std::unique_ptr. This is an
// implementation of C++14's std::make_unique that can be used in Chrome.
//
// MakeUnique<T>(args) should be preferred over WrapUnique(new T(args)): bare
// calls to `new` should be treated with scrutiny.
//
// Usage:
// // ptr is a std::unique_ptr<std::string>
// auto ptr = MakeUnique<std::string>("hello world!");
//
// // arr is a std::unique_ptr<int[]>
// auto arr = MakeUnique<int[]>(5);
// Overload for non-array types. Arguments are forwarded to T's constructor.
template <typename T, typename... Args>
typename internal::MakeUniqueResult<T>::Scalar MakeUnique(Args&&... args) {
return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
}
// Overload for array types of unknown bound, e.g. T[]. The array is allocated
// with `new T[n]()` and value-initialized: note that this is distinct from
// `new T[n]`, which default-initializes.
template <typename T>
typename internal::MakeUniqueResult<T>::Array MakeUnique(size_t size) {
return std::unique_ptr<T>(new typename std::remove_extent<T>::type[size]());
}
// Overload to reject array types of known bound, e.g. T[n].
template <typename T, typename... Args>
typename internal::MakeUniqueResult<T>::Invalid MakeUnique(Args&&... args) =
delete;
} // namespace base
#endif // BASE_MEMORY_PTR_UTIL_H_
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