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/*
* Copyright (C) 2010 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.
*/
#ifndef UNIQUE_PTR_H_included
#define UNIQUE_PTR_H_included
// Default deleter for pointer types.
template <typename T>
struct DefaultDelete {
enum { type_must_be_complete = sizeof(T) };
DefaultDelete() {}
void operator()(T* p) const {
delete p;
}
};
// Default deleter for array types.
template <typename T>
struct DefaultDelete<T[]> {
enum { type_must_be_complete = sizeof(T) };
void operator()(T* p) const {
delete[] p;
}
};
// A smart pointer that deletes the given pointer on destruction.
// Equivalent to C++0x's std::unique_ptr (a combination of boost::scoped_ptr
// and boost::scoped_array).
// Named to be in keeping with Android style but also to avoid
// collision with any other implementation, until we can switch over
// to unique_ptr.
// Use thus:
// UniquePtr<C> c(new C);
template <typename T, typename D = DefaultDelete<T> >
class UniquePtr {
public:
// Construct a new UniquePtr, taking ownership of the given raw pointer.
explicit UniquePtr(T* ptr = nullptr) : mPtr(ptr) { }
UniquePtr(UniquePtr<T, D>&& that) {
mPtr = that.mPtr;
that.mPtr = nullptr;
}
~UniquePtr() {
reset();
}
// Accessors.
T& operator*() const { return *mPtr; }
T* operator->() const { return mPtr; }
T* get() const { return mPtr; }
// Returns the raw pointer and hands over ownership to the caller.
// The pointer will not be deleted by UniquePtr.
T* release() __attribute__((warn_unused_result)) {
T* result = mPtr;
mPtr = nullptr;
return result;
}
// Takes ownership of the given raw pointer.
// If this smart pointer previously owned a different raw pointer, that
// raw pointer will be freed.
void reset(T* ptr = nullptr) {
if (ptr != mPtr) {
D()(mPtr);
mPtr = ptr;
}
}
private:
// The raw pointer.
T* mPtr;
// Comparing unique pointers is probably a mistake, since they're unique.
template <typename T2> bool operator==(const UniquePtr<T2>& p) const = delete;
template <typename T2> bool operator!=(const UniquePtr<T2>& p) const = delete;
// Disallow copy and assignment.
UniquePtr(const UniquePtr&) = delete;
void operator=(const UniquePtr&) = delete;
};
// Partial specialization for array types. Like std::unique_ptr, this removes
// operator* and operator-> but adds operator[].
template <typename T, typename D>
class UniquePtr<T[], D> {
public:
explicit UniquePtr(T* ptr = NULL) : mPtr(ptr) {
}
UniquePtr(UniquePtr<T, D>&& that) {
mPtr = that.mPtr;
that.mPtr = nullptr;
}
~UniquePtr() {
reset();
}
T& operator[](size_t i) const {
return mPtr[i];
}
T* get() const { return mPtr; }
T* release() __attribute__((warn_unused_result)) {
T* result = mPtr;
mPtr = NULL;
return result;
}
void reset(T* ptr = NULL) {
if (ptr != mPtr) {
D()(mPtr);
mPtr = ptr;
}
}
private:
T* mPtr;
// Disallow copy and assignment.
UniquePtr(const UniquePtr&) = delete;
void operator=(const UniquePtr&) = delete;
};
#endif // UNIQUE_PTR_H_included
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