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// Copyright 2011 the V8 project 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 V8_BASE_SMART_POINTERS_H_
#define V8_BASE_SMART_POINTERS_H_
namespace v8 {
namespace base {
template <typename Deallocator, typename T>
class SmartPointerBase {
public:
// Default constructor. Constructs an empty scoped pointer.
SmartPointerBase() : p_(NULL) {}
// Constructs a scoped pointer from a plain one.
explicit SmartPointerBase(T* ptr) : p_(ptr) {}
// Copy constructor removes the pointer from the original to avoid double
// freeing.
SmartPointerBase(const SmartPointerBase<Deallocator, T>& rhs) : p_(rhs.p_) {
const_cast<SmartPointerBase<Deallocator, T>&>(rhs).p_ = NULL;
}
T* operator->() const { return p_; }
T& operator*() const { return *p_; }
T* get() const { return p_; }
// You can use [n] to index as if it was a plain pointer.
T& operator[](size_t i) { return p_[i]; }
// You can use [n] to index as if it was a plain pointer.
const T& operator[](size_t i) const { return p_[i]; }
// We don't have implicit conversion to a T* since that hinders migration:
// You would not be able to change a method from returning a T* to
// returning an SmartArrayPointer<T> and then get errors wherever it is used.
// If you want to take out the plain pointer and don't want it automatically
// deleted then call Detach(). Afterwards, the smart pointer is empty
// (NULL).
T* Detach() {
T* temp = p_;
p_ = NULL;
return temp;
}
void Reset(T* new_value) {
DCHECK(p_ == NULL || p_ != new_value);
if (p_) Deallocator::Delete(p_);
p_ = new_value;
}
// Assignment requires an empty (NULL) SmartArrayPointer as the receiver. Like
// the copy constructor it removes the pointer in the original to avoid
// double freeing.
SmartPointerBase<Deallocator, T>& operator=(
const SmartPointerBase<Deallocator, T>& rhs) {
DCHECK(is_empty());
T* tmp = rhs.p_; // swap to handle self-assignment
const_cast<SmartPointerBase<Deallocator, T>&>(rhs).p_ = NULL;
p_ = tmp;
return *this;
}
bool is_empty() const { return p_ == NULL; }
protected:
// When the destructor of the scoped pointer is executed the plain pointer
// is deleted using DeleteArray. This implies that you must allocate with
// NewArray.
~SmartPointerBase() {
if (p_) Deallocator::Delete(p_);
}
private:
T* p_;
};
// A 'scoped array pointer' that calls DeleteArray on its pointer when the
// destructor is called.
template <typename T>
struct ArrayDeallocator {
static void Delete(T* array) { delete[] array; }
};
template <typename T>
class SmartArrayPointer : public SmartPointerBase<ArrayDeallocator<T>, T> {
public:
SmartArrayPointer() {}
explicit SmartArrayPointer(T* ptr)
: SmartPointerBase<ArrayDeallocator<T>, T>(ptr) {}
SmartArrayPointer(const SmartArrayPointer<T>& rhs)
: SmartPointerBase<ArrayDeallocator<T>, T>(rhs) {}
};
template <typename T>
struct ObjectDeallocator {
static void Delete(T* object) { delete object; }
};
template <typename T>
class SmartPointer : public SmartPointerBase<ObjectDeallocator<T>, T> {
public:
SmartPointer() {}
explicit SmartPointer(T* ptr)
: SmartPointerBase<ObjectDeallocator<T>, T>(ptr) {}
SmartPointer(const SmartPointer<T>& rhs)
: SmartPointerBase<ObjectDeallocator<T>, T>(rhs) {}
};
} // namespace base
} // namespace v8
#endif // V8_SMART_POINTERS_H_
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