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// Copyright 2017 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_UTILS_DETACHABLE_VECTOR_H_
#define V8_UTILS_DETACHABLE_VECTOR_H_
#include <stddef.h>
#include <algorithm>
#include "src/base/logging.h"
#include "src/base/macros.h"
namespace v8 {
namespace internal {
class V8_EXPORT_PRIVATE DetachableVectorBase {
public:
// Clear our reference to the backing store. Does not delete it!
void detach() {
data_ = nullptr;
capacity_ = 0;
size_ = 0;
}
void pop_back() { --size_; }
size_t capacity() const { return capacity_; }
size_t size() const { return size_; }
bool empty() const { return size_ == 0; }
static const size_t kMinimumCapacity;
static const size_t kDataOffset;
static const size_t kCapacityOffset;
static const size_t kSizeOffset;
protected:
void* data_ = nullptr;
size_t capacity_ = 0;
size_t size_ = 0;
};
// This class wraps an array and provides a few of the common member
// functions for accessing the data. Two extra methods are also provided: free()
// and detach(), which allow for manual control of the backing store. This is
// currently required for use in the HandleScopeImplementer. Any other class
// should just use a std::vector.
template <typename T>
class DetachableVector : public DetachableVectorBase {
public:
DetachableVector() = default;
~DetachableVector() { delete[] data(); }
void push_back(const T& value) {
if (size_ == capacity_) {
size_t new_capacity = std::max(kMinimumCapacity, 2 * capacity_);
Resize(new_capacity);
}
data()[size_] = value;
++size_;
}
// Free the backing store and clear our reference to it.
void free() {
delete[] data();
data_ = nullptr;
capacity_ = 0;
size_ = 0;
}
T& at(size_t i) const {
DCHECK_LT(i, size_);
return data()[i];
}
T& back() const { return at(size_ - 1); }
T& front() const { return at(0); }
void shrink_to_fit() {
size_t new_capacity = std::max(size_, kMinimumCapacity);
if (new_capacity < capacity_ / 2) {
Resize(new_capacity);
}
}
private:
T* data() const { return static_cast<T*>(data_); }
void Resize(size_t new_capacity) {
DCHECK_LE(size_, new_capacity);
T* new_data_ = new T[new_capacity];
std::copy(data(), data() + size_, new_data_);
delete[] data();
data_ = new_data_;
capacity_ = new_capacity;
}
};
} // namespace internal
} // namespace v8
#endif // V8_UTILS_DETACHABLE_VECTOR_H_
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