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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_DETACHABLE_VECTOR_H_
#define V8_DETACHABLE_VECTOR_H_
#include <vector>
namespace v8 {
namespace internal {
// This class wraps a std::vector and provides a few of the common member
// functions for accessing the data. It acts as a lazy wrapper of the vector,
// not initiliazing the backing store until push_back() is first called. 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
// directly.
template <typename T>
class DetachableVector {
public:
DetachableVector() : vector_(nullptr) {}
~DetachableVector() { delete vector_; }
void push_back(const T& value) {
ensureAttached();
vector_->push_back(value);
}
// Free the backing store and clear our reference to it.
void free() {
delete vector_;
vector_ = nullptr;
}
// Clear our reference to the backing store. Does not delete it!
void detach() { vector_ = nullptr; }
T& at(typename std::vector<T>::size_type i) const { return vector_->at(i); }
T& back() const { return vector_->back(); }
T& front() const { return vector_->front(); }
void pop_back() { vector_->pop_back(); }
typename std::vector<T>::size_type size() const {
if (vector_) return vector_->size();
return 0;
}
bool empty() const {
if (vector_) return vector_->empty();
return true;
}
private:
std::vector<T>* vector_;
// Attach a vector backing store if not present.
void ensureAttached() {
if (vector_ == nullptr) {
vector_ = new std::vector<T>();
}
}
};
} // namespace internal
} // namespace v8
#endif // V8_DETACHABLE_VECTOR_H_
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