// Copyright 2017 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_DETACHABLE_VECTOR_H_
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#define V8_DETACHABLE_VECTOR_H_
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#include <vector>
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namespace v8 {
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namespace internal {
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// This class wraps a std::vector and provides a few of the common member
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// functions for accessing the data. It acts as a lazy wrapper of the vector,
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// not initiliazing the backing store until push_back() is first called. Two
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// extra methods are also provided: free() and detach(), which allow for manual
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// control of the backing store. This is currently required for use in the
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// HandleScopeImplementer. Any other class should just use a std::vector
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// directly.
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template <typename T>
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class DetachableVector {
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public:
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DetachableVector() : vector_(nullptr) {}
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~DetachableVector() { delete vector_; }
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void push_back(const T& value) {
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ensureAttached();
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vector_->push_back(value);
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}
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// Free the backing store and clear our reference to it.
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void free() {
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delete vector_;
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vector_ = nullptr;
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}
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// Clear our reference to the backing store. Does not delete it!
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void detach() { vector_ = nullptr; }
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T& at(typename std::vector<T>::size_type i) const { return vector_->at(i); }
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T& back() const { return vector_->back(); }
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T& front() const { return vector_->front(); }
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void pop_back() { vector_->pop_back(); }
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typename std::vector<T>::size_type size() const {
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if (vector_) return vector_->size();
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return 0;
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}
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bool empty() const {
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if (vector_) return vector_->empty();
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return true;
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}
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private:
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std::vector<T>* vector_;
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// Attach a vector backing store if not present.
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void ensureAttached() {
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if (vector_ == nullptr) {
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vector_ = new std::vector<T>();
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}
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}
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};
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} // namespace internal
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} // namespace v8
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#endif // V8_DETACHABLE_VECTOR_H_
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