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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef ds_FixedLengthVector_h
#define ds_FixedLengthVector_h
#include "mozilla/Assertions.h" // MOZ_ASSERT
#include "mozilla/OperatorNewExtensions.h" // mozilla::KnownNotNull
#include <stddef.h> // size_t
#include "js/Utility.h" // js_free
#include "vm/JSContext.h" // JSContext
namespace js {
// A dynamically-allocated fixed-length vector with bounds checking assertions.
template <typename T>
class FixedLengthVector {
// The pointer to the storage.
T* data_ = nullptr;
// The size of the storage.
size_t length_ = 0;
public:
FixedLengthVector() = default;
FixedLengthVector(FixedLengthVector&) = delete;
FixedLengthVector(FixedLengthVector&&) = default;
~FixedLengthVector() {
if (initialized()) {
js_free(data_);
}
}
size_t length() const { return length_; }
bool initialized() const { return !!data_; }
// Allocate the storage with the given size, wihtout calling constructor.
//
// If the allocation fails, this returns false and sets the
// pending exception on the given context.
[[nodiscard]] bool allocateUninitialized(JSContext* cx, size_t length) {
MOZ_ASSERT(!initialized());
length_ = length;
data_ = cx->pod_malloc<T>(length);
if (MOZ_UNLIKELY(!data_)) {
return false;
}
return true;
}
// Allocate the storage with the given size and call default constructor.
//
// If the allocation fails, this returns false and sets the
// pending exception on the given context.
[[nodiscard]] bool allocate(JSContext* cx, size_t length) {
if (!allocateUninitialized(cx, length)) {
return false;
}
for (size_t i = 0; i < length; i++) {
new (mozilla::KnownNotNull, &data_[i]) T();
}
return true;
}
T* begin() {
MOZ_ASSERT(initialized());
return data_;
}
const T* begin() const {
MOZ_ASSERT(initialized());
return data_;
}
T* end() {
MOZ_ASSERT(initialized());
return data_ + length_;
}
const T* end() const {
MOZ_ASSERT(initialized());
return data_ + length_;
}
T& operator[](size_t index) {
MOZ_ASSERT(initialized());
MOZ_ASSERT(index < length_);
return begin()[index];
}
const T& operator[](size_t index) const {
MOZ_ASSERT(initialized());
MOZ_ASSERT(index < length_);
return begin()[index];
}
};
} // namespace js
#endif // ds_FixedLengthVector_h
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