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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_LENGTH_PREFIXED_ARRAY_H_
#define ART_RUNTIME_LENGTH_PREFIXED_ARRAY_H_
#include <stddef.h> // for offsetof()
#include "linear_alloc.h"
#include "stride_iterator.h"
#include "base/iteration_range.h"
namespace art {
template<typename T>
class LengthPrefixedArray {
public:
explicit LengthPrefixedArray(uint64_t length) : length_(length) {}
T& At(size_t index, size_t element_size = sizeof(T)) {
DCHECK_LT(index, length_);
return *reinterpret_cast<T*>(&data_[0] + index * element_size);
}
StrideIterator<T> Begin(size_t element_size = sizeof(T)) {
return StrideIterator<T>(reinterpret_cast<T*>(&data_[0]), element_size);
}
StrideIterator<T> End(size_t element_size = sizeof(T)) {
return StrideIterator<T>(reinterpret_cast<T*>(&data_[0] + element_size * length_),
element_size);
}
static size_t OffsetOfElement(size_t index, size_t element_size = sizeof(T)) {
return offsetof(LengthPrefixedArray<T>, data_) + index * element_size;
}
static size_t ComputeSize(size_t num_elements, size_t element_size = sizeof(T)) {
return sizeof(LengthPrefixedArray<T>) + num_elements * element_size;
}
uint64_t Length() const {
return length_;
}
private:
uint64_t length_; // 64 bits for padding reasons.
uint8_t data_[0];
};
// Returns empty iteration range if the array is null.
template<typename T>
IterationRange<StrideIterator<T>> MakeIterationRangeFromLengthPrefixedArray(
LengthPrefixedArray<T>* arr, size_t element_size) {
return arr != nullptr ?
MakeIterationRange(arr->Begin(element_size), arr->End(element_size)) :
MakeEmptyIterationRange(StrideIterator<T>(nullptr, 0));
}
} // namespace art
#endif // ART_RUNTIME_LENGTH_PREFIXED_ARRAY_H_
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