123 lines
3 KiB
C++
123 lines
3 KiB
C++
/*
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* Copyright 2017 WebAssembly Community Group participants
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef WABT_CIRCULAR_ARRAY_H_
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#define WABT_CIRCULAR_ARRAY_H_
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#include <array>
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#include <cassert>
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#include <cstddef>
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#include <type_traits>
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namespace wabt {
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// TODO(karlschimpf) Complete the API
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// Note: Capacity must be a power of 2.
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template <class T, size_t kCapacity>
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class CircularArray {
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public:
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using value_type = T;
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using reference = value_type&;
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using const_reference = const value_type&;
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using size_type = size_t;
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using difference_type = ptrdiff_t;
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CircularArray() {
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static_assert(kCapacity && ((kCapacity & (kCapacity - 1)) == 0),
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"Capacity must be a power of 2.");
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}
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CircularArray(const CircularArray&) = default;
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CircularArray& operator=(const CircularArray&) = default;
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CircularArray(CircularArray&&) = default;
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CircularArray& operator=(CircularArray&&) = default;
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~CircularArray() { clear(); }
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reference at(size_type index) {
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assert(index < size_);
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return (*this)[index];
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}
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const_reference at(size_type index) const {
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assert(index < size_);
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return (*this)[index];
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}
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reference operator[](size_type index) { return contents_[position(index)]; }
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const_reference operator[](size_type index) const {
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return contents_[position(index)];
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}
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reference back() { return at(size_ - 1); }
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const_reference back() const { return at(size_ - 1); }
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bool empty() const { return size_ == 0; }
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reference front() { return at(0); }
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const_reference front() const { return at(0); }
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size_type max_size() const { return kCapacity; }
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void pop_back() {
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assert(size_ > 0);
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SetElement(back());
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--size_;
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}
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void pop_front() {
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assert(size_ > 0);
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SetElement(front());
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front_ = (front_ + 1) & kMask;
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--size_;
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}
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void push_back(const value_type& value) {
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assert(size_ < kCapacity);
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SetElement(at(size_++), value);
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}
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size_type size() const { return size_; }
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void clear() {
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while (!empty()) {
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pop_back();
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}
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}
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private:
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static constexpr size_type kMask = kCapacity - 1;
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size_t position(size_t index) const { return (front_ + index) & kMask; }
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template <typename... Args>
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void SetElement(reference element, Args&&... args) {
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element.~T();
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new (&element) T(std::forward<Args>(args)...);
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}
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std::array<T, kCapacity> contents_;
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size_type size_ = 0;
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size_type front_ = 0;
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};
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} // namespace wabt
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#endif // WABT_CIRCULAR_ARRAY_H_
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