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108 lines (91 loc) · 2.68 KB
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// Copyright 2018 Google LLC
//
// 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 CC_INLINE_VECTOR_H_
#define CC_INLINE_VECTOR_H_
#include <cstdint>
#include <new>
#include <utility>
#include "cc/check.h"
namespace minigo {
// inline_vector is an std::vector-like container that uses inline storage, thus
// avoiding heap allocations.
// Since we currently only need to store POD types in inline_vector, this is
// a fairly bare bones implementation.
template <typename T, int Capacity>
class inline_vector {
public:
inline_vector() = default;
~inline_vector() { clear(); }
inline_vector(const inline_vector& other) {
for (const auto& x : other) {
push_back(x);
}
}
inline_vector& operator=(const inline_vector& other) {
if (&other != this) {
clear();
for (const auto& x : other) {
push_back(x);
}
}
return *this;
}
void clear() {
for (T& x : *this) {
x.~T();
}
size_ = 0;
}
int size() const { return size_; }
int capacity() const { return Capacity; }
bool empty() const { return size_ == 0; }
T* data() { return reinterpret_cast<T*>(storage_); }
const T* data() const { return reinterpret_cast<const T*>(storage_); }
T* begin() { return data(); }
const T* begin() const { return data(); }
T* end() { return data() + size_; }
const T* end() const { return data() + size_; }
T& operator[](int idx) {
MG_DCHECK(idx >= 0);
MG_DCHECK(idx < size_);
return data()[idx];
}
const T& operator[](int idx) const {
MG_DCHECK(idx >= 0);
MG_DCHECK(idx < size_);
return data()[idx];
}
void push_back(const T& t) {
MG_DCHECK(size_ < Capacity);
new (data() + size_) T(t);
++size_;
}
template <typename... Args>
void emplace_back(Args&&... args) {
MG_DCHECK(size_ < Capacity);
new (data() + size_) T(std::forward<Args>(args)...);
++size_;
}
T& back() { return data()[size_ - 1]; }
const T& back() const { return data()[size_ - 1]; }
void pop_back() {
MG_DCHECK(size_ > 0);
--size_;
}
private:
int size_ = 0;
uint8_t __attribute__((aligned(alignof(T)))) storage_[Capacity * sizeof(T)];
};
} // namespace minigo
#endif // CC_INLINE_VECTOR_H_