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/*
*
* Copyright 2017 gRPC authors.
*
* 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 GRPC_CORE_LIB_GPRPP_INLINED_VECTOR_H
#define GRPC_CORE_LIB_GPRPP_INLINED_VECTOR_H
#include <grpc/support/port_platform.h>
#include <cassert>
#include <cstring>
#include "src/core/lib/gprpp/memory.h"
namespace grpc_core {
// NOTE: We eventually want to use absl::InlinedVector here. However,
// there are currently build problems that prevent us from using absl.
// In the interim, we define a custom implementation as a place-holder,
// with the intent to eventually replace this with the absl
// implementation.
//
// This place-holder implementation does not implement the full set of
// functionality from the absl version; it has just the methods that we
// currently happen to need in gRPC. If additional functionality is
// needed before this gets replaced with the absl version, it can be
// added, with the following proviso:
//
// ANY METHOD ADDED HERE MUST COMPLY WITH THE INTERFACE IN THE absl
// IMPLEMENTATION!
//
// TODO(nnoble, roth): Replace this with absl::InlinedVector once we
// integrate absl into the gRPC build system in a usable way.
template <typename T, size_t N>
class InlinedVector {
public:
InlinedVector() { init_data(); }
~InlinedVector() { destroy_elements(); }
// copy constructor
InlinedVector(const InlinedVector& v) {
init_data();
copy_from(v);
}
InlinedVector& operator=(const InlinedVector& v) {
if (this != &v) {
clear();
copy_from(v);
}
return *this;
}
// move constructor
InlinedVector(InlinedVector&& v) {
init_data();
move_from(v);
}
InlinedVector& operator=(InlinedVector&& v) {
if (this != &v) {
clear();
move_from(v);
}
return *this;
}
T* data() {
return dynamic_ != nullptr ? dynamic_ : reinterpret_cast<T*>(inline_);
}
const T* data() const {
return dynamic_ != nullptr ? dynamic_ : reinterpret_cast<const T*>(inline_);
}
T& operator[](size_t offset) {
assert(offset < size_);
return data()[offset];
}
const T& operator[](size_t offset) const {
assert(offset < size_);
return data()[offset];
}
void reserve(size_t capacity) {
if (capacity > capacity_) {
T* new_dynamic = static_cast<T*>(gpr_malloc(sizeof(T) * capacity));
move_elements(data(), new_dynamic, size_);
gpr_free(dynamic_);
dynamic_ = new_dynamic;
capacity_ = capacity;
}
}
template <typename... Args>
void emplace_back(Args&&... args) {
if (size_ == capacity_) {
reserve(capacity_ * 2);
}
new (&(data()[size_])) T(std::forward<Args>(args)...);
++size_;
}
void push_back(const T& value) { emplace_back(value); }
void push_back(T&& value) { emplace_back(std::move(value)); }
void pop_back() {
assert(!empty());
size_t s = size();
T& value = data()[s - 1];
value.~T();
size_--;
}
size_t size() const { return size_; }
bool empty() const { return size_ == 0; }
size_t capacity() const { return capacity_; }
void clear() {
destroy_elements();
init_data();
}
private:
void copy_from(const InlinedVector& v) {
// if v is allocated, make sure we have enough capacity.
if (v.dynamic_ != nullptr) {
reserve(v.capacity_);
}
// copy over elements
for (size_t i = 0; i < v.size_; ++i) {
new (&(data()[i])) T(v[i]);
}
// copy over metadata
size_ = v.size_;
capacity_ = v.capacity_;
}
void move_from(InlinedVector& v) {
// if v is allocated, then we steal its dynamic array; otherwise, we
// move the elements individually.
if (v.dynamic_ != nullptr) {
dynamic_ = v.dynamic_;
} else {
move_elements(v.data(), data(), v.size_);
}
// copy over metadata
size_ = v.size_;
capacity_ = v.capacity_;
// null out the original
v.init_data();
}
static void move_elements(T* src, T* dst, size_t num_elements) {
for (size_t i = 0; i < num_elements; ++i) {
new (&dst[i]) T(std::move(src[i]));
src[i].~T();
}
}
void init_data() {
dynamic_ = nullptr;
size_ = 0;
capacity_ = N;
}
void destroy_elements() {
for (size_t i = 0; i < size_; ++i) {
T& value = data()[i];
value.~T();
}
gpr_free(dynamic_);
}
typename std::aligned_storage<sizeof(T)>::type inline_[N];
T* dynamic_;
size_t size_;
size_t capacity_;
};
} // namespace grpc_core
#endif /* GRPC_CORE_LIB_GPRPP_INLINED_VECTOR_H */
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