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// SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once
#include <iterator>
#include "common/make_unique_for_overwrite.h"
namespace Common {
/**
* ScratchBuffer class
* This class creates a default initialized heap allocated buffer for cases such as intermediate
* buffers being copied into entirely, where value initializing members during allocation or resize
* is redundant.
*/
template <typename T>
class ScratchBuffer {
public:
using element_type = T;
using value_type = T;
using size_type = size_t;
using difference_type = std::ptrdiff_t;
using pointer = T*;
using const_pointer = const T*;
using reference = T&;
using const_reference = const T&;
using iterator = pointer;
using const_iterator = const_pointer;
using iterator_category = std::random_access_iterator_tag;
using iterator_concept = std::contiguous_iterator_tag;
ScratchBuffer() = default;
explicit ScratchBuffer(size_type initial_capacity)
: last_requested_size{initial_capacity}, buffer_capacity{initial_capacity},
buffer{Common::make_unique_for_overwrite<T[]>(initial_capacity)} {}
~ScratchBuffer() = default;
ScratchBuffer(const ScratchBuffer&) = delete;
ScratchBuffer& operator=(const ScratchBuffer&) = delete;
ScratchBuffer(ScratchBuffer&&) = default;
ScratchBuffer& operator=(ScratchBuffer&&) = default;
/// This will only grow the buffer's capacity if size is greater than the current capacity.
/// The previously held data will remain intact.
void resize(size_type size) {
if (size > buffer_capacity) {
auto new_buffer = Common::make_unique_for_overwrite<T[]>(size);
std::move(buffer.get(), buffer.get() + buffer_capacity, new_buffer.get());
buffer = std::move(new_buffer);
buffer_capacity = size;
}
last_requested_size = size;
}
/// This will only grow the buffer's capacity if size is greater than the current capacity.
/// The previously held data will be destroyed if a reallocation occurs.
void resize_destructive(size_type size) {
if (size > buffer_capacity) {
buffer_capacity = size;
buffer = Common::make_unique_for_overwrite<T[]>(buffer_capacity);
}
last_requested_size = size;
}
[[nodiscard]] pointer data() noexcept {
return buffer.get();
}
[[nodiscard]] const_pointer data() const noexcept {
return buffer.get();
}
[[nodiscard]] iterator begin() noexcept {
return data();
}
[[nodiscard]] const_iterator begin() const noexcept {
return data();
}
[[nodiscard]] iterator end() noexcept {
return data() + last_requested_size;
}
[[nodiscard]] const_iterator end() const noexcept {
return data() + last_requested_size;
}
[[nodiscard]] reference operator[](size_type i) {
return buffer[i];
}
[[nodiscard]] const_reference operator[](size_type i) const {
return buffer[i];
}
[[nodiscard]] size_type size() const noexcept {
return last_requested_size;
}
[[nodiscard]] size_type capacity() const noexcept {
return buffer_capacity;
}
void swap(ScratchBuffer& other) noexcept {
std::swap(last_requested_size, other.last_requested_size);
std::swap(buffer_capacity, other.buffer_capacity);
std::swap(buffer, other.buffer);
}
private:
size_type last_requested_size{};
size_type buffer_capacity{};
std::unique_ptr<T[]> buffer{};
};
} // namespace Common
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