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#pragma once
#include "glContainer.h"
#include <cassert>
#include <special_members.h>
#include <utility>
template<typename T> class InstanceVertices : protected glContainer<T> {
using base = glContainer<T>;
public:
class [[nodiscard]] InstanceProxy {
public:
InstanceProxy(InstanceVertices * iv, std::size_t idx) : instances {iv}, index {idx} { }
InstanceProxy(InstanceProxy && other) noexcept :
instances {std::exchange(other.instances, nullptr)}, index {other.index}
{
}
NO_COPY(InstanceProxy);
~InstanceProxy()
{
if (instances) {
instances->release(index);
}
}
InstanceProxy &
operator=(InstanceProxy && other) noexcept
{
if (instances) {
instances->release(index);
}
instances = std::exchange(other.instances, nullptr);
index = other.index;
return *this;
}
template<typename U>
InstanceProxy &
operator=(U && v)
{
instances->lookup(index) = std::forward<U>(v);
return *this;
}
// NOLINTNEXTLINE)hicpp-explicit-conversions
[[nodiscard]] operator T &()
{
return instances->lookup(index);
}
// NOLINTNEXTLINE)hicpp-explicit-conversions
[[nodiscard]] operator const T &() const
{
return instances->lookup(index);
}
[[nodiscard]] T *
get()
{
return &instances->lookup(index);
}
[[nodiscard]] const T *
get() const
{
return &instances->lookup(index);
}
[[nodiscard]] T *
operator->()
{
return get();
}
[[nodiscard]] const T *
operator->() const
{
return get();
}
[[nodiscard]] T &
operator*()
{
return instances->lookup(index);
}
[[nodiscard]] const T &
operator*() const
{
return instances->lookup(index);
}
private:
InstanceVertices<T> * instances;
std::size_t index;
};
template<typename... Params>
[[nodiscard]] InstanceProxy
acquire(Params &&... params)
{
if (!unused.empty()) {
auto idx = unused.back();
unused.pop_back();
index[idx] = base::size();
reverseIndex.emplace_back(idx);
base::emplace_back(std::forward<Params>(params)...);
return InstanceProxy {this, idx};
}
index.emplace_back(base::size());
reverseIndex.push_back(base::size());
base::emplace_back(std::forward<Params>(params)...);
return InstanceProxy {this, index.size() - 1};
}
using base::bufferName;
[[nodiscard]] auto
size() const
{
base::unmap();
return base::size();
}
template<typename Pred>
glContainer<T>::iterator
partition(Pred pred)
{
return partition(base::begin(), base::end(), pred);
}
protected:
static constexpr auto npos = static_cast<size_t>(-1);
friend InstanceProxy;
void
release(const size_t pidx)
{
if (const size_t last = base::size() - 1; last != index[pidx]) {
lookup(pidx) = std::move(base::back());
const auto movedKey = reverseIndex[last];
index[movedKey] = std::exchange(index[pidx], npos);
reverseIndex[index[movedKey]] = movedKey;
}
base::pop_back();
reverseIndex.pop_back();
if (pidx == index.size() - 1) {
index.pop_back();
}
else {
index[pidx] = npos;
// Remember p.index is free index now
unused.emplace_back(pidx);
}
}
[[nodiscard]] T &
lookup(size_t pindex)
{
return base::data()[index[pindex]];
}
template<typename Pred>
glContainer<T>::iterator
partition(glContainer<T>::iterator first, glContainer<T>::iterator last, Pred pred)
{
while (first < last) {
first = std::find_if_not(first, last, pred);
last = --std::find_if(std::make_reverse_iterator(last), std::make_reverse_iterator(first), pred).base();
if (first < last) {
std::iter_swap(first, last);
const auto fidx = static_cast<size_t>(first - base::begin()),
lidx = static_cast<size_t>(last - base::begin());
std::swap(index[reverseIndex[fidx]], index[reverseIndex[lidx]]);
std::swap(reverseIndex[fidx], reverseIndex[lidx]);
}
}
return first;
}
// Index into buffer given to nth proxy
std::vector<size_t> index;
std::vector<size_t> reverseIndex;
// List of free spaces in index
std::vector<size_t> unused;
};
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