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view: shared implementation for storage views

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This commit is contained in:
Michele Caini
2023-12-05 15:00:14 +01:00
parent 9d23522086
commit 4cdff43781
1 changed files with 131 additions and 99 deletions
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230
src/entt/entity/view.hpp
View File

@@ -570,98 +570,31 @@ private:
};
/**
* @brief Storage view specialization.
*
* This specialization offers a boost in terms of performance. It can access the
* underlying data structure directly and avoid superfluous checks.
*
* @sa basic_view
*
* @tparam Get Type of storage iterated by the view.
* @brief Basic storage view implementation.
* @warning For internal use only, backward compatibility not guaranteed.
* @tparam Type Common type among all storage types.
*/
template<typename Get>
class basic_view<get_t<Get>, exclude_t<>, std::void_t<std::enable_if_t<!Get::traits_type::in_place_delete>>> {
public:
template<typename Type>
struct basic_storage_view {
/*! @brief Common type among all storage types. */
using common_type = typename Get::base_type;
using common_type = Type;
/*! @brief Underlying entity identifier. */
using entity_type = typename Get::entity_type;
using entity_type = typename common_type::entity_type;
/*! @brief Unsigned integer type. */
using size_type = std::size_t;
/*! @brief Random access iterator type. */
using iterator = typename common_type::iterator;
/*! @brief Reversed iterator type. */
using reverse_iterator = typename common_type::reverse_iterator;
/*! @brief Iterable view type. */
using iterable = decltype(std::declval<Get>().each());
/*! @brief Default constructor to use to create empty, invalid views. */
basic_view() noexcept
: view{} {}
/**
* @brief Constructs a view from a storage class.
* @param value The storage for the type to iterate.
*/
basic_view(Get &value) noexcept
: view{&value} {}
/**
* @brief Constructs a view from a storage class.
* @param value The storage for the type to iterate.
*/
basic_view(std::tuple<Get &> value, std::tuple<> = {}) noexcept
: basic_view{std::get<0>(value)} {}
/**
* @brief Returns the leading storage of a view, if any.
* @return The leading storage of the view.
*/
[[nodiscard]] const common_type *handle() const noexcept {
return storage();
}
/**
* @brief Returns the storage for a given component type, if any.
* @tparam Type Type of component of which to return the storage.
* @return The storage for the given component type.
*/
template<typename Type = typename Get::value_type>
[[nodiscard]] auto *storage() const noexcept {
static_assert(std::is_same_v<std::remove_const_t<Type>, typename Get::value_type>, "Invalid component type");
return view;
}
/**
* @brief Returns the storage for a given index, if any.
* @tparam Index Index of the storage to return.
* @return The storage for the given index.
*/
template<std::size_t Index>
[[nodiscard]] auto *storage() const noexcept {
static_assert(Index == 0u, "Index out of bounds");
return view;
}
/**
* @brief Assigns a storage to a view.
* @param elem A storage to assign to the view.
*/
void storage(Get &elem) noexcept {
view = &elem;
}
/**
* @brief Assigns a storage to a view.
* @tparam Index Index of the storage to assign to the view.
* @param elem A storage to assign to the view.
*/
template<std::size_t Index>
void storage(Get &elem) noexcept {
static_assert(Index == 0u, "Index out of bounds");
view = &elem;
}
/**
* @brief Returns the number of entities that have the given component.
* @return Number of entities that have the given component.
@@ -686,7 +619,7 @@ public:
* @return An iterator to the first entity of the view.
*/
[[nodiscard]] iterator begin() const noexcept {
return view ? view->common_type::begin() : iterator{};
return view ? view->begin() : iterator{};
}
/**
@@ -694,7 +627,7 @@ public:
* @return An iterator to the entity following the last entity of the view.
*/
[[nodiscard]] iterator end() const noexcept {
return view ? view->common_type::end() : iterator{};
return view ? view->end() : iterator{};
}
/**
@@ -705,7 +638,7 @@ public:
* @return An iterator to the first entity of the reversed view.
*/
[[nodiscard]] reverse_iterator rbegin() const noexcept {
return view ? view->common_type::rbegin() : reverse_iterator{};
return view ? view->rbegin() : reverse_iterator{};
}
/**
@@ -715,7 +648,7 @@ public:
* reversed view.
*/
[[nodiscard]] reverse_iterator rend() const noexcept {
return view ? view->common_type::rend() : reverse_iterator{};
return view ? view->rend() : reverse_iterator{};
}
/**
@@ -724,7 +657,7 @@ public:
* otherwise.
*/
[[nodiscard]] entity_type front() const noexcept {
return empty() ? null : *view->common_type::begin();
return empty() ? null : *view->begin();
}
/**
@@ -733,7 +666,7 @@ public:
* otherwise.
*/
[[nodiscard]] entity_type back() const noexcept {
return empty() ? null : *view->common_type::rbegin();
return empty() ? null : *view->rbegin();
}
/**
@@ -755,15 +688,6 @@ public:
return begin()[pos];
}
/**
* @brief Returns the component assigned to the given entity.
* @param entt A valid identifier.
* @return The component assigned to the given entity.
*/
[[nodiscard]] decltype(auto) operator[](const entity_type entt) const {
return storage()->get(entt);
}
/**
* @brief Checks if a view is fully initialized.
* @return True if the view is fully initialized, false otherwise.
@@ -781,6 +705,117 @@ public:
return view && view->contains(entt);
}
protected:
const common_type *view{};
};
/**
* @brief Storage view specialization.
*
* This specialization offers a boost in terms of performance. It can access the
* underlying data structure directly and avoid superfluous checks.
*
* @sa basic_view
*
* @tparam Get Type of storage iterated by the view.
*/
template<typename Get>
class basic_view<get_t<Get>, exclude_t<>, std::void_t<std::enable_if_t<!Get::traits_type::in_place_delete>>>: public basic_storage_view<typename Get::base_type> {
using base_type = basic_storage_view<typename Get::base_type>;
public:
/*! @brief Common type among all storage types. */
using common_type = typename base_type::common_type;
/*! @brief Underlying entity identifier. */
using entity_type = typename base_type::entity_type;
/*! @brief Unsigned integer type. */
using size_type = typename base_type::size_type;
/*! @brief Random access iterator type. */
using iterator = typename base_type::iterator;
/*! @brief Reversed iterator type. */
using reverse_iterator = typename base_type::reverse_iterator;
/*! @brief Iterable view type. */
using iterable = decltype(std::declval<Get>().each());
/*! @brief Default constructor to use to create empty, invalid views. */
basic_view() noexcept
: base_type{} {}
/**
* @brief Constructs a view from a storage class.
* @param value The storage for the type to iterate.
*/
basic_view(Get &value) noexcept
: basic_view{} {
this->view = &value;
}
/**
* @brief Constructs a view from a storage class.
* @param value The storage for the type to iterate.
*/
basic_view(std::tuple<Get &> value, std::tuple<> = {}) noexcept
: basic_view{std::get<0>(value)} {}
/**
* @brief Returns the storage for a given component type, if any.
* @tparam Type Type of component of which to return the storage.
* @return The storage for the given component type.
*/
template<typename Type = typename Get::value_type>
[[nodiscard]] auto *storage() const noexcept {
static_assert(std::is_same_v<std::remove_const_t<Type>, typename Get::value_type>, "Invalid component type");
return storage<0>();
}
/**
* @brief Returns the storage for a given index, if any.
* @tparam Index Index of the storage to return.
* @return The storage for the given index.
*/
template<std::size_t Index>
[[nodiscard]] auto *storage() const noexcept {
static_assert(Index == 0u, "Index out of bounds");
return static_cast<Get *>(const_cast<constness_as_t<common_type, Get> *>(this->view));
}
/**
* @brief Assigns a storage to a view.
* @param elem A storage to assign to the view.
*/
void storage(Get &elem) noexcept {
this->view = &elem;
}
/**
* @brief Assigns a storage to a view.
* @tparam Index Index of the storage to assign to the view.
* @param elem A storage to assign to the view.
*/
template<std::size_t Index>
void storage(Get &elem) noexcept {
static_assert(Index == 0u, "Index out of bounds");
this->view = &elem;
}
/**
* @brief Returns the component assigned to the given entity.
* @param entt A valid identifier.
* @return The component assigned to the given entity.
*/
[[nodiscard]] decltype(auto) operator[](const entity_type entt) const {
return storage()->get(entt);
}
/**
* @brief Returns the identifier that occupies the given position.
* @param pos Position of the element to return.
* @return The identifier that occupies the given position.
*/
[[nodiscard]] entity_type operator[](const size_type pos) const {
return this->base_type::operator[](pos);
}
/**
* @brief Returns the component assigned to the given entity.
* @tparam Elem Type of the component to get.
@@ -825,17 +860,17 @@ public:
*/
template<typename Func>
void each(Func func) const {
if(view) {
if constexpr(is_applicable_v<Func, decltype(*view->each().begin())>) {
for(const auto pack: view->each()) {
if(auto *elem = storage(); elem) {
if constexpr(is_applicable_v<Func, decltype(*elem->each().begin())>) {
for(const auto pack: elem->each()) {
std::apply(func, pack);
}
} else if constexpr(std::is_invocable_v<Func, decltype(*view->begin())>) {
for(auto &&component: *view) {
} else if constexpr(std::is_invocable_v<Func, decltype(*elem->begin())>) {
for(auto &&component: *elem) {
func(component);
}
} else {
for(size_type pos = view->size(); pos; --pos) {
for(size_type pos = elem->size(); pos; --pos) {
func();
}
}
@@ -852,7 +887,7 @@ public:
* @return An iterable object to use to _visit_ the view.
*/
[[nodiscard]] iterable each() const noexcept {
return storage() ? storage()->each() : iterable{};
return this->view ? storage()->each() : iterable{};
}
/**
@@ -867,9 +902,6 @@ public:
return internal::view_pack<basic_view<get_t<Get, OGet...>, exclude_t<OExclude...>>>(
*this, other, std::index_sequence_for<Get>{}, std::index_sequence_for<>{}, std::index_sequence_for<OGet...>{}, std::index_sequence_for<OExclude...>{});
}
private:
Get *view;
};
/**