From 028b4e129663277d66ece7ddb8eade6b4aa963f1 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Mon, 18 Dec 2023 12:38:58 +0300
Subject: [PATCH] ECS constructors wip

---
 libs/ecs/include/psemek/ecs/container.hpp     | 59 ++++++++++++++-----
 .../psemek/ecs/detail/apply_helper.hpp        | 10 ++++
 .../include/psemek/ecs/detail/callback.hpp    | 22 +++++++
 .../include/psemek/ecs/detail/query_cache.hpp |  5 +-
 libs/ecs/include/psemek/ecs/detail/table.hpp  | 17 +++---
 .../psemek/ecs/detail/table_container.hpp     |  2 +-
 .../ecs/include/psemek/ecs/detail/without.hpp | 12 ++++
 libs/ecs/source/detail/query_cache.cpp        |  5 +-
 libs/ecs/source/detail/table.cpp              | 36 +++++++++--
 libs/ecs/tests/callback.cpp                   | 54 +++++++++++++++++
 10 files changed, 192 insertions(+), 30 deletions(-)
 create mode 100644 libs/ecs/include/psemek/ecs/detail/callback.hpp
 create mode 100644 libs/ecs/tests/callback.cpp

diff --git a/libs/ecs/include/psemek/ecs/container.hpp b/libs/ecs/include/psemek/ecs/container.hpp
index bc5e44c6..5bce2e31 100644
--- a/libs/ecs/include/psemek/ecs/container.hpp
+++ b/libs/ecs/include/psemek/ecs/container.hpp
@@ -19,7 +19,6 @@ namespace psemek::ecs
 {
 
 	using query_cache = std::shared_ptr<detail::query_cache>;
-	using token = std::shared_ptr<void>;
 
 	// TODO:
 	// - Fully document which functions can be called from which callbacks
@@ -283,12 +282,11 @@ namespace psemek::ecs
 		 *  When attaching components to an entity, the constructor is called
 		 *    exactly when the entity didn't match the constructor's component types
 		 *    before attaching new components, and does match them after attaching.
+		 *    TODO: implement this behavior
 		 *
 		 *  The constructor function must have the same signature as a function
 		 *    passed to the `apply<Components...>()` call.
 		 *
-		 *  The constructor can immediately destroy the created entity.
-		 *
 		 *  The constuctor is not considered to be a modification of the entity, i.e. it
 		 *    doesn't trigger modification callbacks.
 		 *
@@ -298,13 +296,11 @@ namespace psemek::ecs
 		 *  @warning If any two of the passed component types are equal, the call fails with
 		 *    a compilation error
 		 *  @warning If the constructor modifies the entity's archetype (i.e. attaches or
-		 *    detaches components), it might be called recursively, leading to
-		 *    infinite recursion. It is best not to change the archetype from the
-		 *    constructor.
+		 *    detaches components), the behavior is undefined
+		 *  @warning If the constructor destroys the entity, the behavior is undefined
 		 */
-		// TODO: implement
 		template <typename ... Components, typename Function>
-		token constructor(Function && function);
+		void constructor(Function && function);
 
 		/** Register a destructor. Each time an entity is destroyed that has
 		 *    the specified set of components, the destructor is called for
@@ -322,6 +318,7 @@ namespace psemek::ecs
 		 *  When detaching components from an entity, the destructor is called
 		 *    exactly when the entity did match the destructor's component types
 		 *    before detaching components, and doesn't match them after detaching.
+		 *    TODO: implement this behavior
 		 *
 		 *  The destructor function must have the same signature as a function
 		 *    passed to the `apply<Components...>()` call.
@@ -337,10 +334,11 @@ namespace psemek::ecs
 		 *    a compilation error
 		 *  @warning If the destructor modifies the entity's archetype (i.e. attaches or
 		 *    detaches components), the behavior is undefined
+		 *  @warning If the destructor destroys the entity recursively, the behavior is undefined
 		 */
 		// TODO: implement
 		template <typename ... Components, typename Function>
-		token destructor(Function && function);
+		void destructor(Function && function);
 
 		/** Register a component modification callback. Each time an entity that has
 		 *    the specified set of components is modified, and the modification affects
@@ -376,7 +374,7 @@ namespace psemek::ecs
 		 */
 		// TODO: implement
 		template <typename ... Components, typename Function>
-		token watch(Function && function);
+		void watch(Function && function);
 
 	private:
 		detail::entity_list entity_list_;
@@ -387,6 +385,8 @@ namespace psemek::ecs
 		std::vector<util::uuid> uuid_helper_;
 		util::hash_set<util::uuid> uuid_set_helper_;
 
+		std::vector<query_cache> callback_caches_;
+
 		detail::table * insert_table(std::vector<std::unique_ptr<detail::column>> columns);
 		void do_destroy(handle const & entity);
 		void remove_row(detail::table & table, std::uint32_t row, util::span<detail::entity_data> entities);
@@ -420,13 +420,16 @@ namespace psemek::ecs
 		if (table->get_iteration_data())
 			table = table->get_delayed_table();
 
-		auto id = entity_list_.create(table, table->row_count());
+		auto row = table->row_count();
+		auto id = entity_list_.create(table, row);
 		handle handle{id, entity_list_.get_entities()[id].epoch};
 		[[maybe_unused]] accessor accessor = get(handle);
 
 		table->push_row(handle);
 		((accessor.get<std::remove_cvref_t<Components>>() = std::forward<Components>(components)), ...);
 
+		table->trigger_constructors(*this, row);
+
 		return handle;
 	}
 
@@ -477,9 +480,9 @@ namespace psemek::ecs
 	template <typename ... Components>
 	void container::detach(handle const & entity)
 	{
-		static_assert(detail::all_different_types_v<std::remove_cvref_t<Components>...>, "all component types must be different");
+		static_assert(detail::all_different_types_v<std::remove_const_t<Components>...>, "all component types must be different");
 
-		(uuid_set_helper_.insert(std::remove_cvref_t<Components>::uuid()), ...);
+		(uuid_set_helper_.insert(std::remove_const_t<Components>::uuid()), ...);
 
 		auto & data = entity_list_.get_entities()[entity.id];
 		for (auto const & column : data.table->columns())
@@ -534,7 +537,7 @@ namespace psemek::ecs
 	{
 		static_assert(detail::all_different_types_v<std::remove_const_t<Components>...>, "all component types must be different");
 
-		using invocable_type = typename detail::filter_with<detail::invocable, std::tuple<std::remove_cvref_t<Components>...>, Function>::type;
+		using invocable_type = typename detail::filter_with<detail::invocable, std::tuple<Components...>, Function>::type;
 
 		static_assert(invocable_type::value, "function is not invocable with these components");
 
@@ -582,7 +585,7 @@ namespace psemek::ecs
 	{
 		static_assert(detail::all_different_types_v<std::remove_const_t<Components>...>, "all component types must be different");
 
-		using invocable_type = typename detail::filter_with<detail::batch_invocable, std::tuple<std::remove_cvref_t<Components>...>, Function>::type;
+		using invocable_type = typename detail::filter_with<detail::batch_invocable, std::tuple<Components...>, Function>::type;
 
 		static_assert(invocable_type::value, "function is not batch-invocable with these components");
 
@@ -602,4 +605,30 @@ namespace psemek::ecs
 		return cache;
 	}
 
+	template <typename ... Components, typename Function>
+	void container::constructor(Function && function)
+	{
+		static_assert(detail::all_different_types_v<std::remove_const_t<Components>...>, "all component types must be different");
+
+		using invocable_type = typename detail::filter_with<detail::invocable, std::tuple<Components ...>, Function>::type;
+
+		static_assert(invocable_type::value, "function is not invocable with these components");
+
+		query_cache cache = this->cache<Components...>();
+
+		cache->constructor_factory = [function = std::move(function)](std::vector<std::uint32_t> const & column_indices) -> detail::table_callback {
+			return [function, column_indices](container & container, detail::table & table, std::uint32_t row){
+				typename detail::filter_with<detail::static_apply_helper, std::tuple<Components  ...>>::type apply_helper(container, table.entity_handles());
+
+				for (std::size_t i = 0; i < apply_helper.column_count; ++i)
+					apply_helper.pointers[i] = table.columns()[column_indices[i]]->data();
+
+				apply_helper.advance(row);
+				apply_helper.apply(function);
+			};
+		};
+
+		callback_caches_.push_back(cache);
+	}
+
 }
diff --git a/libs/ecs/include/psemek/ecs/detail/apply_helper.hpp b/libs/ecs/include/psemek/ecs/detail/apply_helper.hpp
index cdf537ff..00301fdd 100644
--- a/libs/ecs/include/psemek/ecs/detail/apply_helper.hpp
+++ b/libs/ecs/include/psemek/ecs/detail/apply_helper.hpp
@@ -84,6 +84,8 @@ namespace psemek::ecs::detail
 	template <typename ... Components>
 	struct static_apply_helper
 	{
+		static constexpr std::size_t column_count = sizeof...(Components);
+
 		container & parent;
 		std::size_t row_count;
 		handle const * entity_handles_pointer;
@@ -132,6 +134,14 @@ namespace psemek::ecs::detail
 			std::size_t i = 0;
 			((pointers[i++] += stride<Components>()), ...);
 		}
+
+		void advance(std::size_t rows)
+		{
+			entity_handles_pointer += rows;
+
+			std::size_t i = 0;
+			((pointers[i++] += stride<Components>() * rows), ...);
+		}
 	};
 
 }
diff --git a/libs/ecs/include/psemek/ecs/detail/callback.hpp b/libs/ecs/include/psemek/ecs/detail/callback.hpp
new file mode 100644
index 00000000..040626bb
--- /dev/null
+++ b/libs/ecs/include/psemek/ecs/detail/callback.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <psemek/ecs/handle.hpp>
+#include <psemek/util/function.hpp>
+
+#include <memory>
+
+namespace psemek::ecs
+{
+
+	struct container;
+
+	namespace detail
+	{
+
+		struct table;
+
+		using table_callback = util::function<void(container &, table &, std::uint32_t)>;
+
+	}
+
+}
diff --git a/libs/ecs/include/psemek/ecs/detail/query_cache.hpp b/libs/ecs/include/psemek/ecs/detail/query_cache.hpp
index e71b1a77..8ab00fd9 100644
--- a/libs/ecs/include/psemek/ecs/detail/query_cache.hpp
+++ b/libs/ecs/include/psemek/ecs/detail/query_cache.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <psemek/ecs/detail/callback.hpp>
 #include <psemek/util/uuid.hpp>
 
 #include <vector>
@@ -13,7 +14,7 @@ namespace psemek::ecs::detail
 	struct query_cache_entry
 	{
 		struct table * table = nullptr;
-		std::vector<column *> columns;
+		std::vector<std::uint32_t> columns_indices;
 	};
 
 	struct query_cache
@@ -22,6 +23,8 @@ namespace psemek::ecs::detail
 		std::vector<util::uuid> without_uuids;
 		std::vector<query_cache_entry> entries;
 
+		util::function<table_callback(std::vector<std::uint32_t> const &)> constructor_factory;
+
 		void add(table * table);
 	};
 
diff --git a/libs/ecs/include/psemek/ecs/detail/table.hpp b/libs/ecs/include/psemek/ecs/detail/table.hpp
index 2f376eb8..b205909b 100644
--- a/libs/ecs/include/psemek/ecs/detail/table.hpp
+++ b/libs/ecs/include/psemek/ecs/detail/table.hpp
@@ -3,6 +3,7 @@
 #include <psemek/ecs/handle.hpp>
 #include <psemek/ecs/detail/component_hash.hpp>
 #include <psemek/ecs/detail/column.hpp>
+#include <psemek/ecs/detail/callback.hpp>
 #include <psemek/util/uuid.hpp>
 #include <psemek/util/span.hpp>
 #include <psemek/util/hash_table.hpp>
@@ -26,7 +27,8 @@ namespace psemek::ecs::detail
 			return hash_;
 		}
 
-		detail::column * column(util::uuid const & uuid) const;
+		std::optional<std::size_t> column_index(util::uuid const & uuid) const;
+		struct column * column(util::uuid const & uuid) const;
 
 		util::span<handle const> entity_handles() const
 		{
@@ -38,11 +40,6 @@ namespace psemek::ecs::detail
 			return columns_;
 		}
 
-		std::size_t column_count() const
-		{
-			return component_uuid_to_column_.size();
-		}
-
 		std::size_t row_count() const
 		{
 			return entity_handles_.size();
@@ -75,10 +72,14 @@ namespace psemek::ecs::detail
 
 		std::vector<std::type_index> const & non_copyable_components() const;
 
+		void add_constructor(table_callback callback);
+
+		void trigger_constructors(container & container, std::uint32_t row);
+
 	protected:
 		std::size_t hash_;
 		std::vector<std::unique_ptr<detail::column>> columns_;
-		util::hash_map<util::uuid, detail::column *> component_uuid_to_column_;
+		util::hash_map<util::uuid, std::uint32_t> component_uuid_to_column_index_;
 
 		std::vector<handle> entity_handles_;
 
@@ -87,6 +88,8 @@ namespace psemek::ecs::detail
 		std::unique_ptr<table> delayed_table_;
 
 		std::vector<std::type_index> non_copyable_components_;
+
+		std::shared_ptr<std::vector<table_callback>> constructors_;
 	};
 
 }
diff --git a/libs/ecs/include/psemek/ecs/detail/table_container.hpp b/libs/ecs/include/psemek/ecs/detail/table_container.hpp
index a6b4cec5..1d9474b4 100644
--- a/libs/ecs/include/psemek/ecs/detail/table_container.hpp
+++ b/libs/ecs/include/psemek/ecs/detail/table_container.hpp
@@ -26,7 +26,7 @@ namespace psemek::ecs::detail
 	{
 		bool operator()(util::span<util::uuid const> const & uuids, std::unique_ptr<table> const & table) const
 		{
-			if (uuids.size() != table->column_count())
+			if (uuids.size() != table->columns().size())
 				return false;
 			for (auto const & uuid : uuids)
 				if (!table->column(uuid))
diff --git a/libs/ecs/include/psemek/ecs/detail/without.hpp b/libs/ecs/include/psemek/ecs/detail/without.hpp
index c5c1645b..b26edaa4 100644
--- a/libs/ecs/include/psemek/ecs/detail/without.hpp
+++ b/libs/ecs/include/psemek/ecs/detail/without.hpp
@@ -28,6 +28,12 @@ namespace psemek::ecs::detail
 		using type = typename filter_with_impl<MetaFunction, std::tuple<ExtraArgs...>, std::tuple<FilteredComponents...>, RemainingComponents...>::type;
 	};
 
+	template <template <typename ...> typename MetaFunction, typename ... ExtraArgs, typename ... FilteredComponents, typename Component, typename ... RemainingComponents>
+	struct filter_with_impl<MetaFunction, std::tuple<ExtraArgs...>, std::tuple<FilteredComponents...>, ecs::without<Component> const, RemainingComponents...>
+	{
+		using type = typename filter_with_impl<MetaFunction, std::tuple<ExtraArgs...>, std::tuple<FilteredComponents...>, RemainingComponents...>::type;
+	};
+
 	template <template <typename ...> typename MetaFunction, typename ExtraArgsTuple, typename FilteredComponentsTuple, typename ... Components>
 	struct filter_without_impl;
 
@@ -49,6 +55,12 @@ namespace psemek::ecs::detail
 		using type = typename filter_without_impl<MetaFunction, std::tuple<ExtraArgs...>, std::tuple<FilteredComponents..., Component>, RemainingComponents...>::type;
 	};
 
+	template <template <typename ...> typename MetaFunction, typename ... ExtraArgs, typename ... FilteredComponents, typename Component, typename ... RemainingComponents>
+	struct filter_without_impl<MetaFunction, std::tuple<ExtraArgs...>, std::tuple<FilteredComponents...>, const ecs::without<Component>, RemainingComponents...>
+	{
+		using type = typename filter_without_impl<MetaFunction, std::tuple<ExtraArgs...>, std::tuple<FilteredComponents..., Component>, RemainingComponents...>::type;
+	};
+
 	template <template <typename ...> typename MetaFunction, typename ComponentsTuple, typename ... ExtraArgs>
 	struct filter_with;
 
diff --git a/libs/ecs/source/detail/query_cache.cpp b/libs/ecs/source/detail/query_cache.cpp
index c3ac7be8..08a4ac19 100644
--- a/libs/ecs/source/detail/query_cache.cpp
+++ b/libs/ecs/source/detail/query_cache.cpp
@@ -10,7 +10,10 @@ namespace psemek::ecs::detail
 		entry.table = table;
 
 		for (auto const & uuid : with_uuids)
-			entry.columns.push_back(table->column(uuid));
+			entry.columns_indices.push_back(*table->column_index(uuid));
+
+		if (constructor_factory)
+			table->add_constructor(constructor_factory(entry.columns_indices));
 	}
 
 }
diff --git a/libs/ecs/source/detail/table.cpp b/libs/ecs/source/detail/table.cpp
index de1f291f..573ccb88 100644
--- a/libs/ecs/source/detail/table.cpp
+++ b/libs/ecs/source/detail/table.cpp
@@ -7,23 +7,33 @@ namespace psemek::ecs::detail
 	table::table(std::vector<std::unique_ptr<detail::column>> columns)
 	{
 		component_hasher<true> hasher;
-		for (auto & column : columns)
+		for (std::size_t i = 0; i < columns.size(); ++i)
 		{
+			auto const & column = columns[i];
 			auto uuid = column->uuid();
 			hasher(uuid);
-			component_uuid_to_column_.insert({uuid, column.get()});
+			component_uuid_to_column_index_.insert({uuid, i});
 			if (!column->copy_constructible())
 				non_copyable_components_.push_back(column->type());
 		}
 		hash_ = hasher.result;
 
 		columns_ = std::move(columns);
+
+		constructors_ = std::make_shared<std::vector<table_callback>>();
 	}
 
-	detail::column * table::column(util::uuid const & uuid) const
+	std::optional<std::size_t> table::column_index(util::uuid const & uuid) const
 	{
-		if (auto it = component_uuid_to_column_.find(uuid); it != component_uuid_to_column_.end())
+		if (auto it = component_uuid_to_column_index_.find(uuid); it != component_uuid_to_column_index_.end())
 			return it->second;
+		return std::nullopt;
+	}
+
+	column * table::column(util::uuid const & uuid) const
+	{
+		if (auto index = column_index(uuid))
+			return columns_[*index].get();
 		return nullptr;
 	}
 
@@ -95,7 +105,10 @@ namespace psemek::ecs::detail
 		std::vector<std::unique_ptr<detail::column>> columns;
 		for (auto const & column : columns_)
 			columns.push_back(column->clone());
-		return std::make_unique<table>(std::move(columns));
+
+		auto result = std::make_unique<table>(std::move(columns));
+		result->constructors_ = constructors_;
+		return result;
 	}
 
 	table * table::get_delayed_table()
@@ -128,4 +141,17 @@ namespace psemek::ecs::detail
 		return non_copyable_components_;
 	}
 
+	void table::add_constructor(table_callback callback)
+	{
+		constructors_->push_back(std::move(callback));
+	}
+
+	void table::trigger_constructors(container & container, std::uint32_t row)
+	{
+		for (auto const & callback : *constructors_)
+		{
+			callback(container, *this, row);
+		}
+	}
+
 }
diff --git a/libs/ecs/tests/callback.cpp b/libs/ecs/tests/callback.cpp
new file mode 100644
index 00000000..363fbde2
--- /dev/null
+++ b/libs/ecs/tests/callback.cpp
@@ -0,0 +1,54 @@
+#include <psemek/test/test.hpp>
+
+#include <psemek/ecs/container.hpp>
+#include <psemek/ecs/declare_uuid.hpp>
+
+using namespace psemek;
+using namespace psemek::ecs;
+
+namespace
+{
+
+	struct component_1
+	{
+		int value;
+
+		psemek_ecs_declare_uuid("component_1")
+	};
+
+	struct component_2
+	{
+		int value;
+
+		psemek_ecs_declare_uuid("component_2")
+	};
+
+}
+
+test_case(ecs_callback_constructor_create)
+{
+	container container;
+
+	int value = 0;
+	container.constructor<component_1>([&value](component_1 const & c1){
+		value = c1.value;
+	});
+
+	container.create(component_1{10});
+	expect_equal(value, 10);
+
+	container.create(component_1{20});
+	expect_equal(value, 20);
+
+	container.create(component_2{100});
+	expect_equal(value, 20);
+
+	container.create();
+	expect_equal(value, 20);
+
+	container.create(component_1{30});
+	expect_equal(value, 30);
+
+	container.create(component_1{40}, component_2{200});
+	expect_equal(value, 40);
+}