Add prototype ecs implementation with tests

This commit is contained in:
Nikita Lisitsa 2021-07-21 22:08:38 +03:00
parent fca22c93e2
commit 640bbf47c7
2 changed files with 595 additions and 0 deletions

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#pragma once
#include <psemek/util/to_string.hpp>
#include <psemek/util/type_name.hpp>
#include <cstdint>
#include <typeindex>
#include <tuple>
#include <vector>
#include <memory>
#include <string>
#include <string_view>
#include <experimental/type_traits>
namespace psemek::util
{
namespace ecs_detail
{
using handle = std::uint32_t;
struct species_base
{
virtual std::string_view name() const = 0;
virtual void * get_species_component(std::type_index component_type) = 0;
virtual void * get_entity_component(std::type_index component_type) = 0;
template <typename Component>
Component * get_species_component()
{
return reinterpret_cast<Component *>(get_species_component(typeid(Component)));
}
template <typename Component>
typename Component::data * get_entity_component()
{
return reinterpret_cast<typename Component::data *>(get_entity_component(typeid(Component)));
}
virtual handle entity_count() const = 0;
virtual handle add_entity() = 0;
template <typename Behavior>
void apply(Behavior & behavior)
{
apply_impl(behavior, typename Behavior::components{});
}
virtual ~species_base() {}
private:
template <typename Behavior, typename ... Components>
void apply_impl(Behavior & behavior, std::tuple<Components...>)
{
std::tuple<typename Components::data * ...> cptrs;
((std::get<typename Components::data *>(cptrs) = get_entity_component<Components>()), ...);
auto all_nonzero = [](auto * ... ptrs)
{
return ((ptrs != nullptr) && ...);
};
if (!std::apply(all_nonzero, cptrs))
return;
std::tuple<Components *...> cs;
((std::get<Components *>(cs) = get_species_component<Components>()), ...);
auto visit = [&](auto * ... ptrs)
{
if constexpr (std::is_invocable_v<Behavior, typename Components::data & ..., std::tuple<Components *...> const &>)
{
behavior(*ptrs..., cs);
}
else
{
behavior(*ptrs...);
}
};
auto increment = [](auto * & ... ptrs)
{
((++ptrs), ...);
};
std::size_t const count = entity_count();
for (std::size_t i = 0; i < count; ++i)
{
std::apply(visit, cptrs);
std::apply(increment, cptrs);
}
}
};
template <typename ... Components>
struct species_impl
: species_base
{
species_impl(std::string name, Components && ... components)
: name_(std::move(name))
, species_components_{std::move(components)...}
{}
std::string_view name() const override
{
return name_;
}
using species_base::get_species_component;
using species_base::get_entity_component;
void * get_species_component(std::type_index component_type) override
{
return get_species_component_impl(component_type, std::make_index_sequence<sizeof...(Components)>{});
}
void * get_entity_component(std::type_index component_type) override
{
return get_entity_component_impl(component_type, std::make_index_sequence<sizeof...(Components)>{});
}
handle entity_count() const override
{
return std::get<0>(entity_components_).size();
}
handle add_entity() override
{
handle result = entity_count();
add_entity_impl(std::make_index_sequence<sizeof...(Components)>{});
return result;
}
private:
std::string name_;
std::tuple<Components...> species_components_;
std::tuple<std::vector<typename Components::data>...> entity_components_;
template <std::size_t ... I>
void * get_species_component_impl(std::type_index component_type, std::index_sequence<I...>)
{
void * result = nullptr;
((result = (component_type == typeid(std::tuple_element_t<I, std::tuple<Components...>>)) ? &std::get<I>(species_components_) : result), ...);
return result;
}
template <std::size_t ... I>
void * get_entity_component_impl(std::type_index component_type, std::index_sequence<I...>)
{
void * result = nullptr;
((result = (component_type == typeid(std::tuple_element_t<I, std::tuple<Components...>>)) ? std::get<I>(entity_components_).data() : result), ...);
return result;
}
template <std::size_t ... I>
void add_entity_impl(std::index_sequence<I...>)
{
((std::get<I>(entity_components_).emplace_back()), ...);
}
};
template <>
struct species_impl<>
: species_base
{
species_impl(std::string name)
: name_(std::move(name))
{}
std::string_view name() const override
{
return name_;
}
using species_base::get_species_component;
using species_base::get_entity_component;
void * get_species_component(std::type_index) override { return nullptr; }
void * get_entity_component(std::type_index) override { return nullptr; }
virtual handle entity_count() const
{
return entity_count_;
}
virtual handle add_entity()
{
return entity_count_++;
}
private:
std::string name_;
std::size_t entity_count_ = 0;
};
template <typename Behavior>
using prepare_helper = decltype(std::declval<Behavior>().prepare());
template <typename Behavior>
using has_prepare = std::experimental::is_detected<prepare_helper, Behavior>;
}
struct ecs
{
template <typename ... Components>
struct behavior
{
using components = std::tuple<Components...>;
using component_ptrs = std::tuple<Components *...>;
};
using handle = ecs_detail::handle;
template <typename ... Components>
handle register_species(std::string name, Components && ... components);
handle add_entity(handle species);
handle entity_count(handle species) const;
template <typename Component>
Component & get(handle species);
template <typename Component>
Component const & get(handle species) const;
template <typename Component>
typename Component::data & get(handle species, handle entity);
template <typename Component>
typename Component::data const & get(handle species, handle entity) const;
template <typename Behavior>
void apply(Behavior && behavior) const;
private:
std::vector<std::unique_ptr<ecs_detail::species_base>> species_;
};
template <typename ... Components>
ecs::handle ecs::register_species(std::string name, Components && ... components)
{
handle result = species_.size();
species_.push_back(std::make_unique<ecs_detail::species_impl<Components...>>(std::move(name), std::move(components)...));
return result;
}
inline ecs::handle ecs::add_entity(handle species)
{
return species_[species]->add_entity();
}
inline ecs::handle ecs::entity_count(handle species) const
{
return species_[species]->entity_count();
}
template <typename Component>
Component & ecs::get(handle species)
{
auto p = species_[species]->get_species_component<Component>();
if (!p)
throw std::runtime_error(util::to_string("Component ", type_name<Component>(), " is not present in species ", species_[species]->name()));
return *p;
}
template <typename Component>
Component const & ecs::get(handle species) const
{
return const_cast<typename Component::data const &>(const_cast<ecs *>(this)->get<Component>(species));
}
template <typename Component>
typename Component::data & ecs::get(handle species, handle entity)
{
auto p = species_[species]->get_entity_component<Component>();
if (!p)
throw std::runtime_error(util::to_string("Component ", type_name<Component>(), " is not present in species ", species_[species]->name()));
return p[entity];
}
template <typename Component>
typename Component::data const & ecs::get(handle species, handle entity) const
{
return const_cast<typename Component::data const &>(const_cast<ecs *>(this)->get<Component>(species, entity));
}
template <typename Behavior>
void ecs::apply(Behavior && behavior) const
{
if constexpr (ecs_detail::has_prepare<Behavior>::value)
{
behavior.prepare();
}
for (auto & s : species_)
s->apply(behavior);
}
}

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libs/util/tests/ecs.cpp Normal file
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#include <psemek/test/test.hpp>
#include <psemek/util/ecs.hpp>
namespace
{
using namespace psemek::util;
struct test_component_1
{
int species_value_1;
struct data
{
int entity_value_1;
};
};
struct test_component_2
{
int species_value_2;
struct data
{
int entity_value_2;
};
};
struct test_behavior_1
: ecs::behavior<test_component_1>
{
int call_count = 0;
int value_sum = 0;
void operator()(test_component_1::data & c)
{
call_count += 1;
value_sum += c.entity_value_1;
}
};
struct test_behavior_12
: ecs::behavior<test_component_1, test_component_2>
{
int call_count = 0;
int value_sum_1 = 0;
int value_sum_2 = 0;
void operator()(test_component_1::data & c1, test_component_2::data & c2)
{
call_count += 1;
value_sum_1 += c1.entity_value_1;
value_sum_2 += c2.entity_value_2;
}
};
struct test_behavior_species_12
: ecs::behavior<test_component_1, test_component_2>
{
int expected_value_1;
int expected_value_2;
int call_count = 0;
void operator()(test_component_1::data &, test_component_2::data &, components const & cs)
{
expect_equal(std::get<test_component_1>(cs).species_value_1, expected_value_1);
expect_equal(std::get<test_component_2>(cs).species_value_2, expected_value_2);
++call_count;
}
};
}
test_case(util_ecs_species__impl_component)
{
using namespace psemek::util::ecs_detail;
species_impl<test_component_1> species("species 1", test_component_1{10});
expect_different_ptr(species.get_species_component<test_component_1>(), nullptr);
expect_equal(species.get_species_component<test_component_1>()->species_value_1, 10);
expect_equal_ptr(species.get_species_component<test_component_2>(), nullptr);
species_impl<test_component_2> species_2("species 2", test_component_2{20});
expect_equal_ptr(species_2.get_species_component<test_component_1>(), nullptr);
expect_different_ptr(species_2.get_species_component<test_component_2>(), nullptr);
expect_equal(species_2.get_species_component<test_component_2>()->species_value_2, 20);
species_impl<test_component_1, test_component_2> species_12("species 12", test_component_1{100}, test_component_2{200});
expect_different_ptr(species_12.get_species_component<test_component_1>(), nullptr);
expect_equal(species_12.get_species_component<test_component_1>()->species_value_1, 100);
expect_different_ptr(species_12.get_species_component<test_component_2>(), nullptr);
expect_equal(species_12.get_species_component<test_component_2>()->species_value_2, 200);
}
test_case(util_ecs_species__impl_entity)
{
using namespace psemek::util::ecs_detail;
species_impl<test_component_1> species("species", test_component_1{10});
expect_equal(species.entity_count(), 0);
int const N = 10;
for (std::size_t i = 0; i < N; ++i)
species.add_entity();
expect_equal(species.entity_count(), N);
test_component_1::data * cptr_1 = species.get_entity_component<test_component_1>();
expect_different(cptr_1, nullptr);
for (std::size_t i = 0; i < N; ++i)
cptr_1[i].entity_value_1 = i;
for (std::size_t i = 0; i < N; ++i)
species.add_entity();
expect_equal(species.entity_count(), 2 * N);
cptr_1 = species.get_entity_component<test_component_1>();
expect_different(cptr_1, nullptr);
for (std::size_t i = 0; i < N; ++i)
expect_equal(cptr_1[i].entity_value_1, i);
}
test_case(util_ecs_entity)
{
using namespace psemek;
util::ecs ecs;
auto species = ecs.register_species("species", test_component_1{10});
expect_equal(ecs.entity_count(species), 0);
auto entity = ecs.add_entity(species);
ecs.get<test_component_1>(species, entity).entity_value_1 = 100;
expect_equal(ecs.get<test_component_1>(species, entity).entity_value_1, 100);
expect_throw(ecs.get<test_component_2>(species, entity), std::exception);
}
test_case(util_ecs_behavior_1)
{
using namespace psemek;
util::ecs ecs;
auto species = ecs.register_species("species", test_component_1{10});
expect_equal(ecs.entity_count(species), 0);
int N = 100;
for (int i = 0; i < N; ++i)
{
auto entity = ecs.add_entity(species);
ecs.get<test_component_1>(species, entity).entity_value_1 = i;
}
test_behavior_1 behavior_1;
ecs.apply(behavior_1);
expect_equal(behavior_1.call_count, N);
expect_equal(behavior_1.value_sum, (N * (N - 1)) / 2);
test_behavior_12 behavior_12;
ecs.apply(behavior_12);
expect_equal(behavior_12.call_count, 0);
expect_equal(behavior_12.value_sum_1, 0);
expect_equal(behavior_12.value_sum_2, 0);
}
test_case(util_ecs_behavior_1__2)
{
using namespace psemek;
util::ecs ecs;
auto species_1 = ecs.register_species("species 1", test_component_1{10});
auto species_2 = ecs.register_species("species 2", test_component_2{20});
int N = 100;
for (int i = 0; i < N; ++i)
{
auto entity = ecs.add_entity(species_1);
ecs.get<test_component_1>(species_1, entity).entity_value_1 = i;
}
for (int i = 0; i < N; ++i)
{
auto entity = ecs.add_entity(species_2);
ecs.get<test_component_2>(species_2, entity).entity_value_2 = -i;
}
test_behavior_1 behavior;
ecs.apply(behavior);
expect_equal(behavior.call_count, N);
expect_equal(behavior.value_sum, (N * (N - 1)) / 2);
test_behavior_12 behavior_12;
ecs.apply(behavior_12);
expect_equal(behavior_12.call_count, 0);
expect_equal(behavior_12.value_sum_1, 0);
expect_equal(behavior_12.value_sum_2, 0);
}
test_case(util_ecs_behavior_12)
{
using namespace psemek;
util::ecs ecs;
auto species = ecs.register_species("species", test_component_1{10}, test_component_2{20});
int N = 100;
for (int i = 0; i < N; ++i)
{
auto entity = ecs.add_entity(species);
ecs.get<test_component_1>(species, entity).entity_value_1 = i;
ecs.get<test_component_2>(species, entity).entity_value_2 = -i;
}
test_behavior_1 behavior;
ecs.apply(behavior);
expect_equal(behavior.call_count, N);
expect_equal(behavior.value_sum, (N * (N - 1)) / 2);
test_behavior_12 behavior_12;
ecs.apply(behavior_12);
expect_equal(behavior_12.call_count, N);
expect_equal(behavior_12.value_sum_1, (N * (N - 1)) / 2);
expect_equal(behavior_12.value_sum_2, - (N * (N - 1)) / 2);
}
test_case(util_ecs_behavior_species)
{
using namespace psemek;
util::ecs ecs;
auto species = ecs.register_species("species", test_component_1{10}, test_component_2{20});
int N = 100;
for (int i = 0; i < N; ++i)
{
auto entity = ecs.add_entity(species);
ecs.get<test_component_1>(species, entity).entity_value_1 = 0;
ecs.get<test_component_2>(species, entity).entity_value_2 = 0;
}
test_behavior_species_12 behavior;
behavior.expected_value_1 = 10;
behavior.expected_value_2 = 20;
ecs.apply(behavior);
expect_equal(behavior.call_count, N);
}