impl.hpp

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/**
 * @file addons/cpp/mixins/module/impl.hpp
 * @brief Module implementation.
 */
 
#pragma once
 
namespace flecs {
 
namespace _ {
 
template <typename T>
ecs_entity_t do_import(world& world, const char *symbol) {
    ecs_trace("#[magenta]import#[reset] %s", _::type_name<T>());
    ecs_log_push();
 
    ecs_entity_t scope = ecs_set_scope(world, 0);
 
    // Initialize module component type and don't allow it to be registered as a
    // tag, as this would prevent calling emplace().
    auto c_ = component<T>(world, nullptr, false);
 
    // Make module component sparse so that it'll never move in memory. This
    // guarantees that a module destructor can be reliably used to clean up
    // module resources.
    c_.add(flecs::Sparse);
 
#ifdef FLECS_CONSTRAINT_TRAITS
    c_.add(flecs::Singleton);
#endif
 
    ecs_add_id(world, c_, EcsModule);
 
    ecs_set_scope(world, c_);
    world.emplace<T>(world);
    ecs_set_scope(world, scope);
 
    // It should now be possible to look up the module.
    ecs_entity_t m = ecs_lookup_symbol(world, symbol, false, false);
    ecs_assert(m != 0, ECS_MODULE_UNDEFINED, "%s", symbol);
    ecs_assert(m == c_, ECS_INTERNAL_ERROR, nullptr);
 
    ecs_log_pop();
 
    return m;
}
 
template <typename T>
flecs::entity import(world& world) {
    char *symbol = ecs_cpp_get_symbol_name(nullptr, type_name<T>(), 0);
 
    ecs_entity_t m = ecs_lookup_symbol(world, symbol, true, false);
 
    if (!_::type<T>::registered(world)) {
        // Module is registered with world, initialize static data.
        if (m) {
            _::type<T>::init_builtin(world, m, false);
 
        // Module is not yet registered, register it now.
        } else {
            m = _::do_import<T>(world, symbol);
        }
 
    // Module has been registered, but could have been for another world.
    // Import if module hasn't been registered for this world.
    } else if (!m) {
        m = _::do_import<T>(world, symbol);
    }
 
    ecs_os_free(symbol);
    return flecs::entity(world, m);
}
 
}
 
/**
 * @defgroup cpp_addons_modules Modules
 * @ingroup cpp_addons
 * Modules organize components, systems, and more in reusable units of code.
 *
 * @{
 */
 
template <typename Module>
inline flecs::entity world::module(const char *name) const {
    flecs::entity result = this->entity(
        _::type<Module>::register_id(world_, nullptr, false));
 
    if (name) {
        flecs::entity prev_parent = result.parent();
        ecs_add_path_w_sep(world_, result, 0, name, "::", "::");
        flecs::entity parent = result.parent();
        if (prev_parent != parent) {
            if (parent && result.has(flecs::Module)) {
                parent.add(flecs::Module);
            }
 
            // Module was reparented, clean up old parent(s).
            flecs::entity cur = prev_parent, next;
            while (cur) {
                // Stop if the old parent is an ancestor of the new parent.
                flecs::entity p = parent;
                while (p && p != cur) {
                    p = p.parent();
                }
                if (p == cur) {
                    break;
                }
 
                next = cur.parent();
 
                // Move entities that were created in the old parent to the
                // renamed module.
                bool has_modules = false;
                ecs_defer_begin(world_);
                ecs_iter_t it = ecs_children(world_, cur);
                while (ecs_children_next(&it)) {
                    for (int32_t i = 0; i < it.count; i ++) {
                        flecs::entity_t child = it.entities[i];
                        if (ecs_has_id(world_, child, EcsModule)) {
                            has_modules = true;
                            continue;
                        }
                        if (ecs_has_pair(world_, child, ecs_id(EcsPoly), 
                            EcsWildcard))
                        {
                            continue;
                        }
                        ecs_add_pair(world_, child, EcsChildOf, result);
                    }
                }
                ecs_defer_end(world_);
 
                if (has_modules) {
                    break;
                }
 
                cur.destruct();
                this->set_version(cur);
                cur = next;
            }
        }
    }
 
    return result;
}
 
template <typename Module>
inline flecs::entity world::import() {
    return flecs::_::import<Module>(*this);
}
 
/** @} */
 
}