From 5e3a2492c7bb73daa4e27398daaf490d09980ff3 Mon Sep 17 00:00:00 2001
From: Jon Santmyer <jon@jonsantmyer.com>
Date: Wed, 22 Jun 2022 17:41:59 -0400
Subject: Base system viewer with data loaded from csv files

---
 include/ecs.hpp | 139 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 include/ecs.hpp

(limited to 'include/ecs.hpp')

diff --git a/include/ecs.hpp b/include/ecs.hpp
new file mode 100644
index 0000000..ab5e2b2
--- /dev/null
+++ b/include/ecs.hpp
@@ -0,0 +1,139 @@
+#ifndef ECS_HPP
+#define ECS_HPP 1
+
+#include "entitycomponents.hpp"
+#include "util.hpp"
+#include <bitset>
+#include <typeindex>
+#include <queue>
+#include <cassert>
+#include <ranges>
+#include <span>
+#include <iostream>
+
+namespace ecs {
+
+struct ComponentContainer {
+    std::vector<component_variant> packed{};
+    std::vector<int> sparse{};
+    std::queue<unsigned> free{};
+
+    void resize(size_t n) { sparse.resize(n, -1); }
+
+    template<component_type T>
+    void insert(unsigned id, const T &c) {
+        assert(sparse.size() > id);
+        if(free.empty()) {
+            sparse[id] = (int)packed.size();
+            packed.push_back(c);
+        }else {
+            sparse[id] = (int)free.front();
+            packed[sparse[id]] = c;
+            free.pop();
+        }
+    }
+
+    void remove(unsigned id) {
+        assert(sparse.size() > id);
+        if(sparse[id] > -1) {
+            free.push((unsigned)sparse[id]);
+        }
+        sparse[id] = -1;
+    }
+
+    template<component_type T>
+    T &reduce(unsigned id) {
+        assert(sparse.size() > id);
+        assert(sparse[id] > -1);
+        return std::get<T>(packed[sparse[id]]);
+    }
+};
+
+class EntityMan;
+struct Entity {
+    EntityMan *man;
+    component_sig sig{};
+    unsigned id;
+
+    Entity(const Entity &e) = default;
+    Entity(EntityMan *Man, unsigned Id) :
+        man(Man), sig(0), id(Id) {}
+
+
+    template<component_type T>
+    constexpr bool contains() { return sig.test(get_index<T, component_variant>()); }
+
+    template<component_type T>
+    T &get();
+
+    template<component_type T>
+    Entity &addComponent(const T &component);
+};
+
+class EntityMan {
+    std::array<ComponentContainer, std::variant_size_v<component_variant>> m_components;
+    std::vector<Entity> m_entities;
+    std::queue<unsigned> m_free;
+public:
+    Entity &operator[](std::size_t i) { return m_entities[i]; }
+
+    Entity newEntity() {
+        std::size_t newid = 0;
+        if(!m_free.empty()) {
+            newid = m_free.front();
+            m_free.pop();
+        }else{
+            newid = m_entities.size();
+            m_entities.emplace_back(this, newid);
+            for(auto &container : m_components) container.resize(m_entities.size());
+        }
+        return m_entities[newid];
+    }
+
+    void deleteEntity(Entity &e) {
+        for(auto &container : m_components) container.remove(e.id);
+        e.sig.reset();
+        m_free.push(e.id);
+    }
+
+    template<component_type T>
+    T &get(const Entity &e) {
+        constexpr unsigned cid = get_index<T, component_variant>();
+        return m_components[cid].reduce<T>(e.id);
+    }
+
+    template<component_type T>
+    auto getWith() {
+        constexpr unsigned cid = get_index<T, component_variant>();
+        auto e_hc = [](Entity const e) { return e.sig[cid]; };
+        return std::ranges::views::filter(m_entities, e_hc);
+    }
+
+    std::span<Entity> all() {
+        return std::span<Entity>(m_entities.begin(), m_entities.end());
+    }
+
+    std::size_t size() { return m_entities.size(); }
+
+    template<component_type T>
+    Entity &addComponent(Entity &entity, const T& component) {
+        constexpr unsigned cid = get_index<T, component_variant>();
+        m_components[cid].insert(entity.id, component);
+        m_entities[entity.id].sig[cid] = 1;
+        return entity;
+    }
+};
+
+template<component_type T>
+T &Entity::get() {
+    return man->get<T>(*this);
+}
+
+template<component_type T>
+Entity &Entity::addComponent(const T& component) {
+    return man->addComponent(*this, component);
+}
+
+}
+
+#endif
-- 
cgit v1.2.1