[nostalgia/core] Add AssetManager

src/nostalgia/core/assetmanager.hpp

@@ -0,0 +1,183 @@
+/*
+ * Copyright 2016 - 2021 gary@drinkingtea.net
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+#include <ox/model/typenamecatcher.hpp>
+#include <ox/fs/fs.hpp>
+#include <ox/std/hashmap.hpp>
+#include <ox/std/utility.hpp>
+
+namespace nostalgia::core {
+
+template<typename T>
+class AssetRef;
+
+template<typename T>
+struct AssetContainer {
+
+	friend AssetRef<T>;
+
+	private:
+		T m_obj;
+		mutable int m_references = 0;
+
+	public:
+		template<class... Args>
+		explicit AssetContainer(Args&&... args): m_obj(ox::forward<Args>(args)...) {
+		}
+
+		constexpr T *get() noexcept {
+			 return &m_obj;
+		}
+
+		constexpr const T *get() const noexcept {
+			 return &m_obj;
+		}
+
+	protected:
+		constexpr void incRefs() const noexcept {
+			++m_references;
+		}
+
+		constexpr void decRefs() const noexcept {
+			--m_references;
+		}
+
+};
+
+template<typename T>
+class AssetRef {
+	private:
+		const AssetContainer<T> *m_ctr = nullptr;
+
+	public:
+		explicit AssetRef(const AssetContainer<T> *c = nullptr) noexcept: m_ctr(c) {
+		}
+
+		AssetRef(const AssetRef &h) noexcept {
+			m_ctr = h.m_ctr;
+			if (m_ctr) {
+				m_ctr->incRefs();
+			}
+		}
+
+		AssetRef(AssetRef &&h) noexcept {
+			m_ctr = h.m_ctr;
+			h.m_ctr = nullptr;
+		}
+
+		~AssetRef() noexcept {
+			if (m_ctr) {
+				m_ctr->decRefs();
+			}
+		}
+
+		constexpr const T *get() const noexcept {
+			return m_ctr->get();
+		}
+
+		constexpr const T &operator*() const & noexcept {
+			return *m_ctr->get();
+		}
+
+		constexpr const T &&operator*() const && noexcept {
+			return *m_ctr->get();
+		}
+
+		constexpr const T *operator->() const noexcept {
+			return m_ctr->get();
+		}
+
+		AssetRef &operator=(const AssetRef &h) noexcept {
+			if (this == &h) {
+				return *this;
+			}
+			if (m_ctr) {
+				m_ctr->decRefs();
+			}
+			m_ctr = h.m_ctr;
+			if (m_ctr) {
+				m_ctr->incRefs();
+			}
+			return *this;
+		}
+
+		AssetRef &operator=(AssetRef &&h) noexcept {
+			if (this == &h) {
+				return *this;
+			}
+			m_ctr = h.m_ctr;
+			h.m_ctr = nullptr;
+			return *this;
+		}
+
+		explicit constexpr operator bool() const noexcept {
+			return m_ctr;
+		}
+
+};
+
+class AssetManager {
+	private:
+		class AssetTypeManagerBase {
+			public:
+				virtual ~AssetTypeManagerBase() = default;
+		};
+
+		template<typename T>
+		class AssetTypeManager: public AssetTypeManagerBase {
+			private:
+				ox::HashMap<ox::String, ox::UniquePtr<AssetContainer<T>>> m_cache;
+
+			public:
+				ox::Result<AssetRef<T>> getAsset(const ox::String &path) const noexcept {
+					auto out = m_cache.at(path);
+					oxReturnError(out);
+					return AssetRef<T>(out.value.get());
+				}
+
+				ox::Result<AssetRef<T>> setAsset(const ox::String &path, const T &obj) noexcept {
+					auto &p = m_cache[path] = ox::make_unique<AssetContainer<T>>(obj);
+					return AssetRef<T>(p.get());
+				}
+		};
+
+		ox::HashMap<ox::String, ox::UniquePtr<AssetTypeManagerBase>> m_assetTypeManagers;
+
+		template<typename T>
+		AssetTypeManager<T> *getTypeManager() noexcept {
+#if __cplusplus >= 202002L
+			constexpr auto typeName = ox::getModelTypeName<T>();
+			static_assert(ox_strcmp(typeName, "") != 0, "Types must have TypeName to use AssetManager");
+#else
+			const auto typeName = ox::getModelTypeName<T>();
+			oxAssert(ox_strcmp(typeName, "") != 0, "Types must have TypeName to use AssetManager");
+#endif
+			auto &am = m_assetTypeManagers[typeName];
+			if (!am) {
+				am = ox::make_unique<AssetTypeManager<T>>();
+			}
+			return dynamic_cast<AssetTypeManager<T>*>(am.get());
+		}
+
+	public:
+		template<typename T>
+		ox::Result<AssetRef<T>> getAsset(const ox::String &path) noexcept {
+			auto m = getTypeManager<T>();
+			return m->getAsset(path);
+		}
+
+		template<typename T>
+		ox::Result<AssetRef<T>> setAsset(const ox::String &path, const T &obj) noexcept {
+			auto m = getTypeManager<T>();
+			return m->setAsset(path, obj);
+		}
+};
+
+}