8 files changed, 160 insertions, 8 deletions

diff --git a/src/crepe/api/Asset.cpp b/src/crepe/api/Asset.cpp
new file mode 100644
index 0000000..e148367
--- /dev/null
+++ b/src/crepe/api/Asset.cpp
@@ -0,0 +1,54 @@
+#include <filesystem>
+#include <stdexcept>
+#include <whereami.h>
+
+#include "api/Config.h"
+
+#include "Asset.h"
+
+using namespace crepe;
+using namespace std;
+
+Asset::Asset(const string & src) : src(find_asset(src)) {}
+Asset::Asset(const char * src) : src(find_asset(src)) {}
+
+const string & Asset::get_path() const noexcept { return this->src; }
+
+string Asset::find_asset(const string & src) const {
+	auto & cfg = Config::get_instance();
+	string & root_pattern = cfg.asset.root_pattern;
+
+	// if root_pattern is empty, find_asset must return all paths as-is
+	if (root_pattern.empty()) return src;
+
+	// absolute paths do not need to be resolved, only canonicalized
+	filesystem::path path = src;
+	if (path.is_absolute()) return filesystem::canonical(path);
+
+	// find directory matching root_pattern
+	filesystem::path root = this->whereami();
+	while (1) {
+		if (filesystem::exists(root / root_pattern)) break;
+		if (!root.has_parent_path())
+			throw runtime_error(format("Asset: Cannot find root pattern ({})", root_pattern));
+		root = root.parent_path();
+	}
+
+	// join path to root (base directory) and canonicalize
+	return filesystem::canonical(root / path);
+}
+
+string Asset::whereami() const noexcept {
+	string path;
+	size_t path_length = wai_getExecutablePath(NULL, 0, NULL);
+	path.resize(path_length + 1); // wai writes null byte
+	wai_getExecutablePath(path.data(), path_length, NULL);
+	path.resize(path_length);
+	return path;
+}
+
+bool Asset::operator==(const Asset & other) const noexcept { return this->src == other.src; }
+
+size_t std::hash<const Asset>::operator()(const Asset & asset) const noexcept {
+	return std::hash<string>{}(asset.get_path());
+};
diff --git a/src/crepe/api/Asset.h b/src/crepe/api/Asset.h
new file mode 100644
index 0000000..bfd0ac7
--- /dev/null
+++ b/src/crepe/api/Asset.h
@@ -0,0 +1,84 @@
+#pragma once
+
+#include <string>
+
+namespace crepe {
+
+/**
+ * \brief Asset location helper
+ *
+ * This class is used to locate game asset files, and should *always* be used
+ * instead of reading file paths directly.
+ */
+class Asset {
+public:
+	/**
+	 * \param src  Unique identifier to asset
+	 */
+	Asset(const std::string & src);
+	/**
+	 * \param src  Unique identifier to asset
+	 */
+	Asset(const char * src);
+
+public:
+	/**
+	 * \brief Get the path to this asset
+	 * \return path to this asset
+	 */
+	const std::string & get_path() const noexcept;
+
+	/**
+	 * \brief Comparison operator
+	 * \param other Possibly different instance of \c Asset to test equality against
+	 * \return True if \c this and \c other are equal
+	 */
+	bool operator==(const Asset & other) const noexcept;
+
+private:
+	//! path to asset
+	const std::string src;
+
+private:
+	/**
+	 * \brief Locate asset path, or throw exception if it cannot be found
+	 *
+	 * This function resolves asset locations relative to crepe::Config::root_pattern if it is
+	 * set and \p src is a relative path. If \p src is an absolute path, it is canonicalized.
+	 * This function only returns if the file can be found.
+	 *
+	 * \param src Arbitrary path to resource file
+	 *
+	 * \returns \p src if crepe::Config::root_pattern is empty
+	 * \returns Canonical path to \p src
+	 *
+	 * \throws std::runtime_error if root_pattern cannot be found
+	 * \throws std::filesystem::filesystem_error if the resolved path does not exist
+	 * \throws std::filesystem::filesystem_error if the path cannot be canonicalized
+	 */
+	std::string find_asset(const std::string & src) const;
+	/**
+	 * \returns The path to the current executable
+	 */
+	std::string whereami() const noexcept;
+};
+
+} // namespace crepe
+
+namespace std {
+
+//! Hash helper struct
+template <>
+struct hash<const crepe::Asset> {
+	/**
+	 * \brief Hash operator for crepe::Asset
+	 *
+	 * This function hashes a crepe::Asset instance, allowing it to be used as a key in an \c
+	 * std::unordered_map.
+	 *
+	 * \returns Hash value
+	 */
+	size_t operator()(const crepe::Asset & asset) const noexcept;
+};
+
+} // namespace std
diff --git a/src/crepe/api/CMakeLists.txt b/src/crepe/api/CMakeLists.txt
index a63c5ff..602ab52 100644
--- a/src/crepe/api/CMakeLists.txt
+++ b/src/crepe/api/CMakeLists.txt
@@ -22,6 +22,7 @@ target_sources(crepe PUBLIC
 	IMouseListener.cpp
 	LoopManager.cpp
 	LoopTimer.cpp
+	Asset.cpp
 	EventHandler.cpp
 	Script.cpp
 )
@@ -57,4 +58,5 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	IMouseListener.h
 	LoopManager.h
 	LoopTimer.h
+	Asset.h
 )
diff --git a/src/crepe/api/Config.h b/src/crepe/api/Config.h
index 3ab877a..13eabd1 100644
--- a/src/crepe/api/Config.h
+++ b/src/crepe/api/Config.h
@@ -62,6 +62,20 @@ public:
 		 */
 		double gravity = 1;
 	} physics;
+
+	//! Asset loading options
+	struct {
+		/**
+		 * \brief Pattern to match for Asset base directory
+		 *
+		 * All non-absolute paths resolved using \c Asset will be made relative to
+		 * the first parent directory relative to the calling executable where
+		 * appending this pattern results in a path that exists. If this string is
+		 * empty, path resolution is disabled, and Asset will return all paths
+		 * as-is.
+		 */
+		std::string root_pattern = ".crepe-root";
+	} asset;
 };
 
 } // namespace crepe
diff --git a/src/crepe/api/GameObject.cpp b/src/crepe/api/GameObject.cpp
index 287e81d..4874426 100644
--- a/src/crepe/api/GameObject.cpp
+++ b/src/crepe/api/GameObject.cpp
@@ -23,12 +23,10 @@ void GameObject::set_parent(const GameObject & parent) {
 	ComponentManager & mgr = this->component_manager;
 
 	// Set parent on own Metadata component
-	vector<reference_wrapper<Metadata>> this_metadata
-		= mgr.get_components_by_id<Metadata>(this->id);
+	RefVector<Metadata> this_metadata = mgr.get_components_by_id<Metadata>(this->id);
 	this_metadata.at(0).get().parent = parent.id;
 
 	// Add own id to children list of parent's Metadata component
-	vector<reference_wrapper<Metadata>> parent_metadata
-		= mgr.get_components_by_id<Metadata>(parent.id);
+	RefVector<Metadata> parent_metadata = mgr.get_components_by_id<Metadata>(parent.id);
 	parent_metadata.at(0).get().children.push_back(this->id);
 }
diff --git a/src/crepe/api/Script.h b/src/crepe/api/Script.h
index 8356fd2..43efd15 100644
--- a/src/crepe/api/Script.h
+++ b/src/crepe/api/Script.h
@@ -78,7 +78,7 @@ protected:
 	 * \returns List of component references
 	 */
 	template <typename T>
-	std::vector<std::reference_wrapper<T>> get_components() const;
+	RefVector<T> get_components() const;
 
 	/**
 	 * \brief Log a message using Log::logf
diff --git a/src/crepe/api/Script.hpp b/src/crepe/api/Script.hpp
index e60be07..e94278d 100644
--- a/src/crepe/api/Script.hpp
+++ b/src/crepe/api/Script.hpp
@@ -10,7 +10,7 @@ namespace crepe {
 template <typename T>
 T & Script::get_component() const {
 	using namespace std;
-	vector<reference_wrapper<T>> all_components = this->get_components<T>();
+	RefVector<T> all_components = this->get_components<T>();
 	if (all_components.size() < 1)
 		throw runtime_error(
 			format("Script: no component found with type = {}", typeid(T).name()));
@@ -19,7 +19,7 @@ T & Script::get_component() const {
 }
 
 template <typename T>
-std::vector<std::reference_wrapper<T>> Script::get_components() const {
+RefVector<T> Script::get_components() const {
 	ComponentManager & mgr = *this->component_manager_ref;
 
 	return mgr.get_components_by_id<T>(*this->game_object_id_ref);
diff --git a/src/crepe/api/Texture.cpp b/src/crepe/api/Texture.cpp
index 734a5bb..9be9421 100644
--- a/src/crepe/api/Texture.cpp
+++ b/src/crepe/api/Texture.cpp
@@ -26,7 +26,7 @@ Texture::~Texture() {
 
 void Texture::load(unique_ptr<Asset> res) {
 	SDLContext & ctx = SDLContext::get_instance();
-	this->texture = std::move(ctx.texture_from_path(res->get_canonical()));
+	this->texture = std::move(ctx.texture_from_path(res->get_path()));
 }
 
 int Texture::get_width() const {