Fix SIOF [1] in asset system and rework for better flexibility

[1]: https://en.cppreference.com/w/cpp/language/siof

7 files changed, 84 insertions, 44 deletions

diff --git a/src/AllAssets.hpp b/src/AllAssets.hpp
new file mode 100644
index 0000000..00e7100
--- /dev/null
+++ b/src/AllAssets.hpp
@@ -0,0 +1,16 @@
+#pragma once
+
+#define ALL_ASSETS \
+    X(Shaders::terrain, vertex,   shaders_terrain_vert_glsl) \
+    X(Shaders::terrain, fragment, shaders_terrain_frag_glsl) \
+    \
+    X(Shaders::clouds, vertex,   shaders_clouds_vert_glsl) \
+    X(Shaders::clouds, fragment, shaders_clouds_frag_glsl) \
+    \
+    X(Shaders::block_outline, vertex,   shaders_block_outline_vert_glsl) \
+    X(Shaders::block_outline, fragment, shaders_block_outline_frag_glsl) \
+    \
+    X(Shaders::image_viewer, vertex,   shaders_image_viewer_vert_glsl) \
+    X(Shaders::image_viewer, fragment, shaders_image_viewer_frag_glsl) \
+    \
+    X(Images, atlas, images_atlas_ppm)
diff --git a/src/Assets.cpp b/src/Assets.cpp
deleted file mode 100644
index 7cf361c..0000000
--- a/src/Assets.cpp
+++ /dev/null
@@ -1,19 +0,0 @@
-#include "Assets.hpp"
-
-#define ASSET(ns, name, raw_name) \
-    namespace ns { Char const* name = ::MC::Assets::Files::raw_name; }
-
-#define SHADER_ASSET(name) \
-    ASSET(Shaders::name, vertex, shaders_##name##_vertex) \
-    ASSET(Shaders::name, fragment, shaders_##name##_fragment)
-
-namespace MC::Assets {
-
-SHADER_ASSET(terrain)
-SHADER_ASSET(clouds)
-SHADER_ASSET(block_outline)
-SHADER_ASSET(image_viewer)
-
-ASSET(Images, atlas, images_atlas_ppm)
-
-}
\ No newline at end of file
diff --git a/src/Assets.hpp b/src/Assets.hpp
index 0de6d90..0d1c635 100644
--- a/src/Assets.hpp
+++ b/src/Assets.hpp
@@ -1,30 +1,48 @@
 #pragma once
 
 #include "Common/Sizes.hpp"
+#include "Common/Assert.hpp"
+#include "Common/Unique.hpp"
 
-#define MC_DECLARE_ASSET(ns, name, raw_name) \
-    namespace Files { extern char const* raw_name; } \
-    namespace ns { extern Char const* name; }
+#include "AllAssets.hpp"
 
-#define MC_DECLARE_SHADER_ASSET(name) \
-    MC_DECLARE_ASSET(Shaders::name, vertex, shaders_##name##_vertex) \
-    MC_DECLARE_ASSET(Shaders::name, fragment, shaders_##name##_fragment)
+namespace MC {
 
-namespace MC::Assets {
+using Asset = Char const* const;
+using AssetToken = U64;
 
-MC_DECLARE_SHADER_ASSET(terrain)
-MC_DECLARE_SHADER_ASSET(clouds)
-MC_DECLARE_SHADER_ASSET(block_outline)
-MC_DECLARE_SHADER_ASSET(image_viewer)
+#define X(ns, _name, file_path) namespace Assets::Files { extern Asset file_path; }
+ALL_ASSETS
+#undef X
 
-MC_DECLARE_ASSET(Images, atlas, images_atlas_ppm)
+namespace Assets {
+    constexpr AssetToken invalid_asset = 0;
 
+    #define X(ns, name, _file_path) namespace ns { constexpr AssetToken name = UNIQUE_NUMBER; }
+    ALL_ASSETS
+    #undef X
 }
 
-// NOTE: We need to declare dependencies both in Assets.cpp and and here
-// in Assets.hpp but only because we rename the variable name from it's
-// file name to a more readable name. If we didn't do that we could just
-// declare the variable in the hpp file, without needing another compilation
-// unit at all.
-// This would work easily if there was a using x = y; directive that didn't
-// just work for types but for variables as well. But there isn't, I think.. :(
\ No newline at end of file
+constexpr Asset lookup(AssetToken token) {
+    switch (token) {
+        #define X(ns, name, file_path) case Assets::ns::name: return Assets::Files::file_path;
+        ALL_ASSETS
+        #undef X
+
+        default: UNREACHABLE("Invalid asset token.");
+    }
+}
+
+template <AssetToken T = Assets::invalid_asset>
+constexpr Asset asset(AssetToken t = Assets::invalid_asset) {
+    static_assert(T != Assets::invalid_asset, "Invalid asset token.");
+    ASSERT(t == Assets::invalid_asset || t == T, "Can't lookup asset both dynamically and statically at the same time.");
+    
+    return lookup(T);
+}
+
+template <> inline Asset asset<Assets::invalid_asset>(AssetToken token) {
+    return lookup(token);
+}
+
+}
diff --git a/src/Common/Unique.hpp b/src/Common/Unique.hpp
new file mode 100644
index 0000000..147fb0e
--- /dev/null
+++ b/src/Common/Unique.hpp
@@ -0,0 +1,12 @@
+#pragma once
+
+// TODO: Put this macro in it's own Common header,
+// it's useful often.
+#define _UNIQUE_CONCAT(a, b) _UNIQUE_CONCAT2(a, b)
+#define _UNIQUE_CONCAT2(a, b) a##b
+
+#define _UNIQUE_NAME_PREFIX _unique_name_
+#define UNIQUE_NAME _UNIQUE_CONCAT(_UNIQUE_NAME_PREFIX, __COUNTER__)
+
+#define _UNIQUE_NUMBER_PREFIX 0xAEF
+#define UNIQUE_NUMBER _UNIQUE_CONCAT(_UNIQUE_NUMBER_PREFIX, __COUNTER__)
diff --git a/src/GFX/Resources.hpp b/src/GFX/Resources.hpp
index 4206e33..8f9a79a 100644
--- a/src/GFX/Resources.hpp
+++ b/src/GFX/Resources.hpp
@@ -24,10 +24,23 @@ private:
     };
 
     static inline std::array<ProgramMetadata, ProgramCount> const m_program_metadata = {{
-        {Program::Terrain, Assets::Shaders::terrain::vertex, Assets::Shaders::terrain::fragment},
-        {Program::Clouds, Assets::Shaders::clouds::vertex, Assets::Shaders::clouds::fragment},
-        {Program::ImageViewer, Assets::Shaders::image_viewer::vertex, Assets::Shaders::image_viewer::fragment},
-        {Program::BlockOutline, Assets::Shaders::block_outline::vertex, Assets::Shaders::block_outline::fragment},
+        {
+            Program::Terrain,
+            asset<Assets::Shaders::terrain::vertex>(),
+            asset<Assets::Shaders::terrain::fragment>()
+        }, {
+            Program::Clouds,
+            asset<Assets::Shaders::clouds::vertex>(),
+            asset<Assets::Shaders::clouds::fragment>()
+        }, {
+            Program::ImageViewer,
+            asset<Assets::Shaders::image_viewer::vertex>(),
+            asset<Assets::Shaders::image_viewer::fragment>()
+        }, {
+            Program::BlockOutline,
+            asset<Assets::Shaders::block_outline::vertex>(),
+            asset<Assets::Shaders::block_outline::fragment>()
+        },
     }};
 
     Bool m_initialized = false;
diff --git a/src/Render.cpp b/src/Render.cpp
index 58d5a42..c4ed147 100644
--- a/src/Render.cpp
+++ b/src/Render.cpp
@@ -26,7 +26,8 @@ void Render::run() {
         glViewport(0, 0, w, h);
     });
 
-    auto image = GFX::Image::PPMParser(Assets::Images::atlas).parse();
+    auto atlas_asset = MC::asset<MC::Assets::Images::atlas>();
+    auto image = GFX::Image::PPMParser(atlas_asset).parse();
     auto texture = GFX::Texture(image);
 
     glEnable(GL_DEPTH_TEST);
diff --git a/src/meson.build b/src/meson.build
index 9a33eed..498274c 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -5,7 +5,6 @@ source_files = files([
     'Input.cpp',
     'Time.cpp',
     'Transform.cpp',
-    'Assets.cpp',
 
     'Math/AABB.cpp',
     'Math/Grid.cpp',