[core] Split layer type specific code in mbgl::Programs

Progams code for a certain layer type is encapsulted within
a dedicated `<layer type>Programs` class, inherited from
the generic base `LayerTypePrograms` class.

`mbgl::Programs::get<layer type>Programs()` lazily initializes the
layer type-specific programs code using pointer to the base class,
which allows LTO to remove this code from binaries (if the corresponding
`get<layer type>Programs()` method can never be invoked).

1 files changed, 13 insertions, 0 deletions

diff --git a/src/mbgl/programs/fill_extrusion_program.hpp b/src/mbgl/programs/fill_extrusion_program.hpp
index 657238d4c0..4573119e70 100644
--- a/src/mbgl/programs/fill_extrusion_program.hpp
+++ b/src/mbgl/programs/fill_extrusion_program.hpp
@@ -2,6 +2,7 @@
 
 #include <mbgl/programs/program.hpp>
 #include <mbgl/programs/attributes.hpp>
+#include <mbgl/programs/extrusion_texture_program.hpp>
 #include <mbgl/programs/uniforms.hpp>
 #include <mbgl/shaders/fill_extrusion.hpp>
 #include <mbgl/shaders/fill_extrusion_pattern.hpp>
@@ -112,4 +113,16 @@ public:
 using FillExtrusionLayoutVertex = FillExtrusionProgram::LayoutVertex;
 using FillExtrusionAttributes = FillExtrusionProgram::Attributes;
 
+
+class FillExtrusionLayerPrograms final : public LayerTypePrograms {
+public:
+    FillExtrusionLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : fillExtrusion(context, programParameters),
+          fillExtrusionPattern(context, programParameters),
+          extrusionTexture(context, programParameters) {}
+    ProgramMap<FillExtrusionProgram> fillExtrusion;
+    ProgramMap<FillExtrusionPatternProgram> fillExtrusionPattern;
+    ExtrusionTextureProgram extrusionTexture;
+};
+
 } // namespace mbgl