[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_program.hpp b/src/mbgl/programs/fill_program.hpp
index 9c623fee22..12544ec073 100644
--- a/src/mbgl/programs/fill_program.hpp
+++ b/src/mbgl/programs/fill_program.hpp
@@ -103,4 +103,17 @@ public:
 using FillLayoutVertex = FillProgram::LayoutVertex;
 using FillAttributes = FillProgram::Attributes;
 
+class FillLayerPrograms final : public LayerTypePrograms {
+public:
+    FillLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : fill(context, programParameters),
+          fillPattern(context, programParameters),
+          fillOutline(context, programParameters),
+          fillOutlinePattern(context, programParameters) {}
+    ProgramMap<FillProgram> fill;
+    ProgramMap<FillPatternProgram> fillPattern;
+    ProgramMap<FillOutlineProgram> fillOutline;
+    ProgramMap<FillOutlinePatternProgram> fillOutlinePattern;
+};
+
 } // namespace mbgl