From 5e9bbfdd44ef9c0a2c5850566c28a40aa2a05151 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Konstantin=20K=C3=A4fer?= <mail@kkaefer.com>
Date: Fri, 1 Jun 2018 11:49:15 +0200
Subject: [PATCH] [core] introduce TypeListConcat and TypeList::ExpandInto

---
 include/mbgl/util/type_list.hpp               | 28 +++++++++++++++++--
 src/mbgl/gl/attribute.hpp                     | 18 ++----------
 src/mbgl/gl/uniform.hpp                       | 19 ++-----------
 src/mbgl/programs/symbol_program.hpp          |  4 +--
 .../renderer/layers/render_line_layer.hpp     |  4 +--
 src/mbgl/style/properties.hpp                 |  9 ++----
 6 files changed, 36 insertions(+), 46 deletions(-)

diff --git a/include/mbgl/util/type_list.hpp b/include/mbgl/util/type_list.hpp
index 4a5e95c8a..1b594bf7f 100644
--- a/include/mbgl/util/type_list.hpp
+++ b/include/mbgl/util/type_list.hpp
@@ -5,8 +5,11 @@
 
 namespace mbgl {
 
-template <class...>
-class TypeList {};
+template <class... Ts>
+struct TypeList {
+    template <template <class...> class T, class... Ps>
+    using ExpandInto = T<Ps..., Ts...>;
+};
 
 namespace detail {
 
@@ -32,9 +35,30 @@ struct TypeFilter<TypeList<T, Ts...>, Predicate> {
     using Type = std::conditional_t<Predicate<T>::value, typename TypeCons<T, Tail>::Type, Tail>;
 };
 
+template <class...>
+struct TypeListConcat;
+
+template <>
+struct TypeListConcat<> {
+    using Type = TypeList<>;
+};
+
+template <class... As>
+struct TypeListConcat<TypeList<As...>> {
+    using Type = TypeList<As...>;
+};
+
+template <class... As, class... Bs, class... Rs>
+struct TypeListConcat<TypeList<As...>, TypeList<Bs...>, Rs...> {
+    using Type = typename TypeListConcat<TypeList<As..., Bs...>, Rs...>::Type;
+};
+
 } // namespace detail
 
 template <class TypeList, template <class> class Predicate>
 using FilteredTypeList = typename detail::TypeFilter<TypeList, Predicate>::Type;
 
+template <class... Ts>
+using TypeListConcat = typename detail::TypeListConcat<Ts...>::Type;
+
 } // namespace mbgl
diff --git a/src/mbgl/gl/attribute.hpp b/src/mbgl/gl/attribute.hpp
index de95be073..8cdb03bfe 100644
--- a/src/mbgl/gl/attribute.hpp
+++ b/src/mbgl/gl/attribute.hpp
@@ -294,22 +294,8 @@ public:
     }
 };
 
-namespace detail {
-
-template <class...>
-struct ConcatenateAttributes;
-
-template <class... As, class... Bs>
-struct ConcatenateAttributes<TypeList<As...>, TypeList<Bs...>> {
-    using Type = Attributes<As..., Bs...>;
-};
-
-} // namespace detail
-
-template <class A, class B>
-using ConcatenateAttributes = typename detail::ConcatenateAttributes<
-    typename A::Types,
-    typename B::Types>::Type;
+template <class... As>
+using ConcatenateAttributes = typename TypeListConcat<typename As::Types...>::template ExpandInto<Attributes>;
 
 } // namespace gl
 } // namespace mbgl
diff --git a/src/mbgl/gl/uniform.hpp b/src/mbgl/gl/uniform.hpp
index 5a78068fc..d8a167c38 100644
--- a/src/mbgl/gl/uniform.hpp
+++ b/src/mbgl/gl/uniform.hpp
@@ -120,23 +120,8 @@ public:
     }
 };
 
-
-namespace detail {
-
-template <class...>
-struct ConcatenateUniforms;
-
-template <class... As, class... Bs>
-struct ConcatenateUniforms<TypeList<As...>, TypeList<Bs...>> {
-    using Type = Uniforms<As..., Bs...>;
-};
-
-} // namespace detail
-
-template <class A, class B>
-using ConcatenateUniforms = typename detail::ConcatenateUniforms<
-    typename A::Types,
-    typename B::Types>::Type;
+template <class... Us>
+using ConcatenateUniforms = typename TypeListConcat<typename Us::Types...>::template ExpandInto<Uniforms>;
 
 } // namespace gl
 } // namespace mbgl
diff --git a/src/mbgl/programs/symbol_program.hpp b/src/mbgl/programs/symbol_program.hpp
index a1a4621b6..27bcd7b42 100644
--- a/src/mbgl/programs/symbol_program.hpp
+++ b/src/mbgl/programs/symbol_program.hpp
@@ -252,7 +252,7 @@ public:
     using LayoutAttributes = LayoutAttrs;
     using LayoutVertex = typename LayoutAttributes::Vertex;
 
-    using LayoutAndSizeAttributes = gl::ConcatenateAttributes<LayoutAttributes, gl::ConcatenateAttributes<SymbolDynamicLayoutAttributes, SymbolOpacityAttributes>>;
+    using LayoutAndSizeAttributes = gl::ConcatenateAttributes<LayoutAttributes, SymbolDynamicLayoutAttributes, SymbolOpacityAttributes>;
 
     using PaintProperties = PaintProps;
     using PaintPropertyBinders = typename PaintProperties::Binders;
@@ -262,7 +262,7 @@ public:
     using UniformValues = typename Uniforms::Values;
     using SizeUniforms = typename SymbolSizeBinder::Uniforms;
     using PaintUniforms = typename PaintPropertyBinders::Uniforms;
-    using AllUniforms = gl::ConcatenateUniforms<Uniforms, gl::ConcatenateUniforms<SizeUniforms, PaintUniforms>>;
+    using AllUniforms = gl::ConcatenateUniforms<Uniforms, SizeUniforms, PaintUniforms>;
 
     using ProgramType = gl::Program<Primitive, Attributes, AllUniforms>;
 
diff --git a/src/mbgl/renderer/layers/render_line_layer.hpp b/src/mbgl/renderer/layers/render_line_layer.hpp
index facab6064..1e0100548 100644
--- a/src/mbgl/renderer/layers/render_line_layer.hpp
+++ b/src/mbgl/renderer/layers/render_line_layer.hpp
@@ -13,8 +13,8 @@ struct LineFloorwidth : style::DataDrivenPaintProperty<float, attributes::a_floo
 };
 
 class RenderLinePaintProperties : public style::ConcatenateProperties<
-    style::LinePaintProperties::PropertyTypes,
-    TypeList<LineFloorwidth>>::Type {};
+    style::LinePaintProperties,
+    style::Properties<LineFloorwidth>> {};
 
 class RenderLineLayer: public RenderLayer {
 public:
diff --git a/src/mbgl/style/properties.hpp b/src/mbgl/style/properties.hpp
index 9206e9698..e7f05db95 100644
--- a/src/mbgl/style/properties.hpp
+++ b/src/mbgl/style/properties.hpp
@@ -233,13 +233,8 @@ public:
     };
 };
 
-template <class...>
-struct ConcatenateProperties;
-
-template <class... As, class... Bs>
-struct ConcatenateProperties<TypeList<As...>, TypeList<Bs...>> {
-    using Type = Properties<As..., Bs...>;
-};
+template <class... Ps>
+using ConcatenateProperties = typename TypeListConcat<typename Ps::PropertyTypes...>::template ExpandInto<Properties>;
 
 } // namespace style
 } // namespace mbgl