[core] Introduce a fully-evaluated tuple type for layout properties

11 files changed, 69 insertions, 27 deletions

diff --git a/src/mbgl/layout/symbol_instance.cpp b/src/mbgl/layout/symbol_instance.cpp
index 8bdc528bbb..2264bfdc92 100644
--- a/src/mbgl/layout/symbol_instance.cpp
+++ b/src/mbgl/layout/symbol_instance.cpp
@@ -9,7 +9,7 @@ SymbolInstance::SymbolInstance(Anchor& anchor,
                                const GeometryCoordinates& line,
                                const std::pair<Shaping, Shaping>& shapedTextOrientations,
                                const PositionedIcon& shapedIcon,
-                               const SymbolLayoutProperties::Evaluated& layout,
+                               const SymbolLayoutProperties::PossiblyEvaluated& layout,
                                const bool addToBuffers,
                                const uint32_t index_,
                                const float textBoxScale,
diff --git a/src/mbgl/layout/symbol_instance.hpp b/src/mbgl/layout/symbol_instance.hpp
index 70ebfeefa2..0980eb492b 100644
--- a/src/mbgl/layout/symbol_instance.hpp
+++ b/src/mbgl/layout/symbol_instance.hpp
@@ -16,7 +16,7 @@ public:
                    const GeometryCoordinates& line,
                    const std::pair<Shaping, Shaping>& shapedTextOrientations,
                    const PositionedIcon& shapedIcon,
-                   const style::SymbolLayoutProperties::Evaluated&,
+                   const style::SymbolLayoutProperties::PossiblyEvaluated&,
                    const bool inside,
                    const uint32_t index,
                    const float textBoxScale,
diff --git a/src/mbgl/layout/symbol_layout.hpp b/src/mbgl/layout/symbol_layout.hpp
index 5b14090d97..bd72d3cd3f 100644
--- a/src/mbgl/layout/symbol_layout.hpp
+++ b/src/mbgl/layout/symbol_layout.hpp
@@ -78,7 +78,7 @@ private:
     const float zoom;
     const MapMode mode;
 
-    style::SymbolLayoutProperties::Evaluated layout;
+    style::SymbolLayoutProperties::PossiblyEvaluated layout;
     float textMaxSize;
 
     SpriteAtlas& spriteAtlas;
diff --git a/src/mbgl/renderer/line_bucket.hpp b/src/mbgl/renderer/line_bucket.hpp
index 8d1ff2a3f2..5a126ba18e 100644
--- a/src/mbgl/renderer/line_bucket.hpp
+++ b/src/mbgl/renderer/line_bucket.hpp
@@ -29,7 +29,7 @@ public:
     void upload(gl::Context&) override;
     void render(Painter&, PaintParameters&, const style::Layer&, const RenderTile&) override;
 
-    style::LineLayoutProperties::Evaluated layout;
+    style::LineLayoutProperties::PossiblyEvaluated layout;
 
     gl::VertexVector<LineLayoutVertex> vertices;
     gl::IndexVector<gl::Triangles> triangles;
diff --git a/src/mbgl/renderer/symbol_bucket.cpp b/src/mbgl/renderer/symbol_bucket.cpp
index 1f2c81bc1c..b046571740 100644
--- a/src/mbgl/renderer/symbol_bucket.cpp
+++ b/src/mbgl/renderer/symbol_bucket.cpp
@@ -8,7 +8,7 @@ namespace mbgl {
 
 using namespace style;
 
-SymbolBucket::SymbolBucket(style::SymbolLayoutProperties::Evaluated layout_,
+SymbolBucket::SymbolBucket(style::SymbolLayoutProperties::PossiblyEvaluated layout_,
                            const std::map<std::string, std::pair<
                                style::IconPaintProperties::Evaluated, style::TextPaintProperties::Evaluated>>& layerPaintProperties,
                            float zoom,
diff --git a/src/mbgl/renderer/symbol_bucket.hpp b/src/mbgl/renderer/symbol_bucket.hpp
index d5141d2d96..7a498ab17d 100644
--- a/src/mbgl/renderer/symbol_bucket.hpp
+++ b/src/mbgl/renderer/symbol_bucket.hpp
@@ -16,7 +16,7 @@ namespace mbgl {
 
 class SymbolBucket : public Bucket {
 public:
-    SymbolBucket(style::SymbolLayoutProperties::Evaluated,
+    SymbolBucket(style::SymbolLayoutProperties::PossiblyEvaluated,
                  const std::map<std::string, std::pair<style::IconPaintProperties::Evaluated, style::TextPaintProperties::Evaluated>>&,
                  float zoom,
                  bool sdfIcons,
@@ -29,7 +29,7 @@ public:
     bool hasIconData() const;
     bool hasCollisionBoxData() const;
 
-    const style::SymbolLayoutProperties::Evaluated layout;
+    const style::SymbolLayoutProperties::PossiblyEvaluated layout;
     const bool sdfIcons;
     const bool iconsNeedLinear;
 
diff --git a/src/mbgl/style/layers/symbol_layer_impl.cpp b/src/mbgl/style/layers/symbol_layer_impl.cpp
index ff59b14d65..e4557c953f 100644
--- a/src/mbgl/style/layers/symbol_layer_impl.cpp
+++ b/src/mbgl/style/layers/symbol_layer_impl.cpp
@@ -68,7 +68,7 @@ TextPaintProperties::Evaluated SymbolLayer::Impl::textPaintProperties() const {
 }
 
 
-SymbolPropertyValues SymbolLayer::Impl::iconPropertyValues(const SymbolLayoutProperties::Evaluated& layout_) const {
+SymbolPropertyValues SymbolLayer::Impl::iconPropertyValues(const SymbolLayoutProperties::PossiblyEvaluated& layout_) const {
     return SymbolPropertyValues {
         layout_.get<IconRotationAlignment>(), // icon-pitch-alignment is not yet implemented; inherit the rotation alignment
         layout_.get<IconRotationAlignment>(),
@@ -83,7 +83,7 @@ SymbolPropertyValues SymbolLayer::Impl::iconPropertyValues(const SymbolLayoutPro
     };
 }
 
-SymbolPropertyValues SymbolLayer::Impl::textPropertyValues(const SymbolLayoutProperties::Evaluated& layout_) const {
+SymbolPropertyValues SymbolLayer::Impl::textPropertyValues(const SymbolLayoutProperties::PossiblyEvaluated& layout_) const {
     return SymbolPropertyValues {
         layout_.get<TextPitchAlignment>(),
         layout_.get<TextRotationAlignment>(),
diff --git a/src/mbgl/style/layers/symbol_layer_impl.hpp b/src/mbgl/style/layers/symbol_layer_impl.hpp
index 1e9f05e4c7..0c4b74e833 100644
--- a/src/mbgl/style/layers/symbol_layer_impl.hpp
+++ b/src/mbgl/style/layers/symbol_layer_impl.hpp
@@ -72,8 +72,8 @@ public:
     IconPaintProperties::Evaluated iconPaintProperties() const;
     TextPaintProperties::Evaluated textPaintProperties() const;
     
-    SymbolPropertyValues iconPropertyValues(const SymbolLayoutProperties::Evaluated&) const;
-    SymbolPropertyValues textPropertyValues(const SymbolLayoutProperties::Evaluated&) const;
+    SymbolPropertyValues iconPropertyValues(const SymbolLayoutProperties::PossiblyEvaluated&) const;
+    SymbolPropertyValues textPropertyValues(const SymbolLayoutProperties::PossiblyEvaluated&) const;
 
     SymbolLayoutProperties layout;
     SymbolPaintProperties paint;
diff --git a/src/mbgl/style/layout_property.hpp b/src/mbgl/style/layout_property.hpp
index 25cff4b92d..624ff2bdc5 100644
--- a/src/mbgl/style/layout_property.hpp
+++ b/src/mbgl/style/layout_property.hpp
@@ -16,7 +16,7 @@ class LayoutProperty {
 public:
     using UnevaluatedType = PropertyValue<T>;
     using EvaluatorType = PropertyEvaluator<T>;
-    using EvaluatedType = T;
+    using PossiblyEvaluatedType = T;
     using Type = T;
 };
 
@@ -25,7 +25,7 @@ class DataDrivenLayoutProperty {
 public:
     using UnevaluatedType = DataDrivenPropertyValue<T>;
     using EvaluatorType = DataDrivenPropertyEvaluator<T>;
-    using EvaluatedType = PossiblyEvaluatedPropertyValue<T>;
+    using PossiblyEvaluatedType = PossiblyEvaluatedPropertyValue<T>;
     using Type = T;
 };
 
@@ -33,23 +33,65 @@ template <class... Ps>
 class LayoutProperties {
 public:
     using Properties = TypeList<Ps...>;
-    using EvaluatedTypes = TypeList<typename Ps::EvaluatedType...>;
-    using UnevaluatedTypes = TypeList<typename Ps::UnevaluatedType...>;
 
     template <class TypeList>
     using Tuple = IndexedTuple<Properties, TypeList>;
 
+    /*
+        For layout properties we implement a two step evaluation process: if you have a zoom level,
+        you can evaluate a set of unevaluated property values, producing a set of possibly evaluated
+        values, where non-data-driven property values have been fully evaluated, and data-driven values
+        have not.
+
+        Once you also have a particular feature, you can evaluate that set of possibly evaluated values
+        fully, producing a set of fully evaluated values.
+
+        This is in theory maximally efficient in terms of avoiding repeated evaluation of camera
+        functions, though it's more of a historical accident that a purposeful optimization.
+    */
+
+    using       UnevaluatedTypes = TypeList<typename Ps::UnevaluatedType...>;
+    using PossiblyEvaluatedTypes = TypeList<typename Ps::PossiblyEvaluatedType...>;
+    using         EvaluatedTypes = TypeList<typename Ps::Type...>;
+
     class Evaluated : public Tuple<EvaluatedTypes> {
     public:
         using Tuple<EvaluatedTypes>::Tuple;
+    };
+
+    class PossiblyEvaluated : public Tuple<PossiblyEvaluatedTypes> {
+    public:
+        using Tuple<PossiblyEvaluatedTypes>::Tuple;
+
+        template <class T>
+        static T evaluate(float, const GeometryTileFeature&, const T& t, const T&) {
+            return t;
+        }
+
+        template <class T>
+        static T evaluate(float z, const GeometryTileFeature& feature,
+                          const PossiblyEvaluatedPropertyValue<T>& v, const T& defaultValue) {
+            return v.match(
+                [&] (const T& t) {
+                    return t;
+                },
+                [&] (const SourceFunction<T>& t) {
+                    return t.evaluate(feature, defaultValue);
+                },
+                [&] (const CompositeFunction<T>& t) {
+                    return t.evaluate(z, feature, defaultValue);
+                });
+        }
 
         template <class P>
-        typename P::Type evaluate(float z, const GeometryTileFeature& feature) const {
-            using T = typename P::Type;
-            return this->template get<P>().match(
-                [&] (const T& t) { return t; },
-                [&] (const SourceFunction<T>& t) { return t.evaluate(feature, P::defaultValue()); },
-                [&] (const CompositeFunction<T>& t) { return t.evaluate(z, feature, P::defaultValue()); });
+        auto evaluate(float z, const GeometryTileFeature& feature) const {
+            return evaluate(z, feature, this->template get<P>(), P::defaultValue());
+        }
+
+        Evaluated evaluate(float z, const GeometryTileFeature& feature) const {
+            return Evaluated {
+                evaluate<Ps>(z, feature)...
+            };
         }
     };
 
@@ -65,8 +107,8 @@ public:
             .evaluate(Evaluator(parameters, P::defaultValue()));
     }
 
-    Evaluated evaluate(const PropertyEvaluationParameters& parameters) const {
-        return Evaluated {
+    PossiblyEvaluated evaluate(const PropertyEvaluationParameters& parameters) const {
+        return PossiblyEvaluated {
             evaluate<Ps>(parameters)...
         };
     }
diff --git a/src/mbgl/text/quads.cpp b/src/mbgl/text/quads.cpp
index b13a6a71e5..d3edafa1a0 100644
--- a/src/mbgl/text/quads.cpp
+++ b/src/mbgl/text/quads.cpp
@@ -18,7 +18,7 @@ const float globalMinScale = 0.5f; // underscale by 1 zoom level
 SymbolQuad getIconQuad(const Anchor& anchor,
                        const PositionedIcon& shapedIcon,
                        const GeometryCoordinates& line,
-                       const SymbolLayoutProperties::Evaluated& layout,
+                       const SymbolLayoutProperties::PossiblyEvaluated& layout,
                        const style::SymbolPlacementType placement, 
                        const Shaping& shapedText) {
     auto image = *(shapedIcon.image);
@@ -292,7 +292,7 @@ SymbolQuads getGlyphQuads(Anchor& anchor,
                           const Shaping& shapedText,
                           const float boxScale,
                           const GeometryCoordinates& line,
-                          const SymbolLayoutProperties::Evaluated& layout,
+                          const SymbolLayoutProperties::PossiblyEvaluated& layout,
                           const style::SymbolPlacementType placement,
                           const GlyphPositions& face) {
     const float textRotate = layout.get<TextRotate>() * util::DEG2RAD;
diff --git a/src/mbgl/text/quads.hpp b/src/mbgl/text/quads.hpp
index f1529d8829..7e3b5ca405 100644
--- a/src/mbgl/text/quads.hpp
+++ b/src/mbgl/text/quads.hpp
@@ -54,7 +54,7 @@ typedef std::vector<SymbolQuad> SymbolQuads;
 SymbolQuad getIconQuad(const Anchor& anchor,
                        const PositionedIcon& shapedIcon,
                        const GeometryCoordinates& line,
-                       const style::SymbolLayoutProperties::Evaluated&,
+                       const style::SymbolLayoutProperties::PossiblyEvaluated&,
                        style::SymbolPlacementType placement,
                        const Shaping& shapedText);
 
@@ -62,7 +62,7 @@ SymbolQuads getGlyphQuads(Anchor& anchor,
                           const Shaping& shapedText,
                           const float boxScale,
                           const GeometryCoordinates& line,
-                          const style::SymbolLayoutProperties::Evaluated&,
+                          const style::SymbolLayoutProperties::PossiblyEvaluated&,
                           style::SymbolPlacementType placement,
                           const GlyphPositions& face);