12 files changed, 55 insertions, 1 deletions
diff --git a/include/mbgl/renderer/renderer.hpp b/include/mbgl/renderer/renderer.hpp
index f1800dbfb8..7a1ddde1c1 100644
--- a/include/mbgl/renderer/renderer.hpp
+++ b/include/mbgl/renderer/renderer.hpp
@@ -49,6 +49,15 @@ public:
                                                  const std::string& extensionField,
                                                  const optional<std::map<std::string, Value>>& args = {}) const;
 
+    void setFeatureState(const std::string& sourceID, const optional<std::string>& sourceLayerID,
+                         const std::string& featureID, const FeatureState& state);
+
+    void getFeatureState(FeatureState& state, const std::string& sourceID, const optional<std::string>& sourceLayerID,
+                         const std::string& featureID) const;
+
+    void removeFeatureState(const std::string& sourceID, const optional<std::string>& sourceLayerID,
+                            const optional<std::string>& featureID, const optional<std::string>& stateKey);
+
     // Debug
     void dumpDebugLogs();
 
diff --git a/include/mbgl/style/expression/expression.hpp b/include/mbgl/style/expression/expression.hpp
index ad57748677..1341a8d041 100644
--- a/include/mbgl/style/expression/expression.hpp
+++ b/include/mbgl/style/expression/expression.hpp
@@ -34,6 +34,8 @@ public:
     EvaluationContext(optional<mbgl::Value> accumulated_, GeometryTileFeature const * feature_) :
         accumulated(std::move(accumulated_)), feature(feature_)
     {}
+    EvaluationContext(float zoom_, GeometryTileFeature const* feature_, const FeatureState* state_)
+        : zoom(zoom_), feature(feature_), featureState(state_) {}
     EvaluationContext(optional<float> zoom_, GeometryTileFeature const * feature_, optional<double> colorRampParameter_) :
         zoom(std::move(zoom_)), feature(feature_), colorRampParameter(std::move(colorRampParameter_))
     {}
@@ -43,12 +45,18 @@ public:
         return *this;
     };
 
+    EvaluationContext& withFeatureState(const FeatureState* featureState_) noexcept {
+        featureState = featureState_;
+        return *this;
+    };
+
     optional<float> zoom;
     optional<mbgl::Value> accumulated;
     GeometryTileFeature const * feature = nullptr;
     optional<double> colorRampParameter;
     // Contains formatted section object, std::unordered_map<std::string, Value>.
     const Value* formattedSection = nullptr;
+    const FeatureState* featureState = nullptr;
 };
 
 template <typename T>
diff --git a/include/mbgl/style/layer.hpp b/include/mbgl/style/layer.hpp
index ecd3f01f70..35577411eb 100644
--- a/include/mbgl/style/layer.hpp
+++ b/include/mbgl/style/layer.hpp
@@ -57,6 +57,12 @@ struct LayerTypeInfo {
      * requires cross-tile indexing and placement. Contains \c CrossTileIndex::NotRequired otherwise.
      */
     const enum class CrossTileIndex { Required, NotRequired } crossTileIndex;
+
+    /**
+     * @brief contains the Id of the supported tile type. Used for internal checks.
+     * The contained values correspond to \c Tile::Kind enum.
+     */
+    const enum class TileKind : uint8_t { Geometry, Raster, RasterDEM, NotRequired } tileKind;
 };
 
 /**
diff --git a/include/mbgl/style/property_expression.hpp b/include/mbgl/style/property_expression.hpp
index 32983e2380..f68285fb1b 100644
--- a/include/mbgl/style/property_expression.hpp
+++ b/include/mbgl/style/property_expression.hpp
@@ -61,6 +61,10 @@ public:
         return evaluate(expression::EvaluationContext(zoom, &feature), finalDefaultValue);
     }
 
+    T evaluate(float zoom, const GeometryTileFeature& feature, const FeatureState& state, T finalDefaultValue) const {
+        return evaluate(expression::EvaluationContext(zoom, &feature, &state), finalDefaultValue);
+    }
+
     std::vector<optional<T>> possibleOutputs() const {
         return expression::fromExpressionValues<T>(expression->possibleOutputs());
     }
diff --git a/include/mbgl/style/source.hpp b/include/mbgl/style/source.hpp
index 2507b67fdc..c3c0609a9f 100644
--- a/include/mbgl/style/source.hpp
+++ b/include/mbgl/style/source.hpp
@@ -22,6 +22,7 @@ class RasterSource;
 class RasterDEMSource;
 class GeoJSONSource;
 class SourceObserver;
+struct LayerTypeInfo;
 
 /**
  * The runtime representation of a [source](https://www.mapbox.com/mapbox-gl-style-spec/#sources) from the Mapbox Style
@@ -74,6 +75,8 @@ public:
     virtual void loadDescription(FileSource&) = 0;
     void dumpDebugLogs() const;
 
+    virtual bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const = 0;
+
     bool loaded = false;
 
     // For use in SDK bindings, which store a reference to a platform-native peer
diff --git a/include/mbgl/style/sources/custom_geometry_source.hpp b/include/mbgl/style/sources/custom_geometry_source.hpp
index a5e545f445..ff04505699 100644
--- a/include/mbgl/style/sources/custom_geometry_source.hpp
+++ b/include/mbgl/style/sources/custom_geometry_source.hpp
@@ -46,6 +46,7 @@ public:
     // Private implementation
     class Impl;
     const Impl& impl() const;
+    bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const override;
     mapbox::base::WeakPtr<Source> makeWeakPtr() override {
         return weakFactory.makeWeakPtr();
     }
diff --git a/include/mbgl/style/sources/geojson_source.hpp b/include/mbgl/style/sources/geojson_source.hpp
index c99687fad6..a256ad6f15 100644
--- a/include/mbgl/style/sources/geojson_source.hpp
+++ b/include/mbgl/style/sources/geojson_source.hpp
@@ -50,6 +50,8 @@ public:
 
     void loadDescription(FileSource&) final;
 
+    bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const override;
+
     mapbox::base::WeakPtr<Source> makeWeakPtr() override {
         return weakFactory.makeWeakPtr();
     }
diff --git a/include/mbgl/style/sources/image_source.hpp b/include/mbgl/style/sources/image_source.hpp
index 84faab33c9..699a3c6494 100644
--- a/include/mbgl/style/sources/image_source.hpp
+++ b/include/mbgl/style/sources/image_source.hpp
@@ -28,6 +28,8 @@ public:
 
     void loadDescription(FileSource&) final;
 
+    bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const override;
+
     mapbox::base::WeakPtr<Source> makeWeakPtr() override {
         return weakFactory.makeWeakPtr();
     }
diff --git a/include/mbgl/style/sources/raster_dem_source.hpp b/include/mbgl/style/sources/raster_dem_source.hpp
index 82588613bc..42e27cd078 100644
--- a/include/mbgl/style/sources/raster_dem_source.hpp
+++ b/include/mbgl/style/sources/raster_dem_source.hpp
@@ -13,7 +13,7 @@ namespace style {
 class RasterDEMSource : public RasterSource {
 public:
     RasterDEMSource(std::string id, variant<std::string, Tileset> urlOrTileset, uint16_t tileSize);
-
+    bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const override;
 };
 
 template <>
diff --git a/include/mbgl/style/sources/raster_source.hpp b/include/mbgl/style/sources/raster_source.hpp
index 1bdced8da7..00a3b788c2 100644
--- a/include/mbgl/style/sources/raster_source.hpp
+++ b/include/mbgl/style/sources/raster_source.hpp
@@ -25,6 +25,8 @@ public:
 
     void loadDescription(FileSource&) final;
 
+    bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const override;
+
     mapbox::base::WeakPtr<Source> makeWeakPtr() final {
         return weakFactory.makeWeakPtr();
     }
diff --git a/include/mbgl/style/sources/vector_source.hpp b/include/mbgl/style/sources/vector_source.hpp
index 97f0a7e5a8..4165af0a61 100644
--- a/include/mbgl/style/sources/vector_source.hpp
+++ b/include/mbgl/style/sources/vector_source.hpp
@@ -24,6 +24,8 @@ public:
 
     void loadDescription(FileSource&) final;
 
+    bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const override;
+
     mapbox::base::WeakPtr<Source> makeWeakPtr() override {
         return weakFactory.makeWeakPtr();
     }
diff --git a/include/mbgl/util/feature.hpp b/include/mbgl/util/feature.hpp
index 9e2286018c..390cc65720 100644
--- a/include/mbgl/util/feature.hpp
+++ b/include/mbgl/util/feature.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <mbgl/util/optional.hpp>
+#include <mbgl/util/string.hpp>
 
 #include <mapbox/feature.hpp>
 
@@ -11,6 +12,9 @@ using NullValue = mapbox::feature::null_value_t;
 using PropertyMap = mapbox::feature::property_map;
 using FeatureIdentifier = mapbox::feature::identifier;
 using Feature = mapbox::feature::feature<double>;
+using FeatureState = PropertyMap;
+using FeatureStates = std::unordered_map<std::string, FeatureState>;       // <featureID, FeatureState>
+using LayerFeatureStates = std::unordered_map<std::string, FeatureStates>; // <sourceLayer, FeatureStates>
 
 template <class T>
 optional<T> numericValue(const Value& value) {
@@ -29,4 +33,15 @@ optional<T> numericValue(const Value& value) {
         });
 }
 
+inline optional<std::string> featureIDtoString(const FeatureIdentifier& id) {
+    if (id.is<NullValue>()) {
+        return nullopt;
+    }
+
+    return id.match(
+        [](const std::string& value_) { return value_; }, [](uint64_t value_) { return util::toString(value_); },
+        [](int64_t value_) { return util::toString(value_); }, [](double value_) { return util::toString(value_); },
+        [](const auto&) -> optional<std::string> { return nullopt; });
+}
+
 } // namespace mbgl