implement simple clusterOption exression

3 files changed, 26 insertions, 7 deletions

diff --git a/src/mbgl/style/expression/compound_expression.cpp b/src/mbgl/style/expression/compound_expression.cpp
index cc1d58025b..6ca6eec850 100644
--- a/src/mbgl/style/expression/compound_expression.cpp
+++ b/src/mbgl/style/expression/compound_expression.cpp
@@ -368,6 +368,18 @@ const auto& lineProgressCompoundExpression() {
     return signature;
 }
 
+const auto& accumulatedCompoundExpression() {
+    static auto signature = detail::makeSignature("accumulated", [](const EvaluationContext& params) -> Result<double> {
+        if (!params.accumulated) {
+            return EvaluationError {
+                "The 'accumulated' expression is unavailable in the current evaluation context."
+            };
+        }
+        return *(params.accumulated);
+    });
+    return signature;
+}
+    
 const auto& hasContextCompoundExpression() {
     static auto signature = detail::makeSignature("has", [](const EvaluationContext& params, const std::string& key) -> Result<bool> {
         if (!params.feature) {
@@ -870,6 +882,7 @@ MAPBOX_ETERNAL_CONSTEXPR const auto compoundExpressionRegistry = mapbox::eternal
     { "zoom", zoomCompoundExpression },
     { "heatmap-density", heatmapDensityCompoundExpression },
     { "line-progress", lineProgressCompoundExpression },
+    { "accumulated", accumulatedCompoundExpression},
     { "has", hasContextCompoundExpression },
     { "has", hasObjectCompoundExpression },
     { "get", getContextCompoundExpression },
diff --git a/src/mbgl/style/expression/expression.cpp b/src/mbgl/style/expression/expression.cpp
index 1e5b1581d2..e826cf6ec0 100644
--- a/src/mbgl/style/expression/expression.cpp
+++ b/src/mbgl/style/expression/expression.cpp
@@ -5,13 +5,13 @@
 namespace mbgl {
 namespace style {
 namespace expression {
-
+ 
 class GeoJSONFeature : public GeometryTileFeature {
 public:
     const Feature& feature;
-
-    GeoJSONFeature(const Feature& feature_) : feature(feature_) {}
-
+    
+    GeoJSONFeature( const Feature& feature_) : feature(feature_) {}
+    
     FeatureType getType() const override  {
         return apply_visitor(ToFeatureType(), feature.geometry);
     }
@@ -26,13 +26,18 @@ public:
         return optional<mbgl::Value>();
     }
 };
-
-
+   
+    
 EvaluationResult Expression::evaluate(optional<float> zoom, const Feature& feature, optional<double> colorRampParameter) const {
     GeoJSONFeature f(feature);
     return this->evaluate(EvaluationContext(zoom, &f, colorRampParameter));
 }
 
+EvaluationResult Expression::evaluate(const Feature& feature) const{
+    GeoJSONFeature f(feature);
+    return this->evaluate(EvaluationContext(&f));
+}
+
 } // namespace expression
 } // namespace style
 } // namespace mbgl
diff --git a/src/mbgl/style/expression/parsing_context.cpp b/src/mbgl/style/expression/parsing_context.cpp
index a7c04f563d..6ce3a9bfaa 100644
--- a/src/mbgl/style/expression/parsing_context.cpp
+++ b/src/mbgl/style/expression/parsing_context.cpp
@@ -73,7 +73,8 @@ bool isConstant(const Expression& expression) {
     
     return isFeatureConstant(expression) &&
         isGlobalPropertyConstant(expression, std::array<std::string, 2>{{"zoom", "heatmap-density"}}) &&
-        isGlobalPropertyConstant(expression, std::array<std::string, 2>{{"zoom", "line-progress"}});
+        isGlobalPropertyConstant(expression, std::array<std::string, 2>{{"zoom", "line-progress"}}) &&
+        isGlobalPropertyConstant(expression, std::array<std::string, 2>{{"zoom", "accumulated"}});
 }
 
 using namespace mbgl::style::conversion;