4 files changed, 17 insertions, 2 deletions
diff --git a/include/mbgl/style/function/camera_function.hpp b/include/mbgl/style/function/camera_function.hpp
index 25b38e3616..015abd3e62 100644
--- a/include/mbgl/style/function/camera_function.hpp
+++ b/include/mbgl/style/function/camera_function.hpp
@@ -12,7 +12,6 @@
 #include <mbgl/util/interpolate.hpp>
 #include <mbgl/util/variant.hpp>
 
-
 namespace mbgl {
 namespace style {
 
@@ -66,7 +65,11 @@ public:
             [&](auto z) { return z->getCoveringStops(lower, upper); }
         );
     }
-    
+
+    std::vector<optional<T>> possibleOutputs() const {
+        return expression::fromExpressionValues<T>(expression->possibleOutputs());
+    }
+
     friend bool operator==(const CameraFunction& lhs,
                            const CameraFunction& rhs) {
         return *lhs.expression == *rhs.expression;
diff --git a/include/mbgl/style/function/composite_function.hpp b/include/mbgl/style/function/composite_function.hpp
index b44bf8e6fe..24578f599c 100644
--- a/include/mbgl/style/function/composite_function.hpp
+++ b/include/mbgl/style/function/composite_function.hpp
@@ -102,6 +102,10 @@ public:
         );
     }
 
+    std::vector<optional<T>> possibleOutputs() const {
+        return expression::fromExpressionValues<T>(expression->possibleOutputs());
+    }
+
     friend bool operator==(const CompositeFunction& lhs,
                            const CompositeFunction& rhs) {
         return *lhs.expression == *rhs.expression;
diff --git a/include/mbgl/style/function/convert.hpp b/include/mbgl/style/function/convert.hpp
index 9f7b7ed1f8..8e544d3ad5 100644
--- a/include/mbgl/style/function/convert.hpp
+++ b/include/mbgl/style/function/convert.hpp
@@ -45,6 +45,10 @@ public:
         return EvaluationError{message};
     }
 
+    std::vector<optional<Value>> possibleOutputs() const override {
+        return {};
+    }
+
 private:
     std::string message;
 };
diff --git a/include/mbgl/style/function/source_function.hpp b/include/mbgl/style/function/source_function.hpp
index 02e4b604e2..bd7b109fd8 100644
--- a/include/mbgl/style/function/source_function.hpp
+++ b/include/mbgl/style/function/source_function.hpp
@@ -57,6 +57,10 @@ public:
         return defaultValue ? *defaultValue : finalDefaultValue;
     }
 
+    std::vector<optional<T>> possibleOutputs() const {
+        return expression::fromExpressionValues<T>(expression->possibleOutputs());
+    }
+
     friend bool operator==(const SourceFunction& lhs,
                            const SourceFunction& rhs) {
         return *lhs.expression == *rhs.expression;