4 files changed, 94 insertions, 0 deletions
diff --git a/include/mbgl/style/conversion/data_driven_property_value.hpp b/include/mbgl/style/conversion/data_driven_property_value.hpp
index 1e54c15a49..8880d28fb1 100644
--- a/include/mbgl/style/conversion/data_driven_property_value.hpp
+++ b/include/mbgl/style/conversion/data_driven_property_value.hpp
@@ -4,6 +4,13 @@
 #include <mbgl/style/conversion.hpp>
 #include <mbgl/style/conversion/constant.hpp>
 #include <mbgl/style/conversion/function.hpp>
+#include <mbgl/style/conversion/expression.hpp>
+#include <mbgl/style/expression/is_expression.hpp>
+#include <mbgl/style/expression/is_constant.hpp>
+#include <mbgl/style/expression/find_zoom_curve.hpp>
+
+#include <unordered_set>
+
 
 namespace mbgl {
 namespace style {
@@ -11,9 +18,27 @@ namespace conversion {
 
 template <class T>
 struct Converter<DataDrivenPropertyValue<T>> {
+
     optional<DataDrivenPropertyValue<T>> operator()(const Convertible& value, Error& error) const {
         if (isUndefined(value)) {
             return DataDrivenPropertyValue<T>();
+        } else if (expression::isExpression(value)) {
+            optional<std::unique_ptr<Expression>> expression = convert<std::unique_ptr<Expression>>(
+                value,
+                error,
+                valueTypeToExpressionType<T>());
+            
+            if (!expression) {
+                return {};
+            }
+            
+            if (isFeatureConstant(**expression)) {
+                return DataDrivenPropertyValue<T>(CameraFunction<T>(std::move(*expression)));
+            } else if (isZoomConstant(**expression)) {
+                return DataDrivenPropertyValue<T>(SourceFunction<T>(std::move(*expression)));
+            } else {
+                return DataDrivenPropertyValue<T>(CompositeFunction<T>(std::move(*expression)));
+            }
         } else if (!isObject(value)) {
             optional<T> constant = convert<T>(value, error);
             if (!constant) {
diff --git a/include/mbgl/style/conversion/expression.hpp b/include/mbgl/style/conversion/expression.hpp
new file mode 100644
index 0000000000..c5fcf906a7
--- /dev/null
+++ b/include/mbgl/style/conversion/expression.hpp
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <mbgl/style/expression/parsing_context.hpp>
+#include <mbgl/style/expression/type.hpp>
+#include <mbgl/style/conversion.hpp>
+
+#include <memory>
+
+namespace mbgl {
+namespace style {
+namespace conversion {
+
+using namespace mbgl::style::expression;
+
+template<> struct Converter<std::unique_ptr<Expression>> {
+    optional<std::unique_ptr<Expression>> operator()(const Convertible& value, Error& error, type::Type expected) const {
+        ParsingContext ctx(optional<type::Type> {expected});
+        ParseResult parsed = ctx.parse(value);
+        if (parsed) {
+            return std::move(*parsed);
+        }
+        std::string combinedError;
+        for (const ParsingError& parsingError : ctx.getErrors()) {
+            if (combinedError.size() > 0) {
+                combinedError += "\n";
+            }
+            if (parsingError.key.size() > 0) {
+                combinedError += parsingError.key + ": ";
+            }
+            combinedError += parsingError.message;
+        }
+        error = { combinedError };
+        return {};
+    };
+};
+
+} // namespace conversion
+} // namespace style
+} // namespace mbgl
diff --git a/include/mbgl/style/conversion/get_json_type.hpp b/include/mbgl/style/conversion/get_json_type.hpp
new file mode 100644
index 0000000000..f7efebccce
--- /dev/null
+++ b/include/mbgl/style/conversion/get_json_type.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <mbgl/style/conversion.hpp>
+#include <string>
+
+namespace mbgl {
+namespace style {
+namespace conversion {
+
+std::string getJSONType(const Convertible& value);
+
+} // namespace conversion
+} // namespace style
+} // namespace mbgl
diff --git a/include/mbgl/style/conversion/property_value.hpp b/include/mbgl/style/conversion/property_value.hpp
index c7f971ec91..97117de2ec 100644
--- a/include/mbgl/style/conversion/property_value.hpp
+++ b/include/mbgl/style/conversion/property_value.hpp
@@ -4,6 +4,11 @@
 #include <mbgl/style/conversion.hpp>
 #include <mbgl/style/conversion/constant.hpp>
 #include <mbgl/style/conversion/function.hpp>
+#include <mbgl/style/conversion/expression.hpp>
+#include <mbgl/style/expression/value.hpp>
+#include <mbgl/style/expression/is_constant.hpp>
+#include <mbgl/style/expression/is_expression.hpp>
+#include <mbgl/style/expression/find_zoom_curve.hpp>
 
 namespace mbgl {
 namespace style {
@@ -14,6 +19,17 @@ struct Converter<PropertyValue<T>> {
     optional<PropertyValue<T>> operator()(const Convertible& value, Error& error) const {
         if (isUndefined(value)) {
             return PropertyValue<T>();
+        } else if (isExpression(value)) {
+            optional<std::unique_ptr<Expression>> expression = convert<std::unique_ptr<Expression>>(value, error, valueTypeToExpressionType<T>());
+            if (!expression) {
+                return {};
+            }
+            if (isFeatureConstant(**expression)) {
+                return { CameraFunction<T>(std::move(*expression)) };
+            } else {
+                error = { "property expressions not supported" };
+                return {};
+            }
         } else if (isObject(value)) {
             optional<CameraFunction<T>> function = convert<CameraFunction<T>>(value, error);
             if (!function) {