1 files changed, 57 insertions, 3 deletions
diff --git a/src/mbgl/style/expression/formatted.cpp b/src/mbgl/style/expression/formatted.cpp
index 6eb106dfec..d38f47b921 100644
--- a/src/mbgl/style/expression/formatted.cpp
+++ b/src/mbgl/style/expression/formatted.cpp
@@ -44,13 +44,67 @@ namespace conversion {
     
 using namespace mbgl::style::expression;
 
-optional<Formatted> Converter<Formatted>::operator()(const Convertible& value, Error&) const {
+optional<Formatted> Converter<Formatted>::operator()(const Convertible& value, Error& error) const {
     using namespace mbgl::style::expression;
 
-    auto result = toString(value);
-    if (result) {
+    if (isArray(value)) {
+        std::vector<FormattedSection> sections;
+        for (std::size_t i = 0; i < arrayLength(value); ++i) {
+            Convertible section = arrayMember(value, i);
+            std::size_t sectionLength = arrayLength(section);
+            if (sectionLength < 1) {
+                error.message = "Section has to contain a text and optional parameters.";
+                return nullopt;
+            }
+
+            optional<std::string> sectionText = toString(arrayMember(section, 0));
+            if (!sectionText) {
+                error.message = "Section has to contain a text.";
+                return nullopt;
+            }
+
+            optional<double> fontScale;
+            optional<FontStack> textFont;
+            if (sectionLength > 1) {
+                Convertible sectionParams = arrayMember(section, 1);
+                if (!isObject(sectionParams)) {
+                    error.message = "Parameters have to be enclosed in an object.";
+                    return nullopt;
+                }
+
+                optional<Convertible> fontScaleMember = objectMember(sectionParams, "font-scale");
+                if (fontScaleMember) {
+                    fontScale = toDouble(*fontScaleMember);
+                }
+
+                optional<Convertible> textFontMember = objectMember(sectionParams, "text-font");
+                if (textFontMember) {
+                    if (isArray(*textFontMember)) {
+                        std::vector<std::string> fontsVector;
+                        for (std::size_t j = 0; j < arrayLength(*textFontMember); ++j) {
+                            auto font = toString(arrayMember(*textFontMember, j));
+                            if (font) {
+                                fontsVector.push_back(*font);
+                            } else {
+                                error.message = "Font has to be a string.";
+                                return nullopt;
+                            }
+                        }
+                        textFont = fontsVector;
+                    } else {
+                        error.message = "Font stack has to be an array.";
+                        return nullopt;
+                    }
+                }
+            }
+
+            sections.push_back(FormattedSection(*sectionText, fontScale, textFont));
+        }
+        return Formatted(sections);
+    } else if (optional<std::string> result = toString(value)) {
         return Formatted(result->c_str());
     } else {
+        error.message = "Not supported Formatted type property.";
         return nullopt;
     }
 }