[core] Split up and clean up conversion.hpp

src/mbgl/style/conversion.cpp

@@ -1,25 +0,0 @@
-#include <mbgl/style/conversion.hpp>
-
-namespace mbgl {
-namespace style {
-namespace conversion {
-
-Result<Value> normalizeFilterValue(const std::string& key, const optional<Value>& value) {
-    if (!value) {
-        return Error { "filter expression value must be a boolean, number, or string" };
-    } else if (key != "$type") {
-        return *value;
-    } else if (*value == std::string("Point")) {
-        return Value(uint64_t(FeatureType::Point));
-    } else if (*value == std::string("LineString")) {
-        return Value(uint64_t(FeatureType::LineString));
-    } else if (*value == std::string("Polygon")) {
-        return Value(uint64_t(FeatureType::Polygon));
-    } else {
-        return Error { "value for $type filter must be Point, LineString, or Polygon" };
-    }
-}
-
-} // namespace conversion
-} // namespace style
-} // namespace mbgl

src/mbgl/style/parser.cpp

@@ -11,6 +11,7 @@
 #include <mbgl/style/layers/background_layer.hpp>
 #include <mbgl/style/rapidjson_conversion.hpp>
 #include <mbgl/style/conversion.hpp>
+#include <mbgl/style/conversion/filter.hpp>
 
 #include <mbgl/platform/log.hpp>
 
@@ -277,11 +278,11 @@ void Parser::parseLayer(const std::string& id, const JSValue& value, std::unique
         }
 
         if (value.HasMember("filter")) {
-            conversion::Result<Filter> filter = conversion::convertFilter(value["filter"]);
-            if (filter.is<Filter>()) {
-                impl->filter = filter.get<Filter>();
+            conversion::Result<Filter> filter = conversion::convert<Filter>(value["filter"]);
+            if (filter) {
+                impl->filter = *filter;
             } else {
-                Log::Warning(Event::ParseStyle, filter.get<conversion::Error>().message);
+                Log::Warning(Event::ParseStyle, filter.error().message);
             }
         }
 

src/mbgl/style/property_parsing.hpp

@@ -3,7 +3,7 @@
 #include <mbgl/style/property_value.hpp>
 #include <mbgl/style/transition_options.hpp>
 #include <mbgl/style/rapidjson_conversion.hpp>
-#include <mbgl/style/conversion.hpp>
+#include <mbgl/style/conversion/property_value.hpp>
 
 #include <mbgl/platform/log.hpp>
 
@@ -12,12 +12,12 @@ namespace style {
 
 template <typename T>
 PropertyValue<T> parseProperty(const char* name, const JSValue& value) {
-    conversion::Result<PropertyValue<T>> result = conversion::convertPropertyValue<T>(value);
-    if (result.template is<conversion::Error>()) {
-        Log::Warning(Event::ParseStyle, "%s: %s", name, result.template get<conversion::Error>().message);
+    conversion::Result<PropertyValue<T>> result = conversion::convert<PropertyValue<T>>(value);
+    if (!result) {
+        Log::Warning(Event::ParseStyle, "%s: %s", name, result.error().message);
         return {};
     }
-    return result.template get<PropertyValue<T>>();
+    return *result;
 }
 
 optional<TransitionOptions> parseTransitionOptions(const char * name, const JSValue&);