parse min-zoom/max-zoom values

refs mapbox/mapbox-gl-style-spec#65

include/mbgl/style/style_bucket.hpp

@@ -79,6 +79,8 @@ public:
     std::string source_layer;
     FilterExpression filter;
     StyleBucketRender render = std::false_type();
+    float min_zoom = -std::numeric_limits<float>::infinity();
+    float max_zoom = std::numeric_limits<float>::infinity();
 };
 
 

src/style/style_parser.cpp

@@ -2,6 +2,7 @@
 #include <mbgl/style/style_layer_group.hpp>
 #include <mbgl/util/constants.hpp>
 #include <mbgl/util/std.hpp>
+#include <mbgl/platform/log.hpp>
 #include <csscolorparser/csscolorparser.hpp>
 
 namespace mbgl {
@@ -714,6 +715,24 @@ void StyleParser::parseBucket(JSVal value, std::shared_ptr<StyleLayer> &layer) {
         JSVal value_render = replaceConstant(value["render"]);
         parseRender(value_render, layer);
     }
+
+    if (value.HasMember("min-zoom")) {
+        JSVal min_zoom = value["min-zoom"];
+        if (min_zoom.IsNumber()) {
+            layer->bucket->min_zoom = min_zoom.GetDouble();
+        } else {
+            Log::Warning(Event::ParseStyle, "min-zoom of layer %s must be numeric", layer->id.c_str());
+        }
+    }
+
+    if (value.HasMember("max-zoom")) {
+        JSVal max_zoom = value["max-zoom"];
+        if (max_zoom.IsNumber()) {
+            layer->bucket->min_zoom = max_zoom.GetDouble();
+        } else {
+            Log::Warning(Event::ParseStyle, "max-zoom of layer %s must be numeric", layer->id.c_str());
+        }
+    }
 }
 
 FilterExpression StyleParser::parseFilter(JSVal value) {