move style classes to MapData object and make thread safe

src/mbgl/map/map_data.cpp

@@ -0,0 +1,44 @@
+#include "map_data.hpp"
+
+#include <algorithm>
+
+namespace mbgl {
+
+// Adds the class if it's not yet set. Returns true when it added the class, and false when it
+// was already present.
+bool MapData::addClass(const std::string& klass) {
+    Lock lock(mtx);
+    if (std::find(classes.begin(), classes.end(), klass) != classes.end()) return false;
+    classes.push_back(klass);
+    return true;
+}
+
+// Removes the class if it's present. Returns true when it remvoed the class, and false when it
+// was not present.
+bool MapData::removeClass(const std::string& klass) {
+    Lock lock(mtx);
+    const auto it = std::find(classes.begin(), classes.end(), klass);
+    if (it != classes.end()) {
+        classes.erase(it);
+        return true;
+    }
+    return false;
+}
+
+// Returns true when class is present in the list of currently set classes.
+bool MapData::hasClass(const std::string& klass) const {
+    Lock lock(mtx);
+    return std::find(classes.begin(), classes.end(), klass) != classes.end();
+}
+
+void MapData::setClasses(const std::vector<std::string>& klasses) {
+    Lock lock(mtx);
+    classes = klasses;
+}
+
+std::vector<std::string> MapData::getClasses() const {
+    Lock lock(mtx);
+    return classes;
+}
+
+}