2 files changed, 13 insertions, 0 deletions
diff --git a/src/mbgl/text/cross_tile_symbol_index.cpp b/src/mbgl/text/cross_tile_symbol_index.cpp
index 8f4956c4ea..f88bab9d6f 100644
--- a/src/mbgl/text/cross_tile_symbol_index.cpp
+++ b/src/mbgl/text/cross_tile_symbol_index.cpp
@@ -169,6 +169,18 @@ bool CrossTileSymbolIndex::addLayer(RenderSymbolLayer& symbolLayer) {
     return symbolBucketsChanged;
 }
 
+void CrossTileSymbolIndex::pruneUnusedLayers(const std::set<std::string>& usedLayers) {
+    std::vector<std::string> unusedLayers;
+    for (auto layerIndex : layerIndexes) {
+        if (usedLayers.find(layerIndex.first) == usedLayers.end()) {
+            unusedLayers.push_back(layerIndex.first);
+        }
+    }
+    for (auto unusedLayer : unusedLayers) {
+        layerIndexes.erase(unusedLayer);
+    }
+}
+
 void CrossTileSymbolIndex::reset() {
     layerIndexes.clear();
 }
diff --git a/src/mbgl/text/cross_tile_symbol_index.hpp b/src/mbgl/text/cross_tile_symbol_index.hpp
index 5abcde241c..541c2e3661 100644
--- a/src/mbgl/text/cross_tile_symbol_index.hpp
+++ b/src/mbgl/text/cross_tile_symbol_index.hpp
@@ -57,6 +57,7 @@ public:
     CrossTileSymbolIndex();
 
     bool addLayer(RenderSymbolLayer&);
+    void pruneUnusedLayers(const std::set<std::string>&);
 
     void reset();
 private: