move weak_ptr list of tile_data objects to a map for faster lookups

include/llmr/map/source.hpp

@@ -12,6 +12,7 @@
 #include <vector>
 #include <string>
 #include <map>
+#include <set>
 
 namespace llmr {
 
@@ -69,7 +70,7 @@ private:
     const int32_t max_zoom;
 
     std::forward_list<Tile> tiles;
-    std::forward_list<std::weak_ptr<TileData>> tile_data;
+    std::map<Tile::ID, std::weak_ptr<TileData>> tile_data;
 };
 
 }

include/llmr/util/std.hpp

@@ -11,6 +11,23 @@ template<typename T, typename ...Args>
     return ::std::unique_ptr<T>(new T(::std::forward<Args>(args)...));
 }
 
+
+template <typename Container, typename ForwardIterator, typename Predicate>
+void erase_if(Container &container, ForwardIterator it, const ForwardIterator end, Predicate pred) {
+    while (it != end) {
+        if (pred(*it)) {
+            container.erase(it++);
+        } else {
+            ++it;
+        }
+    }
+}
+
+template <typename Container, typename Predicate>
+void erase_if(Container &container, Predicate pred) {
+    erase_if(container, container.begin(), container.end(), pred);
+}
+
 }
 
 #endif