1 files changed, 59 insertions, 0 deletions

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+#ifndef GRID_CACHE_H_67BBE74D
+#define GRID_CACHE_H_67BBE74D
+
+#include <unordered_map>
+#include <unordered_set>
+#include "level.h"
+
+template <typename T>
+class GridCache {
+public:
+
+  explicit GridCache(const Level& level) : width_(level.getSize().w())
+  {
+  }
+
+  void set(T value, vec2s pos)
+  {
+    if (reverse_.count(value))
+    {
+      size_t oldPosIndex = reverse_.at(value);
+      lookup_[oldPosIndex].erase(value);
+    }
+
+    size_t newPosIndex = getIndex(pos);
+    lookup_[newPosIndex].insert(value);
+    reverse_[value] = newPosIndex;
+  }
+
+  void remove(T value)
+  {
+    if (reverse_.count(value))
+    {
+      size_t index = reverse_.at(value);
+      lookup_[index].erase(value);
+      reverse_.erase(value);
+    }
+  }
+
+  const std::unordered_set<T>& at(vec2s pos) const
+  {
+    size_t index = getIndex(pos);
+
+    return lookup_[index];
+  }
+
+private:
+
+  inline size_t getIndex(const vec2s& pos) const
+  {
+    return pos.x() + pos.y() * width_;
+  }
+
+  size_t width_;
+
+  mutable std::unordered_map<size_t, std::unordered_set<T>> lookup_;
+  std::unordered_map<T, size_t> reverse_;
+};
+
+#endif /* end of include guard: GRID_CACHE_H_67BBE74D */