fahhh

App/util/UintSet.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include "Util/DoubleEndedVector.h"
+#include "boost/cstdint.hpp"
+
+namespace RBX {
+
+/**
+ * Attempts to outperform std::set<unsigned int> by using a bitset. This will
+ * use less memory than a tree set when the numbers stored are close together
+ * (roughly, if the average spacing is less than 24 * sizeof(void*) then this
+ * implementation will likely use less memory than a traditional set).
+ */
+struct UintSet {
+	typedef boost::uint32_t BitGroup;
+
+	// these two constants are public for testing
+	static const unsigned int kShiftForGroup;
+	static const BitGroup kBitInGroupMask;
+
+private:
+	struct UpdateBitInfo {
+		const BitGroup bitGroup;
+		const BitGroup bitPosition; // 0-indexed position (not a bitmask)
+		const BitGroup mask;
+
+		UpdateBitInfo(unsigned int intVal);
+	};
+
+	// min group offset, group for data in bitSet[0]
+	unsigned int minBitGroup;
+	// max group offset inclusive (max valid index for bitSet)
+	unsigned int maxBitGroup;
+	// number of uints stored in this BitSet
+	size_t internalSize;
+	bool isEmpty;
+	// actual bitset
+	DoubleEndedVector<BitGroup> bitSet;
+
+public:
+	UintSet();
+
+	size_t size() const;
+
+	bool insert(const unsigned int intVal);
+
+	bool contains(const unsigned int intVal);
+
+	void pop_smallest(unsigned int* out);
+};
+
+}