(svn r8092) -Codechange: header files with miscellaneous template classes (smart pointers, blob, array, hashtable, etc.) moved from src/yapf to src/misc as they can now be used anywhere.

1 files changed, 225 insertions, 0 deletions

diff --git a/src/misc/binaryheap.hpp b/src/misc/binaryheap.hpp
new file mode 100644
index 000000000..7b72a25af
--- /dev/null
+++ b/src/misc/binaryheap.hpp
@@ -0,0 +1,225 @@
+/* $Id$ */
+
+#ifndef  BINARYHEAP_HPP
+#define  BINARYHEAP_HPP
+
+//void* operator new (size_t size, void* p) {return p;}
+#if defined(_MSC_VER) && (_MSC_VER >= 1400)
+//void operator delete (void* p, void* p2) {}
+#endif
+
+
+/**
+ * Binary Heap as C++ template.
+ *
+ * For information about Binary Heap algotithm,
+ *   see: http://www.policyalmanac.org/games/binaryHeaps.htm
+ *
+ * Implementation specific notes:
+ *
+ * 1) It allocates space for item pointers (array). Items are allocated elsewhere.
+ *
+ * 2) ItemPtr [0] is never used. Total array size is max_items + 1, because we
+ *    use indices 1..max_items instead of zero based C indexing.
+ *
+ * 3) Item of the binary heap should support these public members:
+ *    - 'lower-then' operator '<' - used for comparing items before moving
+ *
+ */
+
+template <class Titem_>
+class CBinaryHeapT {
+public:
+	typedef Titem_ *ItemPtr;
+private:
+	int                     m_size;     ///< Number of items in the heap
+	int                     m_max_size; ///< Maximum number of items the heap can hold
+	ItemPtr*                m_items;    ///< The heap item pointers
+
+public:
+	explicit CBinaryHeapT(int max_items = 102400)
+		: m_size(0)
+		, m_max_size(max_items)
+	{
+		m_items = new ItemPtr[max_items + 1];
+	}
+
+	~CBinaryHeapT()
+	{
+		Clear();
+		delete [] m_items;
+		m_items = NULL;
+	}
+
+public:
+	/** Return the number of items stored in the priority queue.
+	 *  @return number of items in the queue */
+	FORCEINLINE int Size() const {return m_size;};
+
+	/** Test if the priority queue is empty.
+	 *  @return true if empty */
+	FORCEINLINE bool IsEmpty() const {return (m_size == 0);};
+
+	/** Test if the priority queue is full.
+	 *  @return true if full. */
+	FORCEINLINE bool IsFull() const {return (m_size >= m_max_size);};
+
+	/** Find the smallest item in the priority queue.
+	 *  Return the smallest item, or throw assert if empty. */
+	FORCEINLINE Titem_& GetHead() {assert(!IsEmpty()); return *m_items[1];}
+
+	/** Insert new item into the priority queue, maintaining heap order.
+	 *  @return false if the queue is full. */
+	bool Push(Titem_& new_item);
+
+	/** Remove and return the smallest item from the priority queue. */
+	FORCEINLINE Titem_& PopHead() {Titem_& ret = GetHead(); RemoveHead(); return ret;};
+
+	/** Remove the smallest item from the priority queue. */
+	void RemoveHead();
+
+	/** Remove item specified by index */
+	void RemoveByIdx(int idx);
+
+	/** return index of the item that matches (using &item1 == &item2) the given item. */
+	int FindLinear(const Titem_& item) const;
+
+	/** Make the priority queue empty.
+	 * All remaining items will remain untouched. */
+	void Clear() {m_size = 0;};
+
+	/** verifies the heap consistency (added during first YAPF debug phase) */
+	void CheckConsistency();
+};
+
+
+template <class Titem_>
+FORCEINLINE bool CBinaryHeapT<Titem_>::Push(Titem_& new_item)
+{
+	if (IsFull()) return false;
+
+	// make place for new item
+	int gap = ++m_size;
+	// Heapify up
+	for (int parent = gap / 2; (parent > 0) && (new_item < *m_items[parent]); gap = parent, parent /= 2)
+		m_items[gap] = m_items[parent];
+	m_items[gap] = &new_item;
+	CheckConsistency();
+	return true;
+}
+
+template <class Titem_>
+FORCEINLINE void CBinaryHeapT<Titem_>::RemoveHead()
+{
+	assert(!IsEmpty());
+
+	// at index 1 we have a gap now
+	int gap = 1;
+
+	// Heapify down:
+	//   last item becomes a candidate for the head. Call it new_item.
+	Titem_& new_item = *m_items[m_size--];
+
+	// now we must maintain relation between parent and its children:
+	//   parent <= any child
+	// from head down to the tail
+	int child  = 2; // first child is at [parent * 2]
+
+	// while children are valid
+	while (child <= m_size) {
+		// choose the smaller child
+		if (child < m_size && *m_items[child + 1] < *m_items[child])
+			child++;
+		// is it smaller than our parent?
+		if (!(*m_items[child] < new_item)) {
+			// the smaller child is still bigger or same as parent => we are done
+			break;
+		}
+		// if smaller child is smaller than parent, it will become new parent
+		m_items[gap] = m_items[child];
+		gap = child;
+		// where do we have our new children?
+		child = gap * 2;
+	}
+	// move last item to the proper place
+	if (m_size > 0) m_items[gap] = &new_item;
+	CheckConsistency();
+}
+
+template <class Titem_>
+inline void CBinaryHeapT<Titem_>::RemoveByIdx(int idx)
+{
+	// at position idx we have a gap now
+	int gap = idx;
+	Titem_& last = *m_items[m_size];
+	if (idx < m_size) {
+		assert(idx >= 1);
+		m_size--;
+		// and the candidate item for fixing this gap is our last item 'last'
+		// Move gap / last item up:
+		while (gap > 1)
+		{
+			// compare [gap] with its parent
+			int parent = gap / 2;
+			if (last < *m_items[parent]) {
+				m_items[gap] = m_items[parent];
+				gap = parent;
+			} else {
+				// we don't need to continue upstairs
+				break;
+			}
+		}
+
+		// Heapify (move gap) down:
+		while (true) {
+			// where we do have our children?
+			int child  = gap * 2; // first child is at [parent * 2]
+			if (child > m_size) break;
+			// choose the smaller child
+			if (child < m_size && *m_items[child + 1] < *m_items[child])
+				child++;
+			// is it smaller than our parent?
+			if (!(*m_items[child] < last)) {
+				// the smaller child is still bigger or same as parent => we are done
+				break;
+			}
+			// if smaller child is smaller than parent, it will become new parent
+			m_items[gap] = m_items[child];
+			gap = child;
+		}
+		// move parent to the proper place
+		if (m_size > 0) m_items[gap] = &last;
+	}
+	else {
+		assert(idx == m_size);
+		m_size--;
+	}
+	CheckConsistency();
+}
+
+template <class Titem_>
+inline int CBinaryHeapT<Titem_>::FindLinear(const Titem_& item) const
+{
+	if (IsEmpty()) return 0;
+	for (ItemPtr *ppI = m_items + 1, *ppLast = ppI + m_size; ppI <= ppLast; ppI++) {
+		if (*ppI == &item) {
+			return ppI - m_items;
+		}
+	}
+	return 0;
+}
+
+template <class Titem_>
+FORCEINLINE void CBinaryHeapT<Titem_>::CheckConsistency()
+{
+	// enable it if you suspect binary heap doesn't work well
+#if 0
+	for (int child = 2; child <= m_size; child++) {
+		int parent = child / 2;
+		assert(!(m_items[child] < m_items[parent]));
+	}
+#endif
+}
+
+
+#endif /* BINARYHEAP_HPP */