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dependency/opencv/opencv-linux-aarch64/include/opencv2/flann/heap.h

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+/***********************************************************************
+ * Software License Agreement (BSD License)
+ *
+ * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
+ * Copyright 2008-2009  David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
+ *
+ * THE BSD LICENSE
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *************************************************************************/
+
+#ifndef OPENCV_FLANN_HEAP_H_
+#define OPENCV_FLANN_HEAP_H_
+
+#include <algorithm>
+#include <vector>
+
+namespace cvflann
+{
+
+/**
+ * Priority Queue Implementation
+ *
+ * The priority queue is implemented with a heap.  A heap is a complete
+ * (full) binary tree in which each parent is less than both of its
+ * children, but the order of the children is unspecified.
+ */
+template <typename T>
+class Heap
+{
+
+    /**
+     * Storage array for the heap.
+     * Type T must be comparable.
+     */
+    std::vector<T> heap;
+    int length;
+
+    /**
+     * Number of element in the heap
+     */
+    int count;
+
+
+
+public:
+    /**
+     * Constructor.
+     *
+     * Params:
+     *     sz = heap size
+     */
+
+    Heap(int sz)
+    {
+        length = sz;
+        heap.reserve(length);
+        count = 0;
+    }
+
+    /**
+     *
+     * Returns: heap size
+     */
+    int size()
+    {
+        return count;
+    }
+
+    /**
+     * Tests if the heap is empty
+     *
+     * Returns: true is heap empty, false otherwise
+     */
+    bool empty()
+    {
+        return size()==0;
+    }
+
+    /**
+     * Clears the heap.
+     */
+    void clear()
+    {
+        heap.clear();
+        count = 0;
+    }
+
+    struct CompareT
+    {
+        bool operator()(const T& t_1, const T& t_2) const
+        {
+            return t_2 < t_1;
+        }
+    };
+
+    /**
+     * Insert a new element in the heap.
+     *
+     * We select the next empty leaf node, and then keep moving any larger
+     * parents down until the right location is found to store this element.
+     *
+     * Params:
+     *     value = the new element to be inserted in the heap
+     */
+    void insert(T value)
+    {
+        /* If heap is full, then return without adding this element. */
+        if (count == length) {
+            return;
+        }
+
+        heap.push_back(value);
+        static CompareT compareT;
+        std::push_heap(heap.begin(), heap.end(), compareT);
+        ++count;
+    }
+
+
+
+    /**
+     * Returns the node of minimum value from the heap (top of the heap).
+     *
+     * Params:
+     *     value = out parameter used to return the min element
+     * Returns: false if heap empty
+     */
+    bool popMin(T& value)
+    {
+        if (count == 0) {
+            return false;
+        }
+
+        value = heap[0];
+        static CompareT compareT;
+        std::pop_heap(heap.begin(), heap.end(), compareT);
+        heap.pop_back();
+        --count;
+
+        return true;  /* Return old last node. */
+    }
+};
+
+}
+
+#endif //OPENCV_FLANN_HEAP_H_