--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/leptonica/src/heap.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,87 @@
+/*====================================================================*
+ -  Copyright (C) 2001 Leptonica.  All rights reserved.
+ -
+ -  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 COPYRIGHT HOLDERS AND CONTRIBUTORS
+ -  ``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 ANY
+ -  CONTRIBUTORS 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  LEPTONICA_HEAP_H
+#define  LEPTONICA_HEAP_H
+
+/*!
+ * \file heap.h
+ *
+ * <pre>
+ *      Expandable priority queue configured as a heap for arbitrary void* data
+ *
+ *      The L_Heap is used to implement a priority queue.  The elements
+ *      in the heap are ordered in either increasing or decreasing key value.
+ *      The key is a float field 'keyval' that is required to be
+ *      contained in the elements of the queue.
+ *
+ *      The heap is a simple binary tree with the following constraints:
+ *         - the key of each node is >= the keys of the two children
+ *         - the tree is complete, meaning that each level (1, 2, 4, ...)
+ *           is filled and the last level is filled from left to right
+ *
+ *      The tree structure is implicit in the queue array, with the
+ *      array elements numbered as a breadth-first search of the tree
+ *      from left to right.  It is thus guaranteed that the largest
+ *      (or smallest) key belongs to the first element in the array.
+ *
+ *      Heap sort is used to sort the array.  Once an array has been
+ *      sorted as a heap, it is convenient to use it as a priority queue,
+ *      because the min (or max) elements are always at the root of
+ *      the tree (element 0), and once removed, the heap can be
+ *      resorted in not more than log[n] steps, where n is the number
+ *      of elements on the heap.  Likewise, if an arbitrary element is
+ *      added to the end of the array A, the sorted heap can be restored
+ *      in not more than log[n] steps.
+ *
+ *      A L_Heap differs from a L_Queue in that the elements in the former
+ *      are sorted by a key.  Internally, the array is maintained
+ *      as a queue, with a pointer to the end of the array.  The
+ *      head of the array always remains at array[0].  The array is
+ *      maintained (sorted) as a heap.  When an item is removed from
+ *      the head, the last item takes its place (thus reducing the
+ *      array length by 1), and this is followed by array element
+ *      swaps to restore the heap property.   When an item is added,
+ *      it goes at the end of the array, and is swapped up to restore
+ *      the heap.  If the ptr array is full, adding another item causes
+ *      the ptr array size to double.
+ *
+ *      For further implementation details, see heap.c.
+ * </pre>
+ */
+
+/*! Heap of arbitrary void* data */
+struct L_Heap
+{
+    l_int32      nalloc;      /*!< size of allocated ptr array               */
+    l_int32      n;           /*!< number of elements stored in the heap     */
+    void       **array;       /*!< ptr array                                 */
+    l_int32      direction;   /*!< L_SORT_INCREASING or L_SORT_DECREASING    */
+};
+typedef struct L_Heap  L_HEAP;
+
+
+#endif  /* LEPTONICA_HEAP_H */