--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/leptonica/src/heap.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,565 @@
+/*====================================================================*
+ -  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.
+ *====================================================================*/
+
+/*!
+ * \file  heap.c
+ * <pre>
+ *
+ *      Create/Destroy L_Heap
+ *          L_HEAP         *lheapCreate()
+ *          void            lheapDestroy()
+ *
+ *      Operations to add/remove to/from the heap
+ *          l_int32         lheapAdd()
+ *          static l_int32  lheapExtendArray()
+ *          void           *lheapRemove()
+ *
+ *      Other accessors
+ *          l_int32         lheapGetCount()
+ *          void           *lheapGetElement()
+ *
+ *      Heap sort
+ *          l_int32         lheapSort()
+ *          l_int32         lheapSortStrictOrder()
+ *
+ *      Low-level heap operations
+ *          static l_int32  lheapSwapUp()
+ *          static l_int32  lheapSwapDown()
+ *
+ *      Debug output
+ *          l_int32         lheapPrint()
+ *
+ *    The L_Heap is useful to implement a priority queue, that is sorted
+ *    on a key in each element of the heap.  The heap is an array
+ *    of nearly arbitrary structs, with a l_float32 the first field.
+ *    This field is the key on which the heap is sorted.
+ *
+ *    Internally, we keep track of the heap size, n.  The item at the
+ *    root of the heap is at the head of the array.  Items are removed
+ *    from the head of the array and added to the end of the array.
+ *    When an item is removed from the head, the item at the end
+ *    of the array is moved to the head.  When items are either
+ *    added or removed, it is usually necessary to swap array items
+ *    to restore the heap order.  It is guaranteed that the number
+ *    of swaps does not exceed log(n).
+ *
+ *    --------------------------  N.B.  ------------------------------
+ *    The items on the heap (or, equivalently, in the array) are cast
+ *    to void*.  Their key is a l_float32, and it is REQUIRED that the
+ *    key be the first field in the struct.  That allows us to get the
+ *    key by simply dereferencing the struct.  Alternatively, we could
+ *    choose (but don't) to pass an application-specific comparison
+ *    function into the heap operation functions.
+ *    --------------------------  N.B.  ------------------------------
+ * </pre>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config_auto.h>
+#endif  /* HAVE_CONFIG_H */
+
+#include <string.h>
+#include "allheaders.h"
+
+    /* Bounds on initial array size */
+static const l_uint32  MaxPtrArraySize = 100000;
+static const l_int32 InitialPtrArraySize = 20;      /*!< n'importe quoi */
+
+#define SWAP_ITEMS(i, j)       { void *tempitem = lh->array[(i)]; \
+                                 lh->array[(i)] = lh->array[(j)]; \
+                                 lh->array[(j)] = tempitem; }
+
+    /* Static functions */
+static l_int32 lheapExtendArray(L_HEAP *lh);
+static l_ok lheapSwapUp(L_HEAP *lh, l_int32 index);
+static l_ok lheapSwapDown(L_HEAP *lh);
+
+
+/*--------------------------------------------------------------------------*
+ *                          L_Heap create/destroy                           *
+ *--------------------------------------------------------------------------*/
+/*!
+ * \brief   lheapCreate()
+ *
+ * \param[in]    n           size of ptr array to be alloc'd; use 0 for default
+ * \param[in]    direction   L_SORT_INCREASING, L_SORT_DECREASING
+ * \return  lheap, or NULL on error
+ */
+L_HEAP *
+lheapCreate(l_int32  n,
+            l_int32  direction)
+{
+L_HEAP  *lh;
+
+    if (n < InitialPtrArraySize || n > MaxPtrArraySize)
+        n = InitialPtrArraySize;
+
+        /* Allocate ptr array and initialize counters. */
+    lh = (L_HEAP *)LEPT_CALLOC(1, sizeof(L_HEAP));
+    if ((lh->array = (void **)LEPT_CALLOC(n, sizeof(void *))) == NULL) {
+        lheapDestroy(&lh, FALSE);
+        return (L_HEAP *)ERROR_PTR("ptr array not made", __func__, NULL);
+    }
+    lh->nalloc = n;
+    lh->n = 0;
+    lh->direction = direction;
+    return lh;
+}
+
+
+/*!
+ * \brief   lheapDestroy()
+ *
+ * \param[in,out]   plh        will be set to null before returning
+ * \param[in]       freeflag   TRUE to free each remaining struct in the array
+ * \return  void
+ *
+ * <pre>
+ * Notes:
+ *      (1) Use %freeflag == TRUE when the items in the array can be
+ *          simply destroyed using free.  If those items require their
+ *          own destroy function, they must be destroyed before
+ *          calling this function, and then this function is called
+ *          with %freeflag == FALSE.
+ *      (2) To destroy the lheap, we destroy the ptr array, then
+ *          the lheap, and then null the contents of the input ptr.
+ * </pre>
+ */
+void
+lheapDestroy(L_HEAP  **plh,
+             l_int32   freeflag)
+{
+l_int32  i;
+L_HEAP  *lh;
+
+    if (plh == NULL) {
+        L_WARNING("ptr address is NULL\n", __func__);
+        return;
+    }
+    if ((lh = *plh) == NULL)
+        return;
+
+    if (freeflag) {  /* free each struct in the array */
+        for (i = 0; i < lh->n; i++)
+            LEPT_FREE(lh->array[i]);
+    } else if (lh->n > 0) {  /* freeflag == FALSE but elements exist on array */
+        L_WARNING("memory leak of %d items in lheap!\n", __func__, lh->n);
+    }
+
+    if (lh->array)
+        LEPT_FREE(lh->array);
+    LEPT_FREE(lh);
+    *plh = NULL;
+}
+
+/*--------------------------------------------------------------------------*
+ *                Operations to add/remove to/from the heap                 *
+ *--------------------------------------------------------------------------*/
+/*!
+ * \brief   lheapAdd()
+ *
+ * \param[in]    lh      heap
+ * \param[in]    item    to be added to the tail of the heap
+ * \return  0 if OK, 1 on error
+ */
+l_ok
+lheapAdd(L_HEAP  *lh,
+         void    *item)
+{
+    if (!lh)
+        return ERROR_INT("lh not defined", __func__, 1);
+    if (!item)
+        return ERROR_INT("item not defined", __func__, 1);
+
+        /* If necessary, expand the allocated array by a factor of 2 */
+    if (lh->n >= lh->nalloc) {
+        if (lheapExtendArray(lh))
+            return ERROR_INT("extension failed", __func__, 1);
+    }
+
+        /* Add the item */
+    lh->array[lh->n] = item;
+    lh->n++;
+
+        /* Restore the heap */
+    lheapSwapUp(lh, lh->n - 1);
+    return 0;
+}
+
+
+/*!
+ * \brief   lheapExtendArray()
+ *
+ * \param[in]    lh    heap
+ * \return  0 if OK, 1 on error
+ */
+static l_int32
+lheapExtendArray(L_HEAP  *lh)
+{
+    if (!lh)
+        return ERROR_INT("lh not defined", __func__, 1);
+
+    if ((lh->array = (void **)reallocNew((void **)&lh->array,
+                                sizeof(void *) * lh->nalloc,
+                                2 * sizeof(void *) * lh->nalloc)) == NULL)
+        return ERROR_INT("new ptr array not returned", __func__, 1);
+
+    lh->nalloc = 2 * lh->nalloc;
+    return 0;
+}
+
+
+/*!
+ * \brief   lheapRemove()
+ *
+ * \param[in]    lh    heap
+ * \return  ptr to item popped from the root of the heap,
+ *              or NULL if the heap is empty or on error
+ */
+void *
+lheapRemove(L_HEAP  *lh)
+{
+void   *item;
+
+    if (!lh)
+        return (void *)ERROR_PTR("lh not defined", __func__, NULL);
+
+    if (lh->n == 0)
+        return NULL;
+
+    item = lh->array[0];
+    lh->array[0] = lh->array[lh->n - 1];  /* move last to the head */
+    lh->array[lh->n - 1] = NULL;  /* set ptr to null */
+    lh->n--;
+
+    lheapSwapDown(lh);  /* restore the heap */
+    return item;
+}
+
+
+/*--------------------------------------------------------------------------*
+ *                            Other accessors                               *
+ *--------------------------------------------------------------------------*/
+/*!
+ * \brief   lheapGetCount()
+ *
+ * \param[in]    lh    heap
+ * \return  count, or 0 on error
+ */
+l_int32
+lheapGetCount(L_HEAP  *lh)
+{
+    if (!lh)
+        return ERROR_INT("lh not defined", __func__, 0);
+
+    return lh->n;
+}
+
+
+/*!
+ * \brief   lheapGetElement()
+ *
+ * \param[in]    lh       heap
+ * \param[in]    index    into the internal heap array
+ * \return  ptr to the element at array[index], or NULL on error
+ *
+ * <pre>
+ * Notes:
+ *      (1) This is useful for retrieving an arbitrary element in the
+ *          heap array without disturbing the heap.  It allows all the
+ *          elements on the heap to be queried in linear time; for
+ *          example, to find the min or max of some value.
+ *      (2) The retrieved element is owned by the heap.  Do not destroy it.
+ * </pre>
+ */
+void *
+lheapGetElement(L_HEAP  *lh,
+                l_int32  index)
+{
+    if (!lh)
+        return ERROR_PTR("lh not defined", __func__, NULL);
+    if (index < 0 || index >= lh->n)
+        return ERROR_PTR("invalid index", __func__, NULL);
+
+    return (void *)lh->array[index];
+}
+
+
+/*--------------------------------------------------------------------------*
+ *                                 Heap sort                                *
+ *--------------------------------------------------------------------------*/
+/*!
+ * \brief   lheapSort()
+ *
+ * \param[in]    lh    heap, with internal array
+ * \return  0 if OK, 1 on error
+ *
+ * <pre>
+ * Notes:
+ *      (1) This sorts an array into heap order.  If the heap is already
+ *          in heap order for the direction given, this has no effect.
+ * </pre>
+ */
+l_ok
+lheapSort(L_HEAP  *lh)
+{
+l_int32  i;
+
+  if (!lh)
+      return ERROR_INT("lh not defined", __func__, 1);
+
+  for (i = 0; i < lh->n; i++)
+      lheapSwapUp(lh, i);
+
+  return 0;
+}
+
+
+/*!
+ * \brief   lheapSortStrictOrder()
+ *
+ * \param[in]    lh    heap, with internal array
+ * \return  0 if OK, 1 on error
+ *
+ * <pre>
+ * Notes:
+ *      (1) This sorts a heap into strict order.
+ *      (2) For each element, starting at the end of the array and
+ *          working forward, the element is swapped with the head
+ *          element and then allowed to swap down onto a heap of
+ *          size reduced by one.  The result is that the heap is
+ *          reversed but in strict order.  The array elements are
+ *          then reversed to put it in the original order.
+ * </pre>
+ */
+l_ok
+lheapSortStrictOrder(L_HEAP  *lh)
+{
+l_int32  i, index, size;
+
+  if (!lh)
+      return ERROR_INT("lh not defined", __func__, 1);
+
+      /* Start from a sorted heap */
+  lheapSort(lh);
+
+  size = lh->n;  /* save the actual size */
+  for (i = 0; i < size; i++) {
+      index = size - i;
+      SWAP_ITEMS(0, index - 1);
+      lh->n--;  /* reduce the apparent heap size by 1 */
+      lheapSwapDown(lh);
+  }
+  lh->n = size;  /* restore the size */
+
+  for (i = 0; i < size / 2; i++)  /* reverse */
+      SWAP_ITEMS(i, size - i - 1);
+
+  return 0;
+}
+
+
+/*--------------------------------------------------------------------------*
+ *                         Low-level heap operations                        *
+ *--------------------------------------------------------------------------*/
+/*!
+ * \brief   lheapSwapUp()
+ *
+ * \param[in]    lh      heap
+ * \param[in]    index   of array corresponding to node to be swapped up
+ * \return  0 if OK, 1 on error
+ *
+ * <pre>
+ * Notes:
+ *      (1) This is called after a new item is put on the heap, at the
+ *          bottom of a complete tree.
+ *      (2) To regain the heap order, we let it bubble up,
+ *          iteratively swapping with its parent, until it either
+ *          reaches the root of the heap or it finds a parent that
+ *          is in the correct position already vis-a-vis the child.
+ * </pre>
+ */
+static l_ok
+lheapSwapUp(L_HEAP  *lh,
+            l_int32  index)
+{
+l_int32    ip;  /* index to heap for parent; 1 larger than array index */
+l_int32    ic;  /* index into heap for child */
+l_float32  valp, valc;
+
+  if (!lh)
+      return ERROR_INT("lh not defined", __func__, 1);
+  if (index < 0 || index >= lh->n)
+      return ERROR_INT("invalid index", __func__, 1);
+
+  ic = index + 1;  /* index into heap: add 1 to array index */
+  if (lh->direction == L_SORT_INCREASING) {
+      while (1) {
+          if (ic == 1)  /* root of heap */
+              break;
+          ip = ic / 2;
+          valc = *(l_float32 *)(lh->array[ic - 1]);
+          valp = *(l_float32 *)(lh->array[ip - 1]);
+          if (valp <= valc)
+             break;
+          SWAP_ITEMS(ip - 1, ic - 1);
+          ic = ip;
+      }
+  } else {  /* lh->direction == L_SORT_DECREASING */
+      while (1) {
+          if (ic == 1)  /* root of heap */
+              break;
+          ip = ic / 2;
+          valc = *(l_float32 *)(lh->array[ic - 1]);
+          valp = *(l_float32 *)(lh->array[ip - 1]);
+          if (valp >= valc)
+             break;
+          SWAP_ITEMS(ip - 1, ic - 1);
+          ic = ip;
+      }
+  }
+  return 0;
+}
+
+
+/*!
+ * \brief   lheapSwapDown()
+ *
+ * \param[in]    lh   heap
+ * \return  0 if OK, 1 on error
+ *
+ * <pre>
+ * Notes:
+ *      (1) This is called after an item has been popped off the
+ *          root of the heap, and the last item in the heap has
+ *          been placed at the root.
+ *      (2) To regain the heap order, we let it bubble down,
+ *          iteratively swapping with one of its children.  For a
+ *          decreasing sort, it swaps with the largest child; for
+ *          an increasing sort, the smallest.  This continues until
+ *          it either reaches the lowest level in the heap, or the
+ *          parent finds that neither child should swap with it
+ *          (e.g., for a decreasing heap, the parent is larger
+ *          than or equal to both children).
+ * </pre>
+ */
+static l_ok
+lheapSwapDown(L_HEAP  *lh)
+{
+l_int32    ip;  /* index to heap for parent; 1 larger than array index */
+l_int32    icr, icl;  /* index into heap for left/right children */
+l_float32  valp, valcl, valcr;
+
+  if (!lh)
+      return ERROR_INT("lh not defined", __func__, 1);
+  if (lheapGetCount(lh) < 1)
+      return 0;
+
+  ip = 1;  /* index into top of heap: corresponds to array[0] */
+  if (lh->direction == L_SORT_INCREASING) {
+      while (1) {
+          icl = 2 * ip;
+          if (icl > lh->n)
+             break;
+          valp = *(l_float32 *)(lh->array[ip - 1]);
+          valcl = *(l_float32 *)(lh->array[icl - 1]);
+          icr = icl + 1;
+          if (icr > lh->n) {  /* only a left child; no iters below */
+              if (valp > valcl)
+                  SWAP_ITEMS(ip - 1, icl - 1);
+              break;
+          } else {  /* both children exist; swap with the smallest if bigger */
+              valcr = *(l_float32 *)(lh->array[icr - 1]);
+              if (valp <= valcl && valp <= valcr)  /* smaller than both */
+                  break;
+              if (valcl <= valcr) {  /* left smaller; swap */
+                  SWAP_ITEMS(ip - 1, icl - 1);
+                  ip = icl;
+              } else { /* right smaller; swap */
+                  SWAP_ITEMS(ip - 1, icr - 1);
+                  ip = icr;
+              }
+          }
+      }
+  } else {  /* lh->direction == L_SORT_DECREASING */
+      while (1) {
+          icl = 2 * ip;
+          if (icl > lh->n)
+             break;
+          valp = *(l_float32 *)(lh->array[ip - 1]);
+          valcl = *(l_float32 *)(lh->array[icl - 1]);
+          icr = icl + 1;
+          if (icr > lh->n) {  /* only a left child; no iters below */
+              if (valp < valcl)
+                  SWAP_ITEMS(ip - 1, icl - 1);
+              break;
+          } else {  /* both children exist; swap with the biggest if smaller */
+              valcr = *(l_float32 *)(lh->array[icr - 1]);
+              if (valp >= valcl && valp >= valcr)  /* bigger than both */
+                  break;
+              if (valcl >= valcr) {  /* left bigger; swap */
+                  SWAP_ITEMS(ip - 1, icl - 1);
+                  ip = icl;
+              } else {  /* right bigger; swap */
+                  SWAP_ITEMS(ip - 1, icr - 1);
+                  ip = icr;
+              }
+          }
+      }
+  }
+
+  return 0;
+}
+
+
+/*---------------------------------------------------------------------*
+ *                            Debug output                             *
+ *---------------------------------------------------------------------*/
+/*!
+ * \brief   lheapPrint()
+ *
+ * \param[in]    fp    file stream
+ * \param[in]    lh    heap
+ * \return  0 if OK; 1 on error
+ */
+l_ok
+lheapPrint(FILE    *fp,
+           L_HEAP  *lh)
+{
+l_int32  i;
+
+    if (!fp)
+        return ERROR_INT("stream not defined", __func__, 1);
+    if (!lh)
+        return ERROR_INT("lh not defined", __func__, 1);
+
+    fprintf(fp, "\n L_Heap: nalloc = %d, n = %d, array = %p\n",
+            lh->nalloc, lh->n, lh->array);
+    for (i = 0; i < lh->n; i++)
+        fprintf(fp,   "keyval[%d] = %f\n", i, *(l_float32 *)lh->array[i]);
+
+    return 0;
+}