/ocr/ocrservice/jni/hydrogen/include/leptonica/queue.h

 1/*====================================================================*
 2 -  Copyright (C) 2001 Leptonica.  All rights reserved.
 3 -  This software is distributed in the hope that it will be
 4 -  useful, but with NO WARRANTY OF ANY KIND.
 5 -  No author or distributor accepts responsibility to anyone for the
 6 -  consequences of using this software, or for whether it serves any
 7 -  particular purpose or works at all, unless he or she says so in
 8 -  writing.  Everyone is granted permission to copy, modify and
 9 -  redistribute this source code, for commercial or non-commercial
10 -  purposes, with the following restrictions: (1) the origin of this
11 -  source code must not be misrepresented; (2) modified versions must
12 -  be plainly marked as such; and (3) this notice may not be removed
13 -  or altered from any source or modified source distribution.
14 *====================================================================*/
15
16#ifndef  LEPTONICA_QUEUE_H
17#define  LEPTONICA_QUEUE_H
18
19/*
20 *  queue.h
21 *
22 *      Expandable pointer queue for arbitrary void* data.
23 *
24 *      The L_Queue is a fifo that implements a queue of void* pointers.
25 *      It can be used to hold a queue of any type of struct.
26 *
27 *      Internally, it maintains two counters:
28 *          nhead:  location of head (in ptrs) from the beginning
29 *                  of the array.
30 *          nelem:  number of ptr elements stored in the queue.
31 *
32 *      The element at the head of the queue, which is the next to
33 *      be removed, is array[nhead].  The location at the tail of the
34 *      queue to which the next element will be added is
35 *      array[nhead + nelem].
36 *               
37 *      As items are added to the queue, nelem increases.
38 *      As items are removed, nhead increases and nelem decreases.
39 *      Any time the tail reaches the end of the allocated array,
40 *      all the pointers are shifted to the left, so that the head
41 *      is at the beginning of the array.
42 *      If the array becomes more than 3/4 full, it doubles in size.
43 *
44 *      The auxiliary stack can be used in a wrapper for re-using
45 *      items popped from the queue.  It is not made by default.
46 *
47 *      For further implementation details, see queue.c.
48 */
49
50struct L_Queue
51{
52    l_int32          nalloc;     /* size of allocated ptr array            */
53    l_int32          nhead;      /* location of head (in ptrs) from the    */
54                                 /* beginning of the array                 */
55    l_int32          nelem;      /* number of elements stored in the queue */
56    void           **array;      /* ptr array                              */
57    struct L_Stack  *stack;      /* auxiliary stack                        */
58
59};
60typedef struct L_Queue L_QUEUE;
61
62
63#endif  /* LEPTONICA_QUEUE_H */