third-party/leptonica/src/list.h
/*====================================================================*
- 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_LIST_H
#define LEPTONICA_LIST_H
/*
* list.h
*
* Cell for double-linked lists
*
* This allows composition of a list of cells with
* prev, next and data pointers. Generic data
* structures hang on the list cell data pointers.
*
* The list is not circular because that would add much
* complexity in traversing the list under general
* conditions where list cells can be added and removed.
* The only disadvantage of not having the head point to
* the last cell is that the list must be traversed to
* find its tail. However, this traversal is fast, and
* the listRemoveFromTail() function updates the tail
* so there is no searching overhead with repeated use.
*
* The list macros are used to run through a list, and their
* use is encouraged. They are invoked, e.g., as
*
* DLLIST *head, *elem;
* ...
* L_BEGIN_LIST_FORWARD(head, elem)
* <do something with elem and/or elem->data >
* L_END_LIST
*
*/
struct DoubleLinkedList
{
struct DoubleLinkedList *prev;
struct DoubleLinkedList *next;
void *data;
};
typedef struct DoubleLinkedList DLLIST;
/* Simple list traverse macros */
#define L_BEGIN_LIST_FORWARD(head, element) \
{ \
DLLIST *_leptvar_nextelem_; \
for ((element) = (head); (element); (element) = _leptvar_nextelem_) { \
_leptvar_nextelem_ = (element)->next;
#define L_BEGIN_LIST_REVERSE(tail, element) \
{ \
DLLIST *_leptvar_prevelem_; \
for ((element) = (tail); (element); (element) = _leptvar_prevelem_) { \
_leptvar_prevelem_ = (element)->prev;
#define L_END_LIST }}
#endif /* LEPTONICA_LIST_H */