| |
| /*====================================================================* |
| - Copyright (C) 2001 Leptonica. All rights reserved. |
| - This software is distributed in the hope that it will be |
| - useful, but with NO WARRANTY OF ANY KIND. |
| - No author or distributor accepts responsibility to anyone for the |
| - consequences of using this software, or for whether it serves any |
| - particular purpose or works at all, unless he or she says so in |
| - writing. Everyone is granted permission to copy, modify and |
| - redistribute this source code, for commercial or non-commercial |
| - purposes, with the following restrictions: (1) the origin of this |
| - source code must not be misrepresented; (2) modified versions must |
| - be plainly marked as such; and (3) this notice may not be removed |
| - or altered from any source or modified source distribution. |
| *====================================================================*/ |
| |
| #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 */ |