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/*
libuundo - micro-undo, a small, callback based undo/redo list implementation
Copyright (C) 2017 Tibor 'Igor2' Palinkas
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Author: libuundo [+at+] igor2.repo.hu
VCS: svn://repo.hu/libuundo/trunk
Web: http://repo.hu/projects/libuundo
*/
#ifndef UUNDO_H
#define UUNDO_H
#include <stddef.h>
typedef struct uundo_list_s uundo_list_t; /* list of undoable actions */
typedef struct uundo_item_s uundo_item_t; /* an item on the list */
typedef struct uundo_oper_s uundo_oper_t; /* operator: user provided function pointers for handling an item */
/* serial number type */
typedef long uundo_serial_t;
#define UUNDO_SERIAL_INVALID (-1)
struct uundo_oper_s {
const char *cookie; /* plugin cookie; always matched as pointer, not as string */
void (*item_free)(void *udata); /* free fields of the undo slot */
int (*item_undo)(void *udata); /* perform undo (don't free slot fields); return 0 on success */
int (*item_redo)(void *udata); /* perform redo (don't free slot fields); return 0 on success */
void (*item_print)(void *udata, char *dst, size_t dst_len); /* debug: print the operator and operands in dst */
};
struct uundo_item_s {
uundo_serial_t serial;
const uundo_oper_t *oper;
uundo_item_t *prev, *next; /* doubly linked list of items */
char udata[1]; /* "flexible-size array" (C89-style); data for the callbacks start here */
};
struct uundo_list_s {
uundo_serial_t serial;
uundo_serial_t saved_serial;
size_t num_undo; /* number of slots on the list (up to tail) */
size_t num_redo; /* number of redo items on the list (beyond tail) */
uundo_item_t *head; /* oldest item */
uundo_item_t *tail; /* newest item; an undo will undo this; the list may extend beyond this item (for redo) */
unsigned long freeze_serial; /* when non-zero, don't change the serial */
unsigned long freeze_add; /* when non-zero, do not store new items */
uundo_item_t *frozen; /* temporary items added under freeze_add */
};
/*** list management ***/
/* Initialize a previously uninitialized list lst; result is an empty list */
void uundo_list_init(uundo_list_t *lst);
/* Clear a previously initialized list lst (free undo slots); result is an empty list */
void uundo_list_clear(uundo_list_t *lst);
/* Clear a previously initialized list lst (free undo slots) */
void uundo_list_uninit(uundo_list_t *lst);
/* Clear the redo section */
void uundo_list_truncate_redo(uundo_list_t *lst);
/* Clear items from the sfirst serial (inclusive) to the tail of the list;
also clears the redo section. */
void uundo_list_truncate_from(uundo_list_t *lst, uundo_serial_t sfirst);
/* Search the undo list from tail back for a cookie; returns the first serial
that references the cookie or -1 if no item references the cookie */
uundo_serial_t uundo_list_find_cookie(uundo_list_t *lst, const char *cookie);
/*** undo/redo ***/
/* Allocate a new undo item at tail; clears the redo section; returns the new
item's udata, allocated to be data_len bytes long */
void *uundo_append(uundo_list_t *lst, const uundo_oper_t *oper, size_t data_len);
/* Performs undo of all items with the highest serial number */
int uundo_undo(uundo_list_t *lst);
/* Performs undo of all items with serial number higher than s_min */
int uundo_undo_above(uundo_list_t *lst, uundo_serial_t s_min);
/* Performs redo of all items with the lowest redoable serial number */
int uundo_redo(uundo_list_t *lst);
/* Performs redo of all redoable items with serial number lower than s_till */
int uundo_redo_below(uundo_list_t *lst, uundo_serial_t s_till);
/*** serial management ***/
/* Save or restore serial number for bundling actions under a single serial number */
#define uundo_inc_serial(lst) \
do { \
if (!((lst)->freeze_serial)) \
(lst)->serial++; \
} while(0) \
#define uundo_save_serial(lst) \
do { \
if (!((lst)->freeze_serial)) \
(lst)->saved_serial = (lst)->serial; \
} while(0) \
#define uundo_restore_serial(lst) \
do { \
if (!((lst)->freeze_serial)) \
(lst)->serial = (lst)->saved_serial; \
} while(0) \
#define uundo_freeze_serial(lst) (lst)->freeze_serial++
#define uundo_unfreeze_serial(lst) \
do { \
if (((lst)->freeze_serial) > 0) \
(lst)->freeze_serial--; \
} while(0) \
/*** add freeze management ***/
#define uundo_freeze_add(lst) (lst)->freeze_add++
#define uundo_unfreeze_add(lst) \
do { \
if (((lst)->freeze_add) > 0) { \
(lst)->freeze_add--; \
if (((lst)->freeze_add) == 0) \
uundo_flush_frozen(lst); \
} \
} while(0) \
/* Internal call: free all frozen temp storage records */
void uundo_flush_frozen(uundo_list_t *lst);
#endif
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