/*
 *	UNDO system
 *	Copyright
 *		(C) 1992 Joseph H. Allen
 *
 *	This file is part of JOE (Joe's Own Editor)
 */
#ifndef _JOE_UNDO_H
#define _JOE_UNDO_H 1

struct undorec {
	LINK(UNDOREC)	link;	/* Doubly-linked list of undo records */
	UNDOREC	*unit;		/* If this is first record of a unit: points to last.  If this is last record of a unit: points to first. */
	int	min;		/* Set to allow merging of undo information with this record (like to small inserts) */
	int	changed;	/* Status of modified flag before this record */
	long	where;		/* Buffer address of this record */
	long	len;		/* Length of insert or delete */
	int	del;		/* Set if this is a delete */
	B	*big;		/* Set to buffer containing a large amount of deleted data */
	unsigned char	*small;		/* Set to malloc block containg a small amount of deleted data */
};

struct undo {
	LINK(UNDO)	link;
	B	*b;
	int	nrecs;		/* Number of units */
	UNDOREC	recs;		/* The undo records: recs.link.prev is latest */
	UNDOREC	*ptr;		/* Pointer to latest "undone" record. */
	UNDOREC	*first;		/* Pointers to first and last records of a group.  The group is */
	UNDOREC	*last;		/* treated as a single undo record. */
};

extern int inundo; /* Set if inserts/deletes are part of an undo operation */
extern int justkilled; /* Last edit was a delete, so store data in yank buffer */

UNDO *undomk PARAMS((B *b));
void undorm PARAMS((UNDO *undo));
int uundo PARAMS((BW *bw));
int uredo PARAMS((BW *bw));
void umclear PARAMS((void)); /* Call this to finalize current undo records.  New changes will create new records. */
void undomark PARAMS((void));
void undoins PARAMS((UNDO *undo, P *p, long int size));
void undodel PARAMS((UNDO *undo, long int where, B *b));
int uyank PARAMS((BW *bw));
int uyankpop PARAMS((BW *bw));
int uyapp PARAMS((BW *bw));
int unotmod PARAMS((BW *bw));
int ucopy PARAMS((BW *bw));

void load_yank PARAMS((FILE *f));
void save_yank PARAMS((FILE *f));
void bw_unlock PARAMS((BW *bw));

extern int undo_keep;

#endif