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	undo.h - ledit - Text editor (WIP)
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	undo.h (4580B)
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	1 #ifndef _UNDO_H_
	2 #define _UNDO_H_
	3
	4 #include <stddef.h>
	5 #include "common.h"
	6 #include "txtbuf.h"
	7
	8 /*
	9 * This handles undo and redo.
	10 *
	11 * Some things need to be explained:
	12 *
	13 * Each stack entry contains text, the text range, and the cursor range.
	14 * The text is the text that was inserted or deleted, the text range is
	15 * the exact line and byte range of the text before it was deleted or
	16 * after it was inserted. The cursor range stores the position of the
	17 * cursor before and after the operation so it can be restored.
	18 *
	19 * Each stack entry has a group, a mode group, and the actual mode store…
	20 * When pushing an operation onto the stack, start_group can be specifie…
	21 * If this is 0, the operation belongs together with the previous operat…
	22 * i.e. they will always be undone or redone together.
	23 * The current mode of the view is stored with each stack entry so that
	24 * all operations belonging to the last "session" in insert mode can be
	25 * undone together.
	26 * Additionally, undo_change_mode_group should be called when the mode of
	27 * the view is changed. This is needed to separate different insert sess…
	28 * so multiple sessions aren't undone together if the user just left ins…
	29 * mode and then returned immediately to insert mode without doing anyth…
	30 * in normal mode.
	31 */
	32
	33 typedef enum {
	34 UNDO_NORMAL,
	35 UNDO_OLDEST_CHANGE,
	36 UNDO_NEWEST_CHANGE
	37 } undo_status;
	38
	39 typedef struct undo_stack undo_stack;
	40
	41 /*
	42 * Callback used for inserting text.
	43 * This is called with (respectively) the given callback data, the line …
	44 * the byte index, the text, and the length of the text.
	45 */
	46 typedef void (undo_insert_callback)(void , size_t, size_t, char *, siz…
	47
	48 /*
	49 * Callback used for deleting text.
	50 * This is called with (respectively) the given callback data, the line …
	51 * byte index of the beginning of the range, and the line and byte index…
	52 * the end of the range.
	53 */
	54 typedef void (undo_delete_callback)(void , size_t, size_t, size_t, siz…
	55
	56 /*
	57 * Create an empty undo stack.
	58 */
	59 undo_stack *undo_stack_create(void);
	60
	61 /*
	62 * Destroy an undo stack.
	63 */
	64 void undo_stack_destroy(undo_stack *undo);
	65
	66 /*
	67 * Change the mode group.
	68 * This does not actually change the mode group yet, it just sets a bit
	69 * so the mode group is changed the next time an item is pushed on the s…
	70 */
	71 void undo_change_mode_group(undo_stack *undo);
	72
	73 /*
	74 * Push an insert action onto the undo stack.
	75 * See documentation at top for details on the other arguments.
	76 * 'text' is copied, so the original should be freed.
	77 */
	78 void undo_push_insert(
	79 undo_stack undo, txtbuf text,
	80 ledit_range insert_range, ledit_range cursor_range,
	81 int start_group, ledit_mode mode
	82 );
	83
	84 /*
	85 * Push an delete action onto the undo stack.
	86 * See documentation at top for details on the other arguments.
	87 * 'text' is copied, so the original should be freed.
	88 */
	89 void undo_push_delete(
	90 undo_stack undo, txtbuf text,
	91 ledit_range delete_range, ledit_range cursor_range,
	92 int start_group, ledit_mode mode
	93 );
	94
	95 /*
	96 * Undo one step.
	97 * 'cur_line_ret' and 'cur_index_ret' are set to the new cursor position.
	98 * 'min_line_ret' is set to the minimum line that was touched so the lin…
	99 * can be recalculated properly.
	100 * WARNING: If nothing was changed, 'min_line_ret' will be SIZE_MAX.
	101 */
	102 undo_status ledit_undo(
	103 undo_stack *undo, ledit_mode mode,
	104 void *callback_data, undo_insert_callback insert_cb, undo_delete_cal…
	105 size_t cur_line_ret, size_t cur_index_ret, size_t *min_line_ret
	106 );
	107
	108 /*
	109 * Redo one step.
	110 * 'cur_line_ret' and 'cur_index_ret' are set to the new cursor position.
	111 * 'min_line_ret' is set to the minimum line that was touched so the lin…
	112 * can be recalculated properly.
	113 * WARNING: If nothing was changed, 'min_line_ret' will be SIZE_MAX.
	114 */
	115 undo_status ledit_redo(
	116 undo_stack *undo, ledit_mode mode,
	117 void *callback_data, undo_insert_callback insert_cb, undo_delete_cal…
	118 size_t cur_line_ret, size_t cur_index_ret, size_t *min_line_ret
	119 );
	120
	121 /*
	122 * Change the cursor range stored for the last operation.
	123 * This is sort of a hack used by view_delete_range and some other
	124 * functions to set the cursor range later if it isn't known yet before
	125 * inserting/deleting text.
	126 * Fails silently if the stack is empty.
	127 */
	128 void undo_change_last_cur_range(undo_stack *undo, ledit_range cur_range);
	129
	130 /*
	131 * Get a string corresponding to an undo_status.
	132 * This string should not be freed.
	133 */
	134 char *undo_state_to_str(undo_status s);
	135
	136 #if TEST
	137 void dump_undo_stack(FILE file, undo_stack undo);
	138 #endif
	139
	140 #endif