[thirdparty/git.git] / iterator.h

#ifndef ITERATOR_H
#define ITERATOR_H

/*
 * Generic constants related to iterators.
 */

/*
 * The attempt to advance the iterator was successful; the iterator
 * reflects the new current entry.
 */
#define ITER_OK 0

/*
 * The iterator is exhausted and has been freed.
 */
#define ITER_DONE -1

/*
 * The iterator experienced an error. The iteration has been aborted
 * and the iterator has been freed.
 */
#define ITER_ERROR -2

/*
 * Return values for selector functions for merge iterators. The
 * numerical values of these constants are important and must be
 * compatible with ITER_DONE and ITER_ERROR.
 */
enum iterator_selection {
	/* End the iteration without an error: */
	ITER_SELECT_DONE = ITER_DONE,

	/* Report an error and abort the iteration: */
	ITER_SELECT_ERROR = ITER_ERROR,

	/*
	 * The next group of constants are masks that are useful
	 * mainly internally.
	 */

	/* The LSB selects whether iter0/iter1 is the "current" iterator: */
	ITER_CURRENT_SELECTION_MASK = 0x01,

	/* iter0 is the "current" iterator this round: */
	ITER_CURRENT_SELECTION_0 = 0x00,

	/* iter1 is the "current" iterator this round: */
	ITER_CURRENT_SELECTION_1 = 0x01,

	/* Yield the value from the current iterator? */
	ITER_YIELD_CURRENT = 0x02,

	/* Discard the value from the secondary iterator? */
	ITER_SKIP_SECONDARY = 0x04,

	/*
	 * The constants that a selector function should usually
	 * return.
	 */

	/* Yield the value from iter0: */
	ITER_SELECT_0 = ITER_CURRENT_SELECTION_0 | ITER_YIELD_CURRENT,

	/* Yield the value from iter0 and discard the one from iter1: */
	ITER_SELECT_0_SKIP_1 = ITER_SELECT_0 | ITER_SKIP_SECONDARY,

	/* Discard the value from iter0 without yielding anything this round: */
	ITER_SKIP_0 = ITER_CURRENT_SELECTION_1 | ITER_SKIP_SECONDARY,

	/* Yield the value from iter1: */
	ITER_SELECT_1 = ITER_CURRENT_SELECTION_1 | ITER_YIELD_CURRENT,

	/* Yield the value from iter1 and discard the one from iter0: */
	ITER_SELECT_1_SKIP_0 = ITER_SELECT_1 | ITER_SKIP_SECONDARY,

	/* Discard the value from iter1 without yielding anything this round: */
	ITER_SKIP_1 = ITER_CURRENT_SELECTION_0 | ITER_SKIP_SECONDARY
};

#endif /* ITERATOR_H */
Commit	Line	Data
3bc581b9 MH	1	#ifndef ITERATOR_H
	2	#define ITERATOR_H
	3
	4	/*
	5	* Generic constants related to iterators.
	6	*/
	7
	8	/*
	9	* The attempt to advance the iterator was successful; the iterator
	10	* reflects the new current entry.
	11	*/
	12	#define ITER_OK 0
	13
	14	/*
	15	* The iterator is exhausted and has been freed.
	16	*/
	17	#define ITER_DONE -1
	18
	19	/*
	20	* The iterator experienced an error. The iteration has been aborted
	21	* and the iterator has been freed.
	22	*/
	23	#define ITER_ERROR -2
	24
	25	/*
	26	* Return values for selector functions for merge iterators. The
	27	* numerical values of these constants are important and must be
	28	* compatible with ITER_DONE and ITER_ERROR.
	29	*/
	30	enum iterator_selection {
	31	/* End the iteration without an error: */
	32	ITER_SELECT_DONE = ITER_DONE,
	33
	34	/* Report an error and abort the iteration: */
	35	ITER_SELECT_ERROR = ITER_ERROR,
	36
	37	/*
	38	* The next group of constants are masks that are useful
	39	* mainly internally.
	40	*/
	41
	42	/* The LSB selects whether iter0/iter1 is the "current" iterator: */
	43	ITER_CURRENT_SELECTION_MASK = 0x01,
	44
	45	/* iter0 is the "current" iterator this round: */
	46	ITER_CURRENT_SELECTION_0 = 0x00,
	47
	48	/* iter1 is the "current" iterator this round: */
	49	ITER_CURRENT_SELECTION_1 = 0x01,
	50
	51	/* Yield the value from the current iterator? */
	52	ITER_YIELD_CURRENT = 0x02,
	53
	54	/* Discard the value from the secondary iterator? */
	55	ITER_SKIP_SECONDARY = 0x04,
	56
	57	/*
	58	* The constants that a selector function should usually
	59	* return.
	60	*/
	61
	62	/* Yield the value from iter0: */
	63	ITER_SELECT_0 = ITER_CURRENT_SELECTION_0 \| ITER_YIELD_CURRENT,
	64
65	/* Yield the value from iter0 and discard the one from iter1: */
66	ITER_SELECT_0_SKIP_1 = ITER_SELECT_0 \| ITER_SKIP_SECONDARY,
67
68	/* Discard the value from iter0 without yielding anything this round: */
69	ITER_SKIP_0 = ITER_CURRENT_SELECTION_1 \| ITER_SKIP_SECONDARY,
70
71	/* Yield the value from iter1: */
72	ITER_SELECT_1 = ITER_CURRENT_SELECTION_1 \| ITER_YIELD_CURRENT,
73
74	/* Yield the value from iter1 and discard the one from iter0: */
75	ITER_SELECT_1_SKIP_0 = ITER_SELECT_1 \| ITER_SKIP_SECONDARY,
76
77	/* Discard the value from iter1 without yielding anything this round: */
78	ITER_SKIP_1 = ITER_CURRENT_SELECTION_0 \| ITER_SKIP_SECONDARY
79	};
80
81	#endif /* ITERATOR_H */