Merge branch 'ah/doc-submodule-ignore-submodules'
[git/git.git] / iterator.h
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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 */
30enum 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 */