diff options
Diffstat (limited to 'sha1-array.h')
| -rw-r--r-- | sha1-array.h | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/sha1-array.h b/sha1-array.h index 55d016c4bf7b..dc1bca9c9aea 100644 --- a/sha1-array.h +++ b/sha1-array.h @@ -1,6 +1,52 @@ #ifndef SHA1_ARRAY_H #define SHA1_ARRAY_H +/** + * The API provides storage and manipulation of sets of object identifiers. + * The emphasis is on storage and processing efficiency, making them suitable + * for large lists. Note that the ordering of items is not preserved over some + * operations. + * + * Examples + * -------- + * ----------------------------------------- + * int print_callback(const struct object_id *oid, + * void *data) + * { + * printf("%s\n", oid_to_hex(oid)); + * return 0; // always continue + * } + * + * void some_func(void) + * { + * struct sha1_array hashes = OID_ARRAY_INIT; + * struct object_id oid; + * + * // Read objects into our set + * while (read_object_from_stdin(oid.hash)) + * oid_array_append(&hashes, &oid); + * + * // Check if some objects are in our set + * while (read_object_from_stdin(oid.hash)) { + * if (oid_array_lookup(&hashes, &oid) >= 0) + * printf("it's in there!\n"); + * + * // Print the unique set of objects. We could also have + * // avoided adding duplicate objects in the first place, + * // but we would end up re-sorting the array repeatedly. + * // Instead, this will sort once and then skip duplicates + * // in linear time. + * + * oid_array_for_each_unique(&hashes, print_callback, NULL); + * } + */ + +/** + * A single array of object IDs. This should be initialized by assignment from + * `OID_ARRAY_INIT`. The `oid` member contains the actual data. The `nr` member + * contains the number of items in the set. The `alloc` and `sorted` members + * are used internally, and should not be needed by API callers. + */ struct oid_array { struct object_id *oid; int nr; @@ -10,18 +56,52 @@ struct oid_array { #define OID_ARRAY_INIT { NULL, 0, 0, 0 } +/** + * Add an item to the set. The object ID will be placed at the end of the array + * (but note that some operations below may lose this ordering). + */ void oid_array_append(struct oid_array *array, const struct object_id *oid); + +/** + * Perform a binary search of the array for a specific object ID. If found, + * returns the offset (in number of elements) of the object ID. If not found, + * returns a negative integer. If the array is not sorted, this function has + * the side effect of sorting it. + */ int oid_array_lookup(struct oid_array *array, const struct object_id *oid); + +/** + * Free all memory associated with the array and return it to the initial, + * empty state. + */ void oid_array_clear(struct oid_array *array); typedef int (*for_each_oid_fn)(const struct object_id *oid, void *data); +/** + * Iterate over each element of the list, executing the callback function for + * each one. Does not sort the list, so any custom hash order is retained. + * If the callback returns a non-zero value, the iteration ends immediately + * and the callback's return is propagated; otherwise, 0 is returned. + */ int oid_array_for_each(struct oid_array *array, for_each_oid_fn fn, void *data); + +/** + * Iterate over each unique element of the list in sorted order, but otherwise + * behave like `oid_array_for_each`. If the array is not sorted, this function + * has the side effect of sorting it. + */ int oid_array_for_each_unique(struct oid_array *array, for_each_oid_fn fn, void *data); + +/** + * Apply the callback function `want` to each entry in the array, retaining + * only the entries for which the function returns true. Preserve the order + * of the entries that are retained. + */ void oid_array_filter(struct oid_array *array, for_each_oid_fn want, void *cbdata); |