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#ifndef OID_ARRAY_H
#define OID_ARRAY_H
#include "hash.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 oid_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;
size_t nr;
size_t alloc;
int sorted;
};
#define OID_ARRAY_INIT { 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);
/**
* Sort the array in order of ascending object id.
*/
void oid_array_sort(struct oid_array *array);
/**
* Find the next unique oid in the array after position "cur".
* The array must be sorted for this to work. You can iterate
* over unique elements like this:
*
* size_t i;
* oid_array_sort(array);
* for (i = 0; i < array->nr; i = oid_array_next_unique(array, i))
* printf("%s", oid_to_hex(array->oids[i]);
*
* Non-unique iteration can just increment with "i++" to visit each element.
*/
static inline size_t oid_array_next_unique(struct oid_array *array, size_t cur)
{
do {
cur++;
} while (cur < array->nr &&
oideq(array->oid + cur, array->oid + cur - 1));
return cur;
}
#endif /* OID_ARRAY_H */