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   1#ifndef OIDSET_H
   2#define OIDSET_H
   3
   4#include "hashmap.h"
   5#include "khash.h"
   6
   7/**
   8 * This API is similar to sha1-array, in that it maintains a set of object ids
   9 * in a memory-efficient way. The major differences are:
  10 *
  11 *   1. It uses a hash, so we can do online duplicate removal, rather than
  12 *      sort-and-uniq at the end. This can reduce memory footprint if you have
  13 *      a large list of oids with many duplicates.
  14 *
  15 *   2. The per-unique-oid memory footprint is slightly higher due to hash
  16 *      table overhead.
  17 */
  18
  19/**
  20 * A single oidset; should be zero-initialized (or use OIDSET_INIT).
  21 */
  22struct oidset {
  23        kh_oid_t set;
  24};
  25
  26#define OIDSET_INIT { { 0 } }
  27
  28
  29/**
  30 * Initialize the oidset structure `set`.
  31 *
  32 * If `initial_size` is bigger than 0 then preallocate to allow inserting
  33 * the specified number of elements without further allocations.
  34 */
  35void oidset_init(struct oidset *set, size_t initial_size);
  36
  37/**
  38 * Returns true iff `set` contains `oid`.
  39 */
  40int oidset_contains(const struct oidset *set, const struct object_id *oid);
  41
  42/**
  43 * Insert the oid into the set; a copy is made, so "oid" does not need
  44 * to persist after this function is called.
  45 *
  46 * Returns 1 if the oid was already in the set, 0 otherwise. This can be used
  47 * to perform an efficient check-and-add.
  48 */
  49int oidset_insert(struct oidset *set, const struct object_id *oid);
  50
  51/**
  52 * Remove the oid from the set.
  53 *
  54 * Returns 1 if the oid was present in the set, 0 otherwise.
  55 */
  56int oidset_remove(struct oidset *set, const struct object_id *oid);
  57
  58/**
  59 * Remove all entries from the oidset, freeing any resources associated with
  60 * it.
  61 */
  62void oidset_clear(struct oidset *set);
  63
  64struct oidset_iter {
  65        kh_oid_t *set;
  66        khiter_t iter;
  67};
  68
  69static inline void oidset_iter_init(struct oidset *set,
  70                                    struct oidset_iter *iter)
  71{
  72        iter->set = &set->set;
  73        iter->iter = kh_begin(iter->set);
  74}
  75
  76static inline struct object_id *oidset_iter_next(struct oidset_iter *iter)
  77{
  78        for (; iter->iter != kh_end(iter->set); iter->iter++) {
  79                if (kh_exist(iter->set, iter->iter))
  80                        return &kh_key(iter->set, iter->iter++);
  81        }
  82        return NULL;
  83}
  84
  85static inline struct object_id *oidset_iter_first(struct oidset *set,
  86                                                  struct oidset_iter *iter)
  87{
  88        oidset_iter_init(set, iter);
  89        return oidset_iter_next(iter);
  90}
  91
  92#endif /* OIDSET_H */