oidset.h

   1 #ifndef OIDSET_H
   2 #define OIDSET_H
   3
   4 #include "khash.h"
   5
   6 /**
   7  * This API is similar to sha1-array, in that it maintains a set of object ids
   8  * in a memory-efficient way. The major differences are:
   9  *
  10  *   1. It uses a hash, so we can do online duplicate removal, rather than
  11  *      sort-and-uniq at the end. This can reduce memory footprint if you have
  12  *      a large list of oids with many duplicates.
  13  *
  14  *   2. The per-unique-oid memory footprint is slightly higher due to hash
  15  *      table overhead.
  16  */
  17
  18 /**
  19  * A single oidset; should be zero-initialized (or use OIDSET_INIT).
  20  */
  21 struct oidset {
  22         kh_oid_set_t set;
  23 };
  24
  25 #define OIDSET_INIT { { 0 } }
  26
  27
  28 /**
  29  * Initialize the oidset structure `set`.
  30  *
  31  * If `initial_size` is bigger than 0 then preallocate to allow inserting
  32  * the specified number of elements without further allocations.
  33  */
  34 void oidset_init(struct oidset *set, size_t initial_size);
  35
  36 /**
  37  * Returns true iff `set` contains `oid`.
  38  */
  39 int oidset_contains(const struct oidset *set, const struct object_id *oid);
  40
  41 /**
  42  * Insert the oid into the set; a copy is made, so "oid" does not need
  43  * to persist after this function is called.
  44  *
  45  * Returns 1 if the oid was already in the set, 0 otherwise. This can be used
  46  * to perform an efficient check-and-add.
  47  */
  48 int oidset_insert(struct oidset *set, const struct object_id *oid);
  49
  50 /**
  51  * Remove the oid from the set.
  52  *
  53  * Returns 1 if the oid was present in the set, 0 otherwise.
  54  */
  55 int oidset_remove(struct oidset *set, const struct object_id *oid);
  56
  57 /**
  58  * Remove all entries from the oidset, freeing any resources associated with
  59  * it.
  60  */
  61 void oidset_clear(struct oidset *set);
  62
  63 /**
  64  * Add the contents of the file 'path' to an initialized oidset.  Each line is
  65  * an unabbreviated object name.  Comments begin with '#', and trailing comments
  66  * are allowed.  Leading whitespace and empty or white-space only lines are
  67  * ignored.
  68  */
  69 void oidset_parse_file(struct oidset *set, const char *path);
  70
  71 struct oidset_iter {
  72         kh_oid_set_t *set;
  73         khiter_t iter;
  74 };
  75
  76 static inline void oidset_iter_init(struct oidset *set,
  77                                     struct oidset_iter *iter)
  78 {
  79         iter->set = &set->set;
  80         iter->iter = kh_begin(iter->set);
  81 }
  82
  83 static inline struct object_id *oidset_iter_next(struct oidset_iter *iter)
  84 {
  85         for (; iter->iter != kh_end(iter->set); iter->iter++) {
  86                 if (kh_exist(iter->set, iter->iter))
  87                         return &kh_key(iter->set, iter->iter++);
  88         }
  89         return NULL;
  90 }
  91
  92 static inline struct object_id *oidset_iter_first(struct oidset *set,
  93                                                   struct oidset_iter *iter)
  94 {
  95         oidset_iter_init(set, iter);
  96         return oidset_iter_next(iter);
  97 }
  98
  99 #endif /* OIDSET_H */