decorate.c

   1 /*
   2  * decorate.c - decorate a git object with some arbitrary
   3  * data.
   4  */
   5 #include "cache.h"
   6 #include "object.h"
   7 #include "decorate.h"
   8
   9 static unsigned int hash_obj(const struct object *obj, unsigned int n)
  10 {
  11         return sha1hash(obj->oid.hash) % n;
  12 }
  13
  14 static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
  15 {
  16         int size = n->size;
  17         struct decoration_entry *entries = n->entries;
  18         unsigned int j = hash_obj(base, size);
  19
  20         while (entries[j].base) {
  21                 if (entries[j].base == base) {
  22                         void *old = entries[j].decoration;
  23                         entries[j].decoration = decoration;
  24                         return old;
  25                 }
  26                 if (++j >= size)
  27                         j = 0;
  28         }
  29         entries[j].base = base;
  30         entries[j].decoration = decoration;
  31         n->nr++;
  32         return NULL;
  33 }
  34
  35 static void grow_decoration(struct decoration *n)
  36 {
  37         int i;
  38         int old_size = n->size;
  39         struct decoration_entry *old_entries = n->entries;
  40
  41         n->size = (old_size + 1000) * 3 / 2;
  42         n->entries = xcalloc(n->size, sizeof(struct decoration_entry));
  43         n->nr = 0;
  44
  45         for (i = 0; i < old_size; i++) {
  46                 const struct object *base = old_entries[i].base;
  47                 void *decoration = old_entries[i].decoration;
  48
  49                 if (!decoration)
  50                         continue;
  51                 insert_decoration(n, base, decoration);
  52         }
  53         free(old_entries);
  54 }
  55
  56 void *add_decoration(struct decoration *n, const struct object *obj,
  57                 void *decoration)
  58 {
  59         int nr = n->nr + 1;
  60
  61         if (nr > n->size * 2 / 3)
  62                 grow_decoration(n);
  63         return insert_decoration(n, obj, decoration);
  64 }
  65
  66 void *lookup_decoration(struct decoration *n, const struct object *obj)
  67 {
  68         unsigned int j;
  69
  70         /* nothing to lookup */
  71         if (!n->size)
  72                 return NULL;
  73         j = hash_obj(obj, n->size);
  74         for (;;) {
  75                 struct decoration_entry *ref = n->entries + j;
  76                 if (ref->base == obj)
  77                         return ref->decoration;
  78                 if (!ref->base)
  79                         return NULL;
  80                 if (++j == n->size)
  81                         j = 0;
  82         }
  83 }