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         unsigned int hash = *(unsigned int *)obj->sha1;
  12         return hash % n;
  13 }
  14
  15 static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
  16 {
  17         int size = n->size;
  18         struct object_decoration *hash = n->hash;
  19         int j = hash_obj(base, size);
  20
  21         while (hash[j].base) {
  22                 if (hash[j].base == base) {
  23                         void *old = hash[j].decoration;
  24                         hash[j].decoration = decoration;
  25                         return old;
  26                 }
  27                 if (++j >= size)
  28                         j = 0;
  29         }
  30         hash[j].base = base;
  31         hash[j].decoration = decoration;
  32         n->nr++;
  33         return NULL;
  34 }
  35
  36 static void grow_decoration(struct decoration *n)
  37 {
  38         int i;
  39         int old_size = n->size;
  40         struct object_decoration *old_hash = n->hash;
  41
  42         n->size = (old_size + 1000) * 3 / 2;
  43         n->hash = xcalloc(n->size, sizeof(struct object_decoration));
  44         n->nr = 0;
  45
  46         for (i = 0; i < old_size; i++) {
  47                 const struct object *base = old_hash[i].base;
  48                 void *decoration = old_hash[i].decoration;
  49
  50                 if (!base)
  51                         continue;
  52                 insert_decoration(n, base, decoration);
  53         }
  54         free(old_hash);
  55 }
  56
  57 /* Add a decoration pointer, return any old one */
  58 void *add_decoration(struct decoration *n, const struct object *obj,
  59                 void *decoration)
  60 {
  61         int nr = n->nr + 1;
  62
  63         if (nr > n->size * 2 / 3)
  64                 grow_decoration(n);
  65         return insert_decoration(n, obj, decoration);
  66 }
  67
  68 /* Lookup a decoration pointer */
  69 void *lookup_decoration(struct decoration *n, const struct object *obj)
  70 {
  71         int j;
  72
  73         /* nothing to lookup */
  74         if (!n->size)
  75                 return NULL;
  76         j = hash_obj(obj, n->size);
  77         for (;;) {
  78                 struct object_decoration *ref = n->hash + j;
  79                 if (ref->base == obj)
  80                         return ref->decoration;
  81                 if (!ref->base)
  82                         return NULL;
  83                 if (++j == n->size)
  84                         j = 0;
  85         }
  86 }