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(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, 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                 j++;
  28                 if (++j >= size)
  29                         j = 0;
  30         }
  31         hash[j].base = base;
  32         hash[j].decoration = decoration;
  33         n->nr++;
  34         return NULL;
  35 }
  36
  37 static void grow_decoration(struct decoration *n)
  38 {
  39         int i;
  40         int old_size = n->size;
  41         struct object_decoration *old_hash;
  42
  43         old_size = n->size;
  44         old_hash = n->hash;
  45
  46         n->size = (old_size + 1000) * 3 / 2;
  47         n->hash = xcalloc(n->size, sizeof(struct object_decoration));
  48         n->nr = 0;
  49
  50         for (i = 0; i < old_size; i++) {
  51                 struct object *base = old_hash[i].base;
  52                 void *decoration = old_hash[i].decoration;
  53
  54                 if (!base)
  55                         continue;
  56                 insert_decoration(n, base, decoration);
  57         }
  58         free(old_hash);
  59 }
  60
  61 /* Add a decoration pointer, return any old one */
  62 void *add_decoration(struct decoration *n, struct object *obj, void *decoration)
  63 {
  64         int nr = n->nr + 1;
  65
  66         if (nr > n->size * 2 / 3)
  67                 grow_decoration(n);
  68         return insert_decoration(n, obj, decoration);
  69 }
  70
  71 /* Lookup a decoration pointer */
  72 void *lookup_decoration(struct decoration *n, struct object *obj)
  73 {
  74         int j;
  75
  76         /* nothing to lookup */
  77         if (!n->size)
  78                 return NULL;
  79         j = hash_obj(obj, n->size);
  80         for (;;) {
  81                 struct object_decoration *ref = n->hash + j;
  82                 if (ref->base == obj)
  83                         return ref->decoration;
  84                 if (!ref->base)
  85                         return NULL;
  86                 if (++j == n->size)
  87                         j = 0;
  88         }
  89 }