libgo/runtime/go-map-delete.c

   1 /* go-map-delete.c -- delete an entry from a map.
   2
   3    Copyright 2009 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include <stddef.h>
   8 #include <stdlib.h>
   9
  10 #include "go-alloc.h"
  11 #include "go-assert.h"
  12 #include "map.h"
  13
  14 /* Delete the entry matching KEY from MAP.  */
  15
  16 void
  17 __go_map_delete (struct __go_map *map, const void *key)
  18 {
  19   const struct __go_map_descriptor *descriptor;
  20   const struct __go_type_descriptor *key_descriptor;
  21   size_t key_offset;
  22   _Bool (*equalfn) (const void*, const void*, size_t);
  23   size_t key_hash;
  24   size_t key_size;
  25   size_t bucket_index;
  26   void **pentry;
  27
  28   descriptor = map->__descriptor;
  29
  30   key_descriptor = descriptor->__map_descriptor->__key_type;
  31   key_offset = descriptor->__key_offset;
  32   key_size = key_descriptor->__size;
  33   __go_assert (key_size != 0 && key_size != -1UL);
  34   equalfn = key_descriptor->__equalfn;
  35
  36   key_hash = key_descriptor->__hashfn (key, key_size);
  37   bucket_index = key_hash % map->__bucket_count;
  38
  39   pentry = map->__buckets + bucket_index;
  40   while (*pentry != NULL)
  41     {
  42       char *entry = (char *) *pentry;
  43       if (equalfn (key, entry + key_offset, key_size))
  44         {
  45           *pentry = *(void **) entry;
  46           __go_free (entry);
  47           map->__element_count -= 1;
  48           break;
  49         }
  50       pentry = (void **) entry;
  51     }
  52 }