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 "go-panic.h"
  13 #include "map.h"
  14
  15 /* Delete the entry matching KEY from MAP.  */
  16
  17 void
  18 __go_map_delete (struct __go_map *map, const void *key)
  19 {
  20   const struct __go_map_descriptor *descriptor;
  21   const struct __go_type_descriptor *key_descriptor;
  22   uintptr_t key_offset;
  23   _Bool (*equalfn) (const void*, const void*, size_t);
  24   size_t key_hash;
  25   size_t key_size;
  26   size_t bucket_index;
  27   void **pentry;
  28
  29   if (map == NULL)
  30     __go_panic_msg ("assignment to entry in nil map");
  31
  32   descriptor = map->__descriptor;
  33
  34   key_descriptor = descriptor->__map_descriptor->__key_type;
  35   key_offset = descriptor->__key_offset;
  36   key_size = key_descriptor->__size;
  37   __go_assert (key_size != 0 && key_size != -1UL);
  38   equalfn = key_descriptor->__equalfn;
  39
  40   key_hash = key_descriptor->__hashfn (key, key_size);
  41   bucket_index = key_hash % map->__bucket_count;
  42
  43   pentry = map->__buckets + bucket_index;
  44   while (*pentry != NULL)
  45     {
  46       char *entry = (char *) *pentry;
  47       if (equalfn (key, entry + key_offset, key_size))
  48         {
  49           *pentry = *(void **) entry;
  50           __go_free (entry);
  51           map->__element_count -= 1;
  52           break;
  53         }
  54       pentry = (void **) entry;
  55     }
  56 }