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 "runtime.h"
  11 #include "malloc.h"
  12 #include "go-alloc.h"
  13 #include "go-assert.h"
  14 #include "map.h"
  15
  16 /* Delete the entry matching KEY from MAP.  */
  17
  18 void
  19 __go_map_delete (struct __go_map *map, const void *key)
  20 {
  21   const struct __go_map_descriptor *descriptor;
  22   const struct __go_type_descriptor *key_descriptor;
  23   uintptr_t key_offset;
  24   _Bool (*equalfn) (const void*, const void*, uintptr_t);
  25   size_t key_hash;
  26   size_t key_size;
  27   size_t bucket_index;
  28   void **pentry;
  29
  30   if (map == NULL)
  31     return;
  32
  33   descriptor = map->__descriptor;
  34
  35   key_descriptor = descriptor->__map_descriptor->__key_type;
  36   key_offset = descriptor->__key_offset;
  37   key_size = key_descriptor->__size;
  38   __go_assert (key_size != 0 && key_size != -1UL);
  39   equalfn = key_descriptor->__equalfn;
  40
  41   key_hash = key_descriptor->__hashfn (key, key_size);
  42   bucket_index = key_hash % map->__bucket_count;
  43
  44   pentry = map->__buckets + bucket_index;
  45   while (*pentry != NULL)
  46     {
  47       char *entry = (char *) *pentry;
  48       if (equalfn (key, entry + key_offset, key_size))
  49         {
  50           *pentry = *(void **) entry;
  51           if (descriptor->__entry_size >= TinySize)
  52             __go_free (entry);
  53           map->__element_count -= 1;
  54           break;
  55         }
  56       pentry = (void **) entry;
  57     }
  58 }