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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libobjc/] [hash.c] - Blame information for rev 800

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1 739 jeremybenn
/* Hash tables for Objective C internal structures
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   Copyright (C) 1993, 1996, 1997, 2004, 2009, 2010
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   Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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GNU General Public License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
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<http://www.gnu.org/licenses/>.  */
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#include "objc-private/common.h"
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#include <assert.h>               /* For assert.  */
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#include "objc/runtime.h"         /* For objc_calloc.  */
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#include "objc-private/hash.h"
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/* These two macros determine when a hash table is full and
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   by how much it should be expanded respectively.
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   These equations are percentages.  */
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#define FULLNESS(cache) \
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   ((((cache)->size * 75) / 100) <= (cache)->used)
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#define EXPANSION(cache) \
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  ((cache)->size * 2)
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cache_ptr
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objc_hash_new (unsigned int size, hash_func_type hash_func,
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               compare_func_type compare_func)
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{
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  cache_ptr cache;
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  /* Pass me a value greater than 0 and a power of 2.  */
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  assert (size);
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  assert (! (size & (size - 1)));
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  /* Allocate the cache structure.  calloc insures its initialization
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     for default values.  */
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  cache = (cache_ptr) objc_calloc (1, sizeof (struct cache));
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  assert (cache);
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  /* Allocate the array of buckets for the cache.  calloc initializes
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     all of the pointers to NULL.  */
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  cache->node_table
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    = (node_ptr *) objc_calloc (size, sizeof (node_ptr));
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  assert (cache->node_table);
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  cache->size  = size;
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  /* This should work for all processor architectures (?).  */
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  cache->mask = (size - 1);
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  /* Store the hashing function so that codes can be computed.  */
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  cache->hash_func = hash_func;
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  /* Store the function that compares hash keys to determine if they
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     are equal.  */
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  cache->compare_func = compare_func;
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  return cache;
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}
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void
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objc_hash_delete (cache_ptr cache)
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{
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  node_ptr node;
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  node_ptr next_node;
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  unsigned int i;
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  /* Purge all key/value pairs from the table.  */
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  /* Step through the nodes one by one and remove every node WITHOUT
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     using objc_hash_next. this makes objc_hash_delete much more
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     efficient. */
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  for (i = 0; i < cache->size; i++)
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    {
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      if ((node = cache->node_table[i]))
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        {
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          /* An entry in the hash table has been found.  Now step
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             through the nodes next in the list and free them.  */
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          while ((next_node = node->next))
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            {
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              objc_hash_remove (cache,node->key);
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              node = next_node;
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            }
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          objc_hash_remove (cache,node->key);
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        }
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    }
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  /* Release the array of nodes and the cache itself.  */
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  objc_free(cache->node_table);
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  objc_free(cache);
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}
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void
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objc_hash_add (cache_ptr *cachep, const void *key, void *value)
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{
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  size_t indx = (*(*cachep)->hash_func) (*cachep, key);
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  node_ptr node = (node_ptr) objc_calloc (1, sizeof (struct cache_node));
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  assert (node);
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  /* Initialize the new node.  */
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  node->key    = key;
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  node->value  = value;
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  node->next  = (*cachep)->node_table[indx];
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  /* Debugging.  Check the list for another key.  */
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#ifdef DEBUG
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  {
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    node_ptr node1 = (*cachep)->node_table[indx];
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    while (node1)
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      {
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        assert (node1->key != key);
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        node1 = node1->next;
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      }
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  }
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#endif
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  /* Install the node as the first element on the list.  */
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  (*cachep)->node_table[indx] = node;
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  /* Bump the number of entries in the cache.  */
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  ++(*cachep)->used;
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  /* Check the hash table's fullness.  We're going to expand if it is
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     above the fullness level.  */
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  if (FULLNESS (*cachep))
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    {
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      /* The hash table has reached its fullness level.  Time to
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         expand it.
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         I'm using a slow method here but is built on other primitive
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         functions thereby increasing its correctness.  */
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      node_ptr node1 = NULL;
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      cache_ptr new = objc_hash_new (EXPANSION (*cachep),
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                                     (*cachep)->hash_func,
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                                     (*cachep)->compare_func);
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      DEBUG_PRINTF ("Expanding cache %#x from %d to %d\n",
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                    (int) *cachep, (*cachep)->size, new->size);
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      /* Copy the nodes from the first hash table to the new one.  */
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      while ((node1 = objc_hash_next (*cachep, node1)))
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        objc_hash_add (&new, node1->key, node1->value);
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      /* Trash the old cache.  */
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      objc_hash_delete (*cachep);
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      /* Return a pointer to the new hash table.  */
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      *cachep = new;
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    }
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}
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void
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objc_hash_remove (cache_ptr cache, const void *key)
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{
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  size_t indx = (*cache->hash_func) (cache, key);
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  node_ptr node = cache->node_table[indx];
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  /* We assume there is an entry in the table.  Error if it is
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     not.  */
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  assert (node);
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  /* Special case.  First element is the key/value pair to be
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     removed.  */
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  if ((*cache->compare_func) (node->key, key))
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    {
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      cache->node_table[indx] = node->next;
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      objc_free(node);
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    }
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  else
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    {
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      /* Otherwise, find the hash entry.  */
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      node_ptr prev = node;
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      BOOL removed = NO;
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      do
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        {
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          if ((*cache->compare_func) (node->key, key))
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            {
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              prev->next = node->next, removed = YES;
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              objc_free(node);
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            }
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          else
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            prev = node, node = node->next;
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        }
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      while (!removed && node);
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      assert (removed);
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    }
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  /* Decrement the number of entries in the hash table.  */
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  --cache->used;
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}
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node_ptr
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objc_hash_next (cache_ptr cache, node_ptr node)
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{
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  /* If the scan is being started then reset the last node visitied
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     pointer and bucket index.  */
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  if (!node)
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    cache->last_bucket  = 0;
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  /* If there is a node visited last then check for another entry in
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     the same bucket.  Otherwise step to the next bucket.  */
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  if (node)
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    {
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      if (node->next)
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        {
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          /* There is a node which follows the last node returned.
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             Step to that node and retun it.  */
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          return node->next;
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        }
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      else
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        ++cache->last_bucket;
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  }
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  /* If the list isn't exhausted then search the buckets for other
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     nodes.  */
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  if (cache->last_bucket < cache->size)
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    {
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      /*  Scan the remainder of the buckets looking for an entry at
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          the head of the list.  Return the first item found.  */
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      while (cache->last_bucket < cache->size)
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        if (cache->node_table[cache->last_bucket])
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          return cache->node_table[cache->last_bucket];
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        else
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          ++cache->last_bucket;
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      /* No further nodes were found in the hash table.  */
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      return NULL;
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    }
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  else
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    return NULL;
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}
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/* Given KEY, return corresponding value for it in CACHE.  Return NULL
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   if the KEY is not recorded.  */
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void *
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objc_hash_value_for_key (cache_ptr cache, const void *key)
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{
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  node_ptr node = cache->node_table[(*cache->hash_func) (cache, key)];
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  void *retval = NULL;
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261
  if (node)
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    do
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      {
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        if ((*cache->compare_func) (node->key, key))
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          {
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            retval = node->value;
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            break;
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          }
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        else
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          node = node->next;
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      }
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    while (! retval && node);
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  return retval;
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}
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/* Given KEY, return YES if it exists in the CACHE.  Return NO if it
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   does not */
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BOOL
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objc_hash_is_key_in_hash (cache_ptr cache, const void *key)
281
{
282
  node_ptr node = cache->node_table[(*cache->hash_func) (cache, key)];
283
 
284
  if (node)
285
    do
286
      {
287
        if ((*cache->compare_func)(node->key, key))
288
          return YES;
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        else
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          node = node->next;
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      }
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    while (node);
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  return NO;
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}

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