/* A fast map/hash table implementation for NSObjects
 * Copyright (C) 1998  Free Software Foundation, Inc.
 * 
 * Author:	Richard Frith-Macdonald <richard@brainstorm.co.uk>
 * Created:	Thu Oct  1 09:30:00 GMT 1998
 * 
 * Based on original o_map code by Albin L. Jones <Albin.L.Jones@Dartmouth.EDU>
 *
 * This file is part of the GNUstep Base Library.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include <config.h>
#include <Foundation/NSObject.h>
#include <Foundation/NSZone.h>

/* To easily un-inline functions for debugging */
#ifndef	INLINE
#define INLINE inline
#endif

/*
 *	This file should be INCLUDED in files wanting to use the FastMap
 *	functions - these are all declared inline for maximum performance.
 *
 *	The file including this one may predefine some macros to alter
 *	the behaviour (default macros assume the items are NSObjects
 *	that are to be retained in the table) ...
 *
 *	FAST_MAP_HAS_VALUE
 *		If defined as 0, then this becomes a hash table rather than
 *		a map table.
 *
 *	FAST_MAP_RETAIN_KEY()
 *		Macro to retain the key item in a map or hash table.
 *
 *	FAST_MAP_RETAIN_VAL()
 *		Macro to retain the value item in a map table.
 *
 *	FAST_MAP_RELEASE_KEY()
 *		Macro to release the key item in a map or hash table.
 *
 *	FAST_MAP_RELEASE_VAL()
 *		Macro to release the value item in a map table.
 *
 *	FAST_MAP_HASH()
 *		Macro to get the hash of a key item.
 *
 *	FAST_MAP_EQUAL()
 *		Macro to compare two key items for equality - produces zero
 *		if the items are not equal.
 */

#ifndef	FAST_MAP_HAS_VALUE
#define	FAST_MAP_HAS_VALUE	1
#endif

#ifndef	FAST_MAP_RETAIN_KEY
#define	FAST_MAP_RETAIN_KEY(X)	[(X).o retain]
#endif

#ifndef	FAST_MAP_RELEASE_KEY
#define	FAST_MAP_RELEASE_KEY(X)	[(X).o release]
#endif

#ifndef	FAST_MAP_RETAIN_VAL
#define	FAST_MAP_RETAIN_VAL(X)	[(X).o retain]
#endif

#ifndef	FAST_MAP_RELEASE_VAL
#define	FAST_MAP_RELEASE_VAL(X)	[(X).o release]
#endif

#ifndef	FAST_MAP_HASH
#define	FAST_MAP_HASH(X)	[(X).o hash]
#endif

#ifndef	FAST_MAP_EQUAL
#define	FAST_MAP_EQUAL(X,Y)	[(X).o isEqual: (Y).o]
#endif

typedef	union {
  id		o;
  NSObject	*O;
  Class		c;
  SEL		C;
  int		i;
  unsigned	I;
  long 		l;
  unsigned long	L;
  void		*p;
  const void	*P;
  char		*s;
  const char	*S;
  gsu8		u8;
  gsu16		u16;
  gsu32		u32;
} FastMapItem;

typedef struct _FastMapTable FastMapTable_t;
typedef struct _FastMapBucket FastMapBucket_t;
typedef struct _FastMapNode FastMapNode_t;
typedef struct _FastMapEnumerator FastMapEnumerator_t;

typedef FastMapTable_t *FastMapTable;
typedef FastMapBucket_t *FastMapBucket;
typedef FastMapNode_t *FastMapNode;
typedef FastMapEnumerator_t *FastMapEnumerator;

struct	_FastMapNode {
  FastMapNode	nextInBucket;	/* Linked list of bucket.	*/
  FastMapNode	nextInMap;	/* For enumerating.		*/
  FastMapItem	key;
#if	FAST_MAP_HAS_VALUE
  FastMapItem	value;
#endif
};

struct	_FastMapBucket {
  size_t	nodeCount;	/* Number of nodes in bucket.	*/
  FastMapNode	firstNode;	/* The linked list of nodes.	*/
};

struct	_FastMapTable {
  NSZone	*zone;
  size_t	nodeCount;	/* Number of nodes in map.	*/
  FastMapNode	firstNode;	/* List for enumerating.	*/
  size_t	bucketCount;	/* Number of buckets in map.	*/
  FastMapBucket	buckets;	/* Array of buckets.		*/
  FastMapNode	freeNodes;	/* List of unused nodes.	*/
  size_t	chunkCount;	/* Number of chunks in array.	*/
  FastMapNode	*nodeChunks;	/* Chunks of allocated memory.	*/
};

struct	_FastMapEnumerator {
  FastMapTable	map;		/* the map being enumerated.	*/
  FastMapNode	node;		/* The next node to use.	*/
};

static INLINE FastMapBucket
FastMapPickBucket(FastMapItem key, FastMapBucket buckets, size_t bucketCount)
{
  return buckets + FAST_MAP_HASH(key) % bucketCount;
}

static INLINE FastMapBucket
FastMapBucketForKey(FastMapTable map, FastMapItem key)
{
  return FastMapPickBucket(key, map->buckets, map->bucketCount);
}

static INLINE void
FastMapLinkNodeIntoBucket(FastMapBucket bucket, FastMapNode node)
{
  node->nextInBucket = bucket->firstNode;
  bucket->firstNode = node;
}

static INLINE void
FastMapUnlinkNodeFromBucket(FastMapBucket bucket, FastMapNode node)
{
  if (node == bucket->firstNode)
    {
      bucket->firstNode = node->nextInBucket;
    }
  else
    {
      FastMapNode	tmp = bucket->firstNode;

      while (tmp->nextInBucket != node)
	{
	  tmp = tmp->nextInBucket;
	}
      tmp->nextInBucket = node->nextInBucket;
    }
  node->nextInBucket = 0;
}

static INLINE void
FastMapLinkNodeIntoMap(FastMapTable map, FastMapNode node)
{
  node->nextInMap = map->firstNode;
  map->firstNode = node;
}

static INLINE void
FastMapUnlinkNodeFromMap(FastMapTable map, FastMapNode node)
{
  if (node == map->firstNode)
    {
      map->firstNode = node->nextInMap;
    }
  else
    {
      FastMapNode	tmp = map->firstNode;

      while (tmp->nextInMap != node)
	{
	  tmp = tmp->nextInMap;
	}
      tmp->nextInMap = node->nextInMap;
    }
  node->nextInMap = 0;
}

static INLINE void
FastMapAddNodeToBucket(FastMapBucket bucket, FastMapNode node)
{
  FastMapLinkNodeIntoBucket(bucket, node);
  bucket->nodeCount += 1;
}

static INLINE void
FastMapAddNodeToMap(FastMapTable map, FastMapNode node)
{
  FastMapBucket	bucket;

  bucket = FastMapBucketForKey(map, node->key);
  FastMapAddNodeToBucket(bucket, node);
  FastMapLinkNodeIntoMap(map, node);
  map->nodeCount++;
}

static INLINE void
FastMapRemoveNodeFromBucket(FastMapBucket bucket, FastMapNode node)
{
  bucket->nodeCount--;
  FastMapUnlinkNodeFromBucket(bucket, node);
}

static INLINE void
FastMapRemoveNodeFromMap(FastMapTable map, FastMapBucket bkt, FastMapNode node)
{
  map->nodeCount--;
  FastMapUnlinkNodeFromMap(map, node);
  FastMapRemoveNodeFromBucket(bkt, node);
}

static INLINE void
FastMapRemangleBuckets(FastMapTable map,
			      FastMapBucket old_buckets,
			      size_t old_bucketCount,
			      FastMapBucket new_buckets,
			      size_t new_bucketCount)
{
  while (old_bucketCount-- > 0)
    {
      FastMapNode	node;

      while ((node = old_buckets->firstNode) != 0)
	{
	  FastMapBucket	bkt;

	  FastMapRemoveNodeFromBucket(old_buckets, node);
	  bkt = FastMapPickBucket(node->key, new_buckets, new_bucketCount);
	  FastMapAddNodeToBucket(bkt, node);
	}
      old_buckets++;
    }
}

static INLINE void
FastMapMoreNodes(FastMapTable map)
{
  FastMapNode	*newArray;
  size_t	arraySize = (map->chunkCount+1)*sizeof(FastMapNode);

  newArray = (FastMapNode*)NSZoneMalloc(map->zone, arraySize);
    
  if (newArray)
    {
      FastMapNode	newNodes;
      size_t		chunkCount;
      size_t		chunkSize;

      memcpy(newArray,map->nodeChunks,(map->chunkCount)*sizeof(FastMapNode));
      if (map->nodeChunks != 0)
	{
	  NSZoneFree(map->zone, map->nodeChunks);
	}
      map->nodeChunks = newArray;

      if (map->chunkCount == 0)
	{
	  chunkCount = map->bucketCount > 1 ? map->bucketCount : 2;
	}
      else
	{
	  chunkCount = ((map->nodeCount>>2)+1)<<1;
	}
      chunkSize = chunkCount * sizeof(FastMapNode_t);
      newNodes = (FastMapNode)NSZoneMalloc(map->zone, chunkSize);
      if (newNodes)
	{
	  map->nodeChunks[map->chunkCount++] = newNodes;
	  newNodes[--chunkCount].nextInMap = map->freeNodes;
	  while (chunkCount--)
	    {
	      newNodes[chunkCount].nextInMap = &newNodes[chunkCount+1];
	    }
	  map->freeNodes = newNodes;
	}
    }
}

#if	FAST_MAP_HAS_VALUE
static INLINE FastMapNode
FastMapNewNode(FastMapTable map, FastMapItem key, FastMapItem value)
{
  FastMapNode	node = map->freeNodes;

  if (node == 0)
    {
      FastMapMoreNodes(map);
      node = map->freeNodes;
      if (node == 0)
	{
	  return 0;
	}
    }

  map->freeNodes = node->nextInMap;
  node->key = key;
  node->value = value;
  node->nextInBucket = 0;
  node->nextInMap = 0;

  return node;
}
#else
static INLINE FastMapNode
FastMapNewNode(FastMapTable map, FastMapItem key)
{
  FastMapNode	node = map->freeNodes;

  if (node == 0)
    {
      FastMapMoreNodes(map);
      node = map->freeNodes;
      if (node == 0)
	{
	  return 0;
	}
    }

  map->freeNodes = node->nextInMap;
  node->key = key;
  node->nextInBucket = 0;
  node->nextInMap = 0;
  return node;
}
#endif

static INLINE void
FastMapFreeNode(FastMapTable map, FastMapNode node)
{
  FAST_MAP_RELEASE_KEY(node->key);
#if	FAST_MAP_HAS_VALUE
  FAST_MAP_RELEASE_VAL(node->value);
#endif
  node->nextInMap = map->freeNodes;
  map->freeNodes = node;
}

static INLINE FastMapNode 
FastMapNodeForKeyInBucket(FastMapBucket bucket, FastMapItem key)
{
  FastMapNode	node = bucket->firstNode;

  while ((node != 0) && FAST_MAP_EQUAL(node->key, key) == NO)
    {
      node = node->nextInBucket;
    }
  return node;
}

static INLINE FastMapNode 
FastMapNodeForKey(FastMapTable map, FastMapItem key)
{
  FastMapBucket	bucket;
  FastMapNode	node;

  if (map->nodeCount == 0)
    return 0;
  bucket = FastMapBucketForKey(map, key);
  node = FastMapNodeForKeyInBucket(bucket, key);
  return node;
}

static INLINE void
FastMapResize(FastMapTable map, size_t new_capacity)
{
  FastMapBucket	new_buckets;
  size_t	size = 1;
  size_t	old = 1;

  /*
   *	Find next size up in the fibonacci series
   */
  while (size < new_capacity)
    {
      size_t	tmp = old;
      old = size;
      size += tmp;
    }
  /*
   *	Avoid 8 - since hash functions frequently generate uneven distributions
   *	around powers of two - we don't want lots of keys falling into a single
   *	bucket.
   */
  if (size == 8) size++;

  /*
   *	Make a new set of buckets for this map
   */
  new_buckets = (FastMapBucket)NSZoneCalloc(map->zone, size,
		sizeof(FastMapBucket_t));
  if (new_buckets != 0)
    {
      FastMapRemangleBuckets(map,
				  map->buckets,
				  map->bucketCount,
				  new_buckets,
				  size);

      if (map->buckets != 0)
	{
	  NSZoneFree(map->zone, map->buckets);
	}
      map->buckets = new_buckets;
      map->bucketCount = size;
    }
}

static INLINE void
FastMapRightSizeMap(FastMapTable map, size_t capacity)
{
  /* FIXME: Now, this is a guess, based solely on my intuition.  If anyone
   * knows of a better ratio (or other test, for that matter) and can
   * provide evidence of its goodness, please get in touch with me, Albin
   * L. Jones <Albin.L.Jones@Dartmouth.EDU>. */

  if (3 * capacity >= 4 * map->bucketCount)
    {
      FastMapResize(map, (3 * capacity)/4 + 1);
    }
}

/** Enumerating **/

/* WARNING: You should not alter a map while an enumeration is
 * in progress.  The results of doing so are reasonably unpremapable.
 * With that in mind, read the following warnings carefully.  But
 * remember, DON'T MESS WITH A MAP WHILE YOU'RE ENUMERATING IT. */

/* IMPORTANT WARNING: Map enumerators, as I have map them up, have a
 * wonderous property.  Namely, that, while enumerating, one may add
 * new elements (i.e., new nodes) to the map while an enumeration is
 * in progress (i.e., after `o_map_enumerator_for_map()' has been
 * called), and the enumeration remains the same. */

/* WARNING: The above warning should not, in any way, be taken as
 * assurance that this property of map enumerators will be preserved
 * in future editions of the library.  I'm still thinking about
 * this. */

/* IMPORTANT WARNING: Enumerators have yet another wonderous property.
 * Once a node has been returned by `FastMapEnumeratorNextNode()', it may be
 * removed from the map without effecting the rest of the current
 * enumeration. */

/* EXTREMELY IMPORTANT WARNING: The purpose of this warning is point
 * out that, at this time, various (i.e., many) functions depend on
 * the behaviours outlined above.  So be prepared for some serious
 * breakage when you go fudging around with these things. */

static INLINE FastMapEnumerator_t
FastMapEnumeratorForMap(FastMapTable map)
{
  FastMapEnumerator_t	enumerator;

  enumerator.map = map;
  enumerator.node = map->firstNode;

  return enumerator;
}

static INLINE FastMapNode 
FastMapEnumeratorNextNode(FastMapEnumerator enumerator)
{
  FastMapNode node;

  node = enumerator->node;

  if (node != 0)
    enumerator->node = node->nextInMap;

  /* Send back NODE. */
  return node;
}

#if	FAST_MAP_HAS_VALUE
static INLINE FastMapNode
FastMapAddPairNoRetain(FastMapTable map, FastMapItem key, FastMapItem value)
{
  FastMapNode node;

  node = FastMapNewNode(map, key, value);

  if (node != 0)
    {
      FastMapRightSizeMap(map, map->nodeCount);
      FastMapAddNodeToMap(map, node);
    }
  return node;
}

static INLINE FastMapNode
FastMapAddPair(FastMapTable map, FastMapItem key, FastMapItem value)
{
  FastMapNode node;

  FAST_MAP_RETAIN_KEY(key);
  FAST_MAP_RETAIN_VAL(value);
  node = FastMapNewNode(map, key, value);

  if (node != 0)
    {
      FastMapRightSizeMap(map, map->nodeCount);
      FastMapAddNodeToMap(map, node);
    }
  return node;
}
#else
static INLINE FastMapNode
FastMapAddKeyNoRetain(FastMapTable map, FastMapItem key)
{
  FastMapNode node;

  node = FastMapNewNode(map, key);

  if (node != 0)
    {
      FastMapRightSizeMap(map, map->nodeCount);
      FastMapAddNodeToMap(map, node);
    }
  return node;
}

static INLINE FastMapNode
FastMapAddKey(FastMapTable map, FastMapItem key)
{
  FastMapNode node;

  FAST_MAP_RETAIN_KEY(key);
  node = FastMapNewNode(map, key);

  if (node != 0)
    {
      FastMapRightSizeMap(map, map->nodeCount);
      FastMapAddNodeToMap(map, node);
    }
  return node;
}
#endif

static INLINE void
FastMapRemoveKey(FastMapTable map, FastMapItem key)
{
  FastMapBucket	bucket = FastMapBucketForKey(map, key);

  if (bucket != 0)
    {
      FastMapNode	node = FastMapNodeForKeyInBucket(bucket, key);

      if (node != 0)
	{
	  FastMapRemoveNodeFromMap(map, bucket, node);
	  FastMapFreeNode(map, node);
	}
    }
}

static INLINE void
FastMapCleanMap(FastMapTable map)
{
  FastMapBucket	bucket = map->buckets;
  int		i;

  for (i = 0; i < map->bucketCount; i++)
    {
      while (bucket->nodeCount != 0)
	{
	  FastMapNode	node = bucket->firstNode;

	  FastMapRemoveNodeFromBucket(bucket, node);
	  FastMapFreeNode(map, node);
	}
      bucket++;
    }
  map->firstNode = 0;
  map->nodeCount = 0;
}

static INLINE void
FastMapEmptyMap(FastMapTable map)
{
  int	i;

  FastMapCleanMap(map);
  if (map->buckets != 0)
    {
      NSZoneFree(map->zone, map->buckets);
      map->buckets = 0;
      map->bucketCount = 0;
    }
  if (map->nodeChunks != 0)
    {
      for (i = 0; i < map->chunkCount; i++)
	{
	  NSZoneFree(map->zone, map->nodeChunks[i]);
	}
      map->chunkCount = 0;
      NSZoneFree(map->zone, map->nodeChunks);
      map->nodeChunks = 0;
    }
  map->freeNodes = 0;
  map->zone = 0;
}

static INLINE FastMapTable 
FastMapInitWithZoneAndCapacity(FastMapTable map, NSZone *zone, size_t capacity)
{
  map->zone = zone;
  map->nodeCount = 0;
  map->bucketCount = 0;
  map->firstNode = 0;
  map->buckets = 0;
  map->nodeChunks = 0;
  map->freeNodes = 0;
  map->chunkCount = 0;
  FastMapRightSizeMap(map, capacity);
  FastMapMoreNodes(map);
}