--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/engine/sqlite/src/hash.cpp	Thu Feb 25 14:29:19 2010 +0000
@@ -0,0 +1,418 @@
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the implementation of generic hash-tables
+** used in SQLite.
+**
+** $Id: hash.cpp 1282 2008-11-13 09:31:33Z LarsPson $
+*/
+#include "sqliteInt.h"
+#include <assert.h>
+
+/* Turn bulk memory into a hash table object by initializing the
+** fields of the Hash structure.
+**
+** "pNew" is a pointer to the hash table that is to be initialized.
+** keyClass is one of the constants SQLITE_HASH_INT, SQLITE_HASH_POINTER,
+** SQLITE_HASH_BINARY, or SQLITE_HASH_STRING.  The value of keyClass 
+** determines what kind of key the hash table will use.  "copyKey" is
+** true if the hash table should make its own private copy of keys and
+** false if it should just use the supplied pointer.  CopyKey only makes
+** sense for SQLITE_HASH_STRING and SQLITE_HASH_BINARY and is ignored
+** for other key classes.
+*/
+void sqlite3HashInit(Hash *pNew, int keyClass, int copyKey){
+  assert( pNew!=0 );
+  assert( keyClass>=SQLITE_HASH_STRING && keyClass<=SQLITE_HASH_BINARY );
+  pNew->keyClass = keyClass;
+#if 0
+  if( keyClass==SQLITE_HASH_POINTER || keyClass==SQLITE_HASH_INT ) copyKey = 0;
+#endif
+  pNew->copyKey = copyKey;
+  pNew->first = 0;
+  pNew->count = 0;
+  pNew->htsize = 0;
+  pNew->ht = 0;
+}
+
+/* Remove all entries from a hash table.  Reclaim all memory.
+** Call this routine to delete a hash table or to reset a hash table
+** to the empty state.
+*/
+void sqlite3HashClear(Hash *pH){
+  HashElem *elem;         /* For looping over all elements of the table */
+
+  assert( pH!=0 );
+  elem = pH->first;
+  pH->first = 0;
+  if( pH->ht ) sqlite3_free(pH->ht);
+  pH->ht = 0;
+  pH->htsize = 0;
+  while( elem ){
+    HashElem *next_elem = elem->next;
+    if( pH->copyKey && elem->pKey ){
+      sqlite3_free(elem->pKey);
+    }
+    sqlite3_free(elem);
+    elem = next_elem;
+  }
+  pH->count = 0;
+}
+
+#if 0 /* NOT USED */
+/*
+** Hash and comparison functions when the mode is SQLITE_HASH_INT
+*/
+static int intHash(const void *pKey, int nKey){
+  return nKey ^ (nKey<<8) ^ (nKey>>8);
+}
+static int intCompare(const void *pKey1, int n1, const void *pKey2, int n2){
+  return n2 - n1;
+}
+#endif
+
+#if 0 /* NOT USED */
+/*
+** Hash and comparison functions when the mode is SQLITE_HASH_POINTER
+*/
+static int ptrHash(const void *pKey, int nKey){
+  uptr x = Addr(pKey);
+  return x ^ (x<<8) ^ (x>>8);
+}
+static int ptrCompare(const void *pKey1, int n1, const void *pKey2, int n2){
+  if( pKey1==pKey2 ) return 0;
+  if( pKey1<pKey2 ) return -1;
+  return 1;
+}
+#endif
+
+/*
+** Hash and comparison functions when the mode is SQLITE_HASH_STRING
+*/
+static int strHash(const void *pKey, int nKey){
+  const char *z = (const char *)pKey;
+  int h = 0;
+  if( nKey<=0 ) nKey = strlen(z);
+  while( nKey > 0  ){
+    h = (h<<3) ^ h ^ sqlite3UpperToLower[(unsigned char)*z++];
+    nKey--;
+  }
+  return h & 0x7fffffff;
+}
+static int strCompare(const void *pKey1, int n1, const void *pKey2, int n2){
+  if( n1!=n2 ) return 1;
+  return sqlite3StrNICmp((const char*)pKey1,(const char*)pKey2,n1);
+}
+
+/*
+** Hash and comparison functions when the mode is SQLITE_HASH_BINARY
+*/
+static int binHash(const void *pKey, int nKey){
+  int h = 0;
+  const char *z = (const char *)pKey;
+  while( nKey-- > 0 ){
+    h = (h<<3) ^ h ^ *(z++);
+  }
+  return h & 0x7fffffff;
+}
+static int binCompare(const void *pKey1, int n1, const void *pKey2, int n2){
+  if( n1!=n2 ) return 1;
+  return memcmp(pKey1,pKey2,n1);
+}
+
+/*
+** Return a pointer to the appropriate hash function given the key class.
+**
+** The C syntax in this function definition may be unfamilar to some 
+** programmers, so we provide the following additional explanation:
+**
+** The name of the function is "hashFunction".  The function takes a
+** single parameter "keyClass".  The return value of hashFunction()
+** is a pointer to another function.  Specifically, the return value
+** of hashFunction() is a pointer to a function that takes two parameters
+** with types "const void*" and "int" and returns an "int".
+*/
+static int (*hashFunction(int keyClass))(const void*,int){
+#if 0  /* HASH_INT and HASH_POINTER are never used */
+  switch( keyClass ){
+    case SQLITE_HASH_INT:     return &intHash;
+    case SQLITE_HASH_POINTER: return &ptrHash;
+    case SQLITE_HASH_STRING:  return &strHash;
+    case SQLITE_HASH_BINARY:  return &binHash;;
+    default: break;
+  }
+  return 0;
+#else
+  if( keyClass==SQLITE_HASH_STRING ){
+    return &strHash;
+  }else{
+    assert( keyClass==SQLITE_HASH_BINARY );
+    return &binHash;
+  }
+#endif
+}
+
+/*
+** Return a pointer to the appropriate hash function given the key class.
+**
+** For help in interpreted the obscure C code in the function definition,
+** see the header comment on the previous function.
+*/
+static int (*compareFunction(int keyClass))(const void*,int,const void*,int){
+#if 0 /* HASH_INT and HASH_POINTER are never used */
+  switch( keyClass ){
+    case SQLITE_HASH_INT:     return &intCompare;
+    case SQLITE_HASH_POINTER: return &ptrCompare;
+    case SQLITE_HASH_STRING:  return &strCompare;
+    case SQLITE_HASH_BINARY:  return &binCompare;
+    default: break;
+  }
+  return 0;
+#else
+  if( keyClass==SQLITE_HASH_STRING ){
+    return &strCompare;
+  }else{
+    assert( keyClass==SQLITE_HASH_BINARY );
+    return &binCompare;
+  }
+#endif
+}
+
+/* Link an element into the hash table
+*/
+static void insertElement(
+  Hash *pH,              /* The complete hash table */
+  Hash::_ht *pEntry,    /* The entry into which pNew is inserted */
+  HashElem *pNew         /* The element to be inserted */
+){
+  HashElem *pHead;       /* First element already in pEntry */
+  pHead = pEntry->chain;
+  if( pHead ){
+    pNew->next = pHead;
+    pNew->prev = pHead->prev;
+    if( pHead->prev ){ pHead->prev->next = pNew; }
+    else             { pH->first = pNew; }
+    pHead->prev = pNew;
+  }else{
+    pNew->next = pH->first;
+    if( pH->first ){ pH->first->prev = pNew; }
+    pNew->prev = 0;
+    pH->first = pNew;
+  }
+  pEntry->count++;
+  pEntry->chain = pNew;
+}
+
+
+/* Resize the hash table so that it cantains "new_size" buckets.
+** "new_size" must be a power of 2.  The hash table might fail 
+** to resize if sqlite3_malloc() fails.
+*/
+static void rehash(Hash *pH, int new_size){
+  Hash::_ht *new_ht;            /* The new hash table */
+  HashElem *elem, *next_elem;    /* For looping over existing elements */
+  int (*xHash)(const void*,int); /* The hash function */
+
+  assert( (new_size & (new_size-1))==0 );
+
+  /* There is a call to sqlite3_malloc() inside rehash(). If there is
+  ** already an allocation at pH->ht, then if this malloc() fails it
+  ** is benign (since failing to resize a hash table is a performance
+  ** hit only, not a fatal error).
+  */
+  sqlite3MallocBenignFailure(pH->htsize>0);
+
+  new_ht = (Hash::_ht *)sqlite3MallocZero( new_size*sizeof(Hash::_ht) );
+  if( new_ht==0 ) return;
+  if( pH->ht ) sqlite3_free(pH->ht);
+  pH->ht = new_ht;
+  pH->htsize = new_size;
+  xHash = hashFunction(pH->keyClass);
+  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
+    int h = (*xHash)(elem->pKey, elem->nKey) & (new_size-1);
+    next_elem = elem->next;
+    insertElement(pH, &new_ht[h], elem);
+  }
+}
+
+/* This function (for internal use only) locates an element in an
+** hash table that matches the given key.  The hash for this key has
+** already been computed and is passed as the 4th parameter.
+*/
+static HashElem *findElementGivenHash(
+  const Hash *pH,     /* The pH to be searched */
+  const void *pKey,   /* The key we are searching for */
+  int nKey,
+  int h               /* The hash for this key. */
+){
+  HashElem *elem;                /* Used to loop thru the element list */
+  int count;                     /* Number of elements left to test */
+  int (*xCompare)(const void*,int,const void*,int);  /* comparison function */
+
+  if( pH->ht ){
+	  Hash::_ht *pEntry = &pH->ht[h];
+    elem = pEntry->chain;
+    count = pEntry->count;
+    xCompare = compareFunction(pH->keyClass);
+    while( count-- && elem ){
+      if( (*xCompare)(elem->pKey,elem->nKey,pKey,nKey)==0 ){ 
+        return elem;
+      }
+      elem = elem->next;
+    }
+  }
+  return 0;
+}
+
+/* Remove a single entry from the hash table given a pointer to that
+** element and a hash on the element's key.
+*/
+static void removeElementGivenHash(
+  Hash *pH,         /* The pH containing "elem" */
+  HashElem* elem,   /* The element to be removed from the pH */
+  int h             /* Hash value for the element */
+){
+	Hash::_ht *pEntry;
+  if( elem->prev ){
+    elem->prev->next = elem->next; 
+  }else{
+    pH->first = elem->next;
+  }
+  if( elem->next ){
+    elem->next->prev = elem->prev;
+  }
+  pEntry = &pH->ht[h];
+  if( pEntry->chain==elem ){
+    pEntry->chain = elem->next;
+  }
+  pEntry->count--;
+  if( pEntry->count<=0 ){
+    pEntry->chain = 0;
+  }
+  if( pH->copyKey ){
+    sqlite3_free(elem->pKey);
+  }
+  sqlite3_free( elem );
+  pH->count--;
+  if( pH->count<=0 ){
+    assert( pH->first==0 );
+    assert( pH->count==0 );
+    sqlite3HashClear(pH);
+  }
+}
+
+/* Attempt to locate an element of the hash table pH with a key
+** that matches pKey,nKey.  Return a pointer to the corresponding 
+** HashElem structure for this element if it is found, or NULL
+** otherwise.
+*/
+HashElem *sqlite3HashFindElem(const Hash *pH, const void *pKey, int nKey){
+  int h;             /* A hash on key */
+  HashElem *elem;    /* The element that matches key */
+  int (*xHash)(const void*,int);  /* The hash function */
+
+  if( pH==0 || pH->ht==0 ) return 0;
+  xHash = hashFunction(pH->keyClass);
+  assert( xHash!=0 );
+  h = (*xHash)(pKey,nKey);
+  assert( (pH->htsize & (pH->htsize-1))==0 );
+  elem = findElementGivenHash(pH,pKey,nKey, h & (pH->htsize-1));
+  return elem;
+}
+
+/* Attempt to locate an element of the hash table pH with a key
+** that matches pKey,nKey.  Return the data for this element if it is
+** found, or NULL if there is no match.
+*/
+void *sqlite3HashFind(const Hash *pH, const void *pKey, int nKey){
+  HashElem *elem;    /* The element that matches key */
+  elem = sqlite3HashFindElem(pH, pKey, nKey);
+  return elem ? elem->data : 0;
+}
+
+/* Insert an element into the hash table pH.  The key is pKey,nKey
+** and the data is "data".
+**
+** If no element exists with a matching key, then a new
+** element is created.  A copy of the key is made if the copyKey
+** flag is set.  NULL is returned.
+**
+** If another element already exists with the same key, then the
+** new data replaces the old data and the old data is returned.
+** The key is not copied in this instance.  If a malloc fails, then
+** the new data is returned and the hash table is unchanged.
+**
+** If the "data" parameter to this function is NULL, then the
+** element corresponding to "key" is removed from the hash table.
+*/
+void *sqlite3HashInsert(Hash *pH, const void *pKey, int nKey, void *data){
+  int hraw;             /* Raw hash value of the key */
+  int h;                /* the hash of the key modulo hash table size */
+  HashElem *elem;       /* Used to loop thru the element list */
+  HashElem *new_elem;   /* New element added to the pH */
+  int (*xHash)(const void*,int);  /* The hash function */
+
+  assert( pH!=0 );
+  xHash = hashFunction(pH->keyClass);
+  assert( xHash!=0 );
+  hraw = (*xHash)(pKey, nKey);
+  assert( (pH->htsize & (pH->htsize-1))==0 );
+  h = hraw & (pH->htsize-1);
+  elem = findElementGivenHash(pH,pKey,nKey,h);
+  if( elem ){
+    void *old_data = elem->data;
+    if( data==0 ){
+      removeElementGivenHash(pH,elem,h);
+    }else{
+      elem->data = data;
+      if( !pH->copyKey ){
+        elem->pKey = (void *)pKey;
+      }
+      assert(nKey==elem->nKey);
+    }
+    return old_data;
+  }
+  if( data==0 ) return 0;
+  new_elem = (HashElem*)sqlite3_malloc( sizeof(HashElem) );
+  if( new_elem==0 ) return data;
+  if( pH->copyKey && pKey!=0 ){
+    new_elem->pKey = sqlite3_malloc( nKey );
+    if( new_elem->pKey==0 ){
+      sqlite3_free(new_elem);
+      return data;
+    }
+    memcpy((void*)new_elem->pKey, pKey, nKey);
+  }else{
+    new_elem->pKey = (void*)pKey;
+  }
+  new_elem->nKey = nKey;
+  pH->count++;
+  if( pH->htsize==0 ){
+    rehash(pH,8);
+    if( pH->htsize==0 ){
+      pH->count = 0;
+      if( pH->copyKey ){
+        sqlite3_free(new_elem->pKey);
+      }
+      sqlite3_free(new_elem);
+      return data;
+    }
+  }
+  if( pH->count > pH->htsize ){
+    rehash(pH,pH->htsize*2);
+  }
+  assert( pH->htsize>0 );
+  assert( (pH->htsize & (pH->htsize-1))==0 );
+  h = hraw & (pH->htsize-1);
+  insertElement(pH, &pH->ht[h], new_elem);
+  new_elem->data = data;
+  return 0;
+}