ubi_splaytree.c

samba-3.0.22.tar.gz 编译smb服务器的源码

                          ubi_btNodePtr  NewNode,
                          ubi_btItemPtr  ItemPtr,
                          ubi_btNodePtr *OldNode )
  /* ------------------------------------------------------------------------ **
   * This function uses a non-recursive algorithm to add a new element to the
   * splay tree.
   *
   *  Input:   RootPtr  -  a pointer to the ubi_btRoot structure that indicates
   *                       the root of the tree to which NewNode is to be added.
   *           NewNode  -  a pointer to an ubi_btNode structure that is NOT
   *                       part of any tree.
   *           ItemPtr  -  A pointer to the sort key that is stored within
   *                       *NewNode.  ItemPtr MUST point to information stored
   *                       in *NewNode or an EXACT DUPLICATE.  The key data
   *                       indicated by ItemPtr is used to place the new node
   *                       into the tree.
   *           OldNode  -  a pointer to an ubi_btNodePtr.  When searching
   *                       the tree, a duplicate node may be found.  If
   *                       duplicates are allowed, then the new node will
   *                       be simply placed into the tree.  If duplicates
   *                       are not allowed, however, then one of two things
   *                       may happen.
   *                       1) if overwritting *is not* allowed, this
   *                          function will return FALSE (indicating that
   *                          the new node could not be inserted), and
   *                          *OldNode will point to the duplicate that is
   *                          still in the tree.
   *                       2) if overwritting *is* allowed, then this
   *                          function will swap **OldNode for *NewNode.
   *                          In this case, *OldNode will point to the node
   *                          that was removed (thus allowing you to free
   *                          the node).
   *                          **  If you are using overwrite mode, ALWAYS  **
   *                          ** check the return value of this parameter! **
   *                 Note: You may pass NULL in this parameter, the
   *                       function knows how to cope.  If you do this,
   *                       however, there will be no way to return a
   *                       pointer to an old (ie. replaced) node (which is
   *                       a problem if you are using overwrite mode).
   *
   *  Output:  a boolean value indicating success or failure.  The function
   *           will return FALSE if the node could not be added to the tree.
   *           Such failure will only occur if duplicates are not allowed,
   *           nodes cannot be overwritten, AND a duplicate key was found
   *           within the tree.
   * ------------------------------------------------------------------------ **
   */
  {
  ubi_btNodePtr OtherP;

  if( !(OldNode) )
    OldNode = &OtherP;

  if( ubi_btInsert( RootPtr, NewNode, ItemPtr, OldNode ) )
    {
    RootPtr->root = Splay( NewNode );
    return( ubi_trTRUE );
    }

  /* Splay the unreplacable, duplicate keyed, unique, old node. */
  RootPtr->root = Splay( (*OldNode) );
  return( ubi_trFALSE );
  } /* ubi_sptInsert */

ubi_btNodePtr ubi_sptRemove( ubi_btRootPtr RootPtr, ubi_btNodePtr DeadNode )
  /* ------------------------------------------------------------------------ **
   * This function removes the indicated node from the tree.
   *
   *  Input:   RootPtr  -  A pointer to the header of the tree that contains
   *                       the node to be removed.
   *           DeadNode -  A pointer to the node that will be removed.
   *
   *  Output:  This function returns a pointer to the node that was removed
   *           from the tree (ie. the same as DeadNode).
   *
   *  Note:    The node MUST be in the tree indicated by RootPtr.  If not,
   *           strange and evil things will happen to your trees.
   * ------------------------------------------------------------------------ **
   */
  {
  ubi_btNodePtr p;

  (void)Splay( DeadNode );                  /* Move dead node to root.        */
  if( NULL != (p = DeadNode->Link[ubi_trLEFT]) )
    {                                       /* If left subtree exists...      */
    ubi_btNodePtr q = DeadNode->Link[ubi_trRIGHT];

    p->Link[ubi_trPARENT] = NULL;           /* Left subtree node becomes root.*/
    p->gender             = ubi_trPARENT;
    p                     = ubi_btLast( p );  /* Find rightmost left node...  */
    p->Link[ubi_trRIGHT]  = q;                /* ...attach right tree.        */
    if( q )
      q->Link[ubi_trPARENT] = p;
    RootPtr->root   = Splay( p );           /* Resplay at p.                  */
    }
  else
    {
    if( NULL != (p = DeadNode->Link[ubi_trRIGHT]) )
      {                               /* No left, but right subtree exists... */
      p->Link[ubi_trPARENT] = NULL;         /* Right subtree root becomes...  */
      p->gender       = ubi_trPARENT;       /* ...overall tree root.          */
      RootPtr->root   = p;
      }
    else
      RootPtr->root = NULL;                 /* No subtrees => empty tree.     */
    }

  (RootPtr->count)--;                       /* Decrement node count.          */
  return( DeadNode );                       /* Return pointer to pruned node. */
  } /* ubi_sptRemove */

ubi_btNodePtr ubi_sptLocate( ubi_btRootPtr RootPtr,
                             ubi_btItemPtr FindMe,
                             ubi_trCompOps CompOp )
  /* ------------------------------------------------------------------------ **
   * The purpose of ubi_btLocate() is to find a node or set of nodes given
   * a target value and a "comparison operator".  The Locate() function is
   * more flexible and (in the case of trees that may contain dupicate keys)
   * more precise than the ubi_btFind() function.  The latter is faster,
   * but it only searches for exact matches and, if the tree contains
   * duplicates, Find() may return a pointer to any one of the duplicate-
   * keyed records.
   *
   *  Input:
   *     RootPtr  -  A pointer to the header of the tree to be searched.
   *     FindMe   -  An ubi_btItemPtr that indicates the key for which to
   *                 search.
   *     CompOp   -  One of the following:
   *                    CompOp     Return a pointer to the node with
   *                    ------     ---------------------------------
   *                   ubi_trLT - the last key value that is less
   *                              than FindMe.
   *                   ubi_trLE - the first key matching FindMe, or
   *                              the last key that is less than
   *                              FindMe.
   *                   ubi_trEQ - the first key matching FindMe.
   *                   ubi_trGE - the first key matching FindMe, or the
   *                              first key greater than FindMe.
   *                   ubi_trGT - the first key greater than FindMe.
   *  Output:
   *     A pointer to the node matching the criteria listed above under
   *     CompOp, or NULL if no node matched the criteria.
   *
   *  Notes:
   *     In the case of trees with duplicate keys, Locate() will behave as
   *     follows:
   *
   *     Find:  3                       Find: 3
   *     Keys:  1 2 2 2 3 3 3 3 3 4 4   Keys: 1 1 2 2 2 4 4 5 5 5 6
   *                  ^ ^         ^                   ^ ^
   *                 LT EQ        GT                 LE GE
   *
   *     That is, when returning a pointer to a node with a key that is LESS
   *     THAN the target key (FindMe), Locate() will return a pointer to the
   *     LAST matching node.
   *     When returning a pointer to a node with a key that is GREATER
   *     THAN the target key (FindMe), Locate() will return a pointer to the
   *     FIRST matching node.
   *
   *  See Also: ubi_btFind(), ubi_btFirstOf(), ubi_btLastOf().
   * ------------------------------------------------------------------------ **
   */
  {
  ubi_btNodePtr p;

  p = ubi_btLocate( RootPtr, FindMe, CompOp );
  if( p )
    RootPtr->root = Splay( p );
  return( p );
  } /* ubi_sptLocate */

ubi_btNodePtr ubi_sptFind( ubi_btRootPtr RootPtr,
                           ubi_btItemPtr FindMe )
  /* ------------------------------------------------------------------------ **
   * This function performs a non-recursive search of a tree for any node
   * matching a specific key.
   *
   *  Input:
   *     RootPtr  -  a pointer to the header of the tree to be searched.
   *     FindMe   -  a pointer to the key value for which to search.
   *
   *  Output:
   *     A pointer to a node with a key that matches the key indicated by
   *     FindMe, or NULL if no such node was found.
   *
   *  Note:   In a tree that allows duplicates, the pointer returned *might
   *          not* point to the (sequentially) first occurance of the
   *          desired key.  In such a tree, it may be more useful to use
   *          ubi_sptLocate().
   * ------------------------------------------------------------------------ **
   */
  {
  ubi_btNodePtr p;

  p = ubi_btFind( RootPtr, FindMe );
  if( p )
    RootPtr->root = Splay( p );
  return( p );
  } /* ubi_sptFind */

void ubi_sptSplay( ubi_btRootPtr RootPtr,
                   ubi_btNodePtr SplayMe )
  /* ------------------------------------------------------------------------ **
   *  This function allows you to splay the tree at a given node, thus moving
   *  the node to the top of the tree.
   *
   *  Input:
   *     RootPtr  -  a pointer to the header of the tree to be splayed.
   *     SplayMe  -  a pointer to a node within the tree.  This will become
   *                 the new root node.
   *  Output: None.
   *
   *  Notes:  This is an uncharacteristic function for this group of modules
   *          in that it provides access to the internal balancing routines,
   *          which would normally be hidden.
   *          Splaying the tree will not damage it (assuming that I've done
   *          *my* job), but there is overhead involved.  I don't recommend
   *          that you use this function unless you understand the underlying
   *          Splay Tree principles involved.
   * ------------------------------------------------------------------------ **
   */
  {
  RootPtr->root = Splay( SplayMe );
  } /* ubi_sptSplay */

int ubi_sptModuleID( int size, char *list[] )
  /* ------------------------------------------------------------------------ **
   * Returns a set of strings that identify the module.
   *
   *  Input:  size  - The number of elements in the array <list>.
   *          list  - An array of pointers of type (char *).  This array
   *                  should, initially, be empty.  This function will fill
   *                  in the array with pointers to strings.
   *  Output: The number of elements of <list> that were used.  If this value
   *          is less than <size>, the values of the remaining elements are
   *          not guaranteed.
   *
   *  Notes:  Please keep in mind that the pointers returned indicate strings
   *          stored in static memory.  Don't free() them, don't write over
   *          them, etc.  Just read them.
   * ------------------------------------------------------------------------ **
   */
  {
  if( size > 0 )
    {
    list[0] = ModuleID;
    if( size > 1 )
      return( 1 + ubi_btModuleID( --size, &(list[1]) ) );
    return( 1 );
    }
  return( 0 );
  } /* ubi_sptModuleID */

/* ================================ The End ================================= */