+/* ========================================================================== **
+ * ubi_BinTree.c
+ *
+ * Copyright (C) 1991-1997 by Christopher R. Hertel
+ *
+ * Email: crh@ubiqx.mn.org
+ * -------------------------------------------------------------------------- **
+ *
+ * ubi_BinTree manages a simple binary tree. Nothing fancy here. No height
+ * balancing, no restructuring. Still, a good tool for creating short, low-
+ * overhead sorted lists of things that need to be found in a hurry.
+ *
+ * In addition, this module provides a good basis for creating other types
+ * of binary tree handling modules.
+ *
+ * -------------------------------------------------------------------------- **
+ *
+ * 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.
+ *
+ * -------------------------------------------------------------------------- **
+ *
+ * $Log: ubi_BinTree.c,v $
+ * Revision 1.1 1997/10/09 04:09:52 crh
+ * This is my library of lists and trees. My hope is to replace all of the
+ * hard coded linked lists that are currently used in Samba with calls to
+ * these modules. This should make the code simpler, smaller, and (I hope)
+ * faster. The tree code, in particular, should speed up processing where
+ * large lists are involved.
+ *
+ * Chris -)-----
+ *
+ * Revision 2.4 1997/07/26 04:11:10 crh
+ * + Just to be annoying I changed ubi_TRUE and ubi_FALSE to ubi_trTRUE
+ * and ubi_trFALSE.
+ * + There is now a type ubi_trBool to go with ubi_trTRUE and ubi_trFALSE.
+ * + There used to be something called "ubi_TypeDefs.h". I got rid of it.
+ * + Added function ubi_btLeafNode().
+ *
+ * Revision 2.3 1997/06/03 05:16:17 crh
+ * Changed TRUE and FALSE to ubi_TRUE and ubi_FALSE to avoid conflicts.
+ * Also changed the interface to function InitTree(). See the comments
+ * for this function for more information.
+ *
+ * Revision 2.2 1995/10/03 22:00:07 CRH
+ * Ubisized!
+ *
+ * Revision 2.1 95/03/09 23:37:10 CRH
+ * Added the ModuleID static string and function. These modules are now
+ * self-identifying.
+ *
+ * Revision 2.0 95/02/27 22:00:17 CRH
+ * Revision 2.0 of this program includes the following changes:
+ *
+ * 1) A fix to a major typo in the RepaceNode() function.
+ * 2) The addition of the static function Border().
+ * 3) The addition of the public functions FirstOf() and LastOf(), which
+ * use Border(). These functions are used with trees that allow
+ * duplicate keys.
+ * 4) A complete rewrite of the Locate() function. Locate() now accepts
+ * a "comparison" operator.
+ * 5) Overall enhancements to both code and comments.
+ *
+ * I decided to give this a new major rev number because the interface has
+ * changed. In particular, there are two new functions, and changes to the
+ * Locate() function.
+ *
+ * Revision 1.0 93/10/15 22:44:59 CRH
+ * With this revision, I have added a set of #define's that provide a single,
+ * standard API to all existing tree modules. Until now, each of the three
+ * existing modules had a different function and typedef prefix, as follows:
+ *
+ * Module Prefix
+ * ubi_BinTree ubi_bt
+ * ubi_AVLtree ubi_avl
+ * ubi_SplayTree ubi_spt
+ *
+ * To further complicate matters, only those portions of the base module
+ * (ubi_BinTree) that were superceeded in the new module had the new names.
+ * For example, if you were using ubi_AVLtree, the AVL node structure was
+ * named "ubi_avlNode", but the root structure was still "ubi_btRoot". Using
+ * SplayTree, the locate function was called "ubi_sptLocate", but the next
+ * and previous functions remained "ubi_btNext" and "ubi_btPrev".
+ *
+ * This was not too terrible if you were familiar with the modules and knew
+ * exactly which tree model you wanted to use. If you wanted to be able to
+ * change modules (for speed comparisons, etc), things could get messy very
+ * quickly.
+ *
+ * So, I have added a set of defined names that get redefined in any of the
+ * descendant modules. To use this standardized interface in your code,
+ * simply replace all occurances of "ubi_bt", "ubi_avl", and "ubi_spt" with
+ * "ubi_tr". The "ubi_tr" names will resolve to the correct function or
+ * datatype names for the module that you are using. Just remember to
+ * include the header for that module in your program file. Because these
+ * names are handled by the preprocessor, there is no added run-time
+ * overhead.
+ *
+ * Note that the original names do still exist, and can be used if you wish
+ * to write code directly to a specific module. This should probably only be
+ * done if you are planning to implement a new descendant type, such as
+ * red/black trees. CRH
+ *
+ * V0.0 - June, 1991 - Written by Christopher R. Hertel (CRH).
+ *
+ * ========================================================================== **
+ */
+
+#include "ubi_BinTree.h" /* Header for this module */
+#include <stdlib.h> /* Standard C definitions. */
+
+/* ========================================================================== **
+ * Static data.
+ */
+
+static char ModuleID[] = "ubi_BinTree\n\
+\t$Revision: 1.1 $\n\
+\t$Date: 1997/10/09 04:09:52 $\n\
+\t$Author: crh $\n";
+
+/* ========================================================================== **
+ * Internal (private) functions.
+ */
+
+static ubi_btNodePtr qFind( ubi_btCompFunc cmp,
+ ubi_btItemPtr FindMe,
+ register ubi_btNodePtr p )
+ /* ------------------------------------------------------------------------ **
+ * This function performs a non-recursive search of a tree for a node
+ * matching a specific key. It is called "qFind()" because it is
+ * faster that TreeFind (below).
+ *
+ * Input:
+ * cmp - a pointer to the tree's comparison function.
+ * FindMe - a pointer to the key value for which to search.
+ * p - a pointer to the starting point of the search. <p>
+ * is considered to be the root of a subtree, and only
+ * the subtree will be searched.
+ *
+ * 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.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ char tmp;
+
+ while( p && (( tmp = AbNormal((*cmp)(FindMe, p)) ) != EQUAL) )
+ p = p->Link[tmp];
+
+ return( p );
+ } /* qFind */
+
+static ubi_btNodePtr TreeFind( ubi_btItemPtr findme,
+ ubi_btNodePtr p,
+ ubi_btNodePtr *parentp,
+ char *gender,
+ ubi_btCompFunc CmpFunc )
+ /* ------------------------------------------------------------------------ **
+ * TreeFind() searches a tree for a given value (findme). It will return a
+ * pointer to the target node, if found, or NULL if the target node was not
+ * found.
+ *
+ * TreeFind() also returns, via parameters, a pointer to the parent of the
+ * target node, and a LEFT or RIGHT value indicating which child of the
+ * parent is the target node. *If the target is not found*, then these
+ * values indicate the place at which the target *should be found*. This
+ * is useful when inserting a new node into a tree or searching for nodes
+ * "near" the target node.
+ *
+ * The parameters are:
+ *
+ * findme - is a pointer to the key information to be searched for.
+ * p - points to the root of the tree to be searched.
+ * parentp - will return a pointer to a pointer to the !parent! of the
+ * target node, which can be especially usefull if the target
+ * was not found.
+ * gender - returns LEFT or RIGHT to indicate which child of *parentp
+ * was last searched.
+ * CmpFunc - points to the comparison function.
+ *
+ * This function is called by ubi_btLocate() and ubi_btInsert().
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ register ubi_btNodePtr tmp_p = p;
+ ubi_btNodePtr tmp_pp = NULL;
+ char tmp_sex = EQUAL;
+ char tmp_cmp;
+
+ while( tmp_p && (EQUAL != (tmp_cmp = AbNormal((*CmpFunc)(findme, tmp_p)))) )
+ {
+ tmp_pp = tmp_p; /* Keep track of previous node. */
+ tmp_sex = tmp_cmp; /* Keep track of sex of child. */
+ tmp_p = tmp_p->Link[tmp_cmp]; /* Go to child. */
+ }
+ *parentp = tmp_pp; /* Return results. */
+ *gender = tmp_sex;
+ return( tmp_p );
+ } /* TreeFind */
+
+static void ReplaceNode( ubi_btNodePtr *parent,
+ ubi_btNodePtr oldnode,
+ ubi_btNodePtr newnode )
+ /* ------------------------------------------------------------------ *
+ * Remove node oldnode from the tree, replacing it with node newnode.
+ *
+ * Input:
+ * parent - A pointer to he parent pointer of the node to be
+ * replaced. <parent> may point to the Link[] field of
+ * a parent node, or it may indicate the root pointer at
+ * the top of the tree.
+ * oldnode - A pointer to the node that is to be replaced.
+ * newnode - A pointer to the node that is to be installed in the
+ * place of <*oldnode>.
+ *
+ * Notes: Don't forget to free oldnode.
+ * Also, this function used to have a really nasty typo
+ * bug. "oldnode" and "newnode" were swapped in the line
+ * that now reads:
+ * ((unsigned char *)newnode)[i] = ((unsigned char *)oldnode)[i];
+ * Bleah!
+ * ------------------------------------------------------------------ *
+ */
+ {
+ register int i;
+ register int btNodeSize = sizeof( ubi_btNode );
+
+ for( i = 0; i < btNodeSize; i++ ) /* Copy node internals to new node. */
+ ((unsigned char *)newnode)[i] = ((unsigned char *)oldnode)[i];
+ (*parent) = newnode; /* Old node's parent points to new child. */
+ /* Now tell the children about their new step-parent. */
+ if( oldnode->Link[LEFT ] ) (oldnode->Link[LEFT ])->Link[PARENT] = newnode;
+ if( oldnode->Link[RIGHT] ) (oldnode->Link[RIGHT])->Link[PARENT] = newnode;
+ } /* ReplaceNode */
+
+static void SwapNodes( ubi_btRootPtr RootPtr,
+ ubi_btNodePtr Node1,
+ ubi_btNodePtr Node2 )
+ /* ------------------------------------------------------------------------ **
+ * This function swaps two nodes in the tree. Node1 will take the place of
+ * Node2, and Node2 will fill in the space left vacant by Node 1.
+ *
+ * Input:
+ * RootPtr - pointer to the tree header structure for this tree.
+ * Node1 - \
+ * > These are the two nodes which are to be swapped.
+ * Node2 - /
+ *
+ * Notes:
+ * This function does a three step swap, using a dummy node as a place
+ * holder. This function is used by ubi_btRemove().
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ ubi_btNodePtr *Parent;
+ ubi_btNode dummy;
+ ubi_btNodePtr dummy_p = &dummy;
+
+ /* Replace Node 1 with the dummy, thus removing Node1 from the tree. */
+ if( Node1->Link[PARENT] )
+ Parent = &((Node1->Link[PARENT])->Link[Node1->gender]);
+ else
+ Parent = &(RootPtr->root);
+ ReplaceNode( Parent, Node1, dummy_p );
+
+ /* Swap Node 1 with Node 2, placing Node 1 back into the tree. */
+ if( Node2->Link[PARENT] )
+ Parent = &((Node2->Link[PARENT])->Link[Node2->gender]);
+ else
+ Parent = &(RootPtr->root);
+ ReplaceNode( Parent, Node2, Node1 );
+
+ /* Swap Node 2 and the dummy, thus placing Node 2 back into the tree. */
+ if( dummy_p->Link[PARENT] )
+ Parent = &((dummy_p->Link[PARENT])->Link[dummy_p->gender]);
+ else
+ Parent = &(RootPtr->root);
+ ReplaceNode( Parent, dummy_p, Node2 );
+ } /* SwapNodes */
+
+/* -------------------------------------------------------------------------- **
+ * These routines allow you to walk through the tree, forwards or backwards.
+ */
+
+static ubi_btNodePtr SubSlide( register ubi_btNodePtr P,
+ register char whichway )
+ /* ------------------------------------------------------------------------ **
+ * Slide down the side of a subtree.
+ *
+ * Given a starting node, this function returns a pointer to the LEFT-, or
+ * RIGHT-most descendent, *or* (if whichway is PARENT) to the tree root.
+ *
+ * Input: P - a pointer to a starting place.
+ * whichway - the direction (LEFT, RIGHT, or PARENT) in which to
+ * travel.
+ * Output: A pointer to a node that is either the root, or has no
+ * whichway-th child but is within the subtree of P. Note that
+ * the return value may be the same as P. The return value *will
+ * be* NULL if P is NULL.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ ubi_btNodePtr Q = NULL;
+
+ while( P )
+ {
+ Q = P;
+ P = P->Link[ whichway ];
+ }
+ return( Q );
+ } /* SubSlide */
+
+static ubi_btNodePtr Neighbor( register ubi_btNodePtr P,
+ register char whichway )
+ /* ------------------------------------------------------------------------ **
+ * Given starting point p, return the (key order) next or preceeding node
+ * in the tree.
+ *
+ * Input: P - Pointer to our starting place node.
+ * whichway - the direction in which to travel to find the
+ * neighbor, i.e., the RIGHT neighbor or the LEFT
+ * neighbor.
+ *
+ * Output: A pointer to the neighboring node, or NULL if P was NULL.
+ *
+ * Notes: If whichway is PARENT, the results are unpredictable.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ if( P )
+ {
+ if( P->Link[ whichway ] )
+ return( SubSlide( P->Link[ whichway ], (char)RevWay(whichway) ) );
+ else
+ while( P->Link[ PARENT ] )
+ {
+ if( (P->Link[ PARENT ])->Link[ whichway ] == P )
+ P = P->Link[ PARENT ];
+ else
+ return( P->Link[ PARENT ] );
+ }
+ }
+ return( NULL );
+ } /* Neighbor */
+
+static ubi_btNodePtr Border( ubi_btRootPtr RootPtr,
+ ubi_btItemPtr FindMe,
+ ubi_btNodePtr p,
+ char whichway )
+ /* ------------------------------------------------------------------------ **
+ * Given starting point p, which has a key value equal to *FindMe, locate
+ * the first (index order) node with the same key value.
+ *
+ * This function is useful in trees that have can have duplicate keys.
+ * For example, consider the following tree:
+ * Tree Traversal
+ * 2 If <p> points to the root and <whichway> is RIGHT, 3
+ * / \ then the return value will be a pointer to the / \
+ * 2 2 RIGHT child of the root node. The tree on 2 5
+ * / / \ the right shows the order of traversal. / / \
+ * 1 2 3 1 4 6
+ *
+ * Input: RootPtr - Pointer to the tree root structure.
+ * FindMe - Key value for comparisons.
+ * p - Pointer to the starting-point node.
+ * whichway - the direction in which to travel to find the
+ * neighbor, i.e., the RIGHT neighbor or the LEFT
+ * neighbor.
+ *
+ * Output: A pointer to the first (index, or "traversal", order) node with
+ * a Key value that matches *FindMe.
+ *
+ * Notes: If whichway is PARENT, or if the tree does not allow duplicate
+ * keys, this function will return <p>.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ register ubi_btNodePtr q;
+
+ /* Exit if there's nothing that can be done. */
+ if( !Dups_OK( RootPtr ) || (PARENT == whichway) )
+ return( p );
+
+ /* First, if needed, move up the tree. We need to get to the root of the
+ * subtree that contains all of the matching nodes.
+ */
+ q = p->Link[PARENT];
+ while( q && (EQUAL == AbNormal( (*(RootPtr->cmp))(FindMe, q) )) )
+ {
+ p = q;
+ q = p->Link[PARENT];
+ }
+
+ /* Next, move back down in the "whichway" direction. */
+ q = p->Link[whichway];
+ while( q )
+ {
+ if( q = qFind( RootPtr->cmp, FindMe, q ) )
+ {
+ p = q;
+ q = p->Link[whichway];
+ }
+ }
+ return( p );
+ } /* Border */
+
+
+/* ========================================================================== **
+ * Exported utilities.
+ */
+
+long ubi_btSgn( register long x )
+ /* ------------------------------------------------------------------------ **
+ * Return the sign of x; {negative,zero,positive} ==> {-1, 0, 1}.
+ *
+ * Input: x - a signed long integer value.
+ *
+ * Output: the "sign" of x, represented as follows:
+ * -1 == negative
+ * 0 == zero (no sign)
+ * 1 == positive
+ *
+ * Note: This utility is provided in order to facilitate the conversion
+ * of C comparison function return values into BinTree direction
+ * values: {LEFT, PARENT, EQUAL}. It is INCORPORATED into the
+ * AbNormal() conversion macro!
+ *
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ return( (x)?((x>0)?(1):(-1)):(0) );
+ } /* ubi_btSgn */
+
+ubi_btNodePtr ubi_btInitNode( ubi_btNodePtr NodePtr )
+ /* ------------------------------------------------------------------------ **
+ * Initialize a tree node.
+ *
+ * Input: a pointer to a ubi_btNode structure to be initialized.
+ * Output: a pointer to the initialized ubi_btNode structure (ie. the
+ * same as the input pointer).
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ NodePtr->Link[ LEFT ] = NULL;
+ NodePtr->Link[ PARENT ] = NULL;
+ NodePtr->Link[ RIGHT ] = NULL;
+ NodePtr->gender = EQUAL;
+ return( NodePtr );
+ } /* ubi_btInitNode */
+
+ubi_btRootPtr ubi_btInitTree( ubi_btRootPtr RootPtr,
+ ubi_btCompFunc CompFunc,
+ unsigned char Flags )
+ /* ------------------------------------------------------------------------ **
+ * Initialize the fields of a Tree Root header structure.
+ *
+ * Input: RootPtr - a pointer to an ubi_btRoot structure to be
+ * initialized.
+ * CompFunc - a pointer to a comparison function that will be used
+ * whenever nodes in the tree must be compared against
+ * outside values.
+ * Flags - One bytes worth of flags. Flags include
+ * ubi_trOVERWRITE and ubi_trDUPKEY. See the header
+ * file for more info.
+ *
+ * Output: a pointer to the initialized ubi_btRoot structure (ie. the
+ * same value as RootPtr).
+ *
+ * Note: The interface to this function has changed from that of
+ * previous versions. The <Flags> parameter replaces two
+ * boolean parameters that had the same basic effect.
+ *
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ if( RootPtr )
+ {
+ RootPtr->root = NULL;
+ RootPtr->count = 0L;
+ RootPtr->cmp = CompFunc;
+ RootPtr->flags = (Flags & ubi_trDUPKEY) ? ubi_trDUPKEY : Flags;
+ } /* There are only two supported flags, and they are
+ * mutually exclusive. ubi_trDUPKEY takes precedence
+ * over ubi_trOVERWRITE.
+ */
+ return( RootPtr );
+ } /* ubi_btInitTree */
+
+ubi_trBool ubi_btInsert( ubi_btRootPtr RootPtr,
+ ubi_btNodePtr NewNode,
+ ubi_btItemPtr ItemPtr,
+ ubi_btNodePtr *OldNode )
+ /* ------------------------------------------------------------------------ **
+ * This function uses a non-recursive algorithm to add a new element to the
+ * 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,
+ parent = NULL;
+ char tmp;
+
+ if( !(OldNode) ) /* If they didn't give us a pointer, supply our own. */
+ OldNode = &OtherP;
+
+ (void)ubi_btInitNode( NewNode ); /* Init the new node's BinTree fields. */
+
+ /* Find a place for the new node. */
+ *OldNode = TreeFind(ItemPtr, (RootPtr->root), &parent, &tmp, (RootPtr->cmp));
+
+ /* Now add the node to the tree... */
+ if (!(*OldNode)) /* The easy one: we have a space for a new node! */
+ {
+ if (!(parent))
+ RootPtr->root = NewNode;
+ else
+ {
+ parent->Link[tmp] = NewNode;
+ NewNode->Link[PARENT] = parent;
+ NewNode->gender = tmp;
+ }
+ (RootPtr->count)++;
+ return( ubi_trTRUE );
+ }
+
+ /* If we reach this point, we know that a duplicate node exists. This
+ * section adds the node to the tree if duplicate keys are allowed.
+ */
+ if( Dups_OK(RootPtr) ) /* Key exists, add duplicate */
+ {
+ ubi_btNodePtr q;
+
+ tmp = RIGHT;
+ q = (*OldNode);
+ *OldNode = NULL;
+ while( q )
+ {
+ parent = q;
+ if( tmp == EQUAL ) tmp = RIGHT;
+ q = q->Link[tmp];
+ if ( q )
+ tmp = AbNormal( (*(RootPtr->cmp))(ItemPtr, q) );
+ }
+ parent->Link[tmp] = NewNode;
+ NewNode->Link[PARENT] = parent;
+ NewNode->gender = tmp;
+ (RootPtr->count)++;
+ return( ubi_trTRUE );
+ }
+
+ /* If we get to *this* point, we know that we are not allowed to have
+ * duplicate nodes, but our node keys match, so... may we replace the
+ * old one?
+ */
+ if( Ovwt_OK(RootPtr) ) /* Key exists, we replace */
+ {
+ if (!(parent))
+ ReplaceNode( &(RootPtr->root), *OldNode, NewNode );
+ else
+ ReplaceNode( &(parent->Link[(*OldNode)->gender]), *OldNode, NewNode );
+ return( ubi_trTRUE );
+ }
+
+ return( ubi_trFALSE ); /* Failure: could not replace an existing node. */
+ } /* ubi_btInsert */
+
+ubi_btNodePtr ubi_btRemove( 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,
+ *parentp;
+ char tmp;
+
+ /* if the node has both left and right subtrees, then we have to swap
+ * it with another node. The other node we choose will be the Prev()ious
+ * node, which is garunteed to have no RIGHT child.
+ */
+ if( (DeadNode->Link[LEFT]) && (DeadNode->Link[RIGHT]) )
+ SwapNodes( RootPtr, DeadNode, ubi_btPrev( DeadNode ) );
+
+ /* The parent of the node to be deleted may be another node, or it may be
+ * the root of the tree. Since we're not sure, it's best just to have
+ * a pointer to the parent pointer, whatever it is.
+ */
+ if (DeadNode->Link[PARENT])
+ parentp = &((DeadNode->Link[PARENT])->Link[DeadNode->gender]);
+ else
+ parentp = &( RootPtr->root );
+
+ /* Now link the parent to the only grand-child and patch up the gender. */
+ tmp = ((DeadNode->Link[LEFT])?LEFT:RIGHT);
+
+ p = (DeadNode->Link[tmp]);
+ if( p )
+ {
+ p->Link[PARENT] = DeadNode->Link[PARENT];
+ p->gender = DeadNode->gender;
+ }
+ (*parentp) = p;
+
+ /* Finished, reduce the node count and return. */
+ (RootPtr->count)--;
+ return( DeadNode );
+ } /* ubi_btRemove */
+
+ubi_btNodePtr ubi_btLocate( 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().
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ register ubi_btNodePtr p;
+ ubi_btNodePtr parent;
+ char whichkid;
+
+ /* Start by searching for a matching node. */
+ p = TreeFind( FindMe,
+ RootPtr->root,
+ &parent,
+ &whichkid,
+ RootPtr->cmp );
+
+ if( p ) /* If we have found a match, we can resolve as follows: */
+ {
+ switch( CompOp )
+ {
+ case ubi_trLT: /* It's just a jump to the left... */
+ p = Border( RootPtr, FindMe, p, LEFT );
+ return( Neighbor( p, LEFT ) );
+ case ubi_trGT: /* ...and then a jump to the right. */
+ p = Border( RootPtr, FindMe, p, RIGHT );
+ return( Neighbor( p, RIGHT ) );
+ }
+ p = Border( RootPtr, FindMe, p, LEFT );
+ return( p );
+ }
+
+ /* Else, no match. */
+ if( ubi_trEQ == CompOp ) /* If we were looking for an exact match... */
+ return( NULL ); /* ...forget it. */
+
+ /* We can still return a valid result for GT, GE, LE, and LT.
+ * <parent> points to a node with a value that is either just before or
+ * just after the target value.
+ * Remaining possibilities are LT and GT (including LE & GE).
+ */
+ if( (ubi_trLT == CompOp) || (ubi_trLE == CompOp) )
+ return( (LEFT == whichkid) ? Neighbor( parent, whichkid ) : parent );
+ else
+ return( (RIGHT == whichkid) ? Neighbor( parent, whichkid ) : parent );
+ } /* ubi_btLocate */
+
+ubi_btNodePtr ubi_btFind( 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_btLocate().
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ return( qFind( RootPtr->cmp, FindMe, RootPtr->root ) );
+ } /* ubi_btFind */
+
+ubi_btNodePtr ubi_btNext( ubi_btNodePtr P )
+ /* ------------------------------------------------------------------------ **
+ * Given the node indicated by P, find the (sorted order) Next node in the
+ * tree.
+ * Input: P - a pointer to a node that exists in a binary tree.
+ * Output: A pointer to the "next" node in the tree, or NULL if P pointed
+ * to the "last" node in the tree or was NULL.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ return( Neighbor( P, RIGHT ) );
+ } /* ubi_btNext */
+
+ubi_btNodePtr ubi_btPrev( ubi_btNodePtr P )
+ /* ------------------------------------------------------------------------ **
+ * Given the node indicated by P, find the (sorted order) Previous node in
+ * the tree.
+ * Input: P - a pointer to a node that exists in a binary tree.
+ * Output: A pointer to the "previous" node in the tree, or NULL if P
+ * pointed to the "first" node in the tree or was NULL.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ return( Neighbor( P, LEFT ) );
+ } /* ubi_btPrev */
+
+ubi_btNodePtr ubi_btFirst( ubi_btNodePtr P )
+ /* ------------------------------------------------------------------------ **
+ * Given the node indicated by P, find the (sorted order) First node in the
+ * subtree of which *P is the root.
+ * Input: P - a pointer to a node that exists in a binary tree.
+ * Output: A pointer to the "first" node in a subtree that has *P as its
+ * root. This function will return NULL only if P is NULL.
+ * Note: In general, you will be passing in the value of the root field
+ * of an ubi_btRoot structure.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ return( SubSlide( P, LEFT ) );
+ } /* ubi_btFirst */
+
+ubi_btNodePtr ubi_btLast( ubi_btNodePtr P )
+ /* ------------------------------------------------------------------------ **
+ * Given the node indicated by P, find the (sorted order) Last node in the
+ * subtree of which *P is the root.
+ * Input: P - a pointer to a node that exists in a binary tree.
+ * Output: A pointer to the "last" node in a subtree that has *P as its
+ * root. This function will return NULL only if P is NULL.
+ * Note: In general, you will be passing in the value of the root field
+ * of an ubi_btRoot structure.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ return( SubSlide( P, RIGHT ) );
+ } /* ubi_btLast */
+
+ubi_btNodePtr ubi_btFirstOf( ubi_btRootPtr RootPtr,
+ ubi_btItemPtr MatchMe,
+ ubi_btNodePtr p )
+ /* ------------------------------------------------------------------------ **
+ * Given a tree that a allows duplicate keys, and a pointer to a node in
+ * the tree, this function will return a pointer to the first (traversal
+ * order) node with the same key value.
+ *
+ * Input: RootPtr - A pointer to the root of the tree.
+ * MatchMe - A pointer to the key value. This should probably
+ * point to the key within node *p.
+ * p - A pointer to a node in the tree.
+ * Output: A pointer to the first node in the set of nodes with keys
+ * matching <FindMe>.
+ * Notes: Node *p MUST be in the set of nodes with keys matching
+ * <FindMe>. If not, this function will return NULL.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ /* If our starting point is invalid, return NULL. */
+ if( !p || AbNormal( (*(RootPtr->cmp))( MatchMe, p ) != EQUAL ) )
+ return( NULL );
+ return( Border( RootPtr, MatchMe, p, LEFT ) );
+ } /* ubi_btFirstOf */
+
+ubi_btNodePtr ubi_btLastOf( ubi_btRootPtr RootPtr,
+ ubi_btItemPtr MatchMe,
+ ubi_btNodePtr p )
+ /* ------------------------------------------------------------------------ **
+ * Given a tree that a allows duplicate keys, and a pointer to a node in
+ * the tree, this function will return a pointer to the last (traversal
+ * order) node with the same key value.
+ *
+ * Input: RootPtr - A pointer to the root of the tree.
+ * MatchMe - A pointer to the key value. This should probably
+ * point to the key within node *p.
+ * p - A pointer to a node in the tree.
+ * Output: A pointer to the last node in the set of nodes with keys
+ * matching <FindMe>.
+ * Notes: Node *p MUST be in the set of nodes with keys matching
+ * <FindMe>. If not, this function will return NULL.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ /* If our starting point is invalid, return NULL. */
+ if( !p || AbNormal( (*(RootPtr->cmp))( MatchMe, p ) != EQUAL ) )
+ return( NULL );
+ return( Border( RootPtr, MatchMe, p, RIGHT ) );
+ } /* ubi_btLastOf */
+
+ubi_trBool ubi_btTraverse( ubi_btRootPtr RootPtr,
+ ubi_btActionRtn EachNode,
+ void *UserData )
+ /* ------------------------------------------------------------------------ **
+ * Traverse a tree in sorted order (non-recursively). At each node, call
+ * (*EachNode)(), passing a pointer to the current node, and UserData as the
+ * second parameter.
+ * Input: RootPtr - a pointer to an ubi_btRoot structure that indicates
+ * the tree to be traversed.
+ * EachNode - a pointer to a function to be called at each node
+ * as the node is visited.
+ * UserData - a generic pointer that may point to anything that
+ * you choose.
+ * Output: A boolean value. FALSE if the tree is empty, otherwise TRUE.
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ ubi_btNodePtr p;
+
+ if( !(p = ubi_btFirst( RootPtr->root )) ) return( ubi_trFALSE );
+
+ while( p )
+ {
+ EachNode( p, UserData );
+ p = ubi_btNext( p );
+ }
+ return( ubi_trTRUE );
+ } /* ubi_btTraverse */
+
+ubi_trBool ubi_btKillTree( ubi_btRootPtr RootPtr,
+ ubi_btKillNodeRtn FreeNode )
+ /* ------------------------------------------------------------------------ **
+ * Delete an entire tree (non-recursively) and reinitialize the ubi_btRoot
+ * structure. Note that this function will return FALSE if either parameter
+ * is NULL.
+ *
+ * Input: RootPtr - a pointer to an ubi_btRoot structure that indicates
+ * the root of the tree to delete.
+ * FreeNode - a function that will be called for each node in the
+ * tree to deallocate the memory used by the node.
+ *
+ * Output: A boolean value. FALSE if either input parameter was NULL, else
+ * TRUE.
+ *
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ ubi_btNodePtr p, q;
+
+ if( !(RootPtr) || !(FreeNode) )
+ return( ubi_trFALSE );
+
+ p = ubi_btFirst( RootPtr->root );
+ while( p )
+ {
+ q = p;
+ while( q->Link[RIGHT] )
+ q = SubSlide( q->Link[RIGHT], LEFT );
+ p = q->Link[PARENT];
+ if( p )
+ p->Link[ ((p->Link[LEFT] == q)?LEFT:RIGHT) ] = NULL;
+ FreeNode((void *)q);
+ }
+
+ (void)ubi_btInitTree( RootPtr,
+ RootPtr->cmp,
+ RootPtr->flags );
+ return( ubi_trTRUE );
+ } /* ubi_btKillTree */
+
+ubi_btNodePtr ubi_btLeafNode( ubi_btNodePtr leader )
+ /* ------------------------------------------------------------------------ **
+ * Returns a pointer to a leaf node.
+ *
+ * Input: leader - Pointer to a node at which to start the descent.
+ *
+ * Output: A pointer to a leaf node selected in a somewhat arbitrary
+ * manner.
+ *
+ * Notes: I wrote this function because I was using splay trees as a
+ * database cache. The cache had a maximum size on it, and I
+ * needed a way of choosing a node to sacrifice if the cache
+ * became full. In a splay tree, less recently accessed nodes
+ * tend toward the bottom of the tree, meaning that leaf nodes
+ * are good candidates for removal. (I really can't think of
+ * any other reason to use this function.)
+ * + In a simple binary tree or an AVL tree, the most recently
+ * added nodes tend to be nearer the bottom, making this a *bad*
+ * way to choose which node to remove from the cache.
+ * + Randomizing the traversal order is probably a good idea. You
+ * can improve the randomization of leaf node selection by passing
+ * in pointers to nodes other than the root node each time. A
+ * pointer to any node in the tree will do. Of course, if you
+ * pass a pointer to a leaf node you'll get the same thing back.
+ *
+ * ------------------------------------------------------------------------ **
+ */
+ {
+ ubi_btNodePtr follower = NULL;
+ int whichway = LEFT;
+
+ while( NULL != leader )
+ {
+ follower = leader;
+ leader = follower->Link[ whichway ];
+ if( NULL == leader )
+ {
+ whichway = RevWay( whichway );
+ leader = follower->Link[ whichway ];
+ }
+ }
+
+ return( follower );
+ } /* ubi_btLeafNode */
+
+int ubi_btModuleID( 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 )
+ list[1] = NULL;
+ return( 1 );
+ }
+ return( 0 );
+ } /* ubi_btModuleID */
+
+
+/* ========================================================================== */
git.samba.org / kai / samba.git / commitdiff