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Diffstat (limited to 'source3/ubi_BinTree.c')
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diff --git a/source3/ubi_BinTree.c b/source3/ubi_BinTree.c new file mode 100644 index 0000000000..e6db1a4816 --- /dev/null +++ b/source3/ubi_BinTree.c @@ -0,0 +1,1042 @@ +/* ========================================================================== ** + * 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 */ + + +/* ========================================================================== */ |