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7735e4d586
a better way to handle the node pointer array used in ubi_BinTree. The
change simplified the code a bigbunch. It also forced updates to all of
the binary tree modules. CRH
(This used to be commit db9898559f)
1047 lines
42 KiB
C
1047 lines
42 KiB
C
/* ========================================================================== **
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* ubi_BinTree.c
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*
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* Copyright (C) 1991-1997 by Christopher R. Hertel
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*
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* Email: crh@ubiqx.mn.org
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* -------------------------------------------------------------------------- **
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*
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* This module implements simple binary trees.
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*
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* -------------------------------------------------------------------------- **
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free
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* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* -------------------------------------------------------------------------- **
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*
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* Log: ubi_BinTree.c,v
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* Revision 3.0 1997/12/08 06:49:11 crh
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* This is a new major revision level for all ubiqx binary tree modules.
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* In previous releases, the ubi_trNode structure looked like this:
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*
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* typedef struct ubi_btNodeStruct
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* {
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* struct ubi_btNodeStruct *Link[3];
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* signed char gender;
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* } ubi_btNode;
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*
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* As a result, the pointers were indexed as
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*
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* Link[0] == Left Child
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* Link[1] == Parent
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* Link[2] == Right Child
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*
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* With this release, the node structure changes to:
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*
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* typedef struct ubi_btNodeStruct
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* {
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* struct ubi_btNodeStruct *leftlink
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* struct ubi_btNodeStruct *Link[2];
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* signed char gender;
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* } ubi_btNode;
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*
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* The leftlink field is used as a place holder, and the pointers are now
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* index as
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*
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* Link[-1] == Left Child (aka. leftlink)
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* Link[ 0] == Parent
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* Link[ 1] == Right Child
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*
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* which is much nicer. Doing things this way removes the need to shift
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* values between the two numbering schemes, thus removing one macro,
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* simplifying another, and getting rid of a whole bunch of increment &
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* decrement operations.
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*
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* Revision 2; 1995/02/27 - 1997/12/07 included:
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* - The addition of the ModuleID static string and ubi_ModuleID() function.
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* - The addition of the public functions FirstOf() and LastOf(). These
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* functions are used with trees that allow duplicate keys.
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* - The addition of the ubi_btLeafNode() function.
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* - A rewrite of the Locate() function.
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* - A change to the parameter list in function ubi_btInitTree().
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* - Bugfixes.
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*
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* Revision 1; 93/10/15 - 95/02/27:
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* Revision 1 introduced a set of #define's that provide a single API to all
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* of the existing tree modules. Each of these modules has a different name
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* prefix, as follows:
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*
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* Module Prefix
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* ubi_BinTree ubi_bt
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* ubi_AVLtree ubi_avl
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* ubi_SplayTree ubi_spt
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*
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* Only those portions of the base module (ubi_BinTree) that are superceeded
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* in the descendant module have new names. For example, the AVL node
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* structure in ubi_AVLtree.h is named "ubi_avlNode", but the root structure
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* is still "ubi_btRoot". Using SplayTree, the locate function is called
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* "ubi_sptLocate", but the next and previous functions remained "ubi_btNext"
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* and "ubi_btPrev".
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*
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* This is confusing.
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*
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* So, I added a set of defined names that get redefined in any of the
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* descendant modules. To use this standardized interface in your code,
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* simply replace all occurances of "ubi_bt", "ubi_avl", and "ubi_spt" with
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* "ubi_tr". The "ubi_tr" names will resolve to the correct function or
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* datatype names for the module that you are using. Just remember to
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* include the header for that module in your program file. Because these
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* names are handled by the preprocessor, there is no added run-time
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* overhead.
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*
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* Note that the original names do still exist, and can be used if you wish
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* to write code directly to a specific module. This should probably only be
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* done if you are planning to implement a new descendant type, such as
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* red/black trees, or if you plan to use two or more specific tree types
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* in the same piece of code. CRH
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*
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* V0.0 - June, 1991 - Written by Christopher R. Hertel (CRH).
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*
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* ========================================================================== **
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*/
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#include "ubi_BinTree.h" /* Header for this module */
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#include <stdlib.h> /* Standard C definitions. */
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/* ========================================================================== **
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* Static data.
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*/
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static char ModuleID[] = "ubi_BinTree\n\
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\tRevision: 3.0\n\
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\tDate: 1997/12/08 06:49:11\n\
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\tAuthor: crh\n";
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/* ========================================================================== **
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* Internal (private) functions.
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*/
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static ubi_btNodePtr qFind( ubi_btCompFunc cmp,
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ubi_btItemPtr FindMe,
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register ubi_btNodePtr p )
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/* ------------------------------------------------------------------------ **
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* This function performs a non-recursive search of a tree for a node
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* matching a specific key. It is called "qFind()" because it is
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* (probably a little bit) faster that TreeFind (below).
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*
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* Input:
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* cmp - a pointer to the tree's comparison function.
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* FindMe - a pointer to the key value for which to search.
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* p - a pointer to the starting point of the search. <p>
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* is considered to be the root of a subtree, and only
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* the subtree will be searched.
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*
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* Output:
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* A pointer to a node with a key that matches the key indicated by
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* FindMe, or NULL if no such node was found.
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*
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* Note: In a tree that allows duplicates, the pointer returned *might
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* not* point to the (sequentially) first occurance of the
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* desired key.
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* ------------------------------------------------------------------------ **
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*/
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{
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signed char tmp;
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while( p && (( tmp = ubi_trNormalize((*cmp)(FindMe, p)) ) != ubi_trEQUAL) )
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p = p->Link[tmp];
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return( p );
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} /* qFind */
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static ubi_btNodePtr TreeFind( ubi_btItemPtr findme,
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ubi_btNodePtr p,
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ubi_btNodePtr *parentp,
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signed char *gender,
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ubi_btCompFunc CmpFunc )
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/* ------------------------------------------------------------------------ **
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* TreeFind() searches a tree for a given value (findme). It will return a
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* pointer to the target node, if found, or NULL if the target node was not
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* found.
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*
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* TreeFind() also returns, via parameters, a pointer to the parent of the
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* target node, and a LEFT or RIGHT value indicating which child of the
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* parent is the target node. *If the target is not found*, then these
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* values indicate the place at which the target *should be found*. This
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* is useful when inserting a new node into a tree or searching for nodes
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* "near" the target node.
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*
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* The parameters are:
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*
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* findme - is a pointer to the key information to be searched for.
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* p - points to the root of the tree to be searched.
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* parentp - will return a pointer to a pointer to the !parent! of the
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* target node, which can be especially usefull if the target
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* was not found.
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* gender - returns LEFT or RIGHT to indicate which child of *parentp
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* was last searched.
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* CmpFunc - points to the comparison function.
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*
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* This function is called by ubi_btLocate() and ubi_btInsert().
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* ------------------------------------------------------------------------ **
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*/
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{
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register ubi_btNodePtr tmp_p = p;
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ubi_btNodePtr tmp_pp = NULL;
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signed char tmp_gender = ubi_trEQUAL;
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signed char tmp_cmp;
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while( tmp_p
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&& (ubi_trEQUAL != (tmp_cmp = ubi_trNormalize((*CmpFunc)(findme, tmp_p))))
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)
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{
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tmp_pp = tmp_p; /* Keep track of previous node. */
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tmp_gender = tmp_cmp; /* Keep track of sex of child. */
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tmp_p = tmp_p->Link[tmp_cmp]; /* Go to child. */
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}
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*parentp = tmp_pp; /* Return results. */
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*gender = tmp_gender;
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return( tmp_p );
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} /* TreeFind */
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static void ReplaceNode( ubi_btNodePtr *parent,
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ubi_btNodePtr oldnode,
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ubi_btNodePtr newnode )
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/* ------------------------------------------------------------------------ **
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* Remove node oldnode from the tree, replacing it with node newnode.
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*
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* Input:
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* parent - A pointer to he parent pointer of the node to be
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* replaced. <parent> may point to the Link[] field of
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* a parent node, or it may indicate the root pointer at
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* the top of the tree.
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* oldnode - A pointer to the node that is to be replaced.
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* newnode - A pointer to the node that is to be installed in the
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* place of <*oldnode>.
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*
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* Notes: Don't forget to free oldnode.
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*
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* ------------------------------------------------------------------------ **
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*/
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{
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register int i;
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register int btNodeSize = sizeof( ubi_btNode );
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for( i = 0; i < btNodeSize; i++ ) /* Copy node internals to new node. */
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((unsigned char *)newnode)[i] = ((unsigned char *)oldnode)[i];
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/* Old node's parent points to new child. */
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(*parent) = newnode;
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/* Now tell the children about their new step-parent. */
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if( oldnode->Link[ubi_trLEFT ] )
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(oldnode->Link[ubi_trLEFT ])->Link[ubi_trPARENT] = newnode;
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if( oldnode->Link[ubi_trRIGHT] )
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(oldnode->Link[ubi_trRIGHT])->Link[ubi_trPARENT] = newnode;
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} /* ReplaceNode */
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static void SwapNodes( ubi_btRootPtr RootPtr,
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ubi_btNodePtr Node1,
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ubi_btNodePtr Node2 )
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/* ------------------------------------------------------------------------ **
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* This function swaps two nodes in the tree. Node1 will take the place of
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* Node2, and Node2 will fill in the space left vacant by Node 1.
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*
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* Input:
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* RootPtr - pointer to the tree header structure for this tree.
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* Node1 - \
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* > These are the two nodes which are to be swapped.
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* Node2 - /
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*
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* Notes:
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* This function does a three step swap, using a dummy node as a place
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* holder. This function is used by ubi_btRemove().
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* ------------------------------------------------------------------------ **
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*/
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{
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ubi_btNodePtr *Parent;
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ubi_btNode dummy;
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ubi_btNodePtr dummy_p = &dummy;
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/* Replace Node 1 with the dummy, thus removing Node1 from the tree. */
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if( Node1->Link[ubi_trPARENT] )
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Parent = &((Node1->Link[ubi_trPARENT])->Link[Node1->gender]);
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else
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Parent = &(RootPtr->root);
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ReplaceNode( Parent, Node1, dummy_p );
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/* Swap Node 1 with Node 2, placing Node 1 back into the tree. */
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if( Node2->Link[ubi_trPARENT] )
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Parent = &((Node2->Link[ubi_trPARENT])->Link[Node2->gender]);
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else
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Parent = &(RootPtr->root);
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ReplaceNode( Parent, Node2, Node1 );
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/* Swap Node 2 and the dummy, thus placing Node 2 back into the tree. */
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if( dummy_p->Link[ubi_trPARENT] )
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Parent = &((dummy_p->Link[ubi_trPARENT])->Link[dummy_p->gender]);
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else
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Parent = &(RootPtr->root);
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ReplaceNode( Parent, dummy_p, Node2 );
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} /* SwapNodes */
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/* -------------------------------------------------------------------------- **
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* These routines allow you to walk through the tree, forwards or backwards.
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*/
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static ubi_btNodePtr SubSlide( register ubi_btNodePtr P,
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register signed char whichway )
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/* ------------------------------------------------------------------------ **
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* Slide down the side of a subtree.
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*
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* Given a starting node, this function returns a pointer to the LEFT-, or
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* RIGHT-most descendent, *or* (if whichway is PARENT) to the tree root.
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*
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* Input: P - a pointer to a starting place.
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* whichway - the direction (LEFT, RIGHT, or PARENT) in which to
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* travel.
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* Output: A pointer to a node that is either the root, or has no
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* whichway-th child but is within the subtree of P. Note that
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* the return value may be the same as P. The return value *will
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* be* NULL if P is NULL.
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* ------------------------------------------------------------------------ **
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*/
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{
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ubi_btNodePtr Q = NULL;
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while( P )
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{
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Q = P;
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P = P->Link[ whichway ];
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}
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return( Q );
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} /* SubSlide */
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static ubi_btNodePtr Neighbor( register ubi_btNodePtr P,
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register signed char whichway )
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/* ------------------------------------------------------------------------ **
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* Given starting point p, return the (key order) next or preceeding node
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* in the tree.
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*
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* Input: P - Pointer to our starting place node.
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* whichway - the direction in which to travel to find the
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* neighbor, i.e., the RIGHT neighbor or the LEFT
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* neighbor.
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*
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* Output: A pointer to the neighboring node, or NULL if P was NULL.
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*
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* Notes: If whichway is PARENT, the results are unpredictable.
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* ------------------------------------------------------------------------ **
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*/
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{
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if( P )
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{
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if( P->Link[ whichway ] )
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return( SubSlide( P->Link[ whichway ], ubi_trRevWay(whichway) ) );
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else
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while( P->Link[ ubi_trPARENT ] )
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{
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if( (P->Link[ ubi_trPARENT ])->Link[ whichway ] == P )
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P = P->Link[ ubi_trPARENT ];
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else
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return( P->Link[ ubi_trPARENT ] );
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}
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}
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return( NULL );
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} /* Neighbor */
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static ubi_btNodePtr Border( ubi_btRootPtr RootPtr,
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ubi_btItemPtr FindMe,
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ubi_btNodePtr p,
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signed char whichway )
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/* ------------------------------------------------------------------------ **
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* Given starting point p, which has a key value equal to *FindMe, locate
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* the first (index order) node with the same key value.
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*
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* This function is useful in trees that have can have duplicate keys.
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* For example, consider the following tree:
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* Tree Traversal
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* 2 If <p> points to the root and <whichway> is RIGHT, 3
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* / \ then the return value will be a pointer to the / \
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* 2 2 RIGHT child of the root node. The tree on 2 5
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* / / \ the right shows the order of traversal. / / \
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* 1 2 3 1 4 6
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*
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* Input: RootPtr - Pointer to the tree root structure.
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* FindMe - Key value for comparisons.
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* p - Pointer to the starting-point node.
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* whichway - the direction in which to travel to find the
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* neighbor, i.e., the RIGHT neighbor or the LEFT
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* neighbor.
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*
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* Output: A pointer to the first (index, or "traversal", order) node with
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* a Key value that matches *FindMe.
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*
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* Notes: If whichway is PARENT, or if the tree does not allow duplicate
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* keys, this function will return <p>.
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* ------------------------------------------------------------------------ **
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*/
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{
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register ubi_btNodePtr q;
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/* Exit if there's nothing that can be done. */
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if( !ubi_trDups_OK( RootPtr ) || (ubi_trPARENT == whichway) )
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return( p );
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/* First, if needed, move up the tree. We need to get to the root of the
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* subtree that contains all of the matching nodes.
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*/
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q = p->Link[ubi_trPARENT];
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while( q && (ubi_trEQUAL == ubi_trNormalize( (*(RootPtr->cmp))(FindMe, q) )) )
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{
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p = q;
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q = p->Link[ubi_trPARENT];
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}
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/* Next, move back down in the "whichway" direction. */
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q = p->Link[whichway];
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while( q )
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{
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if( q = qFind( RootPtr->cmp, FindMe, q ) )
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{
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p = q;
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q = p->Link[whichway];
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}
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}
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return( p );
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} /* Border */
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/* ========================================================================== **
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* Exported utilities.
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*/
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long ubi_btSgn( register long x )
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/* ------------------------------------------------------------------------ **
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* Return the sign of x; {negative,zero,positive} ==> {-1, 0, 1}.
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*
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* Input: x - a signed long integer value.
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*
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* Output: -1, 0, or 1 representing the "sign" of x as follows:
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* -1 == negative
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* 0 == zero (no sign)
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* 1 == positive
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*
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* Note: This utility is provided in order to facilitate the conversion
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* of C comparison function return values into BinTree direction
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* values: {ubi_trLEFT, ubi_trPARENT, ubi_trEQUAL}. It is
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* incorporated into the ubi_trNormalize() conversion macro.
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*
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* ------------------------------------------------------------------------ **
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*/
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{
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return( (x)?((x>0)?(1):(-1)):(0) );
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} /* ubi_btSgn */
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ubi_btNodePtr ubi_btInitNode( ubi_btNodePtr NodePtr )
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/* ------------------------------------------------------------------------ **
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* Initialize a tree node.
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*
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* Input: a pointer to a ubi_btNode structure to be initialized.
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* Output: a pointer to the initialized ubi_btNode structure (ie. the
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* same as the input pointer).
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* ------------------------------------------------------------------------ **
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*/
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{
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NodePtr->Link[ ubi_trLEFT ] = NULL;
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NodePtr->Link[ ubi_trPARENT ] = NULL;
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NodePtr->Link[ ubi_trRIGHT ] = NULL;
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NodePtr->gender = ubi_trEQUAL;
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return( NodePtr );
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} /* ubi_btInitNode */
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ubi_btRootPtr ubi_btInitTree( ubi_btRootPtr RootPtr,
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ubi_btCompFunc CompFunc,
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unsigned char Flags )
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/* ------------------------------------------------------------------------ **
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* Initialize the fields of a Tree Root header structure.
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*
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* Input: RootPtr - a pointer to an ubi_btRoot structure to be
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* initialized.
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* CompFunc - a pointer to a comparison function that will be used
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* whenever nodes in the tree must be compared against
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* outside values.
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* Flags - One bytes worth of flags. Flags include
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* ubi_trOVERWRITE and ubi_trDUPKEY. See the header
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* file for more info.
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*
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* Output: a pointer to the initialized ubi_btRoot structure (ie. the
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* same value as RootPtr).
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|
*
|
|
* 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;
|
|
signed 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[ubi_trPARENT] = 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( ubi_trDups_OK(RootPtr) ) /* Key exists, add duplicate */
|
|
{
|
|
ubi_btNodePtr q;
|
|
|
|
tmp = ubi_trRIGHT;
|
|
q = (*OldNode);
|
|
*OldNode = NULL;
|
|
while( q )
|
|
{
|
|
parent = q;
|
|
if( tmp == ubi_trEQUAL )
|
|
tmp = ubi_trRIGHT;
|
|
q = q->Link[tmp];
|
|
if ( q )
|
|
tmp = ubi_trNormalize( (*(RootPtr->cmp))(ItemPtr, q) );
|
|
}
|
|
parent->Link[tmp] = NewNode;
|
|
NewNode->Link[ubi_trPARENT] = 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( ubi_trOvwt_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;
|
|
signed 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[ubi_trLEFT]) && (DeadNode->Link[ubi_trRIGHT]) )
|
|
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[ubi_trPARENT])
|
|
parentp = &((DeadNode->Link[ubi_trPARENT])->Link[DeadNode->gender]);
|
|
else
|
|
parentp = &( RootPtr->root );
|
|
|
|
/* Now link the parent to the only grand-child and patch up the gender. */
|
|
tmp = ((DeadNode->Link[ubi_trLEFT]) ? ubi_trLEFT : ubi_trRIGHT);
|
|
|
|
p = (DeadNode->Link[tmp]);
|
|
if( p )
|
|
{
|
|
p->Link[ubi_trPARENT] = DeadNode->Link[ubi_trPARENT];
|
|
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;
|
|
signed 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, ubi_trLEFT );
|
|
return( Neighbor( p, ubi_trLEFT ) );
|
|
case ubi_trGT: /* ...and then a jump to the right. */
|
|
p = Border( RootPtr, FindMe, p, ubi_trRIGHT );
|
|
return( Neighbor( p, ubi_trRIGHT ) );
|
|
}
|
|
p = Border( RootPtr, FindMe, p, ubi_trLEFT );
|
|
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( (ubi_trLEFT == whichkid) ? Neighbor( parent, whichkid ) : parent );
|
|
else
|
|
return( (ubi_trRIGHT == 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, ubi_trRIGHT ) );
|
|
} /* 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, ubi_trLEFT ) );
|
|
} /* 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, ubi_trLEFT ) );
|
|
} /* 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, ubi_trRIGHT ) );
|
|
} /* 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 || ubi_trNormalize( (*(RootPtr->cmp))( MatchMe, p ) != ubi_trEQUAL ) )
|
|
return( NULL );
|
|
return( Border( RootPtr, MatchMe, p, ubi_trLEFT ) );
|
|
} /* 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 || ubi_trNormalize( (*(RootPtr->cmp))( MatchMe, p ) != ubi_trEQUAL ) )
|
|
return( NULL );
|
|
return( Border( RootPtr, MatchMe, p, ubi_trRIGHT ) );
|
|
} /* 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[ubi_trRIGHT] )
|
|
q = SubSlide( q->Link[ubi_trRIGHT], ubi_trLEFT );
|
|
p = q->Link[ubi_trPARENT];
|
|
if( p )
|
|
p->Link[ ((p->Link[ubi_trLEFT] == q)?ubi_trLEFT:ubi_trRIGHT) ] = 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.
|
|
* + If using a splay tree, splaying the tree will tend to randomize
|
|
* things a bit too. See ubi_SplayTree for more info.
|
|
*
|
|
* ------------------------------------------------------------------------ **
|
|
*/
|
|
{
|
|
ubi_btNodePtr follower = NULL;
|
|
int whichway = ubi_trLEFT;
|
|
|
|
while( NULL != leader )
|
|
{
|
|
/* The next line is a weak attempt at randomizing. */
|
|
whichway = ((int)leader & 0x0010) ? whichway : ubi_trRevWay(whichway);
|
|
follower = leader;
|
|
leader = leader->Link[ whichway ];
|
|
if( NULL == leader )
|
|
{
|
|
whichway = ubi_trRevWay( 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 */
|
|
|
|
/* ========================================================================== */
|