diff options
Diffstat (limited to 'source3/ubiqx/ubi_BinTree.h')
| -rw-r--r-- | source3/ubiqx/ubi_BinTree.h | 735 |
1 files changed, 735 insertions, 0 deletions
diff --git a/source3/ubiqx/ubi_BinTree.h b/source3/ubiqx/ubi_BinTree.h new file mode 100644 index 0000000000..ee512989f9 --- /dev/null +++ b/source3/ubiqx/ubi_BinTree.h @@ -0,0 +1,735 @@ +#ifndef ubi_BinTree_H +#define ubi_BinTree_H +/* ========================================================================== ** + * ubi_BinTree.h + * + * 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. + * + * -------------------------------------------------------------------------- ** + * + * Revision 2.4 1997/07/26 04:11:14 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 05:15:27 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 22:00:40 CRH + * Ubisized! + * + * Revision 2.1 95/03/09 23:43:46 CRH + * Added the ModuleID static string and function. These modules are now + * self-identifying. + * + * Revision 2.0 95/02/27 22:00:33 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 22:55:04 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). + * + * ========================================================================== ** + */ + +/* -------------------------------------------------------------------------- ** + * Macros and constants. + * + * General purpose: + * ubi_trTRUE - Boolean TRUE. + * ubi_trFALSE - Boolean FALSE. + * + * Flags used in the tree header: + * ubi_trOVERWRITE - This flag indicates that an existing node may be + * overwritten by a new node with a matching key. + * ubi_trDUPKEY - This flag indicates that the tree allows duplicate + * keys. If the tree does allow duplicates, the + * overwrite flag is ignored. + * + * Node link array index constants: (Each node has an array of three + * pointers. One to the left, one to the right, and one back to the + * parent.) + * LEFT - Left child pointer. + * PARENT - Parent pointer. + * RIGHT - Right child pointer. + * EQUAL - Synonym for PARENT. + * + * ubi_trCompOps: These values are used in the ubi_trLocate() function. + * ubi_trLT - request the first instance of the greatest key less than + * the search key. + * ubi_trLE - request the first instance of the greatest key that is less + * than or equal to the search key. + * ubi_trEQ - request the first instance of key that is equal to the + * search key. + * ubi_trGE - request the first instance of a key that is greater than + * or equal to the search key. + * ubi_trGT - request the first instance of the first key that is greater + * than the search key. + * -------------------------------------------------------------------------- ** + */ + +#define ubi_trTRUE 0xFF +#define ubi_trFALSE 0x00 + +#define ubi_trOVERWRITE 0x01 /* Turn on allow overwrite */ +#define ubi_trDUPKEY 0x02 /* Turn on allow duplicate keys */ + +/* Pointer array index constants... */ +#define LEFT 0x00 +#define PARENT 0x01 +#define RIGHT 0x02 +#define EQUAL PARENT + +typedef enum { + ubi_trLT = 1, + ubi_trLE, + ubi_trEQ, + ubi_trGE, + ubi_trGT + } ubi_trCompOps; + +/* -------------------------------------------------------------------------- ** + * These three macros allow simple manipulation of pointer index values (LEFT, + * RIGHT, and PARENT). + * + * Normalize() - converts {LEFT, PARENT, RIGHT} into {-1, 0 ,1}. C + * uses {negative, zero, positive} values to indicate + * {less than, equal to, greater than}. + * AbNormal() - converts {negative, zero, positive} to {LEFT, PARENT, + * RIGHT} (opposite of Normalize()). Note: C comparison + * functions, such as strcmp(), return {negative, zero, + * positive} values, which are not necessarily {-1, 0, + * 1}. This macro uses the the ubi_btSgn() function to + * compensate. + * RevWay() - converts LEFT to RIGHT and RIGHT to LEFT. PARENT (EQUAL) + * is left as is. + * -------------------------------------------------------------------------- ** + */ +#define Normalize(W) ((char)((W)-EQUAL)) +#define AbNormal(W) ((char)( EQUAL+((char)ubi_btSgn( (W) )) )) +#define RevWay(W) ((char)((W)==LEFT?RIGHT:((W)==RIGHT?LEFT:EQUAL))) + +/* -------------------------------------------------------------------------- ** + * These macros allow us to quickly read the values of the OVERWRITE and + * DUPlicate KEY bits of the tree root flags field. + * -------------------------------------------------------------------------- ** + */ +#define Dups_OK(A) ((ubi_trDUPKEY & ((A)->flags))?(ubi_trTRUE):(ubi_trFALSE)) +#define Ovwt_OK(A) ((ubi_trOVERWRITE & ((A)->flags))?(ubi_trTRUE):(ubi_trFALSE)) + +/* -------------------------------------------------------------------------- ** + * Typedefs... + * + * ubi_trBool - Your typcial true or false... + * + * Item Pointer: The ubi_btItemPtr is a generic pointer. It is used to + * indicate a key that is being searched for within the tree. + * Searching occurs whenever the ubi_trFind(), ubi_trLocate(), + * or ubi_trInsert() functions are called. + * -------------------------------------------------------------------------- ** + */ + +typedef unsigned char ubi_trBool; + +typedef void *ubi_btItemPtr; /* A pointer to data within a node. */ + +/* ------------------------------------------------------------------------- ** + * Binary Tree Node Structure: This structure defines the basic elements of + * the tree nodes. In general you *SHOULD NOT PLAY WITH THESE FIELDS*! + * But, of course, I have to put the structure into this header so that + * you can use it as a building block. + * + * The fields are as follows: + * Link - an array of pointers. These pointers are manipulated by + * the BT routines. The pointers indicate the left and right + * child nodes and the parent node. By keeping track of the + * parent pointer, we avoid the need for recursive routines or + * hand-tooled stacks to keep track of our path back to the + * root. The use of these pointers is subject to change without + * notice. + * gender - a one-byte field indicating whether the node is the RIGHT or + * LEFT child of its parent. If the node is the root of the + * tree, gender will be PARENT. + * ------------------------------------------------------------------------- ** + */ +typedef struct ubi_btNodeStruct { + struct ubi_btNodeStruct *Link[ 3 ]; + char gender; + } ubi_btNode; + +typedef ubi_btNode *ubi_btNodePtr; /* Pointer to an ubi_btNode structure. */ + +/* ------------------------------------------------------------------------- ** + * The next three typedefs define standard function types used by the binary + * tree management routines. In particular: + * + * ubi_btCompFunc is a pointer to a comparison function. Comparison + * functions are passed an ubi_btItemPtr and an + * ubi_btNodePtr. They return a value that is (<0), 0, + * or (>0) to indicate that the Item is (respectively) + * "less than", "equal to", or "greater than" the Item + * contained within the node. (See ubi_btInitTree()). + * ubi_btActionRtn is a pointer to a function that may be called for each + * node visited when performing a tree traversal (see + * ubi_btTraverse()). The function will be passed two + * parameters: the first is a pointer to a node in the + * tree, the second is a generic pointer that may point to + * anything that you like. + * ubi_btKillNodeRtn is a pointer to a function that will deallocate the + * memory used by a node (see ubi_btKillTree()). Since + * memory management is left up to you, deallocation may + * mean anything that you want it to mean. Just remember + * that the tree *will* be destroyed and that none of the + * node pointers will be valid any more. + * ------------------------------------------------------------------------- ** + */ + +typedef int (*ubi_btCompFunc)( ubi_btItemPtr, ubi_btNodePtr ); + +typedef void (*ubi_btActionRtn)( ubi_btNodePtr, void * ); + +typedef void (*ubi_btKillNodeRtn)( ubi_btNodePtr ); + +/* -------------------------------------------------------------------------- ** + * Tree Root Structure: This structure gives us a convenient handle for + * accessing whole AVL trees. The fields are: + * root - A pointer to the root node of the AVL tree. + * count - A count of the number of nodes stored in the tree. + * cmp - A pointer to the comparison routine to be used when building or + * searching the tree. + * flags - A set of bit flags. Two flags are currently defined: + * + * ubi_trOVERWRITE - If set, this flag indicates that a new node should + * (bit 0x01) overwrite an old node if the two have identical + * keys (ie., the keys are equal). + * ubi_trDUPKEY - If set, this flag indicates that the tree is + * (bit 0x02) allowed to contain nodes with duplicate keys. + * + * NOTE: ubi_trInsert() tests ubi_trDUPKEY before ubi_trOVERWRITE. + * + * All of these values are set when you initialize the root structure by + * calling ubi_trInitTree(). + * -------------------------------------------------------------------------- ** + */ + +typedef struct { + ubi_btNodePtr root; /* A pointer to the root node of the tree */ + unsigned long count; /* A count of the number of nodes in the tree */ + ubi_btCompFunc cmp; /* A pointer to the tree's comparison function */ + unsigned char flags; /* Overwrite Y|N, Duplicate keys Y|N... */ + } ubi_btRoot; + +typedef ubi_btRoot *ubi_btRootPtr; /* Pointer to an ubi_btRoot structure. */ + + +/* -------------------------------------------------------------------------- ** + * Function Prototypes. + */ + +long ubi_btSgn( 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! + * + * ------------------------------------------------------------------------ ** + */ + +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). + * ------------------------------------------------------------------------ ** + */ + +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. + * ------------------------------------------------------------------------ ** + */ + +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 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 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(). + * ------------------------------------------------------------------------ ** + */ + +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(). + * ------------------------------------------------------------------------ ** + */ + +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. + * ------------------------------------------------------------------------ ** + */ + +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. + * ------------------------------------------------------------------------ ** + */ + +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. + * ------------------------------------------------------------------------ ** + */ + +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. + * ------------------------------------------------------------------------ ** + */ + +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. + * ------------------------------------------------------------------------ ** + */ + +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. + * ------------------------------------------------------------------------ ** + */ + +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_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 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. + * + * ------------------------------------------------------------------------ ** + */ + + +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. + * ------------------------------------------------------------------------ ** + */ + +/* -------------------------------------------------------------------------- ** + * Masquarade... + * + * This set of defines allows you to write programs that will use any of the + * implemented binary tree modules (currently BinTree, AVLtree, and SplayTree). + * Instead of using ubi_bt..., use ubi_tr..., and select the tree type by + * including the appropriate module header. + */ + +#define ubi_trItemPtr ubi_btItemPtr + +#define ubi_trNode ubi_btNode +#define ubi_trNodePtr ubi_btNodePtr + +#define ubi_trRoot ubi_btRoot +#define ubi_trRootPtr ubi_btRootPtr + +#define ubi_trCompFunc ubi_btCompFunc +#define ubi_trActionRtn ubi_btActionRtn +#define ubi_trKillNodeRtn ubi_btKillNodeRtn + +#define ubi_trSgn( x ) ubi_btSgn( x ) + +#define ubi_trInitNode( Np ) ubi_btInitNode( (ubi_btNodePtr)(Np) ) + +#define ubi_trInitTree( Rp, Cf, Fl ) \ + ubi_btInitTree( (ubi_btRootPtr)(Rp), (ubi_btCompFunc)(Cf), (Fl) ) + +#define ubi_trInsert( Rp, Nn, Ip, On ) \ + ubi_btInsert( (ubi_btRootPtr)(Rp), (ubi_btNodePtr)(Nn), \ + (ubi_btItemPtr)(Ip), (ubi_btNodePtr *)(On) ) + +#define ubi_trRemove( Rp, Dn ) \ + ubi_btRemove( (ubi_btRootPtr)(Rp), (ubi_btNodePtr)(Dn) ) + +#define ubi_trLocate( Rp, Ip, Op ) \ + ubi_btLocate( (ubi_btRootPtr)(Rp), \ + (ubi_btItemPtr)(Ip), \ + (ubi_trCompOps)(Op) ) + +#define ubi_trFind( Rp, Ip ) \ + ubi_btFind( (ubi_btRootPtr)(Rp), (ubi_btItemPtr)(Ip) ) + +#define ubi_trNext( P ) ubi_btNext( (ubi_btNodePtr)(P) ) + +#define ubi_trPrev( P ) ubi_btPrev( (ubi_btNodePtr)(P) ) + +#define ubi_trFirst( P ) ubi_btFirst( (ubi_btNodePtr)(P) ) + +#define ubi_trLast( P ) ubi_btLast( (ubi_btNodePtr)(P) ) + +#define ubi_trFirstOf( Rp, Ip, P ) \ + ubi_btFirstOf( (ubi_btRootPtr)(Rp), \ + (ubi_btItemPtr)(Ip), \ + (ubi_btNodePtr)(P) ) + +#define ubi_trLastOf( Rp, Ip, P ) \ + ubi_btLastOf( (ubi_btRootPtr)(Rp), \ + (ubi_btItemPtr)(Ip), \ + (ubi_btNodePtr)(P) ) + +#define ubi_trTraverse( Rp, En, Ud ) \ + ubi_btTraverse((ubi_btRootPtr)(Rp), (ubi_btActionRtn)(En), (void *)(Ud)) + +#define ubi_trKillTree( Rp, Fn ) \ + ubi_btKillTree( (ubi_btRootPtr)(Rp), (ubi_btKillNodeRtn)(Fn) ) + +#define ubi_trLeafNode( Nd ) \ + ubi_btLeafNode( (ubi_btNodePtr)(Nd) ) + +#define ubi_trModuleID( s, l ) ubi_btModuleID( s, l ) + +/* ========================================================================== */ +#endif /* ubi_BinTree_H */ |