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Diffstat (limited to 'source3/ubiqx/ubi_SplayTree.c')
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diff --git a/source3/ubiqx/ubi_SplayTree.c b/source3/ubiqx/ubi_SplayTree.c new file mode 100644 index 0000000000..88be2ba9f4 --- /dev/null +++ b/source3/ubiqx/ubi_SplayTree.c @@ -0,0 +1,462 @@ +/* ========================================================================== ** + * ubi_SplayTree.c + * + * Copyright (C) 1993-1995 by Christopher R. Hertel + * + * Email: crh@ubiqx.mn.org + * -------------------------------------------------------------------------- ** + * + * This module implements "splay" trees. Splay trees are binary trees + * that are rearranged (splayed) whenever a node is accessed. The + * splaying process *tends* to make the tree bushier (improves balance), + * and the nodes that are accessed most frequently *tend* to be closer to + * the top. + * + * References: "Self-Adjusting Binary Search Trees", by Daniel Sleator and + * Robert Tarjan. Journal of the Association for Computing + * Machinery Vol 32, No. 3, July 1985 pp. 652-686 + * + * -------------------------------------------------------------------------- ** + * + * 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 2.5 1997/07/26 04:15:42 crh + * + Cleaned up a few minor syntax annoyances that gcc discovered for me. + * + Changed ubi_TRUE and ubi_FALSE to ubi_trTRUE and ubi_trFALSE. + * + * Revision 2.4 1997/06/03 04:42:21 crh + * Changed TRUE and FALSE to ubi_TRUE and ubi_FALSE to avoid causing + * problems. + * + * Revision 2.3 1995/10/03 22:19:07 CRH + * Ubisized! + * Also, added the function ubi_sptSplay(). + * + * Revision 2.1 95/03/09 23:54:42 CRH + * Added the ModuleID static string and function. These modules are now + * self-identifying. + * + * Revision 2.0 95/02/27 22:34:46 CRH + * This module was updated to match the interface changes made to the + * ubi_BinTree module. In particular, the interface to the Locate() function + * has changed. See ubi_BinTree for more information on changes and new + * functions. + * + * The revision number was also upped to match ubi_BinTree. + * + * Revision 1.1 93/10/18 20:35:16 CRH + * I removed the hard-coded logical device names from the include file + * specifications. CRH + * + * Revision 1.0 93/10/15 23:00:15 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 + * + * Revision 0.1 93/04/25 22:03:32 CRH + * Simply changed the <exec/types.h> #include reference the .c file to + * use <stdlib.h> instead. The latter is portable, the former is not. + * + * Revision 0.0 93/04/21 23:05:52 CRH + * Initial version, written by Christopher R. Hertel. + * This module implements Splay Trees using the ubi_BinTree module as a basis. + * + * ========================================================================== ** + */ + +#include <stdlib.h> /* Defines NULL for us. */ +#include "ubi_SplayTree.h" /* Header for THIS module. */ + +/* ========================================================================== ** + * Static data. + */ + +static char ModuleID[] = "ubi_SplayTree\n\ +\tRevision: 2.5\n\ +\tDate: 1997/07/26 04:15:42\n\ +\tAuthor: crh\n"; + + +/* ========================================================================== ** + * Private functions... + */ + +static void Rotate( ubi_btNodePtr p ) + /* ------------------------------------------------------------------------ ** + * This function performs a single rotation, moving node *p up one level + * in the tree. + * + * Input: p - a pointer to an ubi_btNode in a tree. + * + * Output: None. + * + * Notes: This implements a single rotation in either direction (left + * or right). This is the basic building block of all splay + * tree rotations. + * ------------------------------------------------------------------------ ** + */ + { + ubi_btNodePtr parentp; + ubi_btNodePtr tmp; + char way; + char revway; + + parentp = p->Link[PARENT]; /* Find parent. */ + + if( parentp ) /* If no parent, then we're already the root. */ + { + way = p->gender; + revway = RevWay(way); + tmp = p->Link[revway]; + + parentp->Link[way] = tmp; + if( tmp ) + { + tmp->Link[PARENT] = parentp; + tmp->gender = way; + } + + tmp = parentp->Link[PARENT]; + p->Link[PARENT] = tmp; + p->gender = parentp->gender; + if( tmp ) + tmp->Link[p->gender] = p; + + parentp->Link[PARENT] = p; + parentp->gender = revway; + p->Link[revway] = parentp; + } + } /* Rotate */ + +static ubi_btNodePtr Splay( ubi_btNodePtr SplayWithMe ) + /* ------------------------------------------------------------------------ ** + * Move the node indicated by SplayWithMe to the root of the tree by + * splaying the tree. + * + * Input: SplayWithMe - A pointer to an ubi_btNode within a tree. + * + * Output: A pointer to the root of the splay tree (i.e., the same as + * SplayWithMe). + * ------------------------------------------------------------------------ ** + */ + { + ubi_btNodePtr parent; + + while( (parent = SplayWithMe->Link[PARENT]) ) + { + if( parent->gender == SplayWithMe->gender ) /* Zig-Zig */ + Rotate( parent ); + else + { + if( EQUAL != parent->gender ) /* Zig-Zag */ + Rotate( SplayWithMe ); + } + Rotate( SplayWithMe ); /* Zig */ + } /* while */ + return( SplayWithMe ); + } /* Splay */ + +/* ========================================================================== ** + * Exported utilities. + */ + +ubi_trBool ubi_sptInsert( 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 + * splay tree. + * + * Input: RootPtr - a pointer to the ubi_btRoot structure that indicates + * the root of the tree to which NewNode is to be added. + * NewNode - a pointer to an ubi_btNode structure that is NOT + * part of any tree. + * ItemPtr - A pointer to the sort key that is stored within + * *NewNode. ItemPtr MUST point to information stored + * in *NewNode or an EXACT DUPLICATE. The key data + * indicated by ItemPtr is used to place the new node + * into the tree. + * OldNode - a pointer to an ubi_btNodePtr. When searching + * the tree, a duplicate node may be found. If + * duplicates are allowed, then the new node will + * be simply placed into the tree. If duplicates + * are not allowed, however, then one of two things + * may happen. + * 1) if overwritting *is not* allowed, this + * function will return FALSE (indicating that + * the new node could not be inserted), and + * *OldNode will point to the duplicate that is + * still in the tree. + * 2) if overwritting *is* allowed, then this + * function will swap **OldNode for *NewNode. + * In this case, *OldNode will point to the node + * that was removed (thus allowing you to free + * the node). + * ** If you are using overwrite mode, ALWAYS ** + * ** check the return value of this parameter! ** + * Note: You may pass NULL in this parameter, the + * function knows how to cope. If you do this, + * however, there will be no way to return a + * pointer to an old (ie. replaced) node (which is + * a problem if you are using overwrite mode). + * + * Output: a boolean value indicating success or failure. The function + * will return FALSE if the node could not be added to the tree. + * Such failure will only occur if duplicates are not allowed, + * nodes cannot be overwritten, AND a duplicate key was found + * within the tree. + * ------------------------------------------------------------------------ ** + */ + { + ubi_btNodePtr OtherP; + + if( !(OldNode) ) + OldNode = &OtherP; + + if( ubi_btInsert( RootPtr, NewNode, ItemPtr, OldNode ) ) + { + RootPtr->root = Splay( NewNode ); + return( ubi_trTRUE ); + } + + /* Splay the unreplacable, duplicate keyed, unique, old node. */ + RootPtr->root = Splay( (*OldNode) ); + return( ubi_trFALSE ); + } /* ubi_sptInsert */ + +ubi_btNodePtr ubi_sptRemove( ubi_btRootPtr RootPtr, ubi_btNodePtr DeadNode ) + /* ------------------------------------------------------------------------ ** + * This function removes the indicated node from the tree. + * + * Input: RootPtr - A pointer to the header of the tree that contains + * the node to be removed. + * DeadNode - A pointer to the node that will be removed. + * + * Output: This function returns a pointer to the node that was removed + * from the tree (ie. the same as DeadNode). + * + * Note: The node MUST be in the tree indicated by RootPtr. If not, + * strange and evil things will happen to your trees. + * ------------------------------------------------------------------------ ** + */ + { + ubi_btNodePtr p; + + (void)Splay( DeadNode ); /* Move dead node to root. */ + if( (p = DeadNode->Link[LEFT]) ) /* If left subtree exists... */ + { + ubi_btNodePtr q = DeadNode->Link[RIGHT]; + + p->Link[PARENT] = NULL; /* Left subtree node becomes root.*/ + p->gender = PARENT; + p = ubi_btLast( p ); /* Find rightmost left tree node..*/ + p->Link[RIGHT] = q; /* ...attach right tree. */ + if( q ) + q->Link[PARENT] = p; + RootPtr->root = Splay( p ); /* Resplay at p. */ + } + else + { + if( (p = DeadNode->Link[RIGHT]) ) /* No left, but right subtree... */ + { /* ...exists... */ + p->Link[PARENT] = NULL; /* Right subtree root becomes... */ + p->gender = PARENT; /* ...overall tree root. */ + RootPtr->root = p; + } + else + RootPtr->root = NULL; /* No subtrees => empty tree. */ + } + + (RootPtr->count)--; /* Decrement node count. */ + return( DeadNode ); /* Return pointer to pruned node. */ + } /* ubi_sptRemove */ + +ubi_btNodePtr ubi_sptLocate( ubi_btRootPtr RootPtr, + ubi_btItemPtr FindMe, + ubi_trCompOps CompOp ) + /* ------------------------------------------------------------------------ ** + * The purpose of ubi_btLocate() is to find a node or set of nodes given + * a target value and a "comparison operator". The Locate() function is + * more flexible and (in the case of trees that may contain dupicate keys) + * more precise than the ubi_btFind() function. The latter is faster, + * but it only searches for exact matches and, if the tree contains + * duplicates, Find() may return a pointer to any one of the duplicate- + * keyed records. + * + * Input: + * RootPtr - A pointer to the header of the tree to be searched. + * FindMe - An ubi_btItemPtr that indicates the key for which to + * search. + * CompOp - One of the following: + * CompOp Return a pointer to the node with + * ------ --------------------------------- + * ubi_trLT - the last key value that is less + * than FindMe. + * ubi_trLE - the first key matching FindMe, or + * the last key that is less than + * FindMe. + * ubi_trEQ - the first key matching FindMe. + * ubi_trGE - the first key matching FindMe, or the + * first key greater than FindMe. + * ubi_trGT - the first key greater than FindMe. + * Output: + * A pointer to the node matching the criteria listed above under + * CompOp, or NULL if no node matched the criteria. + * + * Notes: + * In the case of trees with duplicate keys, Locate() will behave as + * follows: + * + * Find: 3 Find: 3 + * Keys: 1 2 2 2 3 3 3 3 3 4 4 Keys: 1 1 2 2 2 4 4 5 5 5 6 + * ^ ^ ^ ^ ^ + * LT EQ GT LE GE + * + * That is, when returning a pointer to a node with a key that is LESS + * THAN the target key (FindMe), Locate() will return a pointer to the + * LAST matching node. + * When returning a pointer to a node with a key that is GREATER + * THAN the target key (FindMe), Locate() will return a pointer to the + * FIRST matching node. + * + * See Also: ubi_btFind(), ubi_btFirstOf(), ubi_btLastOf(). + * ------------------------------------------------------------------------ ** + */ + { + ubi_btNodePtr p; + + p = ubi_btLocate( RootPtr, FindMe, CompOp ); + if( p ) + RootPtr->root = Splay( p ); + return( p ); + } /* ubi_sptLocate */ + +ubi_btNodePtr ubi_sptFind( ubi_btRootPtr RootPtr, + ubi_btItemPtr FindMe ) + /* ------------------------------------------------------------------------ ** + * This function performs a non-recursive search of a tree for any node + * matching a specific key. + * + * Input: + * RootPtr - a pointer to the header of the tree to be searched. + * FindMe - a pointer to the key value for which to search. + * + * Output: + * A pointer to a node with a key that matches the key indicated by + * FindMe, or NULL if no such node was found. + * + * Note: In a tree that allows duplicates, the pointer returned *might + * not* point to the (sequentially) first occurance of the + * desired key. In such a tree, it may be more useful to use + * ubi_sptLocate(). + * ------------------------------------------------------------------------ ** + */ + { + ubi_btNodePtr p; + + p = ubi_btFind( RootPtr, FindMe ); + if( p ) + RootPtr->root = Splay( p ); + return( p ); + } /* ubi_sptFind */ + +void ubi_sptSplay( ubi_btRootPtr RootPtr, + ubi_btNodePtr SplayMe ) + /* ------------------------------------------------------------------------ ** + * This function allows you to splay the tree at a given node, thus moving + * the node to the top of the tree. + * + * Input: + * RootPtr - a pointer to the header of the tree to be splayed. + * SplayMe - a pointer to a node within the tree. This will become + * the new root node. + * Output: None. + * + * Notes: This is an uncharacteristic function for this group of modules + * in that it provides access to the internal balancing routines, + * which would normally be hidden. + * Splaying the tree will not damage it (assuming that I've done + * *my* job), but there is overhead involved. I don't recommend + * that you use this function unless you understand the underlying + * Splay Tree principles involved. + * ------------------------------------------------------------------------ ** + */ + { + RootPtr->root = Splay( SplayMe ); + } /* ubi_sptSplay */ + +int ubi_sptModuleID( int size, char *list[] ) + /* ------------------------------------------------------------------------ ** + * Returns a set of strings that identify the module. + * + * Input: size - The number of elements in the array <list>. + * list - An array of pointers of type (char *). This array + * should, initially, be empty. This function will fill + * in the array with pointers to strings. + * Output: The number of elements of <list> that were used. If this value + * is less than <size>, the values of the remaining elements are + * not guaranteed. + * + * Notes: Please keep in mind that the pointers returned indicate strings + * stored in static memory. Don't free() them, don't write over + * them, etc. Just read them. + * ------------------------------------------------------------------------ ** + */ + { + if( size > 0 ) + { + list[0] = ModuleID; + if( size > 1 ) + return( 1 + ubi_btModuleID( --size, &(list[1]) ) ); + return( 1 ); + } + return( 0 ); + } /* ubi_sptModuleID */ + +/* ================================ The End ================================= */ |