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michael |
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/* |
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** Copyright (C) 2003 by Kevin L. Mitchell <klmitch@mit.edu> |
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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., 59 Temple Place - Suite 330, Boston, |
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** MA 02111-1307, USA |
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** |
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** @(#)$Id: rt_add.c,v 1.1 2003/06/28 18:48:21 klmitch Exp $ |
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*/ |
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#include "dbprim.h" |
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#include "dbprim_int.h" |
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RCSTAG("@(#)$Id: rt_add.c,v 1.1 2003/06/28 18:48:21 klmitch Exp $"); |
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/* Locate the uncle of the given node */ |
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#define uncle(node) (rn_isleft((node)->rn_parent) ? \ |
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(node)->rn_parent->rn_parent->rn_right : \ |
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(node)->rn_parent->rn_parent->rn_left) |
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/* Flip the color of the given node */ |
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#define flip(node) ((node)->rn_color = \ |
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((node)->rn_color == RB_COLOR_BLACK) ? \ |
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RB_COLOR_RED : RB_COLOR_BLACK) |
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/** \ingroup dbprim_rbtree |
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* \brief Add a node to a red-black tree. |
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* |
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* This function adds a node to a red-black tree. |
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* |
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* \param tree A pointer to a #rb_tree_t. |
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* \param node A pointer to a #rb_node_t to be added to the tree. |
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* \param key A pointer to a #db_key_t containing the key for the |
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* node. |
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* |
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* \retval DB_ERR_BADARGS An invalid argument was given. |
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* \retval DB_ERR_BUSY The node is already in a tree. |
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* \retval DB_ERR_FROZEN The tree is currently frozen. |
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* \retval DB_ERR_DUPLICATE The entry is a duplicate of an |
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* existing node. |
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*/ |
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unsigned long |
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rt_add(rb_tree_t *tree, rb_node_t *node, db_key_t *key) |
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{ |
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initialize_dbpr_error_table(); /* initialize error table */ |
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if (!rt_verify(tree) || !rn_verify(node) || !key) /* verify arguments */ |
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return DB_ERR_BADARGS; |
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if (node->rn_tree) /* it's already in a tree... */ |
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return DB_ERR_BUSY; |
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if (tree->rt_flags & RBT_FLAG_FREEZE) /* don't add to frozen trees */ |
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return DB_ERR_FROZEN; |
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if (_rb_locate(tree, node, key) != node) /* add it to the tree... */ |
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return DB_ERR_DUPLICATE; /* We don't allow duplication! */ |
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/* OK, node has been added, now let's rebalance the tree... */ |
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while (!rn_isblack(node) && !rn_isblack(node->rn_parent)) |
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if (rn_isred(uncle(node))) { |
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flip(node->rn_parent); /* Flip the colors of parent and grandparent */ |
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flip(node->rn_parent->rn_parent); |
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flip(uncle(node)); /* and flip the color of the uncle */ |
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node = node->rn_parent->rn_parent; /* grandparent need balancing? */ |
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} else if ((rn_isleft(node->rn_parent) && rn_isright(node)) || |
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(rn_isright(node->rn_parent) && rn_isleft(node))) { |
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flip(node); /* flip the colors that need flipping... */ |
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flip(node->rn_parent->rn_parent); |
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_rb_rotate(tree, node); /* rotate the node up two levels */ |
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_rb_rotate(tree, node); |
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} else { |
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flip(node->rn_parent); /* flip the colors that need flipping... */ |
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flip(node->rn_parent->rn_parent); |
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_rb_rotate(tree, node->rn_parent); /* move the parent up a level */ |
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node = node->rn_parent; /* new parent need balancing? */ |
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} |
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/* Make sure the root node is black */ |
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tree->rt_root->rn_color = RB_COLOR_BLACK; |
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return 0; |
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} |
