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Diffstat (limited to 'libjava/java/util/Bucket.java')
| -rw-r--r-- | libjava/java/util/Bucket.java | 199 |
1 files changed, 0 insertions, 199 deletions
diff --git a/libjava/java/util/Bucket.java b/libjava/java/util/Bucket.java deleted file mode 100644 index 8c0edf4..0000000 --- a/libjava/java/util/Bucket.java +++ /dev/null @@ -1,199 +0,0 @@ -/* Bucket.java -- a class providing a hash-bucket data structure - (a lightweight linked list) - Copyright (C) 1998, 2000 Free Software Foundation, Inc. - -This file is part of GNU Classpath. - -GNU Classpath is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2, or (at your option) -any later version. - -GNU Classpath 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 -General Public License for more details. - -You should have received a copy of the GNU General Public License -along with GNU Classpath; see the file COPYING. If not, write to the -Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA -02111-1307 USA. - -As a special exception, if you link this library with other files to -produce an executable, this library does not by itself cause the -resulting executable to be covered by the GNU General Public License. -This exception does not however invalidate any other reasons why the -executable file might be covered by the GNU General Public License. */ - - -package java.util; - -/** - * a class representing a simple, lightweight linked-list, using Node - * objects as its linked nodes; this is used by Hashtable and HashMap - * - * @author Jon Zeppieri - * @version $Revision: 1.3 $ - * @modified $Id: Bucket.java,v 1.3 2000/03/15 21:59:08 rao Exp $ - */ -class Bucket -{ - /** the first node of the lined list, originally null */ - Node first; - - /** trivial constructor for a Bucket */ - Bucket() - { - } - - /** add this key / value pair to the list - * - * @param newNode a Node object to be added to this list - * @return the old value mapped to the key if there was one, - * otherwise null. - */ - Object add(Node newNode) - { - Object oKey; - Object oTestKey = newNode.getKey(); - Node it = first; - Node prev = null; - if (it == null) // if the list is empty (the ideal case), we make a new single-node list - { - first = newNode; - return null; - } - else // otherwise try to find where this key already exists in the list, - {// and if it does, replace the value with the new one (and return the old one) - while (it != null) - { - oKey = it.getKey(); - if ((oKey == null) ? (oTestKey == null) : - oKey.equals(oTestKey)) - { - Object oldValue = it.value; - it.value = newNode.getValue(); - return oldValue; - } - prev = it; - it = it.next; - } - prev.next = newNode; // otherwise, just stick this at the - return null; // end of the list - } - } - - /** - * remove a Map.Entry in this list with the supplied key and return its value, - * if it exists, else return null - * - * @param key the key we are looking for in this list - */ - Object removeByKey(Object key) - { - Object oEntryKey; - Node prev = null; - Node it = first; - while (it != null) - { - oEntryKey = it.getKey(); - if ((oEntryKey == null) ? (key == null) : oEntryKey.equals(key)) - { - if (prev == null) // we are removing the first element - first = it.next; - else - prev.next = it.next; - return it.getValue(); - } - else - { - prev = it; - it = it.next; - } - } - return null; - } - - /** - * return the value which the supplied key maps to, if it maps to anything in this list, - * otherwise, return null - * - * @param key the key mapping to a value that we are looking for - */ - Object getValueByKey(Object key) - { - Node entry = getEntryByKey(key); - return (entry == null) ? null : entry.getValue(); - } - - /** - * return the Map.Entry which the supplied key is a part of, if such a Map.Entry exists, - * null otherwise - * - * this method is important for HashMap, which can hold null values and the null key - * - * @param key the key for which we are finding the corresponding Map.Entry - */ - Node getEntryByKey(Object key) - { - Object oEntryKey; - Node it = first; - while (it != null) - { - oEntryKey = it.getKey(); - if ((oEntryKey == null) ? (key == null) : oEntryKey.equals(key)) - return it; - it = it.next; - } - return null; - } - - /** - * return true if this list has a Map.Entry whose value equals() the supplied value - * - * @param value the value we are looking to match in this list - */ - boolean containsValue(Object value) - { - Object oEntryValue; - Node it = first; - while (it != null) - { - oEntryValue = it.getValue(); - if ((oEntryValue == null) ? (value == null) : oEntryValue.equals(value)) - return true; - it = it.next; - } - return false; - } - - // INNSER CLASSES ---------------------------------------------------------- - - /** - * a class represnting a node in our lightweight linked-list - * that we use for hash buckets; a Node object contains a Map.Entry as its - * <pre>value</pre> property and a reference (possibly, even hopefully, null) - * to another Node as its <pre>next</pre> property. - * - * There <i>is</i> a reason for not using a highly generic "LinkedNode" type - * class: we want to eliminate runtime typechecks. - * - * @author Jon Zeppieri - * @version $Revision: 1.3 $ - * @modified $Id: Bucket.java,v 1.3 2000/03/15 21:59:08 rao Exp $ - */ - static class Node extends BasicMapEntry implements Map.Entry - { - /** a reference to the next node in the linked list */ - Node next; - - /** non-trivial contructor -- sets the <pre>value</pre> of the Bucket upon instantiation */ - Node(Object key, Object value) - { - super(key, value); - } - - - } - // EOF ------------------------------------------------------------------------ -} |