001: /*
002: * Copyright 2000-2002 Sun Microsystems, Inc. All Rights Reserved.
003: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004: *
005: * This code is free software; you can redistribute it and/or modify it
006: * under the terms of the GNU General Public License version 2 only, as
007: * published by the Free Software Foundation. Sun designates this
008: * particular file as subject to the "Classpath" exception as provided
009: * by Sun in the LICENSE file that accompanied this code.
010: *
011: * This code is distributed in the hope that it will be useful, but WITHOUT
012: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014: * version 2 for more details (a copy is included in the LICENSE file that
015: * accompanied this code).
016: *
017: * You should have received a copy of the GNU General Public License version
018: * 2 along with this work; if not, write to the Free Software Foundation,
019: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020: *
021: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022: * CA 95054 USA or visit www.sun.com if you need additional information or
023: * have any questions.
024: */
025:
026: package com.sun.jndi.dns;
027:
028: import java.util.Hashtable;
029:
030: /**
031: * A NameNode represents a node in the DNS namespace. Each node
032: * has a label, which is its name relative to its parent (so the
033: * node at Sun.COM has label "Sun"). Each node has a hashtable of
034: * children indexed by their labels converted to lower-case.
035: *
036: * <p> A node may be addressed from another by giving a DnsName
037: * consisting of the sequence of labels from one node to the other.
038: *
039: * <p> Each node also has an <tt>isZoneCut</tt> flag, used to indicate
040: * if the node is a zone cut. A zone cut is a node with an NS record
041: * that is contained in one zone, but that actually belongs to a child zone.
042: *
043: * <p> All access is unsynchronized.
044: *
045: * @author Scott Seligman
046: * @version 1.12 07/05/05
047: */
048:
049: class NameNode {
050:
051: private String label; // name of this node relative to its
052: // parent, or null for root of a tree
053: private Hashtable children = null; // child nodes
054: private boolean isZoneCut = false; // true if this node is a zone cut
055: private int depth = 0; // depth in tree (0 for root)
056:
057: NameNode(String label) {
058: this .label = label;
059: }
060:
061: /*
062: * Returns a newly-allocated NameNode. Used to allocate new nodes
063: * in a tree. Should be overridden in a subclass to return an object
064: * of the subclass's type.
065: */
066: protected NameNode newNameNode(String label) {
067: return new NameNode(label);
068: }
069:
070: /*
071: * Returns the name of this node relative to its parent, or null for
072: * the root of a tree.
073: */
074: String getLabel() {
075: return label;
076: }
077:
078: /*
079: * Returns the depth of this node in the tree. The depth of the root
080: * is 0.
081: */
082: int depth() {
083: return depth;
084: }
085:
086: boolean isZoneCut() {
087: return isZoneCut;
088: }
089:
090: void setZoneCut(boolean isZoneCut) {
091: this .isZoneCut = isZoneCut;
092: }
093:
094: /*
095: * Returns the children of this node, or null if there are none.
096: * The caller must not modify the Hashtable returned.
097: */
098: Hashtable getChildren() {
099: return children;
100: }
101:
102: /*
103: * Returns the child node given the hash key (the down-cased label)
104: * for its name relative to this node, or null if there is no such
105: * child.
106: */
107: NameNode get(String key) {
108: return (children != null) ? (NameNode) children.get(key) : null;
109: }
110:
111: /*
112: * Returns the node at the end of a path, or null if the
113: * node does not exist.
114: * The path is specified by the labels of <tt>name</tt>, beginning
115: * at index idx.
116: */
117: NameNode get(DnsName name, int idx) {
118: NameNode node = this ;
119: for (int i = idx; i < name.size() && node != null; i++) {
120: node = node.get(name.getKey(i));
121: }
122: return node;
123: }
124:
125: /*
126: * Returns the node at the end of a path, creating it and any
127: * intermediate nodes as needed.
128: * The path is specified by the labels of <tt>name</tt>, beginning
129: * at index idx.
130: */
131: NameNode add(DnsName name, int idx) {
132: NameNode node = this ;
133: for (int i = idx; i < name.size(); i++) {
134: String label = name.get(i);
135: String key = name.getKey(i);
136:
137: NameNode child = null;
138: if (node.children == null) {
139: node.children = new Hashtable();
140: } else {
141: child = (NameNode) node.children.get(key);
142: }
143: if (child == null) {
144: child = newNameNode(label);
145: child.depth = node.depth + 1;
146: node.children.put(key, child);
147: }
148: node = child;
149: }
150: return node;
151: }
152: }
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