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package com.sun.jndi.dns;


import java.util.Hashtable;


A NameNode represents a node in the DNS namespace. Each node has a label, which is its name relative to its parent (so the node at Sun.COM has label "Sun"). Each node has a hashtable of children indexed by their labels converted to lower-case.

A node may be addressed from another by giving a DnsName consisting of the sequence of labels from one node to the other.

Each node also has an isZoneCut flag, used to indicate if the node is a zone cut. A zone cut is a node with an NS record that is contained in one zone, but that actually belongs to a child zone.

All access is unsynchronized.

Author:Scott Seligman
/** * A NameNode represents a node in the DNS namespace. Each node * has a label, which is its name relative to its parent (so the * node at Sun.COM has label "Sun"). Each node has a hashtable of * children indexed by their labels converted to lower-case. * * <p> A node may be addressed from another by giving a DnsName * consisting of the sequence of labels from one node to the other. * * <p> Each node also has an {@code isZoneCut} flag, used to indicate * if the node is a zone cut. A zone cut is a node with an NS record * that is contained in one zone, but that actually belongs to a child zone. * * <p> All access is unsynchronized. * * @author Scott Seligman */
class NameNode { private String label; // name of this node relative to its // parent, or null for root of a tree private Hashtable<String,NameNode> children = null; // child nodes private boolean isZoneCut = false; // true if this node is a zone cut private int depth = 0; // depth in tree (0 for root) NameNode(String label) { this.label = label; } /* * Returns a newly-allocated NameNode. Used to allocate new nodes * in a tree. Should be overridden in a subclass to return an object * of the subclass's type. */ protected NameNode newNameNode(String label) { return new NameNode(label); } /* * Returns the name of this node relative to its parent, or null for * the root of a tree. */ String getLabel() { return label; } /* * Returns the depth of this node in the tree. The depth of the root * is 0. */ int depth() { return depth; } boolean isZoneCut() { return isZoneCut; } void setZoneCut(boolean isZoneCut) { this.isZoneCut = isZoneCut; } /* * Returns the children of this node, or null if there are none. * The caller must not modify the Hashtable returned. */ Hashtable<String,NameNode> getChildren() { return children; } /* * Returns the child node given the hash key (the down-cased label) * for its name relative to this node, or null if there is no such * child. */ NameNode get(String key) { return (children != null) ? children.get(key) : null; } /* * Returns the node at the end of a path, or null if the * node does not exist. * The path is specified by the labels of {@code name}, beginning * at index idx. */ NameNode get(DnsName name, int idx) { NameNode node = this; for (int i = idx; i < name.size() && node != null; i++) { node = node.get(name.getKey(i)); } return node; } /* * Returns the node at the end of a path, creating it and any * intermediate nodes as needed. * The path is specified by the labels of {@code name}, beginning * at index idx. */ NameNode add(DnsName name, int idx) { NameNode node = this; for (int i = idx; i < name.size(); i++) { String label = name.get(i); String key = name.getKey(i); NameNode child = null; if (node.children == null) { node.children = new Hashtable<>(); } else { child = node.children.get(key); } if (child == null) { child = newNameNode(label); child.depth = node.depth + 1; node.children.put(key, child); } node = child; } return node; } }