org.apache.zookeeper.server.watch.PathParentIterator Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.zookeeper.server.watch;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* Iterates over a ZooKeeper path. Each iteration goes up one parent path. Thus, the
* effect of the iterator is to iterate over the initial path and then all of its parents.
*/
public class PathParentIterator implements Iterator {
private String path;
private final int maxLevel;
private int level = -1;
/**
* Return a new PathParentIterator that iterates from the
* given path to all parents.
*
* @param path initial path
*/
public static PathParentIterator forAll(String path) {
return new PathParentIterator(path, Integer.MAX_VALUE);
}
/**
* Return a new PathParentIterator that only returns the given path - i.e.
* does not iterate to parent paths.
*
* @param path initial path
*/
public static PathParentIterator forPathOnly(String path) {
return new PathParentIterator(path, 0);
}
private PathParentIterator(String path, int maxLevel) {
// NOTE: asserts that the path has already been validated
this.path = path;
this.maxLevel = maxLevel;
}
/**
* Return an Iterable view so that this Iterator can be used in for each
* statements. IMPORTANT: the returned Iterable is single use only
* @return Iterable
*/
public Iterable asIterable() {
return () -> PathParentIterator.this;
}
@Override
public boolean hasNext() {
return !path.isEmpty() && (level < maxLevel);
}
/**
* Returns true if this iterator is currently at a parent path as opposed
* to the initial path given to the constructor
*
* @return true/false
*/
public boolean atParentPath() {
return level > 0;
}
@Override
public String next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
String localPath = path;
++level;
if (path.equals("/")) {
path = "";
} else {
path = path.substring(0, path.lastIndexOf('/'));
if (path.length() == 0) {
path = "/";
}
}
return localPath;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}