/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.path;
import java.util.HashMap;
import java.util.Map;
import static java.util.Collections.emptyMap;
import static java.util.Collections.unmodifiableMap;
public class PathTrie<T> {
public interface Decoder {
String decode(String value);
}
private final Decoder decoder;
private final TrieNode root;
private T rootValue;
private static final String SEPARATOR = "/";
private static final String WILDCARD = "*";
public PathTrie(Decoder decoder) {
this.decoder = decoder;
root = new TrieNode(SEPARATOR, null, WILDCARD);
}
public class TrieNode {
private transient String key;
private transient T value;
private boolean isWildcard;
private final String wildcard;
private transient String namedWildcard;
private Map<String, TrieNode> children;
public TrieNode(String key, T value, String wildcard) {
this.key = key;
this.wildcard = wildcard;
this.isWildcard = (key.equals(wildcard));
this.value = value;
this.children = emptyMap();
if (isNamedWildcard(key)) {
namedWildcard = key.substring(key.indexOf('{') + 1, key.indexOf('}'));
} else {
namedWildcard = null;
}
}
public void updateKeyWithNamedWildcard(String key) {
this.key = key;
namedWildcard = key.substring(key.indexOf('{') + 1, key.indexOf('}'));
}
public boolean isWildcard() {
return isWildcard;
}
public synchronized void addChild(TrieNode child) {
addInnerChild(child.key, child);
}
private void addInnerChild(String key, TrieNode child) {
Map<String, TrieNode> newChildren = new HashMap<>(children);
newChildren.put(key, child);
children = unmodifiableMap(newChildren);
}
public TrieNode getChild(String key) {
return children.get(key);
}
public synchronized void insert(String[] path, int index, T value) {
if (index >= path.length)
return;
String token = path[index];
String key = token;
if (isNamedWildcard(token)) {
key = wildcard;
}
TrieNode node = children.get(key);
if (node == null) {
T nodeValue = index == path.length - 1 ? value : null;
node = new TrieNode(token, nodeValue, wildcard);
addInnerChild(key, node);
} else {
if (isNamedWildcard(token)) {
node.updateKeyWithNamedWildcard(token);
}
// in case the target(last) node already exist but without a value
// than the value should be updated.
if (index == (path.length - 1)) {
if (node.value != null) {
throw new IllegalArgumentException("Path [" + String.join("/", path)+ "] already has a value ["
+ node.value + "]");
}
if (node.value == null) {
node.value = value;
}
}
}
node.insert(path, index + 1, value);
}
private boolean isNamedWildcard(String key) {
return key.indexOf('{') != -1 && key.indexOf('}') != -1;
}
private String namedWildcard() {
return namedWildcard;
}
private boolean isNamedWildcard() {
return namedWildcard != null;
}
public T retrieve(String[] path, int index, Map<String, String> params) {
if (index >= path.length)
return null;
String token = path[index];
TrieNode node = children.get(token);
boolean usedWildcard;
if (node == null) {
node = children.get(wildcard);
if (node == null) {
return null;
}
usedWildcard = true;
} else {
// If we are at the end of the path, the current node does not have a value but there
// is a child wildcard node, use the child wildcard node
if (index + 1 == path.length && node.value == null && children.get(wildcard) != null) {
node = children.get(wildcard);
usedWildcard = true;
} else {
usedWildcard = token.equals(wildcard);
}
}
put(params, node, token);
if (index == (path.length - 1)) {
return node.value;
}
T res = node.retrieve(path, index + 1, params);
if (res == null && !usedWildcard) {
node = children.get(wildcard);
if (node != null) {
put(params, node, token);
res = node.retrieve(path, index + 1, params);
}
}
return res;
}
private void put(Map<String, String> params, TrieNode node, String value) {
if (params != null && node.isNamedWildcard()) {
params.put(node.namedWildcard(), decoder.decode(value));
}
}
@Override
public String toString() {
return key;
}
}
public void insert(String path, T value) {
String[] strings = path.split(SEPARATOR);
if (strings.length == 0) {
if (rootValue != null) {
throw new IllegalArgumentException("Path [/] already has a value [" + rootValue + "]");
}
rootValue = value;
return;
}
int index = 0;
// supports initial delimiter.
if (strings.length > 0 && strings[0].isEmpty()) {
index = 1;
}
root.insert(strings, index, value);
}
public T retrieve(String path) {
return retrieve(path, null);
}
public T retrieve(String path, Map<String, String> params) {
if (path.length() == 0) {
return rootValue;
}
String[] strings = path.split(SEPARATOR);
if (strings.length == 0) {
return rootValue;
}
int index = 0;
// supports initial delimiter.
if (strings.length > 0 && strings[0].isEmpty()) {
index = 1;
}
return root.retrieve(strings, index, params);
}
}