/*
* Copyright 2014 Google Inc. All Rights Reserved.
*
* Licensed 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 com.google.appengine.tools.cloudstorage.oauth;
import static java.nio.charset.StandardCharsets.UTF_8;
import static javax.xml.stream.XMLStreamConstants.CDATA;
import static javax.xml.stream.XMLStreamConstants.CHARACTERS;
import static javax.xml.stream.XMLStreamConstants.END_ELEMENT;
import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;
import java.io.ByteArrayInputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.LinkedList;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.XMLEvent;
/**
* A simpler XML handler.
* Handler is constructed with byte array content and a set of paths.
* Each matching path is represented as a collection of strings.
* Each next call would return an XmlEvent the content of an XML element that matched
* any part of the given paths.
* Matching is done against the closing XML element (this allows an easier way to group elements).
*/
public final class XmlHandler {
private final XMLEventReader xmlr;
private final PathTrie prefixTrie;
private final LinkedList<String> currentPath = new LinkedList<>();
private final LinkedList<StringBuilder> pathContent = new LinkedList<>();
private XmlHandler.XmlEvent next;
/**
* The type of the XmlEvent.
*/
public enum EventType {
OPEN_ELEMENT,
CLOSE_ELEMENT
}
/**
* Information associated with the callback event.
*/
public static final class XmlEvent {
private final EventType eventType;
private final String name;
private final String value;
XmlEvent(EventType eventType, List<String> path, String value) {
this.eventType = eventType;
this.name = path.isEmpty() ? "" : path.get(path.size() - 1);
this.value = value;
}
public EventType getEventType() {
return eventType;
}
public String getName() {
return name;
}
/**
* Returns an XML element's text (only available for {@link EventType#CLOSE_ELEMENT} events).
*/
public String getValue() {
return value;
}
@Override
public int hashCode() {
return Objects.hash(name, value);
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (getClass() != obj.getClass()) {
return false;
}
XmlEvent other = (XmlEvent) obj;
return Objects.equals(name, other.name) && Objects.equals(value, other.value);
}
@Override
public String toString() {
return "XmlValue [name=" + name + ", value=" + value + "]";
}
}
XmlHandler(byte[] content, Set<? extends Iterable<String>> paths)
throws XMLStreamException {
prefixTrie = new PathTrie(paths);
Reader reader = new InputStreamReader(new ByteArrayInputStream(content), UTF_8);
XMLInputFactory f = XMLInputFactory.newInstance();
xmlr = f.createXMLEventReader(reader);
}
public boolean hasNext() throws XMLStreamException {
if (next == null) {
next = next();
}
return next != null;
}
public XmlHandler.XmlEvent next() throws XMLStreamException {
while (next == null && xmlr.hasNext()) {
XMLEvent event = xmlr.nextEvent();
switch (event.getEventType()) {
case START_ELEMENT:
currentPath.add(event.asStartElement().getName().getLocalPart());
pathContent.add(new StringBuilder());
if (prefixTrie.contains(currentPath)) {
next = new XmlEvent(EventType.OPEN_ELEMENT, currentPath, null);
}
break;
case END_ELEMENT:
if (prefixTrie.contains(currentPath)) {
String text = pathContent.getLast().toString().trim();
next = new XmlEvent(EventType.CLOSE_ELEMENT, currentPath, text);
}
currentPath.removeLast();
pathContent.removeLast();
break;
case CDATA:
case CHARACTERS:
pathContent.getLast().append(event.asCharacters().getData());
break;
default:
break;
}
}
try {
return next;
} finally {
next = null;
}
}
}