/*
* Copyright 2011, 2012 Odysseus Software GmbH
*
* 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 org.apache.synapse.commons.staxon.core.json.stream.util;
import java.io.IOException;
import java.util.Deque;
import java.util.LinkedList;
import java.util.Stack;
import org.apache.synapse.commons.staxon.core.json.JsonXMLStreamWriter;
import org.apache.synapse.commons.staxon.core.json.stream.JsonStreamTarget;
import org.apache.synapse.commons.staxon.core.json.stream.JsonStreamToken;
/**
* Target filter to auto-insert array boundaries.
* <p/>
* Note: this class caches all events and flushes to the
* underlying target after receiving the last close-object
* event, which may cause memory issues for large documents.
* Also, auto-recognition of array boundaries never creates
* arrays with a single element.
* <p/>
* It is recommended to handle array boundaries via the
* {@link JsonXMLStreamWriter#writeStartArray(String)} and
* {@link JsonXMLStreamWriter#writeEndArray()} methods
* or by producing <code><?xml-muliple ...?></code>
* processing instructions.
*/
public class AutoArrayTarget implements JsonStreamTarget {
/**
* Event type
*/
static interface Event {
JsonStreamToken token();
void write(JsonStreamTarget target) throws IOException;
}
static final Event START_OBJECT = new Event() {
@Override
public void write(JsonStreamTarget target) throws IOException {
target.startObject();
}
@Override
public JsonStreamToken token() {
return JsonStreamToken.START_OBJECT;
}
@Override
public String toString() {
return token().name();
}
};
static final Event END_OBJECT = new Event() {
@Override
public void write(JsonStreamTarget target) throws IOException {
target.endObject();
}
@Override
public JsonStreamToken token() {
return JsonStreamToken.END_OBJECT;
}
@Override
public String toString() {
return token().name();
}
};
static final Event END_ARRAY = new Event() {
@Override
public void write(JsonStreamTarget target) throws IOException {
target.endArray();
}
@Override
public JsonStreamToken token() {
return JsonStreamToken.END_ARRAY;
}
@Override
public String toString() {
return token().name();
}
};
static final class NameEvent implements Event {
final String name;
boolean array;
NameEvent(String name) {
this.name = name;
}
@Override
public void write(JsonStreamTarget target) throws IOException {
target.name(name);
if (array) {
target.startArray();
}
}
@Override
public JsonStreamToken token() {
return JsonStreamToken.NAME;
}
public String name() {
return name;
}
public boolean isArray() {
return array;
}
public void setArray(boolean array) {
this.array = array;
}
@Override
public String toString() {
if (array) {
return token().name() + " = " + name + " " + JsonStreamToken.START_ARRAY;
} else {
return token().name() + " = " + name;
}
}
}
static final class ValueEvent implements Event {
final Object value;
ValueEvent(Object value) {
this.value = value;
}
@Override
public void write(JsonStreamTarget target) throws IOException {
target.value(value);
}
@Override
public JsonStreamToken token() {
return JsonStreamToken.VALUE;
}
@Override
public String toString() {
return token().name() + " = " + value;
}
}
/*
* delegate target
*/
private final JsonStreamTarget delegate;
/*
* Event queue
*/
private final Deque<Event> events = new LinkedList<Event>();
/*
* Field stack
*/
private final Stack<NameEvent> fields = new Stack<NameEvent>();
public AutoArrayTarget(JsonStreamTarget delegate) {
this.delegate = delegate;
}
private void pushField(String name) {
events.add(fields.push(new NameEvent(name)));
}
private void popField() {
if (fields.pop().isArray()) {
events.add(END_ARRAY);
}
}
@Override
public void name(String name) throws IOException {
if (events.peekLast().token() == JsonStreamToken.START_OBJECT) {
pushField(name);
} else {
if (name.equals(fields.peek().name())) {
fields.peek().setArray(true);
} else {
popField();
pushField(name);
}
}
}
@Override
public void value(Object value) throws IOException {
events.add(new ValueEvent(value));
}
@Override
public void startObject() throws IOException {
events.add(START_OBJECT);
}
@Override
public void endObject() throws IOException {
if (events.peekLast().token() != JsonStreamToken.START_OBJECT) {
popField();
}
events.add(END_OBJECT);
if (fields.isEmpty()) {
while (!events.isEmpty()) {
events.pollFirst().write(delegate);
}
}
}
@Override
public void startArray() throws IOException {
if (fields.peek().isArray()) {
throw new IllegalStateException();
}
fields.peek().setArray(true);
}
@Override
public void endArray() throws IOException {
if (!fields.peek().isArray()) {
throw new IllegalStateException();
}
// array will be closed automatically
}
@Override
public void close() throws IOException {
while (!events.isEmpty()) {
events.pollFirst().write(delegate);
}
delegate.close();
}
@Override
public void flush() throws IOException {
delegate.flush();
}
}