/*
* Copyright (C) 2006 Joe Walnes.
* Copyright (C) 2006, 2007, 2008 XStream Committers.
* All rights reserved.
*
* The software in this package is published under the terms of the BSD
* style license a copy of which has been included with this distribution in
* the LICENSE.txt file.
*
* Created on 28. November 2008 by Joerg Schaible
*/
package com.thoughtworks.xstream.io.json;
import com.thoughtworks.xstream.converters.ConversionException;
import com.thoughtworks.xstream.core.util.FastStack;
import com.thoughtworks.xstream.core.util.Primitives;
import com.thoughtworks.xstream.core.util.QuickWriter;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.io.ExtendedHierarchicalStreamWriter;
import java.io.Writer;
import java.util.Collection;
import java.util.Map;
/**
* A simple writer that outputs JSON in a pretty-printed indented stream. Arrays, Lists and Sets
* rely on you NOT using XStream.addImplicitCollection(..).
*
* @author Paul Hammant
* @author Jörg Schaible
* @since 1.3.1
*/
public class JsonWriter implements ExtendedHierarchicalStreamWriter {
/**
* DROP_ROOT_MODE drops the JSON root node.
* <p>
* The root node is the first level of the JSON object i.e.
*
* <pre>
* { "person": {
* "name": "Joe"
* }}
* </pre>
*
* will be written without root simply as
*
* <pre>
* {
* "name": "Joe"
* }
* </pre>
*
* Without a root node, the top level element might now also be an array. However, it is
* possible to generate invalid JSON unless {@link #STRICT_MODE} is also set.
* </p>
*
* @since 1.3.1
*/
public static final int DROP_ROOT_MODE = 1;
/**
* STRICT_MODE prevents invalid JSON for single value objects when dropping the root.
* <p>
* The mode is only useful in combination with the {@link #DROP_ROOT_MODE}. An object with a
* single value as first node i.e.
*
* <pre>
* { "name": "Joe" }
* </pre>
*
* is simply written as
*
* <pre>
* "Joe"
* </pre>
*
* However, this is no longer valid JSON. Therefore you can activate {@link #STRICT_MODE}
* and a {@link ConversionException} is thrown instead.
* </p>
*
* @since 1.3.1
*/
public static final int STRICT_MODE = 2;
private final QuickWriter writer;
private final FastStack elementStack = new FastStack(16);
private final char[] lineIndenter;
private int depth;
private boolean readyForNewLine;
private boolean tagIsEmpty;
private final String newLine;
private int mode;
public JsonWriter(Writer writer, char[] lineIndenter, String newLine) {
this(writer, lineIndenter, newLine, 0);
}
public JsonWriter(Writer writer, char[] lineIndenter) {
this(writer, lineIndenter, "\n");
}
public JsonWriter(Writer writer, String lineIndenter, String newLine) {
this(writer, lineIndenter.toCharArray(), newLine);
}
public JsonWriter(Writer writer, String lineIndenter) {
this(writer, lineIndenter.toCharArray());
}
public JsonWriter(Writer writer) {
this(writer, new char[]{' ', ' '});
}
/**
* @since 1.3.1
*/
public JsonWriter(Writer writer, char[] lineIndenter, String newLine, int mode) {
this.writer = new QuickWriter(writer);
this.lineIndenter = lineIndenter;
this.newLine = newLine;
this.mode = mode;
}
/**
* Create a JsonWriter where the writer mode can be chosen.
* <p>
* Following constants can be used as bit mask:
* <ul>
* <li>{@link #DROP_ROOT_MODE}: drop the root node</li>
* <li>{@link #STRICT_MODE}: do not throw {@link ConversionException}, if writer should
* generate invalid JSON</li>
* </ul>
* </p>
*
* @param writer the {@link Writer} where the JSON is written to
* @param mode the JsonWriter mode
* @since 1.3.1
*/
public JsonWriter(Writer writer, int mode) {
this(writer, new char[]{' ', ' '}, "\n", mode);
}
/**
* @deprecated since 1.2, use startNode(String name, Class clazz) instead.
*/
public void startNode(String name) {
startNode(name, null);
}
public void startNode(String name, Class clazz) {
Node currNode = (Node)elementStack.peek();
if (currNode == null
&& ((mode & DROP_ROOT_MODE) == 0 || (depth > 0 && !isCollection(clazz)))) {
writer.write("{");
}
if (currNode != null && currNode.fieldAlready) {
writer.write(",");
readyForNewLine = true;
}
tagIsEmpty = false;
finishTag();
if (currNode == null
|| currNode.clazz == null
|| (currNode.clazz != null && !currNode.isCollection)) {
if (currNode != null && !currNode.fieldAlready) {
writer.write("{");
readyForNewLine = true;
finishTag();
}
if ((mode & DROP_ROOT_MODE) == 0 || depth > 0) {
writer.write("\"");
writer.write(name);
writer.write("\": ");
}
}
if (isCollection(clazz)) {
writer.write("[");
readyForNewLine = true;
}
if (currNode != null) {
currNode.fieldAlready = true;
}
elementStack.push(new Node(name, clazz));
depth++ ;
tagIsEmpty = true;
}
public class Node {
public final String name;
public final Class clazz;
public boolean fieldAlready;
public boolean isCollection;
public Node(String name, Class clazz) {
this.name = name;
this.clazz = clazz;
isCollection = isCollection(clazz);
}
}
public void setValue(String text) {
Node currNode = (Node)elementStack.peek();
if (currNode != null && currNode.fieldAlready) {
startNode("$", String.class);
tagIsEmpty = false;
writeText(text, String.class);
endNode();
} else {
if ((mode & (DROP_ROOT_MODE | STRICT_MODE)) == (DROP_ROOT_MODE | STRICT_MODE)
&& depth == 1) {
throw new ConversionException("Single value cannot be JSON root element");
}
readyForNewLine = false;
tagIsEmpty = false;
finishTag();
writeText(writer, text);
}
}
public void addAttribute(String key, String value) {
Node currNode = (Node)elementStack.peek();
if (currNode == null || !currNode.isCollection) {
startNode('@' + key, String.class);
tagIsEmpty = false;
writeText(value, String.class);
endNode();
}
}
protected void writeAttributeValue(QuickWriter writer, String text) {
writeText(text, null);
}
protected void writeText(QuickWriter writer, String text) {
Node foo = (Node)elementStack.peek();
writeText(text, foo.clazz);
}
private void writeText(String text, Class clazz) {
if (needsQuotes(clazz)) {
writer.write("\"");
}
if ((clazz == Character.class || clazz == Character.TYPE) && "".equals(text)) {
text = "\0";
}
int length = text.length();
for (int i = 0; i < length; i++ ) {
char c = text.charAt(i);
switch (c) {
case '"':
this.writer.write("\\\"");
break;
case '\\':
this.writer.write("\\\\");
break;
default:
if (c > 0x1f) {
this.writer.write(c);
} else {
this.writer.write("\\u");
String hex = "000" + Integer.toHexString(c);
this.writer.write(hex.substring(hex.length() - 4));
}
}
}
if (needsQuotes(clazz)) {
writer.write("\"");
}
}
private boolean isCollection(Class clazz) {
return clazz != null
&& (Collection.class.isAssignableFrom(clazz)
|| clazz.isArray()
|| Map.class.isAssignableFrom(clazz) || Map.Entry.class.isAssignableFrom(clazz));
}
private boolean needsQuotes(Class clazz) {
clazz = clazz != null && clazz.isPrimitive() ? clazz : Primitives.unbox(clazz);
return clazz == null || clazz == Character.TYPE;
}
public void endNode() {
depth-- ;
Node node = (Node)elementStack.pop();
if (node.clazz != null && node.isCollection) {
if (node.fieldAlready) {
readyForNewLine = true;
}
finishTag();
writer.write("]");
} else if (tagIsEmpty) {
readyForNewLine = false;
writer.write("{}");
finishTag();
} else {
finishTag();
if (node.fieldAlready) {
writer.write("}");
}
}
readyForNewLine = true;
if (depth == 0 && ((mode & DROP_ROOT_MODE) == 0 || (depth > 0 && !node.isCollection))) {
writer.write("}");
writer.flush();
}
}
private void finishTag() {
if (readyForNewLine) {
endOfLine();
}
readyForNewLine = false;
tagIsEmpty = false;
}
protected void endOfLine() {
writer.write(newLine);
for (int i = 0; i < depth; i++ ) {
writer.write(lineIndenter);
}
}
public void flush() {
writer.flush();
}
public void close() {
writer.close();
}
public HierarchicalStreamWriter underlyingWriter() {
return this;
}
}