/*

  * Copyright 2002-2009 the original author or authors.

  *

  * 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 net.sf.json.util;

 import java.io.StringWriter;

 /**

  * JSONStringer provides a quick and convenient way of producing JSON text. The

  * texts produced strictly conform to JSON syntax rules. No whitespace is added,

  * so the results are ready for transmission or storage. Each instance of

  * JSONStringer can produce one JSON text.

  * <p>

  * A JSONStringer instance provides a <code>value</code> method for appending

  * values to the text, and a <code>key</code> method for adding keys before

  * values in objects. There are <code>array</code> and <code>endArray</code>

  * methods that make and bound array values, and <code>object</code> and

  * <code>endObject</code> methods which make and bound object values. All of

  * these methods return the JSONWriter instance, permitting cascade style. For

  * example,

  *

  * <pre>

  * myString = new JSONStringer()

  *     .object()

  *         .key("JSON")

  *         .value("Hello, World!")

  *     .endObject()

  *     .toString();</pre>

  *

  * which produces the string

  *

  * <pre>

  * {"JSON":"Hello, World!"}</pre>

  *

  * <p>

  * The first method called must be <code>array</code> or <code>object</code>.

  * There are no methods for adding commas or colons. JSONStringer adds them for

  * you. Objects and arrays can be nested up to 20 levels deep.

  * <p>

  * This can sometimes be easier than using a JSONObject to build a string.

  *

  * @author JSON.org

  * @version 2

  */

 public class JSONStringer extends JSONBuilder {

    /**

     * Make a fresh JSONStringer. It can be used to build one JSON text.

     */

    public JSONStringer() {

       super( new StringWriter() );

    }

    /**

     * Return the JSON text. This method is used to obtain the product of the

     * JSONStringer instance. It will return <code>null</code> if there was a

     * problem in the construction of the JSON text (such as the calls to

     * <code>array</code> were not properly balanced with calls to

     * <code>endArray</code>).

     *

     * @return The JSON text.

     */

    public String toString() {

       return this.mode == 'd' ? this.writer.toString() : null;

    }

 }