JSON.java

/*
 * 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;

import java.io.IOException;
import java.io.Writer;
import java.io.Serializable;

/**
 * Marker interface, identifies a valid JSON value.<br>
 * A JSON value may be a {@link JSONObject}, a {@link JSONArray} or a
 * {@link JSONNull}.
 *
 * @author Andres Almiray <aalmiray@users.sourceforge.net>
 */
public interface JSON extends Serializable {
   /**
    * Returns true if this object is a JSONArray, false otherwise.
    */
   boolean isArray();

   /**
    * Returns true if this object has no elements or keys.
    *
    * @throws JSONException if called on a 'null' object
    */
   boolean isEmpty();

   /**
    * Returns the number of properties in an object or the size of the array.
    *
    * @return the size of an json object or array
    * @throws JSONException if called on a 'null' object
    */
   int size();

   /**
    * Make a prettyprinted JSON text.
    * <p>
    * Warning: This method assumes that the data structure is acyclical.
    *
    * @param indentFactor The number of spaces to add to each level of
    *        indentation.
    * @return a printable, displayable, portable, transmittable representation
    *         of the object, beginning with <code>{</code> <small>(left
    *         brace)</small> and ending with <code>}</code> <small>(right
    *         brace)</small>.
    * @throws JSONException If the object contains an invalid number.
    */
   String toString( int indentFactor );

   /**
    * Make a prettyprinted JSON text.
    * <p>
    * Warning: This method assumes that the data structure is acyclical.
    *
    * @param indentFactor The number of spaces to add to each level of
    *        indentation.
    * @param indent The indentation of the top level.
    * @return a printable, displayable, transmittable representation of the
    *         object, beginning with <code>{</code> <small>(left brace)</small>
    *         and ending with <code>}</code> <small>(right brace)</small>.
    * @throws JSONException If the object contains an invalid number.
    */
   String toString( int indentFactor, int indent );

   /**
    * Write the contents as JSON text to a writer. For compactness, no
    * whitespace is added.
    * <p>
    * Warning: This method assumes that the data structure is acyclical.
    *
    * @return The writer.
    * @throws JSONException
    */
   Writer write( Writer writer ) throws IOException;

    /**
     * Writes the canonicalized form of this JSON object.
     */
    Writer writeCanonical(Writer w) throws IOException;
}