hal/src/zutil/parser/json/JSONWriter.java

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 Ziver Koc
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package zutil.parser.json;

import zutil.io.StringOutputStream;
import zutil.parser.DataNode;
import zutil.parser.DataNode.DataType;

import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.Iterator;

/**
 * Writes An JSONNode to an String or stream
 *
 * @author Ziver
 */
public class JSONWriter{
    private PrintWriter out;

    /**
     * Creates a new instance of the writer
     *
     * @param out the OutputStream that the Nodes will be sent to
     */
    public JSONWriter(OutputStream out){
        this( new PrintWriter(out) );
    }

    /**
     * Creates a new instance of the writer
     *
     * @param out the OutputStream that the Nodes will be sent to
     */
    public JSONWriter(Writer out){
        this( new PrintWriter(out) );
    }

    /**
     * Creates a new instance of the writer
     *
     * @param out the OutputStream that the Nodes will be sent to
     */
    public JSONWriter(PrintWriter out){
        this.out = out;
    }

    /**
     * Writes the specified node to the stream
     *
     * @param root is the root node
     */
    public void write(DataNode root){
        if(root == null){
            out.print("null");
            return;
        }

        boolean first = true;
        switch(root.getType()){
            // Write Map
            case Map:
                out.append('{');
                Iterator<String> it = root.keyIterator();
                while(it.hasNext()){
                    if(!first)
                        out.append(", ");
                    String key = it.next();
                    out.append('\"');
                    out.append(escapeString(key));
                    out.append("\": ");
                    write(root.get(key));
                    first = false;
                }
                out.append('}');
                break;
            // Write List
            case List:
                out.append('[');
                for(DataNode node : root){
                    if(!first)
                        out.append(", ");
                    write(node);
                    first = false;
                }
                out.append(']');
                break;
            default:
                if(root.getString() != null && root.getType() == DataType.String){
                    out.append('\"');
                    out.append(escapeString(root.toString()));
                    out.append('\"');
                } else
                    out.append(root.toString());
                break;
        }
    }

    private static String escapeString(String str){
        // Replace one backslash with two
        return str.replaceAll("\\\\", "\\\\\\\\");
    }

    /**
     * Closes the internal stream
     */
    public void close(){
        out.close();
    }

    /**
     * @return JSON String that is generated from the input DataNode graph
     */
    public static String toString(DataNode root){
        StringOutputStream out = new StringOutputStream();
        JSONWriter writer = new JSONWriter(out);
        writer.write(root);
        writer.close();
        return out.toString();
    }

    public void flush(){
        out.flush();
    }
}