zcommon/src/main/java/org/zkoss/json/parser/JSONParser.java
/*
* $Id: JSONParser.java,v 1.1 2006/04/15 14:10:48 platform Exp $
* Created on 2006-4-15
*/
package org.zkoss.json.parser;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import org.zkoss.json.JSONArray;
import org.zkoss.json.JSONObject;
/**
* Parser for JSON text. Please note that JSONParser is NOT thread-safe.
*
* @author FangYidong<fangyidong@yahoo.com.cn>
*/
@SuppressWarnings("unchecked")
public class JSONParser {
public static final int S_INIT=0;
public static final int S_IN_FINISHED_VALUE=1;//string,number,boolean,null,object,array
public static final int S_IN_OBJECT=2;
public static final int S_IN_ARRAY=3;
public static final int S_PASSED_PAIR_KEY=4;
public static final int S_IN_PAIR_VALUE=5;
public static final int S_END=6;
public static final int S_IN_ERROR=-1;
private LinkedList handlerStatusStack;
private Yylex lexer = new Yylex((Reader)null);
private Yytoken token = null;
private int status = S_INIT;
private int peekStatus(LinkedList statusStack){
if(statusStack.size()==0)
return -1;
Integer status=(Integer)statusStack.getFirst();
return status.intValue();
}
/**
* Reset the parser to the initial state without resetting the underlying reader.
*
*/
public void reset(){
token = null;
status = S_INIT;
handlerStatusStack = null;
}
/**
* Reset the parser to the initial state with a new character reader.
*
* @param in - The new character reader.
* @throws IOException
* @throws ParseException
*/
public void reset(Reader in){
lexer.yyreset(in);
reset();
}
/**
* @return The position of the beginning of the current token.
*/
public int getPosition(){
return lexer.getPosition();
}
public Object parse(String s) throws ParseException{
return parse(s, (ContainerFactory)null);
}
public Object parse(String s, ContainerFactory containerFactory) throws ParseException{
StringReader in=new StringReader(s);
try{
return parse(in, containerFactory);
}
catch(IOException ie){
/*
* Actually it will never happen.
*/
throw new ParseException(-1, ParseException.ERROR_UNEXPECTED_EXCEPTION, ie);
}
}
public Object parse(Reader in) throws IOException, ParseException{
return parse(in, (ContainerFactory)null);
}
/**
* Parse JSON text into java object from the input source.
*
* @param in
* @param containerFactory - Use this factory to create your own JSON object and JSON array containers.
* @return Instance of the following:
* org.zkoss.json.JSONObject,
* org.zkoss.json.JSONArray,
* java.lang.String,
* java.lang.Number,
* java.lang.Boolean,
* null
*
* @throws IOException
* @throws ParseException
*/
public Object parse(Reader in, ContainerFactory containerFactory) throws IOException, ParseException{
reset(in);
LinkedList statusStack = new LinkedList();
LinkedList valueStack = new LinkedList();
try{
do{
nextToken();
switch(status){
case S_INIT:
switch(token.type){
case Yytoken.TYPE_VALUE:
status=S_IN_FINISHED_VALUE;
statusStack.addFirst(new Integer(status));
valueStack.addFirst(token.value);
break;
case Yytoken.TYPE_LEFT_BRACE:
status=S_IN_OBJECT;
statusStack.addFirst(new Integer(status));
valueStack.addFirst(createObjectContainer(containerFactory));
break;
case Yytoken.TYPE_LEFT_SQUARE:
status=S_IN_ARRAY;
statusStack.addFirst(new Integer(status));
valueStack.addFirst(createArrayContainer(containerFactory));
break;
default:
status=S_IN_ERROR;
}//inner switch
break;
case S_IN_FINISHED_VALUE:
if(token.type==Yytoken.TYPE_EOF)
return valueStack.removeFirst();
else
throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
case S_IN_OBJECT:
switch(token.type){
case Yytoken.TYPE_COMMA:
break;
case Yytoken.TYPE_VALUE:
if(token.value instanceof String){
String key=(String)token.value;
valueStack.addFirst(key);
status=S_PASSED_PAIR_KEY;
statusStack.addFirst(new Integer(status));
}
else{
status=S_IN_ERROR;
}
break;
case Yytoken.TYPE_RIGHT_BRACE:
if(valueStack.size()>1){
statusStack.removeFirst();
valueStack.removeFirst();
status=peekStatus(statusStack);
}
else{
status=S_IN_FINISHED_VALUE;
}
break;
default:
status=S_IN_ERROR;
break;
}//inner switch
break;
case S_PASSED_PAIR_KEY:
switch(token.type){
case Yytoken.TYPE_COLON:
break;
case Yytoken.TYPE_VALUE:
statusStack.removeFirst();
String key=(String)valueStack.removeFirst();
Map parent=(Map)valueStack.getFirst();
parent.put(key,token.value);
status=peekStatus(statusStack);
break;
case Yytoken.TYPE_LEFT_SQUARE:
statusStack.removeFirst();
key=(String)valueStack.removeFirst();
parent=(Map)valueStack.getFirst();
List newArray=createArrayContainer(containerFactory);
parent.put(key,newArray);
status=S_IN_ARRAY;
statusStack.addFirst(new Integer(status));
valueStack.addFirst(newArray);
break;
case Yytoken.TYPE_LEFT_BRACE:
statusStack.removeFirst();
key=(String)valueStack.removeFirst();
parent=(Map)valueStack.getFirst();
Map newObject=createObjectContainer(containerFactory);
parent.put(key,newObject);
status=S_IN_OBJECT;
statusStack.addFirst(new Integer(status));
valueStack.addFirst(newObject);
break;
default:
status=S_IN_ERROR;
}
break;
case S_IN_ARRAY:
switch(token.type){
case Yytoken.TYPE_COMMA:
break;
case Yytoken.TYPE_VALUE:
List val=(List)valueStack.getFirst();
val.add(token.value);
break;
case Yytoken.TYPE_RIGHT_SQUARE:
if(valueStack.size()>1){
statusStack.removeFirst();
valueStack.removeFirst();
status=peekStatus(statusStack);
}
else{
status=S_IN_FINISHED_VALUE;
}
break;
case Yytoken.TYPE_LEFT_BRACE:
val=(List)valueStack.getFirst();
Map newObject=createObjectContainer(containerFactory);
val.add(newObject);
status=S_IN_OBJECT;
statusStack.addFirst(new Integer(status));
valueStack.addFirst(newObject);
break;
case Yytoken.TYPE_LEFT_SQUARE:
val=(List)valueStack.getFirst();
List newArray=createArrayContainer(containerFactory);
val.add(newArray);
status=S_IN_ARRAY;
statusStack.addFirst(new Integer(status));
valueStack.addFirst(newArray);
break;
default:
status=S_IN_ERROR;
}//inner switch
break;
case S_IN_ERROR:
throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
}//switch
if(status==S_IN_ERROR){
throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
}
}while(token.type!=Yytoken.TYPE_EOF);
}
catch(IOException ie){
throw ie;
}
throw new ParseException(getPosition(), ParseException.ERROR_UNEXPECTED_TOKEN, token);
}
private void nextToken() throws ParseException, IOException{
token = lexer.yylex();
if(token == null)
token = new Yytoken(Yytoken.TYPE_EOF, null);
}
private Map createObjectContainer(ContainerFactory containerFactory){
if(containerFactory == null)
return new JSONObject();
Map m = containerFactory.createObjectContainer();
if(m == null)
return new JSONObject();
return m;
}
private List createArrayContainer(ContainerFactory containerFactory){
if(containerFactory == null)
return new JSONArray();
List l = containerFactory.creatArrayContainer();
if(l == null)
return new JSONArray();
return l;
}
}