dubbo-common/src/main/java/com/alibaba/dubbo/common/json/JSONReader.java

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * 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 com.alibaba.dubbo.common.json;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;

/**
 * JSON reader.
 * 
 * @author qian.lei
 */

public class JSONReader
{
	private static ThreadLocal<Yylex> LOCAL_LEXER = new ThreadLocal<Yylex>(){};

	private Yylex mLex;

	public JSONReader(InputStream is, String charset) throws UnsupportedEncodingException
	{
		this(new InputStreamReader(is, charset));
	}

	public JSONReader(Reader reader)
	{
		mLex = getLexer(reader);
	}

	public JSONToken nextToken() throws IOException, ParseException
	{
		return mLex.yylex();
	}

	public JSONToken nextToken(int expect) throws IOException, ParseException
	{
		JSONToken ret = mLex.yylex();
		if( ret == null )
			throw new ParseException("EOF error.");
		if( expect != JSONToken.ANY && expect != ret.type )
			throw new ParseException("Unexcepted token.");
		return ret;
	}

	private static Yylex getLexer(Reader reader)
	{
		Yylex ret = LOCAL_LEXER.get();
		if( ret == null )
		{
			ret = new Yylex(reader);
			LOCAL_LEXER.set(ret);
		}
		else
		{
			ret.yyreset(reader);
		}
		return ret;
	}
}