org.codehaus.swizzle.stream.StreamLexer Maven / Gradle / Ivy

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/**
 *
 * Copyright 2006 David Blevins
 *
 *  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 org.codehaus.swizzle.stream;

import java.io.InputStream;
import java.io.IOException;

/**
 * @version $Revision$ $Date$
 */
public class StreamLexer {
    private final InputStream in;

    public StreamLexer(InputStream in) {
        this.in = in;
    }

    /**
     * Seeks in the stream till it finds the start token, reads into a buffer till it finds the end token, then
     * returns the token (the buffer) as a String.
     *
     * Given the input stream contained the sequence "123ABC456EFG"
     *
     * InputStream in ...
     * StreamLexer lexer = new StreamLexer(in);
     * String token = lexer.readToken("3","C"); // returns the string "AB"
     * char character = (char)in.read(); // returns the character '4'
     *
     * Does not support regular expression matching.
     *
     * @deprecated Experimental, the api of this class may change
     * @param begin  start token
     * @param end end token
     * @return the token inbetween the start and end token or null if the end of the stream was reached
     * @throws Exception
     */
    public String readToken(String begin, String end) throws Exception {
        final String[] token = {null};
        InputStream search = new DelimitedTokenReplacementInputStream(in, begin, end, new StringTokenHandler(){
            public String handleToken(String string) throws IOException {
                token[0] = string;
                return string;
            }
        });

        int i = search.read();
        while (i != -1 && token[0] == null){
            i = search.read();
        }
        return token[0];
    }

    /**
     * Seeks in the stream till it finds and has completely read the token, then stops.
     * Useful for seeking up to a certain point in the stream.
     *
     * Given the input stream contained the sequence "000[A]111[B]222[C]345[D]"
     *
     * InputStream in ...
     * StreamLexer lexer = new StreamLexer(in);
     * String token = lexer.readToken("222"); // returns the string "222"
     * token = lexer.readToken("[", "]"); // returns the string "C"
     * char character = (char)in.read(); // returns the character '3'
     *
     * Does not support regular expression matching.
     *
     * @deprecated Experimental, the api of this class may change
     * @param string the token to find in the stream
     * @return the token if found in the stream or null if the stream was reached (i.e. the token was not found)
     * @throws Exception
     */
    public String readToken(String string) throws Exception {
        final String[] token = {null};
        InputStream search = new FixedTokenReplacementInputStream(in, string, new StringTokenHandler(){
            public String handleToken(String string) throws IOException {
                token[0] = string;
                return string;
            }
        });

        int i = search.read();
        while (i != -1 && token[0] == null){
            i = search.read();
        }
        return token[0];
    }


}