LineReader.java Source code

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Here is the source code for LineReader.java

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/*
 * Copyright 2008-2009 SHOP.COM
 *
 * 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.shop.util;

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

/**
 * A line reading wrapper that works with byte streams. Has the same sematics as
 * {@link BufferedReader}<br>
 * 
 * @author Jordan Zimmerman
 */
public class LineReader extends InputStream {
    public LineReader(InputStream in) {
        fIn = in;
        fBuffer = new StringBuilder();
        fLastWasCR = false;
        fPushbackChar = 0;
    }

    @Override
    public synchronized int read() throws IOException {
        if (fPushbackChar == 0) {
            return streamRead();
        } else {
            return pushbackRead();
        }
    }

    /**
     * copied from {@link BufferedReader#readLine()}
     * 
     * Reads a line of text. A line is considered to be terminated by any one of
     * a line feed ('\n'), a carriage return ('\r'), or a carriage return
     * followed immediately by a linefeed.
     * 
     * @return A String containing the contents of the line, not including any
     *         line-termination characters, or null if the end of the stream has
     *         been reached
     * 
     * @exception IOException
     *                If an I/O error occurs
     */
    public synchronized String readLine() throws IOException {
        fBuffer.setLength(0);

        boolean eof = false;
        for (;;) {
            int b = read();
            if (b == -1) {
                eof = true;
                break;
            }

            if (b == '\r') {
                fLastWasCR = true;
                break;
            }

            if (b == '\n') {
                break;
            }
            fBuffer.append((char) (b & 0xFF));
        }
        return ((fBuffer.length() == 0) && eof) ? null : fBuffer.toString();
    }

    @Override
    public synchronized void close() throws IOException {
        super.close();
        fBuffer = null;
        fIn.close();
    }

    /**
     * Push the given char so that the next() read will return this char
     * 
     * @param c
     *            char to push back
     */
    public synchronized void pushback(int c) {
        fPushbackChar = c;
    }

    private int pushbackRead() {
        int b = fPushbackChar;
        fPushbackChar = 0;
        return b;
    }

    private int streamRead() throws IOException {
        int b = fIn.read();
        if (fLastWasCR) {
            fLastWasCR = false;

            char c = (char) (b & 0xff);
            if (c == '\n') {
                return read();
            }
        }

        return b;
    }

    private InputStream fIn;
    private StringBuilder fBuffer;
    private boolean fLastWasCR;
    private int fPushbackChar;
}