Dépôt officiel du code source de l'ERP OpenConcerto

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 2011-2019 OpenConcerto, by ILM Informatique. All rights reserved.
 * 
 * The contents of this file are subject to the terms of the GNU General Public License Version 3
 * only ("GPL"). You may not use this file except in compliance with the License. You can obtain a
 * copy of the License at http://www.gnu.org/licenses/gpl-3.0.html See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each file.
 */
 
 package org.openconcerto.utils.doml;

import java.io.IOException;
import java.io.Reader;

public class PushBackReader extends Reader {
    /**
     * The underlying character-input stream.
     */
    protected Reader in;
    /** Pushback buffer */
    private char[] buf;

    /** Current position in buffer */
    private int pos;

    /**
     * Creates a new pushback reader with a pushback buffer of the given size.
     *
     * @param in The reader from which characters will be read
     * @param size The size of the pushback buffer
     * @exception IllegalArgumentException if {@code size <= 0}
     */
    public PushBackReader(Reader in, int size) {
        this.in = in;
        if (size <= 0) {
            throw new IllegalArgumentException("size <= 0");
        }
        this.buf = new char[size];
        this.pos = size;
    }

    /**
     * Creates a new pushback reader with a one-character pushback buffer.
     *
     * @param in The reader from which characters will be read
     */
    public PushBackReader(Reader in) {
        this(in, 1);
    }

    /**
     * Reads a single character.
     *
     * @return The character read, or -1 if the end of the stream has been reached
     *
     * @exception IOException If an I/O error occurs
     */
    @Override
    public int read() throws IOException {
        if (pos < this.buf.length)
            return this.buf[pos++];
        else
            return this.in.read();
    }

    /**
     * Pushes back a single character by copying it to the front of the pushback buffer. After this
     * method returns, the next character to be read will have the value <code>(char)c</code>.
     *
     * @param c The int value representing a character to be pushed back
     *
     * @exception IOException If the pushback buffer is full, or if some other I/O error occurs
     */
    public void unread(int c) throws IOException {
        this.buf[--pos] = (char) c;
    }

    /**
     * Marks the present position in the stream. The <code>mark</code> for class
     * <code>PushbackReader</code> always throws an exception.
     *
     * @exception IOException Always, since mark is not supported
     */
    @Override
    public void mark(int readAheadLimit) throws IOException {
        throw new IOException("mark/reset not supported");
    }

    /**
     * Resets the stream. The <code>reset</code> method of <code>PushbackReader</code> always throws
     * an exception.
     *
     * @exception IOException Always, since reset is not supported
     */
    @Override
    public void reset() throws IOException {
        throw new IOException("mark/reset not supported");
    }

    /**
     * Tells whether this stream supports the mark() operation, which it does not.
     */
    @Override
    public boolean markSupported() {
        return false;
    }

    /**
     * Closes the stream and releases any system resources associated with it. Once the stream has
     * been closed, further read(), unread(), ready(), or skip() invocations will throw an
     * IOException. Closing a previously closed stream has no effect.
     *
     * @exception IOException If an I/O error occurs
     */
    @Override
    public void close() throws IOException {
        this.in.close();
        this.buf = null;
    }

    @Override
    public int read(char[] cbuf, int off, int len) throws IOException {
        throw new IOException("read not supported");
    }

}