nom.tam.util.BufferEncoder Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of nom-tam-fits Show documentation
Java library for reading and writing FITS files. FITS, the Flexible Image Transport System, is the format commonly used in the archiving and transport of astronomical data.
There is a newer version: 1.21.0
Show newest version
package nom.tam.util;

/*
 * #%L
 * nom.tam FITS library
 * %%
 * Copyright (C) 1996 - 2024 nom-tam-fits
 * %%
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 * #L%
 */

import java.io.IOException;

/**
 * @deprecated Use {@link FitsEncoder} instead which provides a similar function but in a more consistent way and with a
 *                 less misleading name. This is a rusty rail implementation for of an older abandoned class only,
 *                 unsafe for general use. For writing non-FITS encoding you may also use {@link OutputEncoder} as a
 *                 base for implementing efficient custom encoding of binary outputs in general.
 *
 * @see        FitsEncoder
 */
@Deprecated
public abstract class BufferEncoder extends FitsEncoder {

    private BufferPointer p;

    /**
     * @param p Unused, but the position and length fields are set/reset as to pretend that the buffer is perpetually
     *              half filled with data, and with position at 0. However, at no point will there be any data actually
     *              in the buffer of this object. You should by all means avoid directly writing data from this buffer
     *              to the output stream, other than the hopefully untriggered write of an existing
     *              needBuffer(int) implementation (and it's safest if you don't override or ever call
     *              needBuffer(int) from your code!).
     */
    public BufferEncoder(BufferPointer p) {
        super();

        this.p = p;

        pretendHalfPopulated();

        setOutput(new OutputWriter() {

            private byte[] b1 = new byte[1];

            @Override
            public void write(int b) throws IOException {
                b1[0] = (byte) b;
                BufferEncoder.this.write(b1, 0, 1);
            }

            @Override
            public void write(byte[] b, int from, int length) throws IOException {
                BufferEncoder.this.write(b, from, length);
            }

        });
    }

    /**
     * We'll always pretend the buffer to be half populated at pos=0, in order to avoid triggering a read from the input
     * into the unused buffer of BufferPointer, or a write to the output from that buffer... If the pointer has no
     * buffer, length will be 0 also.
     */
    private void pretendHalfPopulated() {
        p.pos = 0;
        p.length = p.buffer == null ? 0 : p.buffer.length >>> 1;
    }

    /**
     * @deprecated             No longer used internally, kept only for back-compatibility since it used to be a needed
     *                             abstract method. It's safest if you never override or call this method from your
     *                             code!
     *
     * @param      need        the number of consecutive bytes we need available in the conversion buffer
     *
     * @throws     IOException if the buffer could not be flushed to the output to free up space in the buffer.
     */
    @Deprecated
    protected void needBuffer(int need) throws IOException {
    }

    @Override
    void need(int bytes) throws IOException {
        pretendHalfPopulated();
        super.need(bytes);
    }

    @Override
    protected void write(byte[] b, int from, int len) throws IOException {
        throw new UnsupportedOperationException(
                "You need to override this with an implementation that writes to the desired output.");
    }

    /**
     * Writes a single byte to the output, but not before flushing the contents of the conversion buffer. The supplied
     * {@link BufferPointer} is not used at all, and is immediately invalidated (which is consistent with having flushed
     * all pending output). It's not all that efficient, but then again one should be using the new {@link FitsEncoder}
     * instead. This is really just a rusty rail solution. Also, since this methods does not throw an exception, and
     * {@link #needBuffer(int)} (which did throw an exception) is no longer in use, the duct-tape solution is to convert
     * any IOException encountered here into a runtime exception...
     *
     * @param  b                     the byte to write
     *
     * @throws IllegalStateException if there was an IO error flushing the conversion buffer or writing the new byte
     *                                   after it.
     */
    protected void writeUncheckedByte(byte b) throws IllegalStateException {
        try {
            flush();
            write(b);
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
    }
}