/*
* Copyright (c) 2008, Harald Kuhr
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.twelvemonkeys.io;
import java.io.
IOException;
import java.io.
InputStream;
import java.util.
Stack;
/**
* Abstract base class for {@code InputStream}s implementing the {@code Seekable} interface.
* <p/>
* @see SeekableOutputStream
*
* @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/SeekableInputStream.java#4 $
*/
public abstract class
SeekableInputStream extends
InputStream implements
Seekable {
// TODO: It's at the moment not possible to create subclasses outside this
// package, as there's no access to position. position needs to be
// updated from the read/read/read methods...
/** The stream position in this stream */
long
position;
long
flushedPosition;
boolean
closed;
protected
Stack<
Long>
markedPositions = new
Stack<
Long>();
/// InputStream overrides
@
Override
public final int
read(byte[]
pBytes) throws
IOException {
return
read(
pBytes, 0,
pBytes != null ?
pBytes.length : 1);
}
/**
* Implemented using {@code seek(currentPos + pLength)}.
*
* @param pLength the number of bytes to skip
* @return the actual number of bytes skipped (may be equal to or less
* than {@code pLength})
*
* @throws IOException if an I/O exception occurs during skip
*/
@
Override
public final long
skip(final long
pLength) throws
IOException {
long
pos =
position;
long
wantedPosition =
pos +
pLength;
if (
wantedPosition <
flushedPosition) {
throw new
IOException("position < flushedPosition");
}
// Stop at stream length for compatibility, even though it might be allowed
// to seek past end of stream
int
available =
available();
if (
available > 0) {
seek(
Math.
min(
wantedPosition,
pos +
available));
}
// TODO: Add optimization for streams with known length!
else {
// Slow mode...
int
toSkip = (int)
Math.
max(
Math.
min(
pLength, 512), -512);
while (
toSkip > 0 &&
read() >= 0) {
toSkip--;
}
}
return
position -
pos;
}
@
Override
public final void
mark(int
pLimit) {
mark();
// TODO: We don't really need to do this.. Is it a good idea?
try {
flushBefore(
Math.
max(
position -
pLimit,
flushedPosition));
}
catch (
IOException ignore) {
// Ignore, as it's not really critical
}
}
/**
* Returns {@code true}, as marking is always supported.
*
* @return {@code true}.
*/
@
Override
public final boolean
markSupported() {
return true;
}
/// Seekable implementation
public final void
seek(long
pPosition) throws
IOException {
checkOpen();
// NOTE: This is correct according to javax.imageio (IndexOutOfBoundsException),
// but it's kind of inconsistent with reset that throws IOException...
if (
pPosition <
flushedPosition) {
throw new
IndexOutOfBoundsException("position < flushedPosition");
}
seekImpl(
pPosition);
position =
pPosition;
}
protected abstract void
seekImpl(long
pPosition) throws
IOException;
public final void
mark() {
markedPositions.
push(
position);
}
@
Override
public final void
reset() throws
IOException {
checkOpen();
if (!
markedPositions.
isEmpty()) {
long
newPos =
markedPositions.
pop();
// NOTE: This is correct according to javax.imageio (IOException),
// but it's kind of inconsistent with seek that throws IndexOutOfBoundsException...
if (
newPos <
flushedPosition) {
throw new
IOException("Previous marked position has been discarded");
}
seek(
newPos);
}
else {
// TODO: To iron out some wrinkles due to conflicting contracts
// (InputStream and Seekable both declare reset),
// we might need to reset to the last marked position instead..
// However, that becomes REALLY confusing if that position is after
// the current position...
seek(0);
}
}
public final void
flushBefore(long
pPosition) throws
IOException {
if (
pPosition <
flushedPosition) {
throw new
IndexOutOfBoundsException("position < flushedPosition");
}
if (
pPosition >
getStreamPosition()) {
throw new
IndexOutOfBoundsException("position > stream position");
}
checkOpen();
flushBeforeImpl(
pPosition);
flushedPosition =
pPosition;
}
/**
* Discards the initial portion of the stream prior to the indicated postion.
*
* @param pPosition the position to flush to
* @throws IOException if an I/O exception occurs during the flush operation
*
* @see #flushBefore(long)
*/
protected abstract void
flushBeforeImpl(long
pPosition) throws
IOException;
public final void
flush() throws
IOException {
flushBefore(
flushedPosition);
}
public final long
getFlushedPosition() throws
IOException {
checkOpen();
return
flushedPosition;
}
public final long
getStreamPosition() throws
IOException {
checkOpen();
return
position;
}
protected final void
checkOpen() throws
IOException {
if (
closed) {
throw new
IOException("closed");
}
}
@
Override
public final void
close() throws
IOException {
checkOpen();
closed = true;
closeImpl();
}
protected abstract void
closeImpl() throws
IOException;
/**
* Finalizes this object prior to garbage collection. The
* {@code close} method is called to close any open input
* source. This method should not be called from application
* code.
*
* @exception Throwable if an error occurs during superclass
* finalization.
*/
@
Override
protected void
finalize() throws
Throwable {
if (!
closed) {
try {
close();
}
catch (
IOException ignore) {
// Ignroe
}
}
super.finalize();
}
}