src.it.unimi.dsi.fastutil.io.FastByteArrayInputStream Maven / Gradle / Ivy
package it.unimi.dsi.fastutil.io;
/*
* fastutil: Fast & compact type-specific collections for Java
*
* Copyright (C) 2003-2011 Sebastiano Vigna
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 2.1 of the License, or (at your option)
* any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
/** Simple, fast and repositionable byte-array input stream.
*
* Warning: this class implements the correct semantics
* of {@link #read(byte[], int, int)} as described in {@link java.io.InputStream}.
* The implementation given in {@link java.io.ByteArrayInputStream} is broken,
* but it will never be fixed because it's too late.
*
* @author Sebastiano Vigna
*/
public class FastByteArrayInputStream extends MeasurableInputStream implements RepositionableStream {
/** The array backing the input stream. */
public byte[] array;
/** The first valid entry. */
public int offset;
/** The number of valid bytes in {@link #array} starting from {@link #offset}. */
public int length;
/** The current position as a distance from {@link #offset}. */
private int position;
/** The current mark as a position, or -1 if no mark exists. */
private int mark;
/** Creates a new array input stream using a given array fragment.
*
* @param array the backing array.
* @param offset the first valid entry of the array.
* @param length the number of valid bytes.
*/
public FastByteArrayInputStream( final byte[] array, final int offset, final int length ) {
this.array = array;
this.offset = offset;
this.length = length;
}
/** Creates a new array input stream using a given array.
*
* @param array the backing array.
*/
public FastByteArrayInputStream( final byte[] array ) {
this( array, 0, array.length );
}
public boolean markSupported() {
return true;
}
public void reset() {
position = mark;
}
/** Closing a fast byte array input stream has no effect. */
public void close() {}
public void mark( final int dummy ) {
mark = position;
}
public int available() {
return length - position;
}
public long skip( long n ) {
if ( n <= length - position ) {
position += (int)n;
return n;
}
n = length - position;
position = length;
return n;
}
public int read() {
if ( length == position ) return -1;
return array[ offset + position++ ] & 0xFF;
}
/** Reads bytes from this byte-array input stream as
* specified in {@link java.io.InputStream#read(byte[], int, int)}.
* Note that the implementation given in {@link java.io.ByteArrayInputStream#read(byte[], int, int)}
* will return -1 on a zero-length read at EOF, contrarily to the specification. We won't.
*/
public int read( final byte b[], final int offset, final int length ) {
if ( this.length == this.position ) return length == 0 ? 0 : -1;
final int n = Math.min( length, this.length - this.position );
System.arraycopy( array, this.offset + this.position, b, offset, n );
this.position += n;
return n;
}
public long position() {
return position;
}
public void position( final long newPosition ) {
position = (int)Math.min( newPosition, length );
}
@Override
public long length() {
return length;
}
}