src.it.unimi.dsi.big.io.FileLinesByteArrayCollection Maven / Gradle / Ivy
package it.unimi.dsi.big.io;
/*
* DSI utilities
*
* Copyright (C) 2005-2017 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 3 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, see An instance of this class allows to access the lines of a file as a
* {@link java.util.Collection} of byte arrays. Reading is performed using
* {@link FastBufferedInputStream#readLine(byte[], EnumSet)}, and follows the rules defined therein.
* No decoding is performed.
*
*
Using {@linkplain java.util.Collection#contains(java.lang.Object)
* direct access} is strongly discouraged (it will require a full scan of the file), but
* the {@link #iterator()} can be fruitfully used to scan the file, and can be called any
* number of times, as it opens an independent input stream at each call. For the
* same reason, the returned iterator type ({@link it.unimi.dsi.io.FileLinesCollection.FileLinesIterator})
* is {@link java.io.Closeable}, and should be closed after usage.
*
*
Using a suitable {@linkplain #FileLinesByteArrayCollection(CharSequence, boolean, EnumSet) constructor}, it is possible
* to specify that the file is compressed in gzip format (in this case, it will be opened using a {@link GZIPInputStream}).
*
*
Note that the first call to {@link #size64()} will require a full file scan.
*
* @author Sebastiano Vigna
* @since 2.2.8
*/
public class FileLinesByteArrayCollection extends AbstractCollection implements Size64 {
/** The filename upon which this file-lines collection is based. */
private final String filename;
/** Whether {@link #filename} is zipped. */
private final boolean zipped;
/** A set of terminators for the underlying {@link FastBufferedInputStream}. */
private final EnumSet terminators;
/** The cached size of the collection. */
private long size = -1;
/** Creates a byte-array file-lines collection for the specified filename, using both CR and LF as {@linkplain LineTerminator line terminators}.
*
* @param filename a filename.
*/
public FileLinesByteArrayCollection(final CharSequence filename) {
this(filename, false);
}
/** Creates a byte-array file-lines collection for the specified filename, optionally assuming
* that the file is compressed using gzip format, using both CR and LF as {@linkplain LineTerminator line terminators}.
*
* @param filename a filename.
* @param zipped whether filename is zipped.
*/
public FileLinesByteArrayCollection(final CharSequence filename, final boolean zipped) {
this(filename, zipped, FastBufferedInputStream.ALL_TERMINATORS);
}
/** Creates a byte-array file-lines collection for the specified filename, optionally assuming
* that the file is compressed using gzip format, using the specified {@linkplain LineTerminator line terminators}.
*
* @param filename a filename.
* @param zipped whether filename is zipped.
* @param terminators line terminators for the underlying {@link FastBufferedInputStream}.
*/
public FileLinesByteArrayCollection(final CharSequence filename, final boolean zipped, final EnumSet terminators) {
this.zipped = zipped;
this.filename = filename.toString();
this.terminators = terminators;
}
/** An iterator over the lines of a {@link FileLinesByteArrayCollection}.
*
* Instances of this class open an {@link java.io.InputStream}, and thus should be {@linkplain Closeable#close() closed} after
* usage. A “safety-net” finaliser tries to take care of the cases in which
* closing an instance is impossible. An exhausted iterator, however, will be closed automagically.
*/
public static final class FileLinesIterator implements Iterator, SafelyCloseable {
private FastBufferedInputStream fbis;
byte[] buffer = new byte[1024];
boolean ready;
int read;
private EnumSet terminators;
private FileLinesIterator(final String filename, final boolean zipped, final EnumSet terminators) {
this.terminators = terminators;
try {
fbis = new FastBufferedInputStream(zipped ? new GZIPInputStream(new FileInputStream(filename)) : new FileInputStream(filename));
} catch (IOException e) {
throw new RuntimeException(e);
}
}
@Override
public boolean hasNext() {
if (ready) return true;
if (fbis == null) return false;
ready = false;
try {
read = 0;
int len;
while((len = fbis.readLine(buffer, read, buffer.length - read, terminators)) == buffer.length - read) {
ready = true;
read += len;
buffer = ByteArrays.grow(buffer, buffer.length + 1);
}
if (len != -1) {
ready = true;
read += len;
}
if (len == -1) close();
} catch (IOException e) {
throw new RuntimeException(e);
}
return ready;
}
@Override
public byte[] next() {
if (! hasNext()) throw new NoSuchElementException();
ready = false;
return Arrays.copyOf(buffer, read);
}
@Override
public synchronized void close() {
if (fbis == null) return;
try {
fbis.close();
}
catch (IOException e) {
throw new RuntimeException(e);
}
finally {
fbis = null;
}
}
@Override
protected synchronized void finalize() throws Throwable {
try {
if (fbis != null) close();
}
finally {
super.finalize();
}
}
}
@Override
public FileLinesIterator iterator() {
return new FileLinesIterator(filename, zipped, terminators);
}
/** {@inheritDoc}
* @deprecated Please use {@link #size64()} instead. */
@Deprecated
@Override
public int size() {
return (int) Math.min(Integer.MAX_VALUE, size64());
}
@Override
public synchronized long size64() {
if (size == -1) {
FileLinesIterator i = iterator();
size = 0;
while(i.hasNext()) {
size++;
i.next();
}
i.close();
}
return size;
}
/** Returns all lines of the file wrapped by this file-lines collection.
*
* @return all lines of the file wrapped by this file-lines collection.
*/
public ObjectBigList allLines() {
final ObjectBigList result = new ObjectBigArrayBigList<>();
for(Iterator i = iterator(); i.hasNext();) result.add(i.next());
return result;
}
@Override
@Deprecated
public Object[] toArray() {
throw new UnsupportedOperationException("Use allLines()");
}
@Override
@Deprecated
public T[] toArray(T[] a) {
throw new UnsupportedOperationException("Use allLines()");
}
@Override
public String toString() {
return this.getClass().getSimpleName() + "(" + filename + "," + zipped + ")";
}
}