src.it.unimi.dsi.io.DelimitedWordReader Maven / Gradle / Ivy
/*
* DSI utilities
*
* Copyright (C) 2009-2023 Sebastiano Vigna
*
* This program and the accompanying materials are made available under the
* terms of the GNU Lesser General Public License v2.1 or later,
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html,
* or the Apache Software License 2.0, which is available at
* https://www.apache.org/licenses/LICENSE-2.0.
*
* This program 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.
*
* SPDX-License-Identifier: LGPL-2.1-or-later OR Apache-2.0
*/
package it.unimi.dsi.io;
import java.io.Reader;
import it.unimi.dsi.fastutil.Hash;
import it.unimi.dsi.fastutil.chars.CharOpenHashSet;
import it.unimi.dsi.fastutil.chars.CharSet;
import it.unimi.dsi.fastutil.chars.CharSets;
import it.unimi.dsi.lang.MutableString;
/** A word reader that breaks words on a given set of characters.
*
* This class is a simple subclass of {@link FastBufferedReader}. It
* overwrites {@link #isWordConstituent(char)} so that word constituents
* are defined negatively by a set of delimiters defined at construction time.
* There is a {@link DelimitedWordReader#DelimitedWordReader(String) constructor
* accepting the delimiter set as a string}. Note that LF and CR are always considered to be delimiters.
*
*/
public class DelimitedWordReader extends FastBufferedReader {
private static final long serialVersionUID = 1L;
/** The set of delimiters used to break the character stream into words. */
private final CharOpenHashSet delimiters;
@Override
protected boolean isWordConstituent(final char c) {
return ! delimiters.contains(c);
}
private void addCrLf() {
delimiters.add('\n');
delimiters.add('\r');
}
/** Creates a new delimited word reader with a given buffer size and set of delimiters.
* The wrapped reader will have to be set later using {@link #setReader(Reader)}.
*
* @param bufferSize the size in bytes of the internal buffer.
* @param delimiters a set of characters that will be considered word delimiters.
*/
public DelimitedWordReader(final int bufferSize, final CharSet delimiters) {
super(bufferSize);
this.delimiters = new CharOpenHashSet(delimiters, Hash.VERY_FAST_LOAD_FACTOR);
addCrLf();
}
/** Creates a new delimited word reader with a buffer of {@link #DEFAULT_BUFFER_SIZE} characters.
* The wrapped reader will have to be set later using {@link #setReader(Reader)}.
* @param delimiters a set of characters that will be considered word delimiters.
*/
public DelimitedWordReader(final CharSet delimiters) {
this.delimiters = new CharOpenHashSet(delimiters, Hash.VERY_FAST_LOAD_FACTOR);
addCrLf();
}
/** Creates a new delimited word reader with a buffer of {@link #DEFAULT_BUFFER_SIZE} characters.
* The wrapped reader will have to be set later using {@link #setReader(Reader)}.
*
*
Warning: it is easy to mistake this method for one whose semantics is
* the same as {@link FastBufferedReader#FastBufferedReader(MutableString)}, that is, wrapping the argument
* string in a reader.
*
* @param delimiters a set of characters that will be considered word delimiters, specified as a string.
*/
public DelimitedWordReader(final String delimiters) {
this(new CharOpenHashSet(delimiters.toCharArray()));
}
/** Creates a new delimited word reader with a given buffer size and set of delimiters.
* The wrapped reader will have to be set later using {@link #setReader(Reader)}.
*
* @param bufferSize the size in bytes of the internal buffer, specified as a string.
* @param delimiters a set of characters that will be considered word delimiters, specified as a string.
*/
public DelimitedWordReader(final String bufferSize, final String delimiters) {
this(Integer.parseInt(bufferSize), new CharOpenHashSet(delimiters.toCharArray()));
}
/** Creates a new delimited word reader by wrapping a given reader with a given buffer size and using a set of delimiters.
*
* @param r a reader to wrap.
* @param bufferSize the size in bytes of the internal buffer.
* @param delimiters a set of characters that will be considered word delimiters.
*/
public DelimitedWordReader(final Reader r, final int bufferSize, final CharSet delimiters) {
super(r, bufferSize);
this.delimiters = new CharOpenHashSet(delimiters, Hash.VERY_FAST_LOAD_FACTOR);
addCrLf();
}
/** Creates a new delimited word reader by wrapping a given reader with a buffer of {@link #DEFAULT_BUFFER_SIZE} characters using a given set of delimiters.
*
* @param r a reader to wrap.
* @param delimiters a set of characters that will be considered word delimiters.
*/
public DelimitedWordReader(final Reader r, final CharSet delimiters) {
super(r);
this.delimiters = new CharOpenHashSet(delimiters, Hash.VERY_FAST_LOAD_FACTOR);
addCrLf();
}
/** Creates a new delimited word reader by wrapping a given fragment of a character array and using a set delimiters.
*
*
The effect of {@link #setReader(Reader)} on a buffer created with
* this constructor is undefined.
*
* @param array the array that will be wrapped by the reader.
* @param offset the first character to be used.
* @param length the number of character to be used.
* @param delimiters a set of characters that will be considered word delimiters.
*/
public DelimitedWordReader(final char[] array, final int offset, final int length, final CharSet delimiters) {
super(array, offset, length);
this.delimiters = new CharOpenHashSet(delimiters, Hash.VERY_FAST_LOAD_FACTOR);
addCrLf();
}
/** Creates a new delimited word reader by wrapping a given character array and using a set delimiters.
*
*
The effect of {@link #setReader(Reader)} on a buffer created with
* this constructor is undefined.
*
* @param array the array that will be wrapped by the reader.
* @param delimiters a set of characters that will be considered word delimiters.
*/
public DelimitedWordReader(final char[] array, final CharSet delimiters) {
super(array);
this.delimiters = new CharOpenHashSet(delimiters, Hash.VERY_FAST_LOAD_FACTOR);
addCrLf();
}
/** Creates a new delimited word reader by wrapping a given mutable string and using a set of delimiters.
*
*
The effect of {@link #setReader(Reader)} on a buffer created with
* this constructor is undefined.
*
* @param s the mutable string that will be wrapped by the reader.
* @param delimiters a set of characters that will be considered word delimiters.
*/
public DelimitedWordReader(final MutableString s, final CharSet delimiters) {
super(s, CharSets.EMPTY_SET);
this.delimiters = new CharOpenHashSet(delimiters, Hash.VERY_FAST_LOAD_FACTOR);
addCrLf();
}
@Override
public DelimitedWordReader copy() {
// TODO: improve this by sharing the backing set.
return new DelimitedWordReader(bufferSize, delimiters);
}
@Override
public String toSpec() {
return toString();
}
@Override
public String toString() {
final String className = getClass().getName();
final CharOpenHashSet additionalDelimiters = delimiters.clone();
additionalDelimiters.remove('\n');
additionalDelimiters.remove('\r');
final String delimiters = new String(additionalDelimiters.toCharArray());
if (bufferSize == DEFAULT_BUFFER_SIZE) return className + "(\"" + delimiters + "\")";
return className + "(" + bufferSize + ",\"" + delimiters + "\")";
}
}