/*
* Copyright 2009 David Jurgens
*
* This file is part of the S-Space package and is covered under the terms and
* conditions therein.
*
* The S-Space package is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation and distributed hereunder to you.
*
* THIS SOFTWARE IS PROVIDED "AS IS" AND NO REPRESENTATIONS OR WARRANTIES,
* EXPRESS OR IMPLIED ARE MADE. BY WAY OF EXAMPLE, BUT NOT LIMITATION, WE MAKE
* NO REPRESENTATIONS OR WARRANTIES OF MERCHANT- ABILITY OR FITNESS FOR ANY
* PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE OR DOCUMENTATION
* WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER
* RIGHTS.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package edu.ucla.sspace.text;
import java.io.BufferedReader;
import java.io.IOError;
import java.io.IOException;
import java.io.StringReader;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* An iterator over all of the tokens present in a {@link BufferedReader} that
* are separated by any amount of white space.
*/
public class WordIterator implements Iterator<String> {
/**
* A fixed pattern matching all non-whitespace characters.
*/
private static final Pattern notWhiteSpace = Pattern.compile("\\S+");
/**
* The stream from which to read tokens
*/
private final BufferedReader br;
/**
* The next token to return
*/
private String next;
/**
* The matcher that is tokenizing the current line
*/
private Matcher matcher;
/**
* The current line being considered
*/
String curLine;
/**
* Constructs an iterator for all the tokens contained in the string
*/
public WordIterator(String str) {
this(new BufferedReader(new StringReader(str)));
}
/**
* Constructs an iterator for all the tokens contained in text of the
* provided reader.
*/
public WordIterator(BufferedReader br) {
this.br = br;
curLine = null;
advance();
}
/**
* Advances to the next word in the buffer.
*/
private void advance() {
try {
// loop until we find a word in the reader, or there are no more
// words
while (true) {
// if we haven't looked at any lines yet, or if the index into
// the current line is already at the end
if (curLine == null || !matcher.find()) {
String line = br.readLine();
// if there aren't any more lines in the reader, then mark
// next as null to indicate that there are no more words
if (line == null) {
next = null;
br.close();
return;
}
// create a new matcher to find all the tokens in this line
matcher = notWhiteSpace.matcher(line);
curLine = line;
// skip lines with no matches
if (!matcher.find())
continue;
}
next = curLine.substring(matcher.start(), matcher.end());
break;
}
} catch (IOException ioe) {
throw new IOError(ioe);
}
}
/**
* Returns {@code true} if there is another word to return.
*/
public boolean hasNext() {
return next != null;
}
/**
* Returns the next word from the reader.
*/
public String next() {
if (next == null) {
throw new NoSuchElementException();
}
String s = next;
advance();
return s;
}
/**
* Throws an {@link UnsupportedOperationException} if called.
*/
public void remove() {
throw new UnsupportedOperationException("remove is not supported");
}
}