Mega Code Archive
An iterator that breaks text into lines The result is equal to BufferedReader readLine()
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/*
* JCommon : a free general purpose class library for the Java(tm) platform
*
*
* (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jcommon/index.html
*
* 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 library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* ----------------------
* LineBreakIterator.java
* ----------------------
* (C)opyright 2003, by Thomas Morgner and Contributors.
*
* Original Author: Thomas Morgner;
* Contributor(s): David Gilbert (for Object Refinery Limited);
*
* $Id: LineBreakIterator.java,v 1.4 2005/11/03 09:55:26 mungady Exp $
*
* Changes
* -------
* 13-03-2003 : Initial version
*/
import java.util.Iterator;
/**
* An iterator that breaks text into lines. The result is equal to
* BufferedReader.readLine().
*
* @author Thomas Morgner
*/
public class LineBreakIterator implements Iterator {
/** A useful constant. */
public static final int DONE = -1;
/** Storage for the text. */
private char[] text;
/** The current position. */
private int position;
/**
* Default constructor.
*/
public LineBreakIterator() {
setText("");
}
/**
* Creates a new line break iterator.
*
* @param text
* the text to be broken up.
*/
public LineBreakIterator(final String text) {
setText(text);
}
/**
* Returns the position of the next break.
*
* @return A position.
*/
public synchronized int nextPosition() {
if (this.text == null) {
return DONE;
}
if (this.position == DONE) {
return DONE;
}
// recognize \n, \r, \r\n
final int nChars = this.text.length;
int nextChar = this.position;
for (;;) {
if (nextChar >= nChars) {
/* End of text reached */
this.position = DONE;
return DONE;
}
boolean eol = false;
char c = 0;
int i;
// search the next line break, either \n or \r
for (i = nextChar; i < nChars; i++) {
c = this.text[i];
if ((c == '\n') || (c == '\r')) {
eol = true;
break;
}
}
nextChar = i;
if (eol) {
nextChar++;
if (c == '\r') {
if ((nextChar < nChars) && (this.text[nextChar] == '\n')) {
nextChar++;
}
}
this.position = nextChar;
return (this.position);
}
}
}
/**
* Same like next(), but returns the End-Of-Text as if there was a linebreak
* added (Reader.readLine() compatible)
*
* @return The next position.
*/
public int nextWithEnd() {
final int pos = this.position;
if (pos == DONE) {
return DONE;
}
if (pos == this.text.length) {
this.position = DONE;
return DONE;
}
final int retval = nextPosition();
if (retval == DONE) {
return this.text.length;
}
return retval;
}
/**
* Returns the text to be broken up.
*
* @return The text.
*/
public String getText() {
return new String(this.text);
}
/**
* Sets the text to be broken up.
*
* @param text
* the text.
*/
public void setText(final String text) {
this.position = 0;
this.text = text.toCharArray();
}
/**
* Returns <tt>true</tt> if the iteration has more elements. (In other
* words, returns <tt>true</tt> if <tt>next</tt> would return an element
* rather than throwing an exception.)
*
* @return <tt>true</tt> if the iterator has more elements.
*/
public boolean hasNext() {
return (this.position != DONE);
}
/**
* Returns the next element in the iteration.
*
* @return the next element in the iteration.
*/
public Object next() {
if (this.position == DONE) {
// allready at the end ...
return null;
}
final int lastFound = this.position;
int pos = nextWithEnd();
if (pos == DONE) {
// the end of the text has been reached ...
return new String(this.text, lastFound, this.text.length - lastFound);
}
// step one char back
if (pos > 0) {
final int end = lastFound;
for (; ((pos) > end) && ((this.text[pos - 1] == '\n') || this.text[pos - 1] == '\r'); pos--) {
// search the end of the current linebreak sequence ..
}
}
// System.out.println ("text: " + new String (text));
// System.out.println ("pos: " + pos + " lastFound: " + lastFound);
return new String(this.text, lastFound, pos - lastFound);
}
/**
*
* Removes from the underlying collection the last element returned by the
* iterator (optional operation). This method can be called only once per call
* to <tt>next</tt>. The behavior of an iterator is unspecified if the
* underlying collection is modified while the iteration is in progress in any
* way other than by calling this method.
*
* @exception UnsupportedOperationException
* if the <tt>remove</tt> operation is not supported by this
* Iterator.
* @exception IllegalStateException
* if the <tt>next</tt> method has not yet been called, or the
* <tt>remove</tt> method has already been called after the
* last call to the <tt>next</tt> method.
*/
public void remove() {
throw new UnsupportedOperationException("This iterator is read-only.");
}
}
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