/*license*\
XBN-Java: Copyright (C) 2014, Jeff Epstein (aliteralmind __DASH__ github __AT__ yahoo __DOT__ com)
This software is dual-licensed under the:
- Lesser General Public License (LGPL) version 3.0 or, at your option, any later version;
- Apache Software License (ASL) version 2.0.
Either license may be applied at your discretion. More information may be found at
- http://en.wikipedia.org/wiki/Multi-licensing.
The text of both licenses is available in the root directory of this project, under the names "LICENSE_lgpl-3.0.txt" and "LICENSE_asl-2.0.txt". The latest copies may be downloaded at:
- LGPL 3.0: https://www.gnu.org/licenses/lgpl-3.0.txt
- ASL 2.0: http://www.apache.org/licenses/LICENSE-2.0.txt
\*license*/
package com.github.xbn.util.itr;
import java.util.Iterator;
import com.github.xbn.lang.CrashIfObject;
import java.util.NoSuchElementException;
/**
<p>Iterator-related utilities.</p>
* @since 0.1.0
* @author Copyright (C) 2014, Jeff Epstein ({@code aliteralmind __DASH__ github __AT__ yahoo __DOT__ com}), dual-licensed under the LGPL (version 3.0 or later) or the ASL (version 2.0). See source code for details. <a href="http://xbnjava.aliteralmind.com">{@code http://xbnjava.aliteralmind.com}</a>, <a href="https://github.com/aliteralmind/xbnjava">{@code https://github.com/aliteralmind/xbnjava}</a>
**/
public class IteratorUtil {
/**
<p>Crash if there are not elements, otherwise <i>return</i> the cause.</p>
* @param itr May not be {@code null}.
*/
public static final void crashIfNoSuchElement(Iterator<?> itr) {
try {
if(!itr.hasNext()) {
throw new NoSuchElementException();
}
} catch(RuntimeException rx) {
throw CrashIfObject.nullOrReturnCause(itr, "itr", null, rx);
}
}
/**
<p>Creates a new iterator, skipping over the first x elements. This can be used to simulate a(n albeit inefficient) double-for loop for comparing elements, such as for detecting duplicates.</p>
{@.codelet.and.out com.github.xbn.examples.util.itr.DetectDupsWithIterators%eliminateCommentBlocksAndPackageDecl()}
*/
public static final <E> Iterator<E> newIteratorStartingAtIndex(int first_wantedIdx, Iterable<E> iterable) {
Iterator<E> itr = iterable.iterator();
while(first_wantedIdx > 0) {
try {
itr.next();
} catch(NoSuchElementException nsex) {
throw new NoSuchElementException("first_wantedIdx=" + first_wantedIdx);
}
first_wantedIdx--;
}
return itr;
}
public IteratorUtil() {
throw new IllegalStateException("Do not instantiate.");
}
}