Helfer AtomCursor

Jan Burse, erstellt 15. Sep 2018
package jekpro.reference.structure;
import java.util.Enumeration;
/**
* <p>The backtracking data for the atom cursor.</p>
* <p/>
* Warranty & Liability
* To the extent permitted by applicable law and unless explicitly
* otherwise agreed upon, XLOG Technologies GmbH makes no warranties
* regarding the provided information. XLOG Technologies GmbH assumes
* no liability that any problems might be solved with the information
* provided by XLOG Technologies GmbH.
* <p/>
* Rights & License
* All industrial property rights regarding the information - copyright
* and patent rights in particular - are the sole property of XLOG
* Technologies GmbH. If the company was not the originator of some
* excerpts, XLOG Technologies GmbH has at least obtained the right to
* reproduce, change and translate the information.
* <p/>
* Reproduction is restricted to the whole unaltered document. Reproduction
* of the information is only allowed for non-commercial uses. Selling,
* giving away or letting of the execution of the library is prohibited.
* The library can be distributed as part of your applications and libraries
* for execution provided this comment remains unchanged.
* <p/>
* Restrictions
* Only to be distributed with programs that add significant and primary
* functionality to the library. Not to be distributed with additional
* software intended to replace any components of the library.
* <p/>
* Trademarks
* Jekejeke is a registered trademark of XLOG Technologies GmbH.
*/
final class AtomCursor implements Enumeration<Integer> {
private String str;
private int cfrom;
private int from;
private int to;
private boolean forward;
/**
* <p>Create a new atom cursor.</p>
*
* @param s The atom.
* @param cf The from codepoint index.
* @param f The from word index.
* @param t The to word index.
*/
AtomCursor(String s, int cf, int f, int t) {
str = s;
cfrom = cf;
from = f;
to = t;
forward = (from <= to);
}
/**
* <p>Retrieve the from codepoint index.</p>
*
* @return The from codepoint index.
*/
Integer getCFrom() {
return Integer.valueOf(cfrom);
}
/**
* <p>Check whether there are more elements.</p>
*
* @return True if there are more elements, otherwise false.
*/
public boolean hasMoreElements() {
return (forward ? from <= to : from >= to);
}
/**
* <p>Retrieve the next element and advance the cursor.</p>
*
* @return The next element.
*/
public Integer nextElement() {
Integer val = Integer.valueOf(from);
if (forward) {
if (from < to) {
cfrom++;
int ch = str.codePointAt(from);
from = from + Character.charCount(ch);
} else {
from++;
}
} else {
if (from > to) {
cfrom--;
int ch = str.codePointBefore(from);
from = from - Character.charCount(ch);
} else {
from--;
}
}
return val;
}
}

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