101 lines
3.3 KiB
Java
101 lines
3.3 KiB
Java
/*
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The contents of this file are subject to the THDL Open Community License
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Version 1.0 (the "License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License on the THDL web site
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(http://www.thdl.org/).
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Software distributed under the License is distributed on an "AS IS" basis,
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WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
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License for the specific terms governing rights and limitations under the
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License.
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The Initial Developer of this software is the Tibetan and Himalayan Digital
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Library (THDL). Portions created by the THDL are Copyright 2003 THDL.
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All Rights Reserved.
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Contributor(s): ______________________________________.
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*/
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package org.thdl.tib.text.ttt;
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import java.util.ArrayList;
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import java.util.ListIterator;
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import java.util.NoSuchElementException;
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/** An object that can iterate over an {@link TParseTree}.
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*
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* @author David Chandler */
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class ParseIterator {
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private ArrayList al = null;
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private int sz;
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private ListIterator[] iterators;
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private boolean first = true;
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private boolean hasNextParse = true;
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/** Constructs a new ParseIterator that iterates over a list of
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* TStackListLists. */
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ParseIterator(ArrayList al) {
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this.al = al;
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sz = al.size();
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iterators = new ListIterator[sz];
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hasNextParse = false;
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for (int i = 0; i < sz; i++) {
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iterators[i] = ((TStackListList)al.get(i)).listIterator();
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if (iterators[i].hasNext())
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hasNextParse = true;
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}
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}
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/** Returns true if and only if there is another parse
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* available. */
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boolean hasNext() {
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return hasNextParse;
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}
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/** Returns the next available parse. */
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TStackList next() {
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if (!hasNextParse)
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throw new NoSuchElementException("no parses left");
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if (first) {
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first = false;
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TStackList x = new TStackList();
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for (int i = 0; i < sz; i++) {
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TStackList nextSL = (TStackList)iterators[i].next();
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x.addAll(nextSL);
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}
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// The next guy is found by taking the previous item of
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// each iterator.
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hasNextParse = false;
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for (int i = sz - 1; i >= 0; i--) {
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if (iterators[i].hasNext()) {
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iterators[i].next();
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hasNextParse = true;
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break;
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}
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}
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return x;
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}
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// Up the rightmost iterator you can. If you can, reset all
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// guys to the right of it. If you can't, we're done.
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TStackList x = new TStackList(sz);
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hasNextParse = false;
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for (int i = sz - 1; i >= 0; i--) {
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TStackList prevSL = (TStackList)iterators[i].previous();
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x.addAll(0, prevSL);
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iterators[i].next();
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if (!hasNextParse && iterators[i].hasNext()) {
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hasNextParse = true;
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iterators[i].next();
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// Reset all iterators to the right of i.
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for (int j = i + 1; j < sz; j++) {
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while (iterators[j].hasPrevious())
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iterators[j].previous();
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iterators[j].next();
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}
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}
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}
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return x;
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}
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}
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