--- /dev/null
+package org.apache.lucene.util.fst;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.apache.lucene.util.IntsRef;
+
+import java.io.IOException;
+
+/** Can next() and advance() through the terms in an FST
+ *
+ * @lucene.experimental
+*/
+
+public final class IntsRefFSTEnum<T> extends FSTEnum<T> {
+ private final IntsRef current = new IntsRef(10);
+ private final InputOutput<T> result = new InputOutput<T>();
+ private IntsRef target;
+
+ public static class InputOutput<T> {
+ public IntsRef input;
+ public T output;
+ }
+
+ /** doFloor controls the behavior of advance: if it's true
+ * doFloor is true, advance positions to the biggest
+ * term before target. */
+ public IntsRefFSTEnum(FST<T> fst) {
+ super(fst);
+ result.input = current;
+ current.offset = 1;
+ }
+
+ public InputOutput<T> current() {
+ return result;
+ }
+
+ public InputOutput<T> next() throws IOException {
+ //System.out.println(" enum.next");
+ doNext();
+ return setResult();
+ }
+
+ /** Seeks to smallest term that's >= target. */
+ public InputOutput<T> seekCeil(IntsRef target) throws IOException {
+ this.target = target;
+ targetLength = target.length;
+ super.doSeekCeil();
+ return setResult();
+ }
+
+ /** Seeks to biggest term that's <= target. */
+ public InputOutput<T> seekFloor(IntsRef target) throws IOException {
+ this.target = target;
+ targetLength = target.length;
+ super.doSeekFloor();
+ return setResult();
+ }
+
+ @Override
+ protected int getTargetLabel() {
+ if (upto-1 == target.length) {
+ return FST.END_LABEL;
+ } else {
+ return target.ints[target.offset + upto - 1];
+ }
+ }
+
+ @Override
+ protected int getCurrentLabel() {
+ // current.offset fixed at 1
+ return current.ints[upto];
+ }
+
+ @Override
+ protected void setCurrentLabel(int label) {
+ current.ints[upto] = label;
+ }
+
+ @Override
+ protected void grow() {
+ current.grow(upto+1);
+ }
+
+ private InputOutput<T> setResult() {
+ if (upto == 0) {
+ return null;
+ } else {
+ current.length = upto-1;
+ result.output = output[upto];
+ return result;
+ }
+ }
+}