| 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 java.io.IOException; |
| |
| import org.apache.lucene.util.BytesRef; |
| |
| /** Can next() and advance() through the terms in an FST |
| * |
| * @lucene.experimental |
| */ |
| |
| public final class BytesRefFSTEnum<T> extends FSTEnum<T> { |
| private final BytesRef current = new BytesRef(10); |
| private final InputOutput<T> result = new InputOutput<T>(); |
| private BytesRef target; |
| |
| public static class InputOutput<T> { |
| public BytesRef 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 BytesRefFSTEnum(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(BytesRef target) throws IOException { |
| this.target = target; |
| targetLength = target.length; |
| super.doSeekCeil(); |
| return setResult(); |
| } |
| |
| /** Seeks to biggest term that's <= target. */ |
| public InputOutput<T> seekFloor(BytesRef 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.bytes[target.offset + upto - 1] & 0xFF; |
| } |
| } |
| |
| @Override |
| protected int getCurrentLabel() { |
| // current.offset fixed at 1 |
| return current.bytes[upto] & 0xFF; |
| } |
| |
| @Override |
| protected void setCurrentLabel(int label) { |
| current.bytes[upto] = (byte) 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; |
| } |
| } |
| } |