| /* |
| * 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. |
| */ |
| package org.apache.lucene.analysis.miscellaneous; |
| |
| import java.io.IOException; |
| import org.apache.lucene.analysis.TokenFilter; |
| import org.apache.lucene.analysis.TokenStream; |
| import org.apache.lucene.analysis.tokenattributes.OffsetAttribute; |
| |
| /** |
| * Lets all tokens pass through until it sees one with a start offset <= a configured limit, |
| * which won't pass and ends the stream. This can be useful to limit highlighting, for example. |
| * |
| * <p>By default, this filter ignores any tokens in the wrapped {@code TokenStream} once the limit |
| * has been exceeded, which can result in {@code reset()} being called prior to {@code |
| * incrementToken()} returning {@code false}. For most {@code TokenStream} implementations this |
| * should be acceptable, and faster then consuming the full stream. If you are wrapping a {@code |
| * TokenStream} which requires that the full stream of tokens be exhausted in order to function |
| * properly, use the {@link #LimitTokenOffsetFilter(TokenStream, int, boolean)} option. |
| */ |
| public final class LimitTokenOffsetFilter extends TokenFilter { |
| |
| private final OffsetAttribute offsetAttrib = addAttribute(OffsetAttribute.class); |
| private int maxStartOffset; |
| private final boolean consumeAllTokens; |
| |
| // some day we may limit by end offset too but no need right now |
| |
| /** |
| * Lets all tokens pass through until it sees one with a start offset <= {@code maxStartOffset} |
| * which won't pass and ends the stream. It won't consume any tokens afterwards. |
| * |
| * @param maxStartOffset the maximum start offset allowed |
| */ |
| public LimitTokenOffsetFilter(TokenStream input, int maxStartOffset) { |
| this(input, maxStartOffset, false); |
| } |
| |
| public LimitTokenOffsetFilter(TokenStream input, int maxStartOffset, boolean consumeAllTokens) { |
| super(input); |
| if (maxStartOffset < 0) { |
| throw new IllegalArgumentException("maxStartOffset must be >= zero"); |
| } |
| this.maxStartOffset = maxStartOffset; |
| this.consumeAllTokens = consumeAllTokens; |
| } |
| |
| @Override |
| public boolean incrementToken() throws IOException { |
| if (!input.incrementToken()) { |
| return false; |
| } |
| if (offsetAttrib.startOffset() <= maxStartOffset) { |
| return true; |
| } |
| if (consumeAllTokens) { |
| while (input.incrementToken()) { |
| // no-op |
| } |
| } |
| return false; |
| } |
| } |