| package org.apache.lucene.analysis.util; |
| |
| /* |
| * 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 java.io.Reader; |
| |
| import org.apache.lucene.analysis.Tokenizer; |
| import org.apache.lucene.analysis.tokenattributes.OffsetAttribute; |
| import org.apache.lucene.analysis.tokenattributes.CharTermAttribute; |
| import org.apache.lucene.util.AttributeFactory; |
| import org.apache.lucene.util.Version; |
| import org.apache.lucene.analysis.util.CharacterUtils.CharacterBuffer; |
| |
| /** |
| * An abstract base class for simple, character-oriented tokenizers. |
| * <p> |
| * <a name="version">You must specify the required {@link Version} compatibility |
| * when creating {@link CharTokenizer}: |
| * <ul> |
| * <li>As of 3.1, {@link CharTokenizer} uses an int based API to normalize and |
| * detect token codepoints. See {@link #isTokenChar(int)} and |
| * {@link #normalize(int)} for details.</li> |
| * </ul> |
| * <p> |
| * A new {@link CharTokenizer} API has been introduced with Lucene 3.1. This API |
| * moved from UTF-16 code units to UTF-32 codepoints to eventually add support |
| * for <a href= |
| * "http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Character.html#supplementary" |
| * >supplementary characters</a>. The old <i>char</i> based API has been |
| * deprecated and should be replaced with the <i>int</i> based methods |
| * {@link #isTokenChar(int)} and {@link #normalize(int)}. |
| * </p> |
| * <p> |
| * As of Lucene 3.1 each {@link CharTokenizer} - constructor expects a |
| * {@link Version} argument. Based on the given {@link Version} either the new |
| * API or a backwards compatibility layer is used at runtime. For |
| * {@link Version} < 3.1 the backwards compatibility layer ensures correct |
| * behavior even for indexes build with previous versions of Lucene. If a |
| * {@link Version} >= 3.1 is used {@link CharTokenizer} requires the new API to |
| * be implemented by the instantiated class. Yet, the old <i>char</i> based API |
| * is not required anymore even if backwards compatibility must be preserved. |
| * {@link CharTokenizer} subclasses implementing the new API are fully backwards |
| * compatible if instantiated with {@link Version} < 3.1. |
| * </p> |
| * <p> |
| * <strong>Note:</strong> If you use a subclass of {@link CharTokenizer} with {@link Version} >= |
| * 3.1 on an index build with a version < 3.1, created tokens might not be |
| * compatible with the terms in your index. |
| * </p> |
| **/ |
| public abstract class CharTokenizer extends Tokenizer { |
| |
| /** |
| * Creates a new {@link CharTokenizer} instance |
| * @param input |
| * the input to split up into tokens |
| */ |
| public CharTokenizer(Reader input) { |
| super(input); |
| charUtils = CharacterUtils.getInstance(); |
| } |
| |
| /** |
| * @deprecated Use {@link #CharTokenizer(Reader)} |
| */ |
| @Deprecated |
| public CharTokenizer(Version matchVersion, Reader input) { |
| super(input); |
| charUtils = CharacterUtils.getInstance(matchVersion); |
| } |
| |
| /** |
| * Creates a new {@link CharTokenizer} instance |
| * |
| * @param factory |
| * the attribute factory to use for this {@link Tokenizer} |
| * @param input |
| * the input to split up into tokens |
| */ |
| public CharTokenizer(AttributeFactory factory, Reader input) { |
| super(factory, input); |
| charUtils = CharacterUtils.getInstance(); |
| } |
| |
| /** |
| * @deprecated Use {@link #CharTokenizer(AttributeFactory, Reader)} |
| */ |
| @Deprecated |
| public CharTokenizer(Version matchVersion, AttributeFactory factory, |
| Reader input) { |
| super(factory, input); |
| charUtils = CharacterUtils.getInstance(matchVersion); |
| } |
| |
| private int offset = 0, bufferIndex = 0, dataLen = 0, finalOffset = 0; |
| private static final int MAX_WORD_LEN = 255; |
| private static final int IO_BUFFER_SIZE = 4096; |
| |
| private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class); |
| private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class); |
| |
| private final CharacterUtils charUtils; |
| private final CharacterBuffer ioBuffer = CharacterUtils.newCharacterBuffer(IO_BUFFER_SIZE); |
| |
| /** |
| * Returns true iff a codepoint should be included in a token. This tokenizer |
| * generates as tokens adjacent sequences of codepoints which satisfy this |
| * predicate. Codepoints for which this is false are used to define token |
| * boundaries and are not included in tokens. |
| */ |
| protected abstract boolean isTokenChar(int c); |
| |
| /** |
| * Called on each token character to normalize it before it is added to the |
| * token. The default implementation does nothing. Subclasses may use this to, |
| * e.g., lowercase tokens. |
| */ |
| protected int normalize(int c) { |
| return c; |
| } |
| |
| @Override |
| public final boolean incrementToken() throws IOException { |
| clearAttributes(); |
| int length = 0; |
| int start = -1; // this variable is always initialized |
| int end = -1; |
| char[] buffer = termAtt.buffer(); |
| while (true) { |
| if (bufferIndex >= dataLen) { |
| offset += dataLen; |
| charUtils.fill(ioBuffer, input); // read supplementary char aware with CharacterUtils |
| if (ioBuffer.getLength() == 0) { |
| dataLen = 0; // so next offset += dataLen won't decrement offset |
| if (length > 0) { |
| break; |
| } else { |
| finalOffset = correctOffset(offset); |
| return false; |
| } |
| } |
| dataLen = ioBuffer.getLength(); |
| bufferIndex = 0; |
| } |
| // use CharacterUtils here to support < 3.1 UTF-16 code unit behavior if the char based methods are gone |
| final int c = charUtils.codePointAt(ioBuffer.getBuffer(), bufferIndex, ioBuffer.getLength()); |
| final int charCount = Character.charCount(c); |
| bufferIndex += charCount; |
| |
| if (isTokenChar(c)) { // if it's a token char |
| if (length == 0) { // start of token |
| assert start == -1; |
| start = offset + bufferIndex - charCount; |
| end = start; |
| } else if (length >= buffer.length-1) { // check if a supplementary could run out of bounds |
| buffer = termAtt.resizeBuffer(2+length); // make sure a supplementary fits in the buffer |
| } |
| end += charCount; |
| length += Character.toChars(normalize(c), buffer, length); // buffer it, normalized |
| if (length >= MAX_WORD_LEN) // buffer overflow! make sure to check for >= surrogate pair could break == test |
| break; |
| } else if (length > 0) // at non-Letter w/ chars |
| break; // return 'em |
| } |
| |
| termAtt.setLength(length); |
| assert start != -1; |
| offsetAtt.setOffset(correctOffset(start), finalOffset = correctOffset(end)); |
| return true; |
| |
| } |
| |
| @Override |
| public final void end() throws IOException { |
| super.end(); |
| // set final offset |
| offsetAtt.setOffset(finalOffset, finalOffset); |
| } |
| |
| @Override |
| public void reset() throws IOException { |
| super.reset(); |
| bufferIndex = 0; |
| offset = 0; |
| dataLen = 0; |
| finalOffset = 0; |
| ioBuffer.reset(); // make sure to reset the IO buffer!! |
| } |
| } |