org.apache.lucene.analysis.path.ReversePathHierarchyTokenizer.java Source code

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Here is the source code for org.apache.lucene.analysis.path.ReversePathHierarchyTokenizer.java

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/*
 * 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.path;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.util.AttributeFactory;

/**
 * Tokenizer for domain-like hierarchies.
 * <p>
 * Take something like:
 *
 * <pre>
 * www.site.co.uk
 * </pre>
 *
 * and make:
 *
 * <pre>
 * www.site.co.uk
 * site.co.uk
 * co.uk
 * uk
 * </pre>
 *
 */
public class ReversePathHierarchyTokenizer extends Tokenizer {

    public ReversePathHierarchyTokenizer() {
        this(DEFAULT_BUFFER_SIZE, DEFAULT_DELIMITER, DEFAULT_DELIMITER, DEFAULT_SKIP);
    }

    public ReversePathHierarchyTokenizer(int skip) {
        this(DEFAULT_BUFFER_SIZE, DEFAULT_DELIMITER, DEFAULT_DELIMITER, skip);
    }

    public ReversePathHierarchyTokenizer(int bufferSize, char delimiter) {
        this(bufferSize, delimiter, delimiter, DEFAULT_SKIP);
    }

    public ReversePathHierarchyTokenizer(char delimiter, char replacement) {
        this(DEFAULT_BUFFER_SIZE, delimiter, replacement, DEFAULT_SKIP);
    }

    public ReversePathHierarchyTokenizer(int bufferSize, char delimiter, char replacement) {
        this(bufferSize, delimiter, replacement, DEFAULT_SKIP);
    }

    public ReversePathHierarchyTokenizer(char delimiter, int skip) {
        this(DEFAULT_BUFFER_SIZE, delimiter, delimiter, skip);
    }

    public ReversePathHierarchyTokenizer(char delimiter, char replacement, int skip) {
        this(DEFAULT_BUFFER_SIZE, delimiter, replacement, skip);
    }

    public ReversePathHierarchyTokenizer(AttributeFactory factory, char delimiter, char replacement, int skip) {
        this(factory, DEFAULT_BUFFER_SIZE, delimiter, replacement, skip);
    }

    public ReversePathHierarchyTokenizer(int bufferSize, char delimiter, char replacement, int skip) {
        this(DEFAULT_TOKEN_ATTRIBUTE_FACTORY, bufferSize, delimiter, replacement, skip);
    }

    public ReversePathHierarchyTokenizer(AttributeFactory factory, int bufferSize, char delimiter, char replacement,
            int skip) {
        super(factory);
        if (bufferSize < 0) {
            throw new IllegalArgumentException("bufferSize cannot be negative");
        }
        if (skip < 0) {
            throw new IllegalArgumentException("skip cannot be negative");
        }
        termAtt.resizeBuffer(bufferSize);
        this.delimiter = delimiter;
        this.replacement = replacement;
        this.skip = skip;
        resultToken = new StringBuilder(bufferSize);
        resultTokenBuffer = new char[bufferSize];
        delimiterPositions = new ArrayList<>(bufferSize / 10);
    }

    private static final int DEFAULT_BUFFER_SIZE = 1024;
    public static final char DEFAULT_DELIMITER = '/';
    public static final int DEFAULT_SKIP = 0;

    private final char delimiter;
    private final char replacement;
    private final int skip;

    private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
    private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
    private final PositionIncrementAttribute posAtt = addAttribute(PositionIncrementAttribute.class);

    private int endPosition = 0;
    private int finalOffset = 0;
    private int skipped = 0;
    private StringBuilder resultToken;

    private List<Integer> delimiterPositions;
    private int delimitersCount = -1;
    private char[] resultTokenBuffer;

    @Override
    public final boolean incrementToken() throws IOException {
        clearAttributes();
        if (delimitersCount == -1) {
            int length = 0;
            delimiterPositions.add(0);
            while (true) {
                int c = input.read();
                if (c < 0) {
                    break;
                }
                length++;
                if (c == delimiter) {
                    delimiterPositions.add(length);
                    resultToken.append(replacement);
                } else {
                    resultToken.append((char) c);
                }
            }
            delimitersCount = delimiterPositions.size();
            if (delimiterPositions.get(delimitersCount - 1) < length) {
                delimiterPositions.add(length);
                delimitersCount++;
            }
            if (resultTokenBuffer.length < resultToken.length()) {
                resultTokenBuffer = new char[resultToken.length()];
            }
            resultToken.getChars(0, resultToken.length(), resultTokenBuffer, 0);
            resultToken.setLength(0);
            int idx = delimitersCount - 1 - skip;
            if (idx >= 0) {
                // otherwise it's ok, because we will skip and return false
                endPosition = delimiterPositions.get(idx);
            }
            finalOffset = correctOffset(length);
            posAtt.setPositionIncrement(1);
        } else {
            posAtt.setPositionIncrement(0);
        }

        while (skipped < delimitersCount - skip - 1) {
            int start = delimiterPositions.get(skipped);
            termAtt.copyBuffer(resultTokenBuffer, start, endPosition - start);
            offsetAtt.setOffset(correctOffset(start), correctOffset(endPosition));
            skipped++;
            return true;
        }

        return false;
    }

    @Override
    public final void end() throws IOException {
        super.end();
        // set final offset
        offsetAtt.setOffset(finalOffset, finalOffset);
    }

    @Override
    public void reset() throws IOException {
        super.reset();
        resultToken.setLength(0);
        finalOffset = 0;
        endPosition = 0;
        skipped = 0;
        delimitersCount = -1;
        delimiterPositions.clear();
    }
}