org.apache.lucene.analysis.util.TokenizerFactory.java Source code

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Here is the source code for org.apache.lucene.analysis.util.TokenizerFactory.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.util;

import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.util.AttributeFactory;

import java.util.Map;
import java.util.Set;

/**
 * Abstract parent class for analysis factories that create {@link Tokenizer}
 * instances.
 *
 * @since 3.1
 */
public abstract class TokenizerFactory extends AbstractAnalysisFactory {

    private static final AnalysisSPILoader<TokenizerFactory> loader = new AnalysisSPILoader<>(
            TokenizerFactory.class);

    /** looks up a tokenizer by name from context classpath */
    public static TokenizerFactory forName(String name, Map<String, String> args) {
        return loader.newInstance(name, args);
    }

    /** looks up a tokenizer class by name from context classpath */
    public static Class<? extends TokenizerFactory> lookupClass(String name) {
        return loader.lookupClass(name);
    }

    /** returns a list of all available tokenizer names from context classpath */
    public static Set<String> availableTokenizers() {
        return loader.availableServices();
    }

    /** looks up a SPI name for the specified tokenizer factory */
    public static String findSPIName(Class<? extends TokenizerFactory> serviceClass) {
        try {
            return lookupSPIName(serviceClass);
        } catch (NoSuchFieldException | IllegalAccessException | IllegalStateException e) {
            throw new IllegalStateException(e);
        }
    }

    /** 
     * Reloads the factory list from the given {@link ClassLoader}.
     * Changes to the factories are visible after the method ends, all
     * iterators ({@link #availableTokenizers()},...) stay consistent. 
     * 
     * <p><b>NOTE:</b> Only new factories are added, existing ones are
     * never removed or replaced.
     * 
     * <p><em>This method is expensive and should only be called for discovery
     * of new factories on the given classpath/classloader!</em>
     */
    public static void reloadTokenizers(ClassLoader classloader) {
        loader.reload(classloader);
    }

    /**
     * Initialize this factory via a set of key-value pairs.
     */
    protected TokenizerFactory(Map<String, String> args) {
        super(args);
    }

    /** Creates a TokenStream of the specified input using the default attribute factory. */
    public final Tokenizer create() {
        return create(TokenStream.DEFAULT_TOKEN_ATTRIBUTE_FACTORY);
    }

    /** Creates a TokenStream of the specified input using the given AttributeFactory */
    abstract public Tokenizer create(AttributeFactory factory);
}