org.apache.druid.java.util.common.parsers.RegexParser.java Source code

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Here is the source code for org.apache.druid.java.util.common.parsers.RegexParser.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.druid.java.util.common.parsers;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import org.apache.druid.java.util.common.collect.Utils;

import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;

/**
 */
public class RegexParser implements Parser<String, Object> {
    private final String pattern;
    private final Splitter listSplitter;
    private final Function<String, Object> valueFunction;
    private final Pattern compiled;

    private List<String> fieldNames = null;

    public RegexParser(final String pattern, final Optional<String> listDelimiter) {
        this.pattern = pattern;
        this.listSplitter = Splitter
                .onPattern(listDelimiter.isPresent() ? listDelimiter.get() : Parsers.DEFAULT_LIST_DELIMITER);
        this.valueFunction = new Function<String, Object>() {
            @Override
            public Object apply(String input) {
                final List retVal = StreamSupport.stream(listSplitter.split(input).spliterator(), false)
                        .map(Strings::emptyToNull).collect(Collectors.toList());
                if (retVal.size() == 1) {
                    return retVal.get(0);
                } else {
                    return retVal;
                }
            }
        };
        this.compiled = Pattern.compile(pattern);
    }

    public RegexParser(final String pattern, final Optional<String> listDelimiter,
            final Iterable<String> fieldNames) {
        this(pattern, listDelimiter);

        setFieldNames(fieldNames);
    }

    @Override
    public Map<String, Object> parseToMap(String input) {
        try {
            final Matcher matcher = compiled.matcher(input);

            if (!matcher.matches()) {
                throw new ParseException("Incorrect Regex: %s . No match found.", pattern);
            }

            List<String> values = Lists.newArrayList();
            for (int i = 1; i <= matcher.groupCount(); i++) {
                values.add(matcher.group(i));
            }

            if (fieldNames == null) {
                setFieldNames(ParserUtils.generateFieldNames(values.size()));
            }

            return Utils.zipMapPartial(fieldNames, Iterables.transform(values, valueFunction));
        } catch (Exception e) {
            throw new ParseException(e, "Unable to parse row [%s]", input);
        }
    }

    @Override
    public void setFieldNames(Iterable<String> fieldNames) {
        ParserUtils.validateFields(fieldNames);
        this.fieldNames = Lists.newArrayList(fieldNames);
    }

    @Override
    public List<String> getFieldNames() {
        return fieldNames;
    }
}