/**
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.heron.spouts.kafka;

import java.util.regex.Pattern;

/**
 * the built-in default pattern provider to create a topic pattern out of a regex string
 */
public class DefaultTopicPatternProvider implements TopicPatternProvider {
  private static final long serialVersionUID = 5534026856505613199L;
  private String regex;

  /**
   * create a provider out of a regular expression string
   *
   * @param regex topic name regular expression
   */
  @SuppressWarnings("WeakerAccess")
  public DefaultTopicPatternProvider(String regex) {
    this.regex = regex;
  }

  @Override
  public Pattern create() {
    if (regex == null) {
      throw new IllegalArgumentException("regex can not be null");
    }
    return Pattern.compile(regex);
  }
}