content: /*
   * 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 com.manning.hip.ch11;
  
  import org.apache.pig.*;
  import org.apache.pig.data.*;
  import org.apache.pig.impl.logicalLayer.FrontendException;
  import org.apache.pig.impl.logicalLayer.schema.Schema;
  
  import java.io.IOException;
  import java.util.*;
  import java.util.regex.*;
  
  /**
   * This function removes tuples that match the supplied regex.
   */
  public class RegExExclusionFilter extends FilterFunc {
  
    Pattern pattern;
  
    public RegExExclusionFilter(String pattern) {
      this.pattern = Pattern.compile(pattern);
    }
  
    public Boolean exec(Tuple t) throws IOException {
      if (t == null || t.size() == 0)
        return false;
  
      String query = extractFieldAsString(t, 0);
      if (query == null) {
        return false;
      }
      Matcher m = pattern.matcher(query);
      return (!m.find());
    }
  
    public String extractFieldAsString(Tuple t, int field) {
      String query;
      try {
        query = (String) t.get(field);
        if (query == null)
          return null;
        query = query.trim();
      } catch (Exception e) {
        System.err.println(
            "RegExExclusionFilter: failed to process input; error - " +
                e.getMessage());
        return null;
      }
  
      if (query.equals("")) {
        return null;
      }
      return query;
    }
  
    @Override
    public List<FuncSpec> getArgToFuncMapping()
        throws FrontendException {
      List<FuncSpec> funcList = new ArrayList<FuncSpec>();
      funcList.add(new FuncSpec(this.getClass().getName(),
          new Schema(new Schema.FieldSchema(null, DataType.CHARARRAY))));
  
      return funcList;
    }
  
  }
  