UDFLtrim.java

/**
 * 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.facebook.hive.udf.string;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;


/**
 * Returns the string s (first argument) with the characters
 * in the string chars (second argument) trimmed off the left
 * side.
 *
 * @author atfiore
 */
@Description(name = "udfltrim",
             value = "_FUNC_(s, chars) - Return the string s " +
                     "with the characters in chars trimmed off " +
                     "the left side.")
public class UDFLtrim extends UDF {
  public String evaluate(String s, String chars) {
    if (s == null) {
      return null;
    }
    if (chars == null) {
      return s;
    }
    int i = 0;
    boolean done = false;
    while (i < s.length() && !done) {
      if (chars.indexOf(s.charAt(i)) == -1) {
        done = true;
      } else {
        i++;
      }
    }
    int j = s.length() - 1;

    if (i > j) {
      return new String();
    }

    // substring(begin, end) takes chars from s[begin] to s[end-1]
    return s.substring(i, j + 1);
  }

  public String evaluate(String s) {
    return this.evaluate(s, " \n\t");
  }
}