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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.validator.routines.checkdigit;
18  
19  /**
20   * Modulus 10 <b>CUSIP</b> (North American Securities)
21   * Check Digit calculation/validation.
22   * <p>
23   * CUSIP Numbers are 9 character alphanumeric codes used
24   * to identify North American Securities.
25   * <p>
26   * Check digit calculation uses the <i>Modulus 10 Double Add Double</i> technique
27   * with every second digit being weighted by 2. Alphabetic characters are
28   * converted to numbers by their position in the alphabet starting with A being 10.
29   * Weighted numbers greater than ten are treated as two separate numbers.
30   * <p>
31   *
32   * <p>
33   * See <a href="http://en.wikipedia.org/wiki/CUSIP">Wikipedia - CUSIP</a>
34   * for more details.
35   *
36   * @version $Revision: 1227719 $ $Date: 2012-01-05 18:45:51 +0100 (Do, 05 Jan 2012) $
37   * @since Validator 1.4
38   */
39  public final class CUSIPCheckDigit extends ModulusCheckDigit {
40  
41      private static final long serialVersionUID = 666941918490152456L;
42  
43      /** Singleton CUSIP Check Digit instance */
44      public static final CheckDigit CUSIP_CHECK_DIGIT = new CUSIPCheckDigit();
45  
46      /** weighting given to digits depending on their right position */
47      private static final int[] POSITION_WEIGHT = new int[] {2, 1};
48  
49      /**
50       * Construct an CUSIP Indetifier Check Digit routine.
51       */
52      public CUSIPCheckDigit() {
53          super(10);
54      }
55  
56      /**
57       * Convert a character at a specified position to an integer value.
58       *
59       * @param character The character to convert
60       * @param leftPos The position of the character in the code, counting from left to right
61       * @param rightPos The positionof the character in the code, counting from right to left
62       * @return The integer value of the character
63       * @throws CheckDigitException if character is not alphanumeric
64       */
65      protected int toInt(char character, int leftPos, int rightPos)
66              throws CheckDigitException {
67          int charValue = Character.getNumericValue(character);
68          if (charValue < 0 || charValue > 35) {
69              throw new CheckDigitException("Invalid Character[" +
70                      leftPos + "] = '" + charValue + "'");
71          }
72          return charValue;
73      }
74  
75      /**
76       * <p>Calculates the <i>weighted</i> value of a charcter in the
77       * code at a specified position.</p>
78       *
79       * <p>For Luhn (from right to left) <b>odd</b> digits are weighted
80       * with a factor of <b>one</b> and <b>even</b> digits with a factor
81       * of <b>two</b>. Weighted values > 9, have 9 subtracted</p>
82       *
83       * @param charValue The numeric value of the character.
84       * @param leftPos The position of the character in the code, counting from left to right
85       * @param rightPos The positionof the character in the code, counting from right to left
86       * @return The weighted value of the character.
87       */
88      protected int weightedValue(int charValue, int leftPos, int rightPos) {
89          int weight = POSITION_WEIGHT[rightPos % 2];
90          int weightedValue = (charValue * weight);
91          return ModulusCheckDigit.sumDigits(weightedValue);
92      }
93  }