    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.validator.routines.checkdigit;
    019
    020/**
    021 * Modulus 10 <strong>CUSIP</strong> (North American Securities) Check Digit calculation/validation.
    022 *
    023 * <p>
    024 * CUSIP Numbers are 9 character alphanumeric codes used to identify North American Securities.
    025 * </p>
    026 *
    027 * <p>
    028 * Check digit calculation uses the <em>Modulus 10 Double Add Double</em> technique with every second digit being weighted by 2. Alphabetic characters are
    029 * converted to numbers by their position in the alphabet starting with A being 10. Weighted numbers greater than ten are treated as two separate numbers.
    030 * </p>
    031 *
    032 * <p>
    033 * See <a href="https://en.wikipedia.org/wiki/CUSIP">Wikipedia - CUSIP</a> for more details.
    034 * </p>
    035 *
    036 * @since 1.4
    037 */
    038public final class CUSIPCheckDigit extends ModulusCheckDigit {
    039
    040    private static final long serialVersionUID = 666941918490152456L;
    041
    042    /**
    043     * Singleton CUSIP Check Digit instance.
    044     */
    045    public static final CheckDigit CUSIP_CHECK_DIGIT = new CUSIPCheckDigit();
    046
    047    /** Weighting given to digits depending on their right position */
    048    private static final int[] POSITION_WEIGHT = { 2, 1 };
    049
    050    /** A CUSIP is exactly nine characters, the last being the check digit. */
    051    private static final int CUSIP_LEN = 9;
    052
    053    /**
    054     * Constructs a CUSIP Identifier Check Digit routine.
    055     */
    056    public CUSIPCheckDigit() {
    057    }
    058
    059    /**
    060     * {@inheritDoc}
    061     *
    062     * <p>
    063     * The weight is taken from {@code rightPos}, which does not change when a character is prepended, so
    064     * {@code ModulusCheckDigit} would accept an over-length code whose leading character lands on a no-op weight (for
    065     * example {@code 0037833100}). The nine-character length is checked here before the check digit test.
    066     * </p>
    067     */
    068    @Override
    069    public boolean isValid(final String code) {
    070        return isLength(code, CUSIP_LEN) && super.isValid(code);
    071    }
    072
    073    /**
    074     * Convert a character at a specified position to an integer value.
    075     *
    076     * @param character The character to convert.
    077     * @param leftPos   The position of the character in the code, counting from left to right.
    078     * @param rightPos  The position of the character in the code, counting from right to left.
    079     * @return The integer value of the character.
    080     * @throws CheckDigitException if the character is not alphanumeric.
    081     */
    082    @Override
    083    protected int toInt(final char character, final int leftPos, final int rightPos) throws CheckDigitException {
    084        final int charValue = Character.getNumericValue(character);
    085        // the final character is only allowed to reach 9
    086        final int charValueMax = rightPos == 1 ? 9 : 35; // CHECKSTYLE IGNORE MagicNumber
    087        if (charValue > charValueMax || !isAsciiAlphaNum(character)) {
    088            throw new CheckDigitException("Invalid Character[%d,%d] = '%d' out of range 0 to %d", leftPos, rightPos, charValue, charValueMax);
    089        }
    090        return charValue;
    091    }
    092
    093    /**
    094     * Calculates the <em>weighted</em> value of a character in the code at a specified position.
    095     *
    096     * <p>
    097     * For CUSIP (from right to left) <strong>odd</strong> digits are weighted with a factor of <strong>one</strong> and <strong>even</strong> digits with a
    098     * factor of <strong>two</strong>. Weighted values &gt; 9, have 9 subtracted
    099     * </p>
    100     *
    101     * @param charValue The numeric value of the character.
    102     * @param leftPos   The position of the character in the code, counting from left to right.
    103     * @param rightPos  The position of the character in the code, counting from right to left.
    104     * @return The weighted value of the character.
    105     */
    106    @Override
    107    protected int weightedValue(final int charValue, final int leftPos, final int rightPos) {
    108        final int weight = POSITION_WEIGHT[rightPos % 2];
    109        final int weightedValue = charValue * weight;
    110        return sumDigits(weightedValue);
    111    }
    112}