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Rewrite the Luhn Algorithm implementation. (#7)
Rewrite the Luhn Algorithm implementation.
1 parent 754f0d9 commit cd21b37

13 files changed

+504
-266
lines changed

‎.gitignore

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index.php
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nbproject/
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.idea/
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.php_cs.cache
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# Created by http://www.gitignore.io
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‎.php_cs.dist

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<?php
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return PhpCsFixer\Config::create()
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->setRules([
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'@PSR2' => true,
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'ordered_imports' => true,
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'phpdoc_order' => true,
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'simplified_null_return' => false,
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'no_unused_imports' => true,
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])->setFinder(
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PhpCsFixer\Finder::create()
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->in(__DIR__.'/src')
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->in(__DIR__.'/tests')
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);

‎.travis.yml

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language: php
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php:
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- '7.0'
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- '7.1'
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- '7.2'
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before_script: composer install

‎README.md

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[![Build Status](https://travis-ci.org/Ekman/Luhn-Algorithm.svg?branch=master)](https://travis-ci.org/Ekman/Luhn-Algorithm)
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This is an implementation of the Luhn Algorithm in PHP. The Luhn Algorithm is
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used to validate things like credit cards and national identifcation numbers.
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More information on the algorithm can be found at [Wikipedia](http://en.wikipedia.org/wiki/Luhn_algorithm)
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used to validate things like credit cards and national identification numbers.
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More information on the algorithm can be found at [Wikipedia](http://en.wikipedia.org/wiki/Luhn_algorithm).
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## Installation
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Can be installed using composer:
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Install with [Composer](https://getcomposer.org/):
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```bash
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composer require nekman/luhn-algorithm
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```
@@ -19,22 +20,21 @@ Use the class like this:
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```php
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use Nekman\LuhnAlgorithm\LuhnAlgorithmFactory;
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use Nekman\LuhnAlgorithm\Number;
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$luhn = LuhnAlgorithmFactory::create();
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if ($luhn->isValid(123456789)) {
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// Number is valid.
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// Validate a credit card number entered in a form.
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$ccNumber = Number::fromString($creditCard);
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if ($luhn->isValid($ccNumber)) {
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// Credit card number is valid.
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}
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$checkSum = $luhn->calcCheckSum(123456789);
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$checkDigit = $luhn->calcCheckDigit(123456789);
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```
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// These methods are used internally by the library. You're free
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// to make use of them as well.
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$number = new Number(12345);
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## Changelog
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$checksum = $luhn->calcChecksum($number);
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* 4.0.0 - Rewrite of the implementation.
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* 3.0.0 - Completely restructured the interface of the library.
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* 2.0.1 - Fixed typos in interface.
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* 2.0.0 - Added namespace.
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* 1.0.0 - Initial release.
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$checkDigit = $luhn->calcCheckDigit($number);
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```

‎composer.json

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}
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},
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"require": {
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"php": "^7.0"
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"php": "^7.1"
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},
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"require-dev": {
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"phpunit/phpunit": "^6.5"
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"phpunit/phpunit": "^6.5",
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"friendsofphp/php-cs-fixer": "^2.10"
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}
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}

‎src/Contract/LuhnAlgorithmInterface.php

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<?php
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/*
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* The MIT License (MIT)
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*
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* Copyright (c) 2014 Niklas Ekman
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
25-
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namespace Nekman\LuhnAlgorithm\Contract;
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/**
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* Handles the Luhn Algorithm.
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*
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* @link http://en.wikipedia.org/wiki/Luhn_algorithm
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*/
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interface LuhnAlgorithmInterface {
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/**
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* Determine if a number is valid according to the Luhn Algorithm.
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*
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* @param string $input The number to validate.
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*
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* @return bool true if number is valid, false otherwise.
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*
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* @throws \InvalidArgumentException If the input is invalid.
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*/
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public function isValid(string $input): bool;
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/**
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* Calculate the check digit for an input.
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*
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* @param int $input The input to calculate the check digit for.
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*
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* @return int The check digit.
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*
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* @throws \InvalidArgumentException If the input is invalid.
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*/
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public function calcCheckDigit(int $input): int;
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/**
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* Calulates the checksum for number.
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*
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* @param int $input The number to calculate the checksum for.
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*
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* @return int The checksum.
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*
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* @throws \InvalidArgumentException If the input is invalid.
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*/
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public function calcChecksum(int $input): int;
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}
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<?php
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/*
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* The MIT License (MIT)
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*
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* Copyright (c) 2014 Niklas Ekman
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
9+
* this software and associated documentation files (the "Software"), to deal in
10+
* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
12+
* the Software, and to permit persons to whom the Software is furnished to do so,
13+
* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
17+
*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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namespace Nekman\LuhnAlgorithm\Contract;
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/**
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* Handles the Luhn Algorithm.
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*
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* @link http://en.wikipedia.org/wiki/Luhn_algorithm
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*/
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interface LuhnAlgorithmInterface
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{
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/**
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* Determine if a number is valid according to the Luhn Algorithm.
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*
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* @param NumberInterface $number The number to validate.
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*
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* @return bool true if number is valid, false otherwise.
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*/
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public function isValid(NumberInterface $number): bool;
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/**
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* Calculate the check digit for an input.
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*
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* @param NumberInterface $number The number to calculate the check digit for.
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*
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* @return int The check digit.
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*
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*/
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public function calcCheckDigit(NumberInterface $number): int;
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/**
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* Calulates the checksum for number.
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*
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* @param NumberInterface $number The number to calculate the checksum for.
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*
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* @return int The checksum.
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*
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*/
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public function calcChecksum(NumberInterface $number): int;
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}

‎src/Contract/NumberInterface.php

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<?php
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/*
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* The MIT License (MIT)
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*
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* Copyright (c) 2014 Niklas Ekman
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
9+
* this software and associated documentation files (the "Software"), to deal in
10+
* the Software without restriction, including without limitation the rights to
11+
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
12+
* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19+
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
21+
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
22+
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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namespace Nekman\LuhnAlgorithm\Contract;
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/**
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* Describes the structure of a number in the Luhn Algorithm.
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*/
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interface NumberInterface
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{
33+
/**
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* Get the number, without check digit.
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*
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* @return int
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*/
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public function getNumber(): int;
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/**
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* Get the check digit for the number.
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*
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* @return int|null The check digit or null if it has not been calculated yet.
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*/
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public function getCheckDigit(): ?int;
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}

‎src/LuhnAlgorithm.php

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namespace Nekman\LuhnAlgorithm;
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use Nekman\LuhnAlgorithm\Contract\LuhnAlgorithmInterface;
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use Nekman\LuhnAlgorithm\Contract\NumberInterface;
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3031
/**
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* Handles the Luhn Algorithm.
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*
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* @link http://en.wikipedia.org/wiki/Luhn_algorithm
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* {@inheritdoc}
3433
*/
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class LuhnAlgorithm implements LuhnAlgorithmInterface {
36-
/**
37-
* {@inheritDoc}
38-
*/
39-
public function isValid(string $input): bool {
40-
// Remove everything except digits from the input.
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$number = (int) preg_replace("/[^\d]/", "", $input);
42-
43-
$checksum = $this->calcChecksum($number);
34+
class LuhnAlgorithm implements LuhnAlgorithmInterface
35+
{
36+
/**
37+
* {@inheritDoc}
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*/
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public function isValid(NumberInterface $number): bool
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{
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if ($number->getCheckDigit() === null) {
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throw new \InvalidArgumentException("Check digit cannot be null.");
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}
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45-
// If the checksum is divisible by 10 it is valid
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return ($checksum % 10) === 0;
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}
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$checksum = $this->calcChecksum($number);
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$sum = $checksum + $number->getCheckDigit();
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49-
/**
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* {@inheritDoc}
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*/
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public function calcCheckDigit(int $input): int {
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$checkSum = (string) $this->calcChecksum($input . 0);
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// Get the last digit of the checksum
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$checkDigit = (int) $checkSum[strlen($checkSum) - 1];
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// If the checksum is divisible by 10 it is valid.
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return ($sum % 10) === 0;
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}
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// If the checkdigit is not 0, then subtract the value from 10
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return $checkDigit === 0 ? $checkDigit : 10 - $checkDigit;
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}
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/**
53+
* {@inheritDoc}
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*/
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public function calcCheckDigit(NumberInterface $number): int
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{
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$checksum = $this->calcChecksum($number);
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// Get the last digit of the checksum.
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$checkDigit = $checksum % 10;
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62-
/**
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* {@inheritDoc}
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*/
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public function calcChecksum(int $input): int {
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$input = (string) $input;
67-
$length = strlen($input);
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// If the check digit is not 0, then subtract the value from 10.
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return $checkDigit === 0
64+
? $checkDigit
65+
: 10 - $checkDigit;
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}
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69-
$checkSum = 0;
68+
/**
69+
* {@inheritDoc}
70+
*/
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public function calcChecksum(NumberInterface $number): int
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{
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$number = (string) $number->getNumber();
74+
$nDigits = strlen($number);
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$checksum = 0;
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$parity = $nDigits % 2;
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71-
// Start at the next last digit
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for ($i = $length - 2; $i >= 0; $i -= 2) {
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// Multiply number with 2
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$tmp = (int) ($input[$i]) * 2;
78+
for ($i = 0; $i < $nDigits; $i++) {
79+
$digit = (int) $number[$i];
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76-
// If a 2 digit number, split and add togheter
77-
if ($tmp > 9) {
78-
$tmp = ($tmp / 10) + ($tmp % 10);
79-
}
81+
// Every other digit, starting from the leftmost,
82+
// shall be doubled.
83+
if (($i % 2) !== $parity) {
84+
$digit *= 2;
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81-
// Sum it upp
82-
$checkSum += $tmp;
83-
}
86+
if ($digit > 9) {
87+
$digit -= 9;
88+
}
89+
}
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85-
// Start at the next last digit
86-
for ($i = $length - 1; $i >= 0; $i -= 2) {
87-
// Sum it upp
88-
$checkSum += (int) $input[$i];
89-
}
91+
$checksum += $digit;
92+
}
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91-
return $checkSum;
92-
}
94+
return $checksum;
95+
}
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}

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