<?php
namespace eMacros\Runtime\Arithmetic;
use eMacros\Runtime\GenericFunction;
class Subtraction extends GenericFunction {
/**
* Obtains the result of subtracting the first element on a list by the rest of the elements.
* Usage: (- 120 30 50)
* Returns: number
* (non-PHPdoc)
* @see \eMacros\Runtime\GenericFunction::execute()
*/
public function execute(array $arguments) {
if (empty($arguments)) {
throw new \InvalidArgumentException("Subtraction: At least 1 argument is required");
}
//emulate CLISP: (- 3) = -3
if (!isset($arguments[1])) {
return -$arguments[0];
}
//obtain first argument
$result = array_shift($arguments);
foreach ($arguments as $value) {
$result -= $value;
}
return $result;
}
}
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