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<?php
/**
* This file is part of the MathExecutor package
*
* (c) Alexander Kiryukhin
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code
*/
namespace NXP\Classes;
use NXP\Classes\Token\InterfaceOperator;
use NXP\Classes\Token\TokenFunction;
use NXP\Classes\Token\TokenNumber;
use NXP\Classes\Token\TokenStringSingleQuoted;
use NXP\Classes\Token\TokenStringDoubleQuoted;
use NXP\Classes\Token\TokenVariable;
use NXP\Exception\IncorrectExpressionException;
use NXP\Exception\UnknownVariableException;
/**
* @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
*/
class Calculator
{
/**
* Calculate array of tokens in reverse polish notation
* @param array $tokens Array of tokens
* @param array $variables Array of variables
* @return number Result
* @throws \NXP\Exception\IncorrectExpressionException
* @throws \NXP\Exception\UnknownVariableException
*/
public function calculate($tokens, $variables)
{
$stack = [];
foreach ($tokens as $token) {
if ($token instanceof TokenNumber) {
array_push($stack, $token);
} else if ($token instanceof TokenStringDoubleQuoted) {
array_push($stack, $token);
} else if ($token instanceof TokenStringSingleQuoted) {
array_push($stack, $token);
} else if ($token instanceof TokenVariable) {
$variable = $token->getValue();
if (!array_key_exists($variable, $variables)) {
throw new UnknownVariableException($variable);
}
$value = $variables[$variable];
array_push($stack, new TokenNumber($value));
} else if ($token instanceof InterfaceOperator || $token instanceof TokenFunction) {
array_push($stack, $token->execute($stack));
}
}
$result = array_pop($stack);
if ($result === null || ! empty($stack)) {
throw new IncorrectExpressionException();
}
return $result->getValue();
}
}
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