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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\Exception\IncorrectExpressionException;
use NXP\Exception\UnknownFunctionException;
use NXP\Exception\UnknownOperatorException;
use NXP\Exception\UnknownVariableException;
/**
* @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
*/
class Calculator
{
/**
* @var CustomFunction[]
*/
private $functions;
/**
* @var Operator[]
*/
private $operators;
/**
* Calculator constructor.
* @param CustomFunction[] $functions
* @param Operator[] $operators
*/
public function __construct(array $functions, array $operators)
{
$this->functions = $functions;
$this->operators = $operators;
}
/**
* Calculate array of tokens in reverse polish notation
* @param Token[] $tokens
* @param array $variables
* @return mixed
* @throws IncorrectExpressionException
* @throws UnknownVariableException
*/
public function calculate($tokens, $variables)
{
/** @var Token[] $stack */
$stack = [];
foreach ($tokens as $token) {
if ($token->type === Token::Literal || $token->type === Token::String) {
$stack[] = $token;
} else if ($token->type === Token::Variable) {
$variable = $token->value;
if (!array_key_exists($variable, $variables)) {
throw new UnknownVariableException($variable);
}
$value = $variables[$variable];
$stack[] = new Token(Token::Literal, $value);
} else if ($token->type === Token::Function) {
if (!array_key_exists($token->value, $this->functions)) {
throw new UnknownFunctionException($token->value);
}
$stack[] = $this->functions[$token->value]->execute($stack);
} elseif ($token->type === Token::Operator) {
if (!array_key_exists($token->value, $this->operators)) {
throw new UnknownOperatorException($token->value);
}
$stack[] = $this->operators[$token->value]->execute($stack);
}
}
$result = array_pop($stack);
if ($result === null || !empty($stack)) {
throw new IncorrectExpressionException();
}
return $result->value;
}
}
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