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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 array<string, CustomFunction> */
private array $functions = [];
/** @var array<Operator> */
private array $operators = [];
/**
* @todo PHP8: Use constructor property promotion -> public function __construct(private array $functions, private array $operators)
*
* @param array<string, CustomFunction> $functions
* @param array<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<string, float|string> $variables
*
* @throws UnknownVariableException
* @throws IncorrectExpressionException
* @return int|float|string|null
*/
public function calculate(array $tokens, array $variables, ?callable $onVarNotFound = null)
{
/** @var Token[] $stack */
$stack = [];
foreach ($tokens as $token) {
if (Token::Literal === $token->type || Token::String === $token->type) {
$stack[] = $token;
} elseif (Token::Variable === $token->type) {
$variable = $token->value;
$value = null;
if (\array_key_exists($variable, $variables)) {
$value = $variables[$variable];
} elseif ($onVarNotFound) {
$value = \call_user_func($onVarNotFound, $variable);
} else {
throw new UnknownVariableException($variable);
}
$stack[] = new Token(Token::Literal, $value, $variable);
} elseif (Token::Function === $token->type) {
if (! \array_key_exists($token->value, $this->functions)) {
throw new UnknownFunctionException($token->value);
}
$stack[] = $this->functions[$token->value]->execute($stack);
} elseif (Token::Operator === $token->type) {
if (! \array_key_exists($token->value, $this->operators)) {
throw new UnknownOperatorException($token->value);
}
$stack[] = $this->operators[$token->value]->execute($stack);
}
}
$result = \array_pop($stack);
if (null === $result || ! empty($stack)) {
throw new IncorrectExpressionException('Stack must be empty');
}
return $result->value;
}
}
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