Calculator

Parse string of math expression and calculate result.

Usage

use Calculator\SimpleCalculator;
use Calculator\SimpleTokenizer;
use Calculator\Evaluator\ReversePolishNotation as RPNEvaluator;
use Calculator\Evaluator\Translator\ReversePolishNotation as RPNTranslator;

$calculator = new SimpleCalculator(
    new SimpleTokenizer(),
    new RPNEvaluator(new RPNTranslator())
);

try {
    echo $calculator->calculate('-1+34/2-4*3');
} catch (Exception $e) {
    echo $e->getMessage();
}

Customization

Calculator\CalculatorInterface is an interface of calculator. Implement it if you need your own calculator with blackjack and ballerinas, e.g. based on WolframAlpha APIs.

Calculator consists of two parts - tokenizer and evaluator.

Tokenizer implements interface Calculator\TokenizerInterface. It parses input string of math expression and produces an array of tokens - operators and operands. Calculator\Token\AbstractToken is an abstract class to represent token. Calculator\Token\Operand\OperandInterface is an interface of operand token. Calculator\Token\Operator\OperatorInterface is an interface of operator token.

Evaluator implements interface Calculator\EvaluatorInterface. It gets array of tokens and calculates result of math expression. In some cases it could be need to reorder array of tokens. For this evaluator uses translator which implements interface Calculator\Evaluator\Translator\TranslatorInterface.

You can replace all calculator components, even calculator it self, by implementing interfaces described above.

Testing

Build Docker image

$ make install

Run unit tests

$ make test