PHP Polish Notation

• 🤖 Overengineered: Built with extensibility in mind, supporting custom behavior while ensuring flexibility.
• 🌀 Abstract Implementation: Based on well-established abstract classes and interfaces to ensure ease of customization and separation of concerns.
• ✨ Custom Expression Support: Easily define your own expression types and structures.
• ⚖️ Custom Operator Priority Support: Fine-tune operator precedence for specialized use cases.
• 🧩 Custom Expression Classifier Support: Define your own rules for classifying expressions.
• 🔄 Custom Converter Support: Convert expressions to different notations with your custom logic.
• 🖋️ Custom Notation Support: Implement and use custom notation formats.
• 📚 Fully Typed API: Fully typed and documented API to ensure reliability and ease of use.

PHP Polish Notation is package designed to convert and validate Polish notation (NPN, PN) and Reverse Polish notation (RPN), also known as Prefix and Postfix notation. It provides a flexible and extensible solution for working with mathematical and custom expressions, while ensuring high-quality, maintainable code by following modern design principles.

Getting Started

Mathematical Expression

To convert and validate standard mathematical expressions, you can use the MathematicalExpression class. The package supports parsing and converting between different notations such as Infix, Prefix, and Postfix.

$expression = MathematicalExpression::fromString("A + (B * C)");
$expression->notation(); // ExpressionNotation::Infix

$expression->withParentheses()->toInfix()->toString();      // 'A + (B * C)'
$expression->withParentheses()->toPrefix()->toString();     // '+ A (* B C)'
$expression->withParentheses()->toPostfix()->toString();    // 'A (B C *) +'

$expression->withoutParentheses()->toInfix()->toString();   // 'A + B * C'
$expression->withoutParentheses()->toPrefix()->toString();  // '+ A * B C'
$expression->withoutParentheses()->toPostfix()->toString(); // 'A B C * +'

Custom Expression

The package allows you to extend its functionality to support custom expressions. Below is an example of how to create a custom expression, define a custom tokenizer, converter factory, classifier, and stringifier.

use Filczek\PhpPolishNotation\Core\Expression\AbstractExpression;
use Filczek\PhpPolishNotation\Core\Expression\Classifier\DefaultExpressionClassifier;
use Filczek\PhpPolishNotation\Core\Expression\Stringifier\WithoutParenthesesExpressionStringifier;

final readonly class ImapExpression extends AbstractExpression
{
    // 'fromString' is custom method, it is not required
    public static function fromString(string $expression): self
    {
        // Custom Tokenizer - returns array of 'ExpressionElement' class
        $elements = (new ImapExpressionTokenizer())->parse($expression);
        // Custom Converter Factory - e.g. from Infix to Prefix, you can use built-in 'DefaultExpressionConverterFactory'
        $converter_factory = new ImapExpressionConverterFactory();
        // ExpressionNotation::Infix, ExpressionNotation::Prefix, ExpressionNotation::Postfix
        $classifier = new DefaultExpressionClassifier();
        // Built-in Expression Stringifier
        $stringifier = new WithoutParenthesesExpressionStringifier();

        return new self(
            elements: $elements,
            converter_factory: $converter_factory,
            classify: $classifier,
            stringify: $stringifier,
        );
    }

    // custom method
    public static function fromArray(array $array): self
    {
        // ...
    }
}

$expression = ImapExpression::fromString("(SUBJECT subject OR BODY body) AND FROM from");
$expression->notation(); // ExpressionNotation::Infix
$expression->toPrefix()->toString(); // 'OR SUBJECT subject BODY body FROM from'

License

This package is licensed under the MIT License.