ExpressionParser.php

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<?php
 
declare(strict_types=1);
 
namespace ILIAS\components\DataCollection\Fields\Formula\FormulaParser;
 
use ILIAS\components\DataCollection\Fields\Formula\FormulaParser\Substitution\FieldSubstitution;
use ILIAS\components\DataCollection\Fields\Formula\FormulaParser\Token\Tokenizer;
use ILIAS\components\DataCollection\Fields\Formula\FormulaParser\Result\MathResultResolver;
use ILIAS\components\DataCollection\Fields\Formula\FormulaParser\Result\SubstitutionResultResolver;
use ILIAS\components\DataCollection\Fields\Formula\FormulaParser\Token\MathToken;
use ILIAS\components\DataCollection\Fields\Formula\FormulaParser\Result\ResultFormatter;
 
class ExpressionParser
{
    private static array $cached_tokens = [];
    private Tokenizer $tokenizer;
    private MathResultResolver $math_result_resolver;
    private SubstitutionResultResolver $substition_result_resolver;
    private ResultFormatter $result_formatter;
 
    public function __construct(
        private string $expression,
        private FieldSubstitution $substitution,
    ) {
        $this->tokenizer = new Tokenizer();
 
        $this->math_result_resolver = new MathResultResolver(
            $substitution,
            $this->tokenizer
        );
        $this->substition_result_resolver = new SubstitutionResultResolver($substitution);
 
        $this->result_formatter = new ResultFormatter();
    }
 
    public function parse(): string
    {
        if (!isset(self::$cached_tokens[$this->substitution->getFieldId()])) {
            self::$cached_tokens[$this->substitution->getFieldId()] = $this->tokenizer->tokenize($this->expression);
        }
        $tokens = self::$cached_tokens[$this->substitution->getFieldId()];
        $parsed = '';
 
        foreach ($tokens as $token) {
            if ($token->getValue() === '') {
                continue;
            }
            if ($token instanceof MathToken) {
                $result = $this->math_result_resolver->resolve($token);
            } else {
                $result = $this->substition_result_resolver->resolve($token);
            }
 
            $parsed .= $this->result_formatter->format($result);
        }
 
        return $parsed;
    }
}