cfnpp/app/Engine/Cfnpp/Expression/Parser.php

<?php

declare(strict_types=1);

namespace App\Engine\Cfnpp\Expression;

class Parser
{
	public const TOKEN_TYPES = [
		TokenNumericLiteral::class,
		TokenOperator::class,
		TokenStringLiteral::class,
		TokenVariable::class
	];

	public function parse(string $value): Expression
	{
		$original_value = $value;
		$value = $value.' ';
		$tokens = [];
		while (strlen($value) > 0)
		{
			foreach (static::TOKEN_TYPES as $token_class)
			{
				if ($token_class::isToken($value))
				{
					$tokens[] = $token_class::getToken($value);

					if (substr($value, 0, 1) != ' ')
					{
						throw new \Exception('Incompletely consumed token at offset '.(strlen($original_value) - strlen($value)).' in expression '.$original_value);
					}

					$value = substr($value, 1);
					continue 2;
				}
			}

			throw new \Exception('Unparseable value at offset '.(strlen($original_value) - strlen($value)).' in expression '.$original_value);
		}

		return new Expression($tokens);
	}
}