smuuf/primi

<?php

declare(strict_types=1);

namespace Smuuf\Primi\Values;

use \Smuuf\Primi\Stdlib\BuiltinTypes;
use \Smuuf\Primi\Helpers\Types;

/**
 * NOTE: You should not instantiate this PHP class directly - use the helper
 * `Interned::regex()` factory to get these.
 */
class RegexValue extends AbstractBuiltinValue {

    public const TYPE = "regex";

    /**
     * Prepared string for 'truthiness' evaluation.
     * Regex value is truthy if the actual pattern, without delimiters and
     * unicode modifier, is empty.
     */
    const EMPTY_REGEX = "\x07\x07u";

    public function __construct(string $regex) {

        // We'll be using ASCII \x07 (bell) character as delimiters, so
        // we won't need to deal with any escaping of input.
        $this->value = "\x07$regex\x07u";

    }

    public function getType(): TypeValue {
        return BuiltinTypes::getRegexType();
    }

    public function isTruthy(): bool {
        return $this->value !== self::EMPTY_REGEX;
    }

    public function getStringRepr(): string {

        // Cut off the first delim and the last delim + "u" modifier.
        $string = $this->value;
        $string = \mb_substr($string, 1, \mb_strlen($string) - 3);

        return "rx\"{$string}\"";

    }

    public function getStringValue(): string {

        // Cut off the first delim and the last delim + "u" modifier.
        $string = $this->value;
        return \mb_substr($string, 1, \mb_strlen($string) - 3);

    }

    public function isEqualTo(AbstractValue $right): ?bool {

        if (!Types::is_any_of_types($right, StringValue::class, RegexValue::class)) {
            return \null;
        }

        if ($right instanceof RegexValue) {
            return $this->value === $right->value;
        }

        return (bool) \preg_match($this->value, $right->value);

    }

}