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<?php declare(strict_types = 1);
namespace PHPStan\Reflection;
use function array_key_exists;
/**
* Describes how a function/method parameter is passed: by value or by reference.
*
* Three modes:
* - **No**: Passed by value — the argument expression is evaluated and its value is copied.
* - **ReadsArgument**: Passed by reference, but the function reads the existing variable.
* The variable must already exist. Example: `sort(&$array)`.
* - **CreatesNewVariable**: Passed by reference, and the function may create the variable
* if it doesn't exist. Example: `preg_match($pattern, $subject, &$matches)` where
* `$matches` doesn't need to be defined beforehand.
*
* This distinction matters for PHPStan's scope analysis — when a function takes a
* parameter by reference with "creates new variable" semantics, PHPStan knows the
* variable will exist after the call even if it wasn't defined before.
*
* Used as the return type of ParameterReflection::passedByReference().
*
* @api
*/
final class PassedByReference
{
private const NO = 1;
private const READS_ARGUMENT = 2;
private const CREATES_NEW_VARIABLE = 3;
/** @var self[] */
private static array $registry = [];
private function __construct(private int $value)
{
}
private static function create(int $value): self
{
if (!array_key_exists($value, self::$registry)) {
self::$registry[$value] = new self($value);
}
return self::$registry[$value];
}
public static function createNo(): self
{
return self::create(self::NO);
}
public static function createCreatesNewVariable(): self
{
return self::create(self::CREATES_NEW_VARIABLE);
}
public static function createReadsArgument(): self
{
return self::create(self::READS_ARGUMENT);
}
public function no(): bool
{
return $this->value === self::NO;
}
public function yes(): bool
{
return !$this->no();
}
public function equals(self $other): bool
{
return $this->value === $other->value;
}
public function createsNewVariable(): bool
{
return $this->value === self::CREATES_NEW_VARIABLE;
}
/** CreatesNewVariable > ReadsArgument > No. */
public function combine(self $other): self
{
if ($this->value > $other->value) {
return $this;
} elseif ($this->value < $other->value) {
return $other;
}
return $this;
}
}