File src/Reflection/PassedByReference.php

1:	<?php declare(strict_types = 1);
2:
3:	namespace PHPStan\Reflection;
4:
5:	use function array_key_exists;
6:
7:	/**
8:	* Describes how a function/method parameter is passed: by value or by reference.
9:	*
10:	* Three modes:
11:	* - No: Passed by value — the argument expression is evaluated and its value is copied.
12:	* - ReadsArgument: Passed by reference, but the function reads the existing variable.
13:	* The variable must already exist. Example: `sort(&$array)`.
14:	* - CreatesNewVariable: Passed by reference, and the function may create the variable
15:	* if it doesn't exist. Example: `preg_match($pattern, $subject, &$matches)` where
16:	* `$matches` doesn't need to be defined beforehand.
17:	*
18:	* This distinction matters for PHPStan's scope analysis — when a function takes a
19:	* parameter by reference with "creates new variable" semantics, PHPStan knows the
20:	* variable will exist after the call even if it wasn't defined before.
21:	*
22:	* Used as the return type of ParameterReflection::passedByReference().
23:	*
24:	* @api
25:	*/
26:	final class PassedByReference
27:	{
28:
29:	private const NO = 1;
30:	private const READS_ARGUMENT = 2;
31:	private const CREATES_NEW_VARIABLE = 3;
32:
33:	/** @var self[] */
34:	private static array $registry = [];
35:
36:	private function __construct(private int $value)
37:	{
38:	}
39:
40:	private static function create(int $value): self
41:	{
42:	if (!array_key_exists($value, self::$registry)) {
43:	self::$registry[$value] = new self($value);
44:	}
45:
46:	return self::$registry[$value];
47:	}
48:
49:	public static function createNo(): self
50:	{
51:	return self::create(self::NO);
52:	}
53:
54:	public static function createCreatesNewVariable(): self
55:	{
56:	return self::create(self::CREATES_NEW_VARIABLE);
57:	}
58:
59:	public static function createReadsArgument(): self
60:	{
61:	return self::create(self::READS_ARGUMENT);
62:	}
63:
64:	public function no(): bool
65:	{
66:	return $this->value === self::NO;
67:	}
68:
69:	public function yes(): bool
70:	{
71:	return !$this->no();
72:	}
73:
74:	public function equals(self $other): bool
75:	{
76:	return $this->value === $other->value;
77:	}
78:
79:	public function createsNewVariable(): bool
80:	{
81:	return $this->value === self::CREATES_NEW_VARIABLE;
82:	}
83:
84:	/** CreatesNewVariable > ReadsArgument > No. */
85:	public function combine(self $other): self
86:	{
87:	if ($this->value > $other->value) {
88:	return $this;
89:	} elseif ($this->value < $other->value) {
90:	return $other;
91:	}
92:
93:	return $this;
94:	}
95:
96:	}
97:

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