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PHP Type Constraint Operations

rascal-0.40.17
php-analysis-0.2.4

Here we document some examples of the type inference constraints we extract from PHP code.

Assign operators (some sort of case)​

$a .= ... // $a is a String
$a *= ... // $a is an Integer
etc...

$x = (int) $y; // $x = Integer
$x = 1; // $x = Integer

Method call​

$a -> methodCall();
// the type of $a has methodCall(); || type of $a has __clone() (magic method)

Conditional statements​

$a instanceOf "C" // is_a
// type of $a is (a child of) class C || type of $a implements interface C

is_numeric($a) // $a is numeric
is_bool($a) // $a is a boolean

Member addition​

class Empty {}
$e = new Empty();
$e->newField = "value"; // newField is added
echo $e->newField; // newField is used

Return types of methods and functions​

function f () { return true }; // return type of f is a boolean

Object instantiation​

$x = new Obj; // $x = instance of class Obj

Parameters (number of required params and type hints) 

function getPersonId(Person $p) {
    return rand(100);
}
getPersonId(new Person()); // correct
getPersonId(new Person(), 1, 2, true); // correct
getPersonId(); // incorrect

self/static/parent **​

self::methodCall(); // current class
parent::methodCall(); // one of the parent classes
static::methodCall(); // class of instantiation

Out of scope​

- Variable variables (resolve to everything)
- Variable method calls (resolve to everything)
- Eval

Other Notes​

non parsing scripts are ignored