Feature Toggling

Edit pageLast modified: 02 February 2025

You can enable or disable a set of parser features if your task requires only partial support of the functionality. Such a feature allows you to conveniently implement more strict functionality.

note

One of the feature flags is the "tolerant" mode, but the logic and meaning of its operation is more complex than simply disabling some feature.

Literals

Literals are concrete values such as 42, 0xDEAD, "string", 0.23, etc.

To enable or disable literals, use the literals: bool flag.

$parser = new TypeLang\Parser\Parser(
    literals: false,
);

$result = $parser->parse('42');
TypeLang\Parser\Exception\ParseException:
Literal values not allowed in "42"

Generics

To enable or disable template arguments (generics), use the generics: bool flag.

$parser = new TypeLang\Parser\Parser(
    generics: false,
);

$result = $parser->parse('Example<T>');
TypeLang\Parser\Exception\ParseException:
Template arguments not allowed in "Example<T>"

Hints

To enable or disable template argument hints (argument modifiers), use the hints: bool flag.

$parser = new TypeLang\Parser\Parser(
    hints: false,
);

$result = $parser->parse('Example<out T, in U>');
TypeLang\Parser\Exception\ParseException:
Template argument hints not allowed in "Example<out T, in U>"

Lists

To enable or disable type lists (legacy/short syntax for iterable types), use the list: bool flag.

$parser = new TypeLang\Parser\Parser(
    list: false,
);

$result = $parser->parse('Example[]');
TypeLang\Parser\Exception\ParseException:
Square bracket list types not allowed in "Example[]"

Offsets

To enable or disable type offsets, use the offsets: bool flag.

$parser = new TypeLang\Parser\Parser(
    offsets: false,
);

$result = $parser->parse('Example[Type]');
TypeLang\Parser\Exception\ParseException:
Type offsets not allowed in "Example[Type]"

Callables

To enable or disable callables (delegates), use the callables: bool flag.

$parser = new TypeLang\Parser\Parser(
    callables: false,
);

$result = $parser->parse('fn()');
TypeLang\Parser\Exception\ParseException:
Callable types not allowed in "fn()"

Shapes

To enable or disable shape fields, use the shapes: bool flag.

$parser = new TypeLang\Parser\Parser(
    shapes: false,
);

$result = $parser->parse(<<<'PHP'
    array{
        foo: T,
        ...
    }
    PHP);
TypeLang\Parser\Exception\ParseException:
Shape fields not allowed in "array{\n foo: T,\n ...\n}"

Unions

To enable or disable union types, use the union: bool flag.

$parser = new TypeLang\Parser\Parser(
    union: false,
);

$result = $parser->parse('T|U');
TypeLang\Parser\Exception\ParseException:
Union types not allowed in "T|U"

Intersections

To enable or disable union types, use the intersection: bool flag.

$parser = new TypeLang\Parser\Parser(
    intersection: false,
);

$result = $parser->parse('T&U');
TypeLang\Parser\Exception\ParseException:
Intersection types not allowed in "T&U"

Conditional

To enable or disable conditional types (expressions), use the conditional: bool flag.

$parser = new TypeLang\Parser\Parser(
    conditional: false,
);

$result = $parser->parse('T is U ? 23 : 42');
TypeLang\Parser\Exception\ParseException:
Conditional expressions not allowed in "T is U ? 23 : 42"

Attributes

To enable or disable attributes, use the attributes: bool flag.

$parser = new TypeLang\Parser\Parser(
    attributes: false,
);

$result = $parser->parse(<<<'PHP'
    array{
        #[name("new_name"), skip_when_empty]
        oldName: int,
    }
    PHP);
TypeLang\Parser\Exception\ParseException:
Shape field attributes not allowed in "array{\n #[name("new_name"),
skip_when_empt…" (19+)