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Typhax

A flexible PHP type hinting syntax.

Installation and documentation

• Available as Composer package eloquent/typhax.
• API documentation available.

What is Typhax?

Typhax is a standard for the specification of PHP types in parameter type hints, and anywhere a type needs to be described in a human-readable form.

It expands on the capabilities of existing conventions for specifying type requirements, such as those used in the PHP documentation and PHPDoc's @param tag.

In addition to scalar and class type hints, Typhax allows powerful features, including the specification of key and value types for arrays, as well as compound types that use boolean logic (e.g. integer|float).

Supported types

Array

array
array<keyType,valueType>

An array. The key type and value type can optionally be specified. See the section on traversable types below.

Equivalent to the is_array() function.

Boolean

boolean

A boolean true or false value. The value must be an actual boolean, and not an equivalent integer.

Equivalent to the is_bool() function.

Callable

callable

A user-defined callback function. This is exactly equivalent to the callable type hint introduced in PHP 5.4.

A callable can be any of the following:

• A string containing the name of a function or static class method.
• An array with an object at index 0 and the method name at index 1.
• An array with a class name at index 0 and the method name at index 1.
• A closure.
• An object with an __invoke() method.
• The result of a create_function() call.

Equivalent to the is_callable() function.

Float

float

A floating-point number. The value must be a true floating point number, and not an equivalent string or integer.

Equivalent to the is_float() function.

Integer

integer

An integer. The value must be a true integer, and not an equivalent string, boolean, or any other kind of value.

Equivalent to the is_int() function.

Mixed

mixed
mixed<keyType,valueType>

The mixed type accepts any value of any type (including null).

Mixed can be treated as a traversable type, as in the second example above. When used in this fashion, mixed indicates any type that can be traversed, such as an array or an instance of the Traversable interface. This is useful in the case that the value must be a collection, but the outer type is not important.

Null

null

A null value.

Equivalent to === null.

Object

object
ClassName
ClassName<keyType,valueType>

The first form, object, indicates a value that is an object of any class. This is equivalent to the is_object() function.

The second form, ClassName, indicates a value that is an object of class ClassName. This includes instances of ClassName, instances of objects whose class extends from ClassName, and instances of objects that implement the ClassName interface. This is equivalent to the instanceof operator.

The third form, ClassName<keyType,valueType>, follows the same rules as the second form, with the additional requirement that the object must implement the Traversable interface. The key type and value type can optionally be specified. See the section on traversable types below.

Regarding namespaces

Namespace resolution should follow the same rules as PHP source code. That is; if the class name is in the current namespace, or has a relevant use statement, it's okay to use the short version.

Cosmos can be used to aid in resolving class names at runtime.

Resource

resource
resource{ofType:resourceType}

The first form, resource, indicates a value that is a resource of any type. This is equivalent to the is_resource() function.

The second form, resource{ofType:resourceType}, indicates a value that is a resource that returns a string equal to 'resourceType' when passed to get_resource_type().

Stream

stream
stream{readable:true,writable:true}
stream{readable:true,writable:false}
stream{readable:false,writable:true}

Represents a stream resource. The readable and writable attributes determine the requirements for the mode of the stream.

The stream type is equvalent to the Typhax type resource{ofType:stream}.

See the PHP documentation for fopen() for more information about stream modes.

String

string

A string. The value must be a true string, and not any other type that can be converted to a string.

Equivalent to the is_string() function.

Stringable

stringable

Represents a value of any type that can be converted to a useful string representation. This includes strings, integers, floats, and objects that have a __toString() method.

Arrays, booleans, nulls, resources, and objects without a __toString() method do not qualify as 'stringable'.

Tuple

tuple<typeA,typeB,typeC,...>

A tuple is an array value of a fixed size, with each element being of a specific type.

Tuples are generally referred to as an n-tuple, where n is the number of elements. For example, a 2-tuple definition where the first element is a string, and the second element is an integer, looks like tuple<string,integer>.

Tuple arrays must be sequential. That is, the keys of the array must be integers, with the first key being 0, and subsequent keys incrementing by 1 for each element of the tuple.

As an example, ['foo', 1] satisfies the constraint tuple<string,integer>.

Legacy types

The following types are also implemented, but are considered deprecated. They exist primarily for compatibility with types and pseudo-types used in the PHP manual, and an effort should be made to avoid their use:

• bool = boolean
• callback = callable
• double = float
• int = integer
• long = integer
• number = integer|float
• numeric = equivalent to is_numeric()
• real = float
• scalar = integer|float|string|boolean

Traversable types

Typhax supports the specification of key and value types for arrays and Traversable objects.

The specification for key and value types is as follows:

primaryType<keyType,valueType>

This specification represents a value of type primaryType which, when iterated over, produces keys of type keyType and values of type valueType.

Omitting a traversable type's key type

The keyType may be omitted:

primaryType<valueType>

This specification represents a value of type primaryType which, when iterated over, produces sequential integer keys starting with 0, and values of type valueType.

Using array without specifying key and value types

For array, both the key, and value types can be omitted:

array

This specification is equivalent to:

array<mixed,mixed>

Meaning that the keys and values can be of any type.

Using mixed as the primary type in a traversable type

A traversable type may specify mixed as the primary type:

mixed<keyType,valueType>

This specification represents a value of any type which can be iterated over, producing keys of type keyType and values of type valueType.

Boolean type logic

Typhax supports boolean logic in type specifications. There are two operators, the pipe symbol (|) which represents boolean OR, and the plus symbol (+) which represents boolean AND.

This specification:

typeA|typeB

represents a type that is either of type typeA OR of type typeB. A real-world example might be integer|float to accept either an integer OR float number.

This specification:

typeA+typeB

represents a type that is both of type typeA AND of type typeB. A real-world example might be InterfaceA+InterfaceB to accept only an object that implements both InterfaceA AND InterfaceB.

Extension types

:ClassName
:ClassName{attribute:value,...}
:ClassName<typeA,typeB,typeC,...>{attribute:value,...}

Extensions provide a means to expand the capabilies of Typhax with custom logic.

White space

In general, Typhax does not care whether white space is used in type specifications. However, the above documentation should serve as a recommended style guide.

Usage

Typhax includes a parser for type expressions, which produces a syntax tree of the parsed type:

Also included is a comparator for determining whether two types are equivalent: