A parameter list.


(String text, Integer length = text.size)
(Element+ elements)

A note about this class’ parameters

It would seem reasonable to instead declare the parameters of this class like this:

class Parameters(RequiredParameter[] required,
    DefaultedParameter[] defaulted,
    VariadicParameter|ParameterReference variadic)

Note that variadic must have the type VariadicParameter|ParameterReference, not just VariadicParameter, because a variadic parameter can also be just a reference, and declared in the body of the function or class. And this is where the problem comes in:


In this parameter list, is param a required or a defaulted parameter? In other words, is this

  • a Parameters { required = [param]; }, or
  • a Parameters { variadic = param; }?

To decide this, you need to look into the body of the function, and check if the declaration of param has a regular or a variadic type. This is a semantical distinction, not a syntactical one, and in general we can’t expect tools that operate on an AST to be able to make this distinction.

Instead, we have just one list of parameters; the separation into required, defaulted, and variadic ones may then be done in later stages of AST processing.

no subtypes hierarchy

Parameters(Parameter[] parameters = [])
  • parameters = []

    The parameters.

childrenshared actual Parameter[] children

The child nodes of this node.

hashshared actual Integer hash

The hash value of the value, which allows the value to be an element of a hash-based set or key of a hash-based map. Implementations must respect the constraint that:

  • if x==y then x.hash==y.hash.

Therefore, a class which refines equals must also refine hash.

Because the Integer type is platform-dependent a compiler for a given platform is permitted to further manipulate the calculated hash for an object, and the resulting hash may differ between platforms.

Refines Object.hash
parametersshared Parameter[] parameters

The parameters.

Inherited Attributes
Attributes inherited from: Node
Attributes inherited from: Object
hash, string
copyshared Parameters copy(Parameter[] parameters = ...)
  • parameters = this.parameters
equalsshared actual Boolean equals(Object that)

Determine if two values are equal. Implementations should respect the constraints that:

  • if x===y then x==y (reflexivity),
  • if x==y then y==x (symmetry),
  • if x==y and y==z then x==z (transitivity).

Furthermore it is recommended that implementations ensure that if x==y then x and y have the same concrete class.

A class which explicitly refines equals() is said to support value equality, and the equality operator == is considered much more meaningful for such classes than for a class which simply inherits the default implementation of identity equality from Identifiable.

Refines Object.equals
transformshared actual Result transform<out Result>(Transformer<Result> transformer)

Transform this node with the given transformer by calling the appropriate transformX method on the transformer.

If you have a Node node that’s actually an LIdentifier instance, then the runtime will call LIdentifier.transform; therefore, this method is by nature narrowing. This means that if transformer is a NarrowingTransformer, calling node.transform(transformer) is equivalent to calling transformer.transformNode(node). On the other hand, if transformer is a WideningTransformer, then the two operations are very different.

visitshared actual void visit(Visitor visitor)

Visit this node with the given visitor. Calls the appropriate visitX method on the visitor.

Refines Node.visit
Inherited Methods
Methods inherited from: Node
Methods inherited from: Object