moduleceylon.ast.core1.3.3
Source Code
ceylon.ast.core
classParameters
extends Node
OverviewPackageInitializerAttributesMethods

A parameter list.

Examples:

()
(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:

(param)

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

Initializer
Parameters(Parameter[] parameters = ...)
Parameters:
  • parameters = s

    The parameters.

Attributes
childrenSource Codeshared actual Parameter[] children

The child nodes of this node.

Refines Node.children
hashSource Codeshared 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.

In general, hash values vary between platforms and between executions of the same program.

Note that when executing on a Java Virtual Machine, the 64-bit Integer value returned by an implementation of hash is truncated to a 32-bit integer value by taking the exclusive disjunction of the 32 lowest-order bits with the 32 highest-order bits, before returning the value to the caller.

Refines Object.hash
parametersSource Codeshared Parameter[] parameters

The parameters.

Inherited Attributes
Attributes inherited from: Node
children, data, string
Attributes inherited from: Object
hash, string
Methods
copySource Codeshared Parameters copy(Parameter[] parameters = ...)
Parameters:
  • parameters = s = this.parame
equalsSource Codeshared actual Boolean equals(Object that)

Determine if two values are equal.

For any two non-null objects x and y, x.equals(y) may be written as:

x == y

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.

Note that an implementation of equals() that always returns false does satisfy the constraints given above, as long as the class does not inherit Identifiable. Therefore, in very rare cases where there is no reasonable definition of value equality for a class, for example, function references (Callable), it is acceptable for equals() to be defined to return false for every argument.

Refines Object.equals
transformSource Codeshared 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.

Refines Node.transform
visitSource Codeshared 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
copyExtraInfoTo(), delete(), get(), getObject(), put(), remove(), set(), transform(), transformChildren(), visit(), visitChildren()
Methods inherited from: Object
equals