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

A ‘case’ expression clause of a ‘switch’ expression (SwitchCaseElseExpression), that is, optionally the keyword ‘else’, then the keyword ‘case’, followed by a case item enclosed in parentheses and an expression.

The expression is parsed with a precedence just below the then (ThenOperation) and else (ElseOperation) operations, to avoid ambiguity with these. Alternatively, it may be an if/then/else expression (IfElseExpression) or let expression (LetExpression).

Examples:

case (is Integer) val / 2
case ('$') 2
else case (is Integer) val.magnitude

no subtypes hierarchy

Initializer
CaseExpression(CaseItem caseItem, DisjoiningExpression|IfElseExpression|LetExpression expression, Boolean elseCase = ...)
Parameters:
  • caseItem

    The case item for this clause.

  • expression

    The expression for this clause.

  • elseCase = ion,

    Whether this is a non-disjoint else case clause or a regular disjoint case clause.

Attributes
caseItemSource Codeshared CaseItem caseItem

The case item for this clause.

childrenSource Codeshared actual [CaseItem, DisjoiningExpression|IfElseExpression|LetExpression] children

The child nodes of this node.

Refines Node.children
elseCaseSource Codeshared Boolean elseCase

Whether this is a non-disjoint else case clause or a regular disjoint case clause.

expressionSource Codeshared DisjoiningExpression|IfElseExpression|LetExpression expression

The expression for this clause.

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
Inherited Attributes
Attributes inherited from: Node
children, data, string
Attributes inherited from: Object
hash, string
Methods
copySource Codeshared CaseExpression copy(CaseItem caseItem = ..., DisjoiningExpression|IfElseExpression|LetExpression expression = ..., Boolean elseCase = ...)
Parameters:
  • caseItem = Item caseItem
  • expression = on expression =
  • elseCase = lean elseCase
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