Denotations
Related Doc:
package core
A denotation is the result of resolving a name (either simple identifier or select) during a given period.
A denotation is the result of resolving a name (either simple identifier or select) during a given period.
Denotations can be combined with & and |.
& is conjunction, | is disjunction.
& will create an overloaded denotation from two
non-overloaded denotations if their signatures differ.
Analogously | of two denotations with different signatures will give
an empty denotation NoDenotation.
A denotation might refer to NoSymbol. This is the case if the denotation
was produced from a disjunction of two denotations with different symbols
and there was no common symbol in a superclass that could substitute for
both symbols. Here is an example:
Say, we have:
class A { def f: A } class B { def f: B } val x: A | B = if (test) new A else new B val y = x.f
Then the denotation of y is SingleDenotation(NoSymbol, A | B).
An error denotation that provides more info about the missing reference.
An error denotation that provides more info about the missing reference. Produced by staticRef, consumed by requiredSymbol.
An overloaded denotation consisting of the alternatives of both given denotations.
An error denotation that provides more info about alternatives that were found but that do not qualify.
An error denotation that provides more info about alternatives that were found but that do not qualify. Produced by staticRef, consumed by requiredSymbol.
A PreDenotation represents a group of single denotations It is used as an optimization to avoid forming MultiDenotations too eagerly.
A non-overloaded denotation
An exception for accessing symbols that are no longer valid in current run
A double definition
Denotations represent the meaning of symbols and named types. The following diagram shows how the principal types of denotations and their denoting entities relate to each other. Lines ending in a down-arrow
vare member methods. The two methods shown in the diagram are "symbol" and "deref". Both methods are parameterized by the current context, and are effectively indexed by current period.Lines ending in a horizontal line mean subtying (right is a subtype of left).
NamedType------TermRefWithSignature | | Symbol---------ClassSymbol | | | | | denot | denot | denot | denot v v v v Denotation-+-----SingleDenotation-+------SymDenotation-+----ClassDenotation | | +-----MultiDenotation | | +--UniqueRefDenotation +--JointRefDenotation
Here's a short summary of the classes in this diagram.
NamedType A type consisting of a prefix type and a name, with fields prefix: Type name: Name It has two subtypes: TermRef and TypeRef TermRefWithSignature A TermRef that has in addition a signature to select an overloaded variant, with new field sig: Signature Symbol A label for a definition or declaration in one compiler run ClassSymbol A symbol representing a class Denotation The meaning of a named type or symbol during a period MultiDenotation A denotation representing several overloaded members SingleDenotation A denotation representing a non-overloaded member or definition, with main fields symbol: Symbol info: Type UniqueRefDenotation A denotation referring to a single definition with some member type JointRefDenotation A denotation referring to a member that could resolve to several definitions SymDenotation A denotation representing a single definition with its original type, with main fields name: Name owner: Symbol flags: Flags privateWithin: Symbol annotations: List[Annotation] ClassDenotation A denotation representing a single class definition.