scala3-compiler-bootstrapped/dotty.tools/dotty.tools.dotc/dotty.tools.dotc.cc

dotty.tools.dotc.cc

Members list

Type members

Classlikes

Capture checking state, which is known to other capture checking components

Attributes

Supertypes: class Object

trait Matchable

class Any

An annotation representing a capture set and whether it is boxed. It simulates a normal @retains annotation except that it is more efficient, supports variables as capture sets, and adds a boxed flag. These annotations are created during capture checking. Before that there are only regular @retains and @retainsByName annotations.

Value parameters

boxed: whether the type carrying the annotation is boxed
cls: the underlying class (either annotation.retains or annotation.retainsByName)
refs: the capture set

Attributes

Supertypes: trait Serializable

trait Product

trait Equals

class Annotation

trait Showable

class Object

trait Matchable

class Any
Show all

A class for capture sets. Capture sets can be constants or variables. Capture sets support inclusion constraints <:< where <:< is subcapturing.

They also allow

mapping with functions from elements to capture sets
filtering with predicates on elements
intersecting wo capture sets

That is, constraints can be of the forms

cs1 <:< cs2 cs1 = ∪ {f(x) | x ∈ cs2} where f is a function from capture references to capture sets. cs1 = ∪ {x | x ∈ cs2, p(x)} where p is a predicate on capture references cs1 = cs2 ∩ cs2

We call the resulting constraint system "monadic set constraints". To support capture propagation across maps, mappings are supported only if the mapped function is either a bijection or if it is idempotent on capture references (c.f. doc comment on map below).

Attributes

Companion: object
Supertypes: trait Showable

class Object

trait Matchable

class Any
Known subtypes: class Const

object Fluid

class Var

class DerivedVar

class BiMapped

class Filtered

class Diff

class Mapped

class Intersected
Show all

Attributes

Companion: class
Supertypes: class Object

trait Matchable

class Any
Self type: CaptureSet.type

A (possibly boxed) capturing type. This is internally represented as an annotated type with a @retains or @retainsByName annotation, but the extractor will succeed only at phase CheckCaptures. That way, we can ignore caturing information until phase CheckCaptures since it is wrapped in a plain annotation.

The same trick does not work for the boxing information. Boxing is context dependent, so we have to add that information in the Setup step preceding CheckCaptures. Boxes are added for all type arguments of methods. For type arguments of applied types a different strategy is used where we box arguments of applied types that are not functions when accessing the argument.

An alternative strategy would add boxes also to arguments of applied types during setup. But this would have to be done for all possibly accessibly types from the compiled units as well as their dependencies. It's difficult to do this in a DenotationTransformer without accidentally forcing symbol infos. That's why this alternative was not implemented. If we would go back on this it would make sense to also treat captuyring types different from annotations and to generate them all during Setup and in DenotationTransformers.

Attributes

Supertypes: class Object

trait Matchable

class Any
Self type: CapturingType.type

The capture checker

Attributes

Companion: class
Supertypes: class Object

trait Matchable

class Any
Self type: CheckCaptures.type

Attributes

Companion: object
Supertypes: class Recheck

trait SymTransformer

trait DenotTransformer

class Phase

class Object

trait Matchable

class Any
Show all
Self type: CheckCaptures

An exception thrown if a @retains argument is not syntactically a CaptureRef

Attributes

Supertypes: class Exception

class Throwable

trait Serializable

class Object

trait Matchable

class Any
Show all

Attributes

Supertypes: class Exception

class Throwable

trait Serializable

class Object

trait Matchable

class Any
Show all

A builder and extractor for annotated types with @retains or @retainsByName annotations.

Attributes

Supertypes: class Object

trait Matchable

class Any
Self type: RetainingType.type

Attributes

Companion: class
Supertypes: class Object

trait Matchable

class Any
Self type: Setup.type

A tree traverser that prepares a compilation unit to be capture checked. It does the following:

For every inferred type, drop any retains annotations, add capture sets to all its parts, add refinements to class types and function types. (c.f. mapInferred)
For explicit capturing types, expand throws aliases to the underlying (pure) function, and add some implied capture sets to curried functions (c.f. expandThrowsAlias, expandAbbreviations).
Add capture sets to self types of classes and objects, unless the self type was written explicitly.
Box the types of mutable variables and type arguments to methods (type arguments of types are boxed on access).
Link the external types of val and def symbols with the inferred types based on their parameter symbols.

Attributes

Companion: object
Supertypes: trait SetupAPI

trait SymTransformer

class PreRecheck

trait DenotTransformer

class Phase

class Object

trait Matchable

class Any
Show all
Self type: Setup

Operations accessed from CheckCaptures

Attributes

Supertypes: class Object

trait Matchable

class Any
Known subtypes: class Setup

Classification and transformation methods for function methods and synthetic case class methods that need to be treated specially. In particular, compute capturing types for some of these methods which have inferred (result-)types that need to be established under separate compilation.

Attributes

Supertypes: class Object

trait Matchable

class Any
Self type: Synthetics.type

Attributes

Supertypes: class Object

trait Matchable

class Any
Self type: ccConfig.type

Value members

Concrete methods

The currently valid CCState

Attributes

A dependent function type with given arguments and result type TODO Move somewhere else where we treat all function type related ops together.

Attributes

Are we at checkCaptures phase?

Attributes

Are we at checkCaptures or Setup phase?

Attributes

Extensions

extension (cls: ClassSymbol)

extension (sym: Symbol)

Does this symbol allow results carrying the universal capability? Currently this is true only for function type applies (since their results are unboxed) and erasedValue since this function is magic in that is allows to conjure global capabilies from nothing (aside: can we find a more controlled way to achieve this?). But it could be generalized to other functions that so that they can take capability classes as arguments.

Attributes

Can this symbol possibly own a local root? TODO: Disallow anonymous functions?

Attributes

A class is pure if:

one its base types has an explicitly declared self type with an empty capture set
or it is a value class
or it is an exception
or it is one of Nothing, Null, or String

Attributes

The owner of the current level. Qualifying owners are

methods other than constructors and anonymous functions
anonymous functions, provided they either define a local root of type caps.Cap, or they are the rhs of a val definition.
classes, if they are not staticOwners
root

Attributes

The level owner enclosing sym which has the given name, or NoSymbol if none exists.

Attributes

The local root corresponding to sym's level owner

Attributes

The outermost symbol owned by both sym and other. if none exists since the owning scopes of sym and other are not nested, invoke onConflict to return a symbol.

Attributes

The innermost symbol owning both sym and other.

Attributes

When applying sym, would the result type be unboxed? This is the case if the result type contains a top-level reference to an enclosing class or method type parameter and the method does not allow root capture. If the type parameter is instantiated to a boxed type, that type would have to be unboxed in the method's result.

Attributes

extension (tp: Type)

Under pureFunctions, add a @retainsByName(*)` annotation to the argument of a by name parameter type, turning the latter into an impure by name parameter type.

Attributes

Under pureFunctions, map regular function type to impure function type

Attributes

If this is a unboxed capturing type with nonempty capture set, its boxed version. Or, if type is a TypeBounds of capturing types, the version where the bounds are boxed. The identity for all other types.

Attributes

The capture set consisting of all top-level captures of tp that appear under a box. Unlike for boxed this also considers parents of capture types, unions and intersections, and type proxies other than abstract types.

Attributes

Drop @retains annotations everywhere

Attributes

If this type is a capturing type, the version with boxed statues as given by boxed. If it is a TermRef of a capturing type, and the box status flips, widen to a capturing type that captures the TermRef.

Attributes

Is type known to be always pure by its class structure, so that adding a capture set to it would not make sense?

Attributes

Is the boxedCaptureSet of this type nonempty?

Attributes

Map capturing type to their parents. Capturing types accessible via dealising are also stripped.

Attributes

extension (tp: AnnotatedType)

Is this a boxed capturing type?

Attributes

extension (tree: Tree)

Under pureFunctions, add a @retainsByName(*)` annotation to the argument of a by name parameter type, turning the latter into an impure by name parameter type.

Attributes

The arguments of a @retains or @retainsByName annotation

Attributes

Map tree with CaptureRef type to its type, throw IllegalCaptureRef otherwise

Attributes

Convert a @retains or @retainsByName annotation tree to the capture set it represents. For efficience, the result is cached as an Attachment on the tree.

Attributes

In this article

Generated with