Scala example source code file (Types.scala)
The Types.scala Scala example source codepackage scala
package reflect
package api
/**
* <span class="badge badge-red" style="float: right;">EXPERIMENTAL</span>
*
* A trait that defines types and operations on them.
*
* Type instances represent information about the type of a corresponding symbol. This includes its members
* (methods, fields, type parameters, nested classes, traits, etc.) either declared directly or inherited, its base types,
* its erasure and so on. Types also provide operations to test for type conformance or equivalence or for widening.
*
* To instantiate a type, most of the time, the [[scala.reflect.api.TypeTags#typeOf]] method can be used. It takes
* a type argument and produces a `Type` instance which represents that argument. For example:
*
* {{{
* scala> typeOf[List[Int]]
* res0: reflect.runtime.universe.Type = scala.List[Int]
* }}}
*
* In this example, a [[scala.reflect.api.Types#TypeRef]] is returned, which corresponds to the type constructor `List`
* applied to the type argument `Int`.
*
* ''Note:'' Method `typeOf` does not work for types with type parameters, such as `typeOf[List[A]]` where `A` is
* a type parameter. In this case, use [[scala.reflect.api.TypeTags#weakTypeOf]] instead.
*
* For other ways to instantiate types, see the [[http://docs.scala-lang.org/overviews/reflection/symbols-trees-types.html corresponding section of the Reflection Guide]].
*
* === Common Operations on Types ===
*
* Types are typically used for type conformance tests or are queried for declarations of members or inner types.
*
* - '''Subtyping Relationships''' can be tested using `<:<` and `weak_<:<`.
* - '''Type Equality''' can be checked with `=:=`. It's important to note that `==` should not be used to compare types for equality-- `==` can't check for type equality in the presence of type aliases, while `=:=` can.
*
* Types can be queried for members and declarations by using the `members` and `declarations` methods (along with
* their singular counterparts `member` and `declaration`), which provide the list of definitions associated with that type.
* For example, to look up the `map` method of `List`, one can do:
*
* {{{
* scala> typeOf[List[_]].member("map": TermName)
* res1: reflect.runtime.universe.Symbol = method map
* }}}
*
* For more information about `Type`s, see the [[http://docs.scala-lang.org/overviews/reflection/symbols-trees-types.html Reflection Guide: Symbols, Trees, and Types]]
*
* @groupname TypeCreators Types - Creation
* @groupname TypeOps Types - Operations
* @group ReflectionAPI
*
* @contentDiagram hideNodes "*Api"
*/
trait Types {
self: Universe =>
/** The type of Scala types, and also Scala type signatures.
* (No difference is internally made between the two).
* @template
* @group Types
*/
type Type >: Null <: AnyRef with TypeApi
/** This constant is used as a special value that indicates that no meaningful type exists.
* @group Types
*/
val NoType: Type
/** This constant is used as a special value denoting the empty prefix in a path dependent type.
* For instance `x.type` is represented as `SingleType(NoPrefix, <x>)`, where `<x>` stands for
* the symbol for `x`.
* @group Types
*/
val NoPrefix: Type
/** The API of types.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*
* @define dealiasWidenWarning Note that type aliases can hide beneath
* singleton types and singleton types can hide inside type aliases.
* Moreover, aliases might lurk in the upper bounds of abstract types.
* Therefore careful thought has to be applied to identify and carry out
* unwrapping logic specific to your use case.
*/
abstract class TypeApi {
/** The term symbol associated with the type, or `NoSymbol` for types
* that do not refer to a term symbol.
*/
def termSymbol: Symbol
/** The type symbol associated with the type, or `NoSymbol` for types
* that do not refer to a type symbol.
*/
def typeSymbol: Symbol
/** @see [[decl]] */
@deprecated("Use `decl` instead", "2.11.0")
def declaration(name: Name): Symbol
/** The defined or declared members with name `name` in this type;
* an OverloadedSymbol if several exist, NoSymbol if none exist.
* Alternatives of overloaded symbol appear in the order they are declared.
*/
def decl(name: Name): Symbol
/** @see [[decls]] */
@deprecated("Use `decls` instead", "2.11.0")
def declarations: MemberScope
/** A `Scope` containing directly declared members of this type.
* Unlike `members` this method doesn't returns inherited members.
*
* Members in the returned scope might appear in arbitrary order.
* Use `declarations.sorted` to get an ordered list of members.
*/
def decls: MemberScope
/** The member with given name, either directly declared or inherited,
* an OverloadedSymbol if several exist, NoSymbol if none exist.
*/
def member(name: Name): Symbol
/** A `Scope` containing all members of this type (directly declared or inherited).
* Unlike `declarations` this method also returns inherited members.
*
* Members in the returned scope might appear in arbitrary order.
* Use `declarations.sorted` to get an ordered list of members.
*/
def members: MemberScope
/** Type signature of the companion of the underlying class symbol.
* NoType if the underlying symbol is not a class symbol, or if it doesn't have a companion.
*/
def companion: Type
/** Is this type a type constructor that is missing its type arguments?
*/
def takesTypeArgs: Boolean
/** Returns the corresponding type constructor (e.g. List for List[T] or List[String])
*/
def typeConstructor: Type
/** Reduce to beta eta-long normal form.
* Expands type aliases and converts higher-kinded TypeRefs to PolyTypes.
* Functions on types are also implemented as PolyTypes.
*
* Example: (in the below, <List> is the type constructor of List)
* TypeRef(pre, <List>, List()) is replaced by
* PolyType(X, TypeRef(pre, <List>, List(X)))
*/
@deprecated("Use `dealias` or `etaExpand` instead", "2.11.0")
def normalize: Type
/** Converts higher-kinded TypeRefs to PolyTypes.
* Functions on types are also implemented as PolyTypes.
*
* Example: (in the below, <List> is the type constructor of List)
* TypeRef(pre, <List>, List()) is replaced by
* PolyType(X, TypeRef(pre, <List>, List(X)))
*/
def etaExpand: Type
/** Does this type conform to given type argument `that`? */
def <:< (that: Type): Boolean
/** Does this type weakly conform to given type argument `that`, i.e., either conforms in terms of `<:<` or both are primitive number types
* that conform according to Section "Weak Conformance" in the spec. For example, Int weak_<:< Long.
*/
def weak_<:<(that: Type): Boolean
/** Is this type equivalent to given type argument `that`? */
def =:= (that: Type): Boolean
/** The list of all base classes of this type (including its own typeSymbol)
* in linearization order, starting with the class itself and ending
* in class Any.
*/
def baseClasses: List[Symbol]
/** The least type instance of given class which is a super-type
* of this type. Example:
* {{{
* class D[T]
* class C extends p.D[Int]
* ThisType(C).baseType(D) = p.D[Int]
* }}}
*/
def baseType(clazz: Symbol): Type
/** This type as seen from prefix `pre` and class `clazz`. This means:
* Replace all `ThisType`s of `clazz` or one of its subclasses
* by `pre` and instantiate all parameters by arguments of `pre`.
* Proceed analogously for `ThisType`s referring to outer classes.
*
* Example:
* {{{
* scala> import scala.reflect.runtime.universe._
* import scala.reflect.runtime.universe._
*
* scala> class D[T] { def m: T = ??? }
* defined class D
*
* scala> class C extends D[Int]
* defined class C
*
* scala> val D = typeOf[D[_]].typeSymbol.asClass
* D: reflect.runtime.universe.ClassSymbol = class D
*
* scala> val C = typeOf[C].typeSymbol.asClass
* C: reflect.runtime.universe.ClassSymbol = class C
*
* scala> val T = D.typeParams(0).asType.toType
* T: reflect.runtime.universe.Type = T
*
* scala> T.asSeenFrom(ThisType(C), D)
* res0: reflect.runtime.universe.Type = scala.Int
* }}}
*/
def asSeenFrom(pre: Type, clazz: Symbol): Type
/** The erased type corresponding to this type after
* all transformations from Scala to Java have been performed.
*/
def erasure: Type
/** If this is a singleton type, widen it to its nearest underlying non-singleton
* base type by applying one or more `underlying` dereferences.
* If this is not a singleton type, returns this type itself.
*
* Example:
*
* class Outer { class C ; val x: C }
* val o: Outer
* <o.x.type>.widen = o.C
*
* $dealiasWidenWarning
*/
def widen: Type
/** Expands type aliases arising from type members.
* $dealiasWidenWarning
*/
def dealias: Type
/******* popular methods from subclasses *******/
/** List of type arguments ingrained in this type reference.
* Depending on your use case you might or might not want to call `dealias` first.
*
* {{{
* scala> type T = List[Int]
* defined type alias T
*
* scala> typeOf[T].typeArgs
* res0: List[reflect.runtime.universe.Type] = List()
*
* scala> typeOf[T].dealias.typeArgs
* res1: List[reflect.runtime.universe.Type] = List(scala.Int)
* }}}
*/
def typeArgs: List[Type]
/** @see [[paramLists]] */
@deprecated("Use `paramLists` instead", "2.11.0")
def paramss: List[List[Symbol]]
/** For a method or poly type, a list of its value parameter sections,
* the empty list of lists for all other types.
*/
def paramLists: List[List[Symbol]]
/** For a poly type, its type parameters,
* the empty list for all other types.
*/
def typeParams: List[Symbol]
/** For a (nullary) method or poly type, its direct result type
* (can be a MethodType if the method has multiple argument lists),
* the type itself for all other types.
*
* {{{
* scala> class C { def foo[T](x: T)(y: T) = ??? }
* defined class C
*
* scala> typeOf[C].member(TermName("foo")).asMethod
* res0: reflect.runtime.universe.MethodSymbol = method foo
*
* scala> res0.info // PolyType wrapping a MethodType
* res1: reflect.runtime.universe.Type = [T](x: T)(y: T)scala.Nothing
*
* scala> res1.resultType // MethodType wrapping a MethodType
* res2: reflect.runtime.universe.Type = (x: T)(y: T)scala.Nothing
*
* scala> res1.resultType.resultType // vanilla MethodType
* res3: reflect.runtime.universe.Type = (y: T)scala.Nothing
*
* scala> res1.resultType.resultType.resultType
* res4: reflect.runtime.universe.Type = scala.Nothing
*
* scala> res1.finalResultType
* res5: reflect.runtime.universe.Type = scala.Nothing
* }}}
*
* @see finalResultType
*/
def resultType: Type
/** For a curried/nullary method or poly type its non-method result type,
* the type itself for all other types.
*
* {{{
* scala> class C {
* | def foo[T](x: T)(y: T) = ???
* | def bar: Int = ???
* | }
* defined class C
*
* scala> typeOf[C].member(TermName("foo")).asMethod
* res0: reflect.runtime.universe.MethodSymbol = method foo
*
* scala> res0.info // PolyType wrapping a MethodType
* res1: reflect.runtime.universe.Type = [T](x: T)(y: T)scala.Nothing
*
* scala> res1.resultType // MethodType wrapping a MethodType
* res2: reflect.runtime.universe.Type = (x: T)(y: T)scala.Nothing
*
* scala> res1.resultType.resultType // vanilla MethodType
* res3: reflect.runtime.universe.Type = (y: T)scala.Nothing
*
* scala> res1.resultType.resultType.resultType
* res4: reflect.runtime.universe.Type = scala.Nothing
*
* scala> res1.finalResultType
* res5: reflect.runtime.universe.Type = scala.Nothing
*
* scala> typeOf[C].member(TermName("bar")).asMethod
* res6: reflect.runtime.universe.MethodSymbol = method bar
*
* scala> res6.info
* res7: reflect.runtime.universe.Type = => scala.Int
*
* scala> res6.info.resultType
* res8: reflect.runtime.universe.Type = scala.Int
*
* scala> res6.info.finalResultType
* res9: reflect.runtime.universe.Type = scala.Int
* }}}
*
* @see resultType
*/
def finalResultType: Type
/******************* helpers *******************/
/** Provides an alternate if type is NoType.
*
* @group Helpers
*/
def orElse(alt: => Type): Type
/** Substitute symbols in `to` for corresponding occurrences of references to
* symbols `from` in this type.
*/
def substituteSymbols(from: List[Symbol], to: List[Symbol]): Type
/** Substitute types in `to` for corresponding occurrences of references to
* symbols `from` in this type.
*/
def substituteTypes(from: List[Symbol], to: List[Type]): Type
/** Apply `f` to each part of this type, returning
* a new type. children get mapped before their parents */
def map(f: Type => Type): Type
/** Apply `f` to each part of this type, for side effects only */
def foreach(f: Type => Unit)
/** Returns optionally first type (in a preorder traversal) which satisfies predicate `p`,
* or None if none exists.
*/
def find(p: Type => Boolean): Option[Type]
/** Is there part of this type which satisfies predicate `p`? */
def exists(p: Type => Boolean): Boolean
/** Does this type contain a reference to given symbol? */
def contains(sym: Symbol): Boolean
}
/** The type of Scala singleton types, i.e., types that are inhabited
* by only one nun-null value. These include types of the forms
* {{{
* C.this.type
* C.super.type
* x.type
* }}}
* as well as [[ConstantType constant types]].
* @template
* @group Types
*/
type SingletonType >: Null <: SingletonTypeApi with Type
/** Has no special methods. Is here to provides erased identity for `SingletonType`.
* @group API
*/
trait SingletonTypeApi
/** A singleton type that describes types of the form on the left with the
* corresponding `ThisType` representation to the right:
* {{{
* C.this.type ThisType(C)
* }}}
* @template
* @group Types
*/
type ThisType >: Null <: ThisTypeApi with SingletonType
/** The constructor/extractor for `ThisType` instances.
* @group Extractors
*/
val ThisType: ThisTypeExtractor
/** An extractor class to create and pattern match with syntax `ThisType(sym)`
* where `sym` is the class prefix of the this type.
* @group Extractors
*/
abstract class ThisTypeExtractor {
def unapply(tpe: ThisType): Option[Symbol]
/** @see [[InternalApi.thisType]] */
@deprecated("Use `internal.thisType` instead", "2.11.0")
def apply(sym: Symbol)(implicit token: CompatToken): Type = internal.thisType(sym)
}
/** The API that all this types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait ThisTypeApi extends TypeApi { this: ThisType =>
/** The underlying class symbol. */
def sym: Symbol
}
/** The `SingleType` type describes types of any of the forms on the left,
* with their TypeRef representations to the right.
* {{{
* (T # x).type SingleType(T, x)
* p.x.type SingleType(p.type, x)
* x.type SingleType(NoPrefix, x)
* }}}
* @template
* @group Types
*/
type SingleType >: Null <: SingleTypeApi with SingletonType
/** The constructor/extractor for `SingleType` instances.
* @group Extractors
*/
val SingleType: SingleTypeExtractor
/** An extractor class to create and pattern match with syntax `SingleType(pre, sym)`
* Here, `pre` is the prefix of the single-type, and `sym` is the stable value symbol
* referred to by the single-type.
* @group Extractors
*/
abstract class SingleTypeExtractor {
def unapply(tpe: SingleType): Option[(Type, Symbol)]
/** @see [[InternalApi.singleType]] */
@deprecated("Use `ClassSymbol.thisPrefix` or `internal.singleType` instead")
def apply(pre: Type, sym: Symbol)(implicit token: CompatToken): Type = internal.singleType(pre, sym)
}
/** The API that all single types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait SingleTypeApi extends TypeApi { this: SingleType =>
/** The type of the qualifier. */
def pre: Type
/** The underlying symbol. */
def sym: Symbol
}
/** The `SuperType` type is not directly written, but arises when `C.super` is used
* as a prefix in a `TypeRef` or `SingleType`. It's internal presentation is
* {{{
* SuperType(thistpe, supertpe)
* }}}
* Here, `thistpe` is the type of the corresponding this-type. For instance,
* in the type arising from C.super, the `thistpe` part would be `ThisType(C)`.
* `supertpe` is the type of the super class referred to by the `super`.
* @template
* @group Types
*/
type SuperType >: Null <: SuperTypeApi with SingletonType
/** The constructor/extractor for `SuperType` instances.
* @group Extractors
*/
val SuperType: SuperTypeExtractor
/** An extractor class to create and pattern match with syntax `SingleType(thistpe, supertpe)`
* @group Extractors
*/
abstract class SuperTypeExtractor {
def unapply(tpe: SuperType): Option[(Type, Type)]
/** @see [[InternalApi.superType]] */
@deprecated("Use `ClassSymbol.superPrefix` or `internal.superType` instead", "2.11.0")
def apply(thistpe: Type, supertpe: Type)(implicit token: CompatToken): Type = internal.superType(thistpe, supertpe)
}
/** The API that all super types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait SuperTypeApi extends TypeApi { this: SuperType =>
/** The type of the qualifier.
* See the example for [[scala.reflect.api.Trees#SuperExtractor]].
*/
def thistpe: Type
/** The type of the selector.
* See the example for [[scala.reflect.api.Trees#SuperExtractor]].
*/
def supertpe: Type
}
/** The `ConstantType` type is not directly written in user programs, but arises as the type of a constant.
* The REPL expresses constant types like `Int(11)`. Here are some constants with their types:
* {{{
* 1 ConstantType(Constant(1))
* "abc" ConstantType(Constant("abc"))
* }}}
* @template
* @group Types
*/
type ConstantType >: Null <: ConstantTypeApi with SingletonType
/** The constructor/extractor for `ConstantType` instances.
* @group Extractors
*/
val ConstantType: ConstantTypeExtractor
/** An extractor class to create and pattern match with syntax `ConstantType(constant)`
* Here, `constant` is the constant value represented by the type.
* @group Extractors
*/
abstract class ConstantTypeExtractor {
def unapply(tpe: ConstantType): Option[Constant]
/** @see [[InternalApi.constantType]] */
@deprecated("Use `value.tpe` or `internal.constantType` instead", "2.11.0")
def apply(value: Constant)(implicit token: CompatToken): ConstantType = internal.constantType(value)
}
/** The API that all constant types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait ConstantTypeApi extends TypeApi { this: ConstantType =>
/** The compile-time constant underlying this type. */
def value: Constant
}
/** The `TypeRef` type describes types of any of the forms on the left,
* with their TypeRef representations to the right.
* {{{
* T # C[T_1, ..., T_n] TypeRef(T, C, List(T_1, ..., T_n))
* p.C[T_1, ..., T_n] TypeRef(p.type, C, List(T_1, ..., T_n))
* C[T_1, ..., T_n] TypeRef(NoPrefix, C, List(T_1, ..., T_n))
* T # C TypeRef(T, C, Nil)
* p.C TypeRef(p.type, C, Nil)
* C TypeRef(NoPrefix, C, Nil)
* }}}
* @template
* @group Types
*/
type TypeRef >: Null <: TypeRefApi with Type
/** The constructor/extractor for `TypeRef` instances.
* @group Extractors
*/
val TypeRef: TypeRefExtractor
/** An extractor class to create and pattern match with syntax `TypeRef(pre, sym, args)`
* Here, `pre` is the prefix of the type reference, `sym` is the symbol
* referred to by the type reference, and `args` is a possible empty list of
* type argumenrts.
* @group Extractors
*/
abstract class TypeRefExtractor {
def unapply(tpe: TypeRef): Option[(Type, Symbol, List[Type])]
/** @see [[InternalApi.typeRef]] */
@deprecated("Use `internal.typeRef` instead", "2.11.0")
def apply(pre: Type, sym: Symbol, args: List[Type])(implicit token: CompatToken): Type = internal.typeRef(pre, sym, args)
}
/** The API that all type refs support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait TypeRefApi extends TypeApi { this: TypeRef =>
/** The prefix of the type reference.
* Is equal to `NoPrefix` if the prefix is not applicable.
*/
def pre: Type
/** The underlying symbol of the type reference. */
def sym: Symbol
/** The arguments of the type reference.
* Is equal to `Nil` if the arguments are not provided.
*/
def args: List[Type]
}
/** A subtype of Type representing refined types as well as `ClassInfo` signatures.
* @template
* @group Types
*/
type CompoundType >: Null <: CompoundTypeApi with Type
/** Has no special methods. Is here to provides erased identity for `CompoundType`.
* @group API
*/
trait CompoundTypeApi
/** The `RefinedType` type defines types of any of the forms on the left,
* with their RefinedType representations to the right.
* {{{
* P_1 with ... with P_m { D_1; ...; D_n} RefinedType(List(P_1, ..., P_m), Scope(D_1, ..., D_n))
* P_1 with ... with P_m RefinedType(List(P_1, ..., P_m), Scope())
* { D_1; ...; D_n} RefinedType(List(AnyRef), Scope(D_1, ..., D_n))
* }}}
* @template
* @group Types
*/
type RefinedType >: Null <: RefinedTypeApi with CompoundType
/** The constructor/extractor for `RefinedType` instances.
* @group Extractors
*/
val RefinedType: RefinedTypeExtractor
/** An extractor class to create and pattern match with syntax `RefinedType(parents, decls)`
* Here, `parents` is the list of parent types of the class, and `decls` is the scope
* containing all declarations in the class.
* @group Extractors
*/
abstract class RefinedTypeExtractor {
def unapply(tpe: RefinedType): Option[(List[Type], Scope)]
/** @see [[InternalApi.refinedType]] */
@deprecated("Use `internal.refinedType` instead", "2.11.0")
def apply(parents: List[Type], decls: Scope)(implicit token: CompatToken): RefinedType = internal.refinedType(parents, decls)
/** @see [[InternalApi.refinedType]] */
@deprecated("Use `internal.refinedType` instead", "2.11.0")
def apply(parents: List[Type], decls: Scope, clazz: Symbol)(implicit token: CompatToken): RefinedType = internal.refinedType(parents, decls, clazz)
}
/** The API that all refined types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait RefinedTypeApi extends TypeApi { this: RefinedType =>
/** The superclasses of the type. */
def parents: List[Type]
/** The scope that holds the definitions comprising the type. */
def decls: MemberScope
}
/** The `ClassInfo` type signature is used to define parents and declarations
* of classes, traits, and objects. If a class, trait, or object C is declared like this
* {{{
* C extends P_1 with ... with P_m { D_1; ...; D_n}
* }}}
* its `ClassInfo` type has the following form:
* {{{
* ClassInfo(List(P_1, ..., P_m), Scope(D_1, ..., D_n), C)
* }}}
* @template
* @group Types
*/
type ClassInfoType >: Null <: ClassInfoTypeApi with CompoundType
/** The constructor/extractor for `ClassInfoType` instances.
* @group Extractors
*/
val ClassInfoType: ClassInfoTypeExtractor
/** An extractor class to create and pattern match with syntax `ClassInfo(parents, decls, clazz)`
* Here, `parents` is the list of parent types of the class, `decls` is the scope
* containing all declarations in the class, and `clazz` is the symbol of the class
* itself.
* @group Extractors
*/
abstract class ClassInfoTypeExtractor {
def unapply(tpe: ClassInfoType): Option[(List[Type], Scope, Symbol)]
/** @see [[InternalApi.classInfoType]] */
@deprecated("Use `internal.classInfoType` instead", "2.11.0")
def apply(parents: List[Type], decls: Scope, typeSymbol: Symbol)(implicit token: CompatToken): ClassInfoType = internal.classInfoType(parents, decls, typeSymbol)
}
/** The API that all class info types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait ClassInfoTypeApi extends TypeApi { this: ClassInfoType =>
/** The superclasses of the class type. */
def parents: List[Type]
/** The scope that holds the definitions comprising the class type. */
def decls: MemberScope
/** The symbol underlying the class type. */
def typeSymbol: Symbol
}
/** The `MethodType` type signature is used to indicate parameters and result type of a method
* @template
* @group Types
*/
type MethodType >: Null <: MethodTypeApi with Type
/** The constructor/extractor for `MethodType` instances.
* @group Extractors
*/
val MethodType: MethodTypeExtractor
/** An extractor class to create and pattern match with syntax `MethodType(params, respte)`
* Here, `params` is a potentially empty list of parameter symbols of the method,
* and `restpe` is the result type of the method. If the method is curried, `restpe` would
* be another `MethodType`.
* Note: `MethodType(Nil, Int)` would be the type of a method defined with an empty parameter list.
* {{{
* def f(): Int
* }}}
* If the method is completely parameterless, as in
* {{{
* def f: Int
* }}}
* its type is a `NullaryMethodType`.
* @group Extractors
*/
abstract class MethodTypeExtractor {
def unapply(tpe: MethodType): Option[(List[Symbol], Type)]
/** @see [[InternalApi.methodType]] */
@deprecated("Use `internal.methodType` instead", "2.11.0")
def apply(params: List[Symbol], resultType: Type)(implicit token: CompatToken): MethodType = internal.methodType(params, resultType)
}
/** The API that all method types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait MethodTypeApi extends TypeApi { this: MethodType =>
/** The symbols that correspond to the parameters of the method. */
def params: List[Symbol]
/** The result type of the method. */
def resultType: Type
}
/** The `NullaryMethodType` type signature is used for parameterless methods
* with declarations of the form `def foo: T`
* @template
* @group Types
*/
type NullaryMethodType >: Null <: NullaryMethodTypeApi with Type
/** The constructor/extractor for `NullaryMethodType` instances.
* @group Extractors
*/
val NullaryMethodType: NullaryMethodTypeExtractor
/** An extractor class to create and pattern match with syntax `NullaryMethodType(resultType)`.
* Here, `resultType` is the result type of the parameterless method.
* @group Extractors
*/
abstract class NullaryMethodTypeExtractor {
def unapply(tpe: NullaryMethodType): Option[(Type)]
/** @see [[InternalApi.nullaryMethodType]] */
@deprecated("Use `internal.nullaryMethodType` instead", "2.11.0")
def apply(resultType: Type)(implicit token: CompatToken): NullaryMethodType = internal.nullaryMethodType(resultType)
}
/** The API that all nullary method types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait NullaryMethodTypeApi extends TypeApi { this: NullaryMethodType =>
/** The result type of the method. */
def resultType: Type
}
/** The `PolyType` type signature is used for polymorphic methods
* that have at least one type parameter.
* @template
* @group Types
*/
type PolyType >: Null <: PolyTypeApi with Type
/** The constructor/extractor for `PolyType` instances.
* @group Extractors
*/
val PolyType: PolyTypeExtractor
/** An extractor class to create and pattern match with syntax `PolyType(typeParams, resultType)`.
* Here, `typeParams` are the type parameters of the method and `resultType`
* is the type signature following the type parameters.
* @group Extractors
*/
abstract class PolyTypeExtractor {
def unapply(tpe: PolyType): Option[(List[Symbol], Type)]
/** @see [[InternalApi.polyType]] */
@deprecated("Use `internal.polyType` instead", "2.11.0")
def apply(typeParams: List[Symbol], resultType: Type)(implicit token: CompatToken): PolyType = internal.polyType(typeParams, resultType)
}
/** The API that all polymorphic types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait PolyTypeApi extends TypeApi { this: PolyType =>
/** The symbols corresponding to the type parameters. */
def typeParams: List[Symbol]
/** The underlying type. */
def resultType: Type
}
/** The `ExistentialType` type signature is used for existential types and
* wildcard types.
* @template
* @group Types
*/
type ExistentialType >: Null <: ExistentialTypeApi with Type
/** The constructor/extractor for `ExistentialType` instances.
* @group Extractors
*/
val ExistentialType: ExistentialTypeExtractor
/** An extractor class to create and pattern match with syntax
* `ExistentialType(quantified, underlying)`.
* Here, `quantified` are the type variables bound by the existential type and `underlying`
* is the type that's existentially quantified.
* @group Extractors
*/
abstract class ExistentialTypeExtractor {
def unapply(tpe: ExistentialType): Option[(List[Symbol], Type)]
/** @see [[InternalApi.existentialType]] */
@deprecated("Use `internal.existentialType` instead", "2.11.0")
def apply(quantified: List[Symbol], underlying: Type)(implicit token: CompatToken): ExistentialType = internal.existentialType(quantified, underlying)
}
/** The API that all existential types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait ExistentialTypeApi extends TypeApi { this: ExistentialType =>
/** The symbols corresponding to the `forSome` clauses of the existential type. */
def quantified: List[Symbol]
/** The underlying type of the existential type. */
def underlying: Type
}
/** The `AnnotatedType` type signature is used for annotated types of the
* for `<type> @<annotation>`.
* @template
* @group Types
*/
type AnnotatedType >: Null <: AnnotatedTypeApi with Type
/** The constructor/extractor for `AnnotatedType` instances.
* @group Extractors
*/
val AnnotatedType: AnnotatedTypeExtractor
/** An extractor class to create and pattern match with syntax
* `AnnotatedType(annotations, underlying)`.
* Here, `annotations` are the annotations decorating the underlying type `underlying`.
* `selfSym` is a symbol representing the annotated type itself.
* @group Extractors
*/
abstract class AnnotatedTypeExtractor {
def unapply(tpe: AnnotatedType): Option[(List[Annotation], Type)]
/** @see [[InternalApi.annotatedType]] */
@deprecated("Use `internal.annotatedType` instead", "2.11.0")
def apply(annotations: List[Annotation], underlying: Type)(implicit token: CompatToken): AnnotatedType = internal.annotatedType(annotations, underlying)
}
/** The API that all annotated types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait AnnotatedTypeApi extends TypeApi { this: AnnotatedType =>
/** The annotations. */
def annotations: List[Annotation]
/** The annotee. */
def underlying: Type
}
/** The `TypeBounds` type signature is used to indicate lower and upper type bounds
* of type parameters and abstract types. It is not a first-class type.
* If an abstract type or type parameter is declared with any of the forms
* on the left, its type signature is the TypeBounds type on the right.
* {{{
* T >: L <: U TypeBounds(L, U)
* T >: L TypeBounds(L, Any)
* T <: U TypeBounds(Nothing, U)
* }}}
* @template
* @group Types
*/
type TypeBounds >: Null <: TypeBoundsApi with Type
/** The constructor/extractor for `TypeBounds` instances.
* @group Extractors
*/
val TypeBounds: TypeBoundsExtractor
/** An extractor class to create and pattern match with syntax `TypeBound(lower, upper)`
* Here, `lower` is the lower bound of the `TypeBounds` pair, and `upper` is
* the upper bound.
* @group Extractors
*/
abstract class TypeBoundsExtractor {
def unapply(tpe: TypeBounds): Option[(Type, Type)]
/** @see [[InternalApi.typeBounds]] */
@deprecated("Use `internal.typeBounds` instead", "2.11.0")
def apply(lo: Type, hi: Type)(implicit token: CompatToken): TypeBounds = internal.typeBounds(lo, hi)
}
/** The API that all type bounds support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait TypeBoundsApi extends TypeApi { this: TypeBounds =>
/** The lower bound.
* Is equal to `definitions.NothingTpe` if not specified explicitly.
*/
def lo: Type
/** The upper bound.
* Is equal to `definitions.AnyTpe` if not specified explicitly.
*/
def hi: Type
}
/** An object representing an unknown type, used during type inference.
* If you see WildcardType outside of inference it is almost certainly a bug.
* @group Types
*/
val WildcardType: Type
/** BoundedWildcardTypes, used only during type inference, are created in
* two places:
*
* 1. If the expected type of an expression is an existential type,
* its hidden symbols are replaced with bounded wildcards.
* 2. When an implicit conversion is being sought based in part on
* the name of a method in the converted type, a HasMethodMatching
* type is created: a MethodType with parameters typed as
* BoundedWildcardTypes.
* @template
* @group Types
*/
type BoundedWildcardType >: Null <: BoundedWildcardTypeApi with Type
/** The constructor/extractor for `BoundedWildcardType` instances.
* @group Extractors
*/
val BoundedWildcardType: BoundedWildcardTypeExtractor
/** An extractor class to create and pattern match with syntax `BoundedWildcardTypeExtractor(bounds)`
* with `bounds` denoting the type bounds.
* @group Extractors
*/
abstract class BoundedWildcardTypeExtractor {
def unapply(tpe: BoundedWildcardType): Option[TypeBounds]
/** @see [[InternalApi.boundedWildcardType]] */
@deprecated("Use `internal.boundedWildcardType` instead", "2.11.0")
def apply(bounds: TypeBounds)(implicit token: CompatToken): BoundedWildcardType = internal.boundedWildcardType(bounds)
}
/** The API that all this types support.
* The main source of information about types is the [[scala.reflect.api.Types]] page.
* @group API
*/
trait BoundedWildcardTypeApi extends TypeApi { this: BoundedWildcardType =>
/** Type bounds for the wildcard type. */
def bounds: TypeBounds
}
/** The least upper bound of a list of types, as determined by `<:<`.
* @group TypeOps
*/
def lub(xs: List[Type]): Type
/** The greatest lower bound of a list of types, as determined by `<:<`.
* @group TypeOps
*/
def glb(ts: List[Type]): Type
/** A creator for type applications
* @group TypeOps
*/
def appliedType(tycon: Type, args: List[Type]): Type
/** @see [[appliedType]] */
def appliedType(tycon: Type, args: Type*): Type
/** @see [[appliedType]] */
def appliedType(sym: Symbol, args: List[Type]): Type
/** @see [[appliedType]] */
def appliedType(sym: Symbol, args: Type*): Type
}
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