scala.reflect.api

# Internals

###
Related Doc: package api

#### trait Internals extends AnyRef

EXPERIMENTAL

This trait assembles APIs occasionally necessary for performing low-level operations on reflection artifacts. See Internals#InternalApi for more information about nature, usefulness and compatibility guarantees of these APIs.

Self Type
  Universe
Source
  Internals.scala

Linear Supertypes
AnyRef, Any
Known Subclasses
JavaUniverse, Universe, Universe
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1. Internals
2. AnyRef
3. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

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### Type Members

1. #### abstract type Compat <: Universe.CompatApi

   See also

     compat

2. #### trait CompatApi extends AnyRef

   See also

     compat

3. #### class CompatToken extends AnyRef

   Presence of an implicit value of this type in scope indicates that source compatibility with Scala 2.10 has been enabled.

   Presence of an implicit value of this type in scope indicates that source compatibility with Scala 2.10 has been enabled.

   Annotations
     @implicitNotFound( ... )

4. #### abstract type FreeTermSymbol >: Null <: Universe.FreeTermSymbolApi with Universe.TermSymbol

   The type of free terms introduced by reification.

5. #### trait FreeTermSymbolApi extends Universe.TermSymbolApi

   The API of free term symbols.

   The API of free term symbols. The main source of information about symbols is the Symbols page.

   $SYMACCESSORS

6. #### abstract type FreeTypeSymbol >: Null <: Universe.FreeTypeSymbolApi with Universe.TypeSymbol

   The type of free types introduced by reification.

7. #### trait FreeTypeSymbolApi extends Universe.TypeSymbolApi

   The API of free type symbols.

   The API of free type symbols. The main source of information about symbols is the Symbols page.

   $SYMACCESSORS

8. #### trait Importer extends AnyRef

   This trait provides support for importers, a facility to migrate reflection artifacts between universes.

   This trait provides support for importers, a facility to migrate reflection artifacts between universes. Note: this trait should typically be used only rarely.

   Reflection artifacts, such as Symbols and Types, are contained in Universes. Typically all processing happens within a single `Universe` (e.g. a compile-time macro `Universe` or a runtime reflection `Universe`), but sometimes there is a need to migrate artifacts from one `Universe` to another. For example, runtime compilation works by importing runtime reflection trees into a runtime compiler universe, compiling the importees and exporting the result back.

   Reflection artifacts are firmly grounded in their `Universe`s, which is reflected by the fact that types of artifacts from different universes are not compatible. By using `Importer`s, however, they be imported from one universe into another. For example, to import `foo.bar.Baz` from the source `Universe` to the target `Universe`, an importer will first check whether the entire owner chain exists in the target `Universe`. If it does, then nothing else will be done. Otherwise, the importer will recreate the entire owner chain and will import the corresponding type signatures into the target `Universe`.

   Since importers match `Symbol` tables of the source and the target `Universe`s using plain string names, it is programmer's responsibility to make sure that imports don't distort semantics, e.g., that `foo.bar.Baz` in the source `Universe` means the same that `foo.bar.Baz` does in the target `Universe`.

   ##### Example

   Here's how one might implement a macro that performs compile-time evaluation of its argument by using a runtime compiler to compile and evaluate a tree that belongs to a compile-time compiler:

       def staticEval[T](x: T) = macro staticEval[T]

       def staticEval[T](c: scala.reflect.macros.blackbox.Context)(x: c.Expr[T]) = {
         // creates a runtime reflection universe to host runtime compilation
         import scala.reflect.runtime.{universe => ru}
         val mirror = ru.runtimeMirror(c.libraryClassLoader)
         import scala.tools.reflect.ToolBox
         val toolBox = mirror.mkToolBox()

         // runtime reflection universe and compile-time macro universe are different
         // therefore an importer is needed to bridge them
         // currently mkImporter requires a cast to correctly assign the path-dependent types
         val importer0 = ru.internal.mkImporter(c.universe)
         val importer = importer0.asInstanceOf[ru.internal.Importer { val from: c.universe.type }]

         // the created importer is used to turn a compiler tree into a runtime compiler tree
         // both compilers use the same classpath, so semantics remains intact
         val imported = importer.importTree(tree)

         // after the tree is imported, it can be evaluated as usual
         val tree = toolBox.untypecheck(imported.duplicate)
         val valueOfX = toolBox.eval(imported).asInstanceOf[T]
         ...
       }

9. #### abstract type Internal <: Universe.InternalApi

   See also

     InternalApi

10. #### trait InternalApi extends AnyRef

    Reflection API exhibits a tension inherent to experimental things: on the one hand we want it to grow into a beautiful and robust API, but on the other hand we have to deal with immaturity of underlying mechanisms by providing not very pretty solutions to enable important use cases.

    Reflection API exhibits a tension inherent to experimental things: on the one hand we want it to grow into a beautiful and robust API, but on the other hand we have to deal with immaturity of underlying mechanisms by providing not very pretty solutions to enable important use cases.

    In Scala 2.10, which was our first stab at reflection API, we didn't have a systematic approach to dealing with this tension, sometimes exposing too much of internals (e.g. Symbol.deSkolemize) and sometimes exposing too little (e.g. there's still no facility to change owners, to do typing transformations, etc). This resulted in certain confusion with some internal APIs living among public ones, scaring the newcomers, and some internal APIs only available via casting, which requires intimate knowledge of the compiler and breaks compatibility guarantees.

    This led to creation of the `internal` API module for the reflection API, which provides advanced APIs necessary for macros that push boundaries of the state of the art, clearly demarcating them from the more or less straightforward rest and providing compatibility guarantees on par with the rest of the reflection API (full compatibility within minor releases, best effort towards backward compatibility within major releases, clear replacement path in case of rare incompatible changes in major releases).

    The `internal` module itself (the value that implements InternalApi) isn't defined here, in scala.reflect.api.Universe, but is provided on per-implementation basis. Runtime API endpoint (scala.reflect.runtime.universe) provides `universe.compat: InternalApi`, whereas compile-time API endpoints (instances of scala.reflect.macros.Context) provide `c.compat: ContextInternalApi`, which extends `InternalApi` with additional universe-specific and context-specific functionality.

11. #### abstract type ReferenceToBoxed >: Null <: Universe.ReferenceToBoxedApi with Universe.TermTree

    Marks underlying reference to id as boxed.

    Marks underlying reference to id as boxed.

    Precondition:<\b> id must refer to a captured variable A reference such marked will refer to the boxed entity, no dereferencing with `.elem` is done on it. This tree node can be emitted by macros such as reify that call referenceCapturedVariable. It is eliminated in LambdaLift, where the boxing conversion takes place.

12. #### trait ReferenceToBoxedApi extends Universe.TermTreeApi

    The API that all references support

13. #### abstract class ReferenceToBoxedExtractor extends AnyRef

    An extractor class to create and pattern match with syntax `ReferenceToBoxed(ident)`.

    An extractor class to create and pattern match with syntax `ReferenceToBoxed(ident)`. This AST node does not have direct correspondence to Scala code, and is emitted by macros to reference capture vars directly without going through `elem`.

    For example:

    var x = ... fun { x }

    Will emit:

    Ident(x)

    Which gets transformed to:

    Select(Ident(x), "elem")

    If `ReferenceToBoxed` were used instead of Ident, no transformation would be performed.

14. #### trait ReificationSupportApi extends AnyRef

    This is an internal implementation class.

15. #### type BuildApi = Universe.ReificationSupportApi

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Use `internal.ReificationSupportApi` instead

### Abstract Value Members

1. #### implicit abstract val FreeTermSymbolTag: ClassTag[Universe.FreeTermSymbol]

   Tag that preserves the identity of `FreeTermSymbol` in the face of erasure.

   Tag that preserves the identity of `FreeTermSymbol` in the face of erasure. Can be used for pattern matching, instance tests, serialization and the like.

2. #### implicit abstract val FreeTypeSymbolTag: ClassTag[Universe.FreeTypeSymbol]

   Tag that preserves the identity of `FreeTermSymbol` in the face of erasure.

   Tag that preserves the identity of `FreeTermSymbol` in the face of erasure. Can be used for pattern matching, instance tests, serialization and the like.

3. #### abstract val ReferenceToBoxed: Universe.ReferenceToBoxedExtractor

   The constructor/extractor for `ReferenceToBoxed` instances.

4. #### implicit abstract val ReferenceToBoxedTag: ClassTag[Universe.ReferenceToBoxed]

   Tag that preserves the identity of `ReferenceToBoxed` in the face of erasure.

   Tag that preserves the identity of `ReferenceToBoxed` in the face of erasure. Can be used for pattern matching, instance tests, serialization and the like.

5. #### abstract val compat: Universe.Compat

   Provides enrichments to ensure source compatibility between Scala 2.10 and Scala 2.11.

   Provides enrichments to ensure source compatibility between Scala 2.10 and Scala 2.11. If in your reflective program for Scala 2.10 you've used something that's now become an internal API, a single `compat._` import will fix things for you.

6. #### abstract val internal: Universe.Internal

   See also

     InternalApi

7. #### abstract val build: Universe.ReificationSupportApi

   Annotations
     @deprecated
   Deprecated

     (Since version 2.11.0) Use `internal.reificationSupport` instead

### Concrete Value Members

1. #### final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     AnyRef → Any

2. #### final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     AnyRef → Any

3. #### def +(other: String): String

   Implicit information
     This member is added by an implicit conversion from Internals to any2stringadd[Internals] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd

4. #### def ->[B](y: B): (Internals, B)

   Implicit information
     This member is added by an implicit conversion from Internals to ArrowAssoc[Internals] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()

5. #### final def ==(arg0: Any): Boolean

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   arg0

     the object to compare against this object for equality.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     AnyRef → Any

6. #### final def asInstanceOf[T0]: T0

   Cast the receiver object to be of type `T0`.

   Cast the receiver object to be of type `T0`.

   Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

   returns

     the receiver object.

   Definition Classes
     Any
   Exceptions thrown

     `ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

7. #### def clone(): AnyRef

   Create a copy of the receiver object.

   Create a copy of the receiver object.

   The default implementation of the `clone` method is platform dependent.

   returns

     a copy of the receiver object.

   Attributes
     protected[java.lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( ... )
   Note

     not specified by SLS as a member of AnyRef

8. #### def ensuring(cond: (Internals) ⇒ Boolean, msg: ⇒ Any): Internals

   Implicit information
     This member is added by an implicit conversion from Internals to Ensuring[Internals] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring

9. #### def ensuring(cond: (Internals) ⇒ Boolean): Internals

   Implicit information
     This member is added by an implicit conversion from Internals to Ensuring[Internals] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring

10. #### def ensuring(cond: Boolean, msg: ⇒ Any): Internals

    Implicit information
      This member is added by an implicit conversion from Internals to Ensuring[Internals] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

11. #### def ensuring(cond: Boolean): Internals

    Implicit information
      This member is added by an implicit conversion from Internals to Ensuring[Internals] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

12. #### final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

    Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

    The `eq` method implements an equivalence relation on non-null instances of `AnyRef`, and has three additional properties:

    - It is consistent: for any non-null instances `x` and `y` of type `AnyRef`, multiple invocations of `x.eq(y)` consistently returns `true` or consistently returns `false`.
    - For any non-null instance `x` of type `AnyRef`, `x.eq(null)` and `null.eq(x)` returns `false`.
    - `null.eq(null)` returns `true`.

    When overriding the `equals` or `hashCode` methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (`o1 eq o2`), they should be equal to each other (`o1 == o2`) and they should hash to the same value (`o1.hashCode == o2.hashCode`).

    returns

      `true` if the argument is a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef

13. #### def equals(arg0: Any): Boolean

    The equality method for reference types.

    The equality method for reference types. Default implementation delegates to `eq`.

    See also `equals` in scala.Any.

    returns

      `true` if the receiver object is equivalent to the argument; `false` otherwise.

    Definition Classes
      AnyRef → Any

14. #### def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )
    Note

      not specified by SLS as a member of AnyRef

15. #### def formatted(fmtstr: String): String

    Implicit information
      This member is added by an implicit conversion from Internals to StringFormat[Internals] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()

16. #### final def getClass(): Class[_]

    A representation that corresponds to the dynamic class of the receiver object.

    A representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

      a representation that corresponds to the dynamic class of the receiver object.

    Definition Classes
      AnyRef → Any
    Note

      not specified by SLS as a member of AnyRef

17. #### def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

      the hash code value for this object.

    Definition Classes
      AnyRef → Any

18. #### final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any

19. #### final def ne(arg0: AnyRef): Boolean

    Equivalent to `!(this eq that)`.

    Equivalent to `!(this eq that)`.

    returns

      `true` if the argument is not a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef

20. #### final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

21. #### final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

22. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

23. #### def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

      a String representation of the object.

    Definition Classes
      AnyRef → Any

24. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

25. #### final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

26. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

27. #### def →[B](y: B): (Internals, B)

    Implicit information
      This member is added by an implicit conversion from Internals to ArrowAssoc[Internals] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Deprecated Value Members

1. #### def mkImporter(from0: Universe): Universe.Importer { val from: from0.type }

   Annotations
     @deprecated
   Deprecated

     (Since version 2.11.0) Use `internal.createImporter` instead

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from Internals to any2stringadd[Internals]

### Inherited by implicit conversion StringFormat from Internals to StringFormat[Internals]

### Inherited by implicit conversion Ensuring from Internals to Ensuring[Internals]

### Inherited by implicit conversion ArrowAssoc from Internals to ArrowAssoc[Internals]

### Internal

### Ungrouped