trait Importer extends AnyRef
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 Universes, which is reflected by the fact that types of artifacts
 from different universes are not compatible. By using Importers, 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 Universes 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] ... }
- Source
- Internals.scala
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Abstract Value Members
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        abstract 
        val
      
      
        from: Universe
      
      
      The source universe of reflection artifacts that will be processed. The source universe of reflection artifacts that will be processed. The target universe is universe that created this importer with mkImporter.
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        abstract 
        def
      
      
        importPosition(pos: Universe.Position): Universe.Position
      
      
      In the current universe, creates a position that corresponds to the provided position in the source universe. 
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        abstract 
        def
      
      
        importSymbol(sym: Universe.Symbol): Universe.Symbol
      
      
      In the current universe, locates or creates a symbol that corresponds to the provided symbol in the source universe. In the current universe, locates or creates a symbol that corresponds to the provided symbol in the source universe. If necessary imports the owner chain, companions, type signature, annotations and attachments. 
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        abstract 
        def
      
      
        importTree(tree: Universe.Tree): Universe.Tree
      
      
      In the current universe, creates a tree that corresponds to the provided tree in the source universe. In the current universe, creates a tree that corresponds to the provided tree in the source universe. If necessary imports the underlying symbols, types and attachments. 
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        abstract 
        def
      
      
        importType(tpe: Universe.Type): Universe.Type
      
      
      In the current universe, locates or creates a type that corresponds to the provided type in the source universe. In the current universe, locates or creates a type that corresponds to the provided type in the source universe. If necessary imports the underlying symbols, annotations, scopes and trees. 
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        abstract 
        val
      
      
        reverse: Universe.Importer { val from: Internals.this.type }
      
      
      An importer that works in reverse direction, namely: imports reflection artifacts from the current universe to the universe specified in from.
Concrete Value Members
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        final 
        def
      
      
        !=(arg0: Any): Boolean
      
      
      Test two objects for inequality. Test two objects for inequality. - returns
- trueif !(this == that), false otherwise.
 - Definition Classes
- AnyRef → Any
 
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        final 
        def
      
      
        ##(): Int
      
      
      Equivalent to x.hashCodeexcept for boxed numeric types andnull.Equivalent to x.hashCodeexcept for boxed numeric types andnull. 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. Fornullreturns a hashcode wherenull.hashCodethrows aNullPointerException.- returns
- a hash value consistent with == 
 - Definition Classes
- AnyRef → Any
 
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        def
      
      
        +(other: String): String
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to any2stringadd[Universe.Importer] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
 
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        def
      
      
        ->[B](y: B): (Universe.Importer, B)
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to ArrowAssoc[Universe.Importer] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
 
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        final 
        def
      
      
        ==(arg0: Any): Boolean
      
      
      The expression x == thatis equivalent toif (x eq null) that eq null else x.equals(that).The expression x == thatis equivalent toif (x eq null) that eq null else x.equals(that).- returns
- trueif the receiver object is equivalent to the argument;- falseotherwise.
 - Definition Classes
- AnyRef → Any
 
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        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 aClassCastExceptionat runtime, while the expressionList(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
- ClassCastExceptionif the receiver object is not an instance of the erasure of type- T0.
 
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        def
      
      
        clone(): AnyRef
      
      
      Create a copy of the receiver object. Create a copy of the receiver object. The default implementation of the clonemethod 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 
 
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        def
      
      
        ensuring(cond: (Universe.Importer) ⇒ Boolean, msg: ⇒ Any): Universe.Importer
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to Ensuring[Universe.Importer] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
 
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        def
      
      
        ensuring(cond: (Universe.Importer) ⇒ Boolean): Universe.Importer
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to Ensuring[Universe.Importer] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
 
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        def
      
      
        ensuring(cond: Boolean, msg: ⇒ Any): Universe.Importer
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to Ensuring[Universe.Importer] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
 
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        def
      
      
        ensuring(cond: Boolean): Universe.Importer
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to Ensuring[Universe.Importer] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
 
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        final 
        def
      
      
        eq(arg0: AnyRef): Boolean
      
      
      Tests whether the argument ( that) is a reference to the receiver object (this).Tests whether the argument ( that) is a reference to the receiver object (this).The eqmethod implements an equivalence relation on non-null instances ofAnyRef, and has three additional properties:- It is consistent: for any non-null instances xandyof typeAnyRef, multiple invocations ofx.eq(y)consistently returnstrueor consistently returnsfalse.
- For any non-null instance xof typeAnyRef,x.eq(null)andnull.eq(x)returnsfalse.
- null.eq(null)returns- true.
 When overriding the equalsorhashCodemethods, 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
- trueif the argument is a reference to the receiver object;- falseotherwise.
 - Definition Classes
- AnyRef
 
- It is consistent: for any non-null instances 
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        def
      
      
        equals(arg0: Any): Boolean
      
      
      The equality method for reference types. 
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        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 finalizemethod is invoked, as well as the interaction betweenfinalizeand 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 
 
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        def
      
      
        formatted(fmtstr: String): String
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to StringFormat[Universe.Importer] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
 
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        final 
        def
      
      
        getClass(): Class[_]
      
      
      Returns the runtime class representation of the object. Returns the runtime class representation of the object. - returns
- a class object corresponding to the runtime type of the receiver. 
 - Definition Classes
- AnyRef → Any
 
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        def
      
      
        hashCode(): Int
      
      
      The hashCode method for reference types. 
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        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 returnfalse, while the expressionList(1).isInstanceOf[List[String]]will returntrue. 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
- trueif the receiver object is an instance of erasure of type- T0;- falseotherwise.
 - Definition Classes
- Any
 
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        final 
        def
      
      
        ne(arg0: AnyRef): Boolean
      
      
      Equivalent to !(this eq that).Equivalent to !(this eq that).- returns
- trueif the argument is not a reference to the receiver object;- falseotherwise.
 - Definition Classes
- AnyRef
 
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        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 
 
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        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 
 
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        final 
        def
      
      
        synchronized[T0](arg0: ⇒ T0): T0
      
      
      - Definition Classes
- AnyRef
 
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        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
 
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        final 
        def
      
      
        wait(): Unit
      
      
      - Definition Classes
- AnyRef
- Annotations
- @throws( ... )
 
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        final 
        def
      
      
        wait(arg0: Long, arg1: Int): Unit
      
      
      - Definition Classes
- AnyRef
- Annotations
- @throws( ... )
 
- 
      
      
      
        
      
    
      
        final 
        def
      
      
        wait(arg0: Long): Unit
      
      
      - Definition Classes
- AnyRef
- Annotations
- @throws( ... )
 
- 
      
      
      
        
      
    
      
        
        def
      
      
        →[B](y: B): (Universe.Importer, B)
      
      
      - Implicit
- This member is added by an implicit conversion from Universe.Importer to ArrowAssoc[Universe.Importer] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc