Importer
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package Internals
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.
In the current universe, creates a position that corresponds to the provided position in the source universe.
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.
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.
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.
An importer that works in reverse direction, namely:
imports reflection artifacts from the current universe to the universe specified in from.
Test two objects for inequality.
Test two objects for inequality.
true if !(this == that), false otherwise.
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.
a hash value consistent with ==
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).
true if the receiver object is equivalent to the argument; false otherwise.
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.
the receiver object.
ClassCastException if the receiver object is not an instance of the erasure of type T0.
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
a copy of the receiver object.
not specified by SLS as a member of AnyRef
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 eq method implements an equivalence relation on
non-null instances of AnyRef, and has three additional properties:
x and y of type AnyRef, multiple invocations of
x.eq(y) consistently returns true or consistently returns false.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).
true if the argument is a reference to the receiver object; false otherwise.
The equality method for reference types.
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.
not specified by SLS as a member of AnyRef
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.
a representation that corresponds to the dynamic class of the receiver object.
not specified by SLS as a member of AnyRef
The hashCode method for reference types.
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.
true if the receiver object is an instance of erasure of type T0; false otherwise.
Equivalent to !(this eq that).
Equivalent to !(this eq that).
true if the argument is not a reference to the receiver object; false otherwise.
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.
not specified by SLS as a member of AnyRef
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.
not specified by SLS as a member of AnyRef
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.
a String representation of the object.
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 macroUniverseor a runtime reflectionUniverse), but sometimes there is a need to migrate artifacts from oneUniverseto 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 usingImporters, however, they be imported from one universe into another. For example, to importfoo.bar.Bazfrom the sourceUniverseto the targetUniverse, an importer will first check whether the entire owner chain exists in the targetUniverse. 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 targetUniverse.Since importers match
Symboltables of the source and the targetUniverses using plain string names, it is programmer's responsibility to make sure that imports don't distort semantics, e.g., thatfoo.bar.Bazin the sourceUniversemeans the same thatfoo.bar.Bazdoes in the targetUniverse.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: