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-package scala
-package reflect
-package api
-
-/**
- * <span class="badge badge-red" style="float: right;">EXPERIMENTAL</span>
- *
- * 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 [[scala.reflect.api.Symbols Symbols]] and [[scala.reflect.api.Types Types]],
- * are contained in [[scala.reflect.api.Universe Universe]]s. 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.mkImporter(c.universe)
- * val importer = importer0.asInstanceOf[ru.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]
- * ...
- * }
- * }}}
- *
- * @group ReflectionAPI
- */
-trait Importers { self: Universe =>
-
- /** Creates an importer that moves reflection artifacts between universes.
- * @group Importers
- */
- def mkImporter(from0: Universe): Importer { val from: from0.type }
-
- /** The API of importers.
- * The main source of information about importers is the [[scala.reflect.api.Importers]] page.
- * @group Importers
- */
- trait Importer {
- /** The source universe of reflection artifacts that will be processed.
- * The target universe is universe that created this importer with `mkImporter`.
- */
- val from: Universe
-
- /** An importer that works in reverse direction, namely:
- * imports reflection artifacts from the current universe to the universe specified in `from`.
- */
- val reverse: from.Importer { val from: self.type }
-
- /** 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.
- */
- def importSymbol(sym: from.Symbol): Symbol
-
- /** 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.
- */
- def importType(tpe: from.Type): Type
-
- /** 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.
- */
- def importTree(tree: from.Tree): Tree
-
- /** In the current universe, creates a position that corresponds to the provided position in the source universe.
- */
- def importPosition(pos: from.Position): Position
- }
-}