Scala example source code file (Internals.scala)

This example Scala source code file (Internals.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

contextinternalapi, internals, symbol, t, transformapi, tree, typingtransformapi

The Internals.scala Scala example source code

package scala
package reflect
package macros

/**
 *  <span class="badge badge-red" style="float: right;">EXPERIMENTAL</span>
 *  @see [[scala.reflect.api.Internals]]
 */
trait Internals {
  self: blackbox.Context =>

  /** @see [[scala.reflect.api.Internals]] */
  val internal: ContextInternalApi

  /** @see [[scala.reflect.api.Internals]] */
  trait ContextInternalApi extends universe.MacroInternalApi {
    /** Symbol associated with the innermost enclosing lexical context.
     *  Walking the owner chain of this symbol will reveal information about more and more enclosing contexts.
     */
    def enclosingOwner: Symbol

    /** Functions that are available during [[transform]].
     *  @see [[transform]]
     */
    trait TransformApi {
      /** Calls the current transformer on the given tree.
       *  Current transformer = argument to the `transform` call.
       */
      def recur(tree: Tree): Tree

      /** Calls the default transformer on the given tree.
       *  Default transformer = recur into tree's children and assemble the results.
       */
      def default(tree: Tree): Tree
    }

    /** Transforms a given tree using the provided function.
     *  @see [[TransformApi]]
     */
    // TODO: explore a more concise notation that Denys and I discussed today
    // when transformer is PartialFunction[Tree, Tree]] and TransformApi is passed magically
    // also cf. https://github.com/dsl-paradise/dsl-paradise
    def transform(tree: Tree)(transformer: (Tree, TransformApi) => Tree): Tree

    /** Functions that are available during [[typingTransform]].
     *  @see [[typingTransform]]
     */
    trait TypingTransformApi extends TransformApi {
      /** Temporarily pushes the given symbol onto the owner stack, creating a new local typer,
       *  invoke the given operation and then rollback the changes to the owner stack.
       */
      def atOwner[T](owner: Symbol)(op: => T): T

      /** Temporarily pushes the given tree onto the recursion stack, and then calls `atOwner(symbol)(trans)`.
       */
      def atOwner[T](tree: Tree, owner: Symbol)(op: => T): T

      /** Returns the symbol currently on the top of the owner stack.
       *  If we're not inside any `atOwner` call, then macro application's context owner will be used.
       */
      def currentOwner: Symbol

      /** Typechecks the given tree using the local typer currently on the top of the owner stack.
       *  If we're not inside any `atOwner` call, then macro application's callsite typer will be used.
       */
      def typecheck(tree: Tree): Tree
    }

    /** Transforms a given tree using the provided function.
     *  @see [[TypingTransformApi]]
     */
    def typingTransform(tree: Tree)(transformer: (Tree, TypingTransformApi) => Tree): Tree

    /** Transforms a given tree at a given owner using the provided function.
     *  @see [[TypingTransformApi]]
     */
    def typingTransform(tree: Tree, owner: Symbol)(transformer: (Tree, TypingTransformApi) => Tree): Tree
  }
}