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package scala
package reflect
package macros
import scala.language.existentials // SI-6541
/**
* <span class="badge badge-red" style="float: right;">EXPERIMENTAL</span>
*
* A slice of [[scala.reflect.macros.BlackboxContext the Scala macros context]] that exposes
* enclosing trees (method, class, compilation unit and currently compiled application),
* the enclosing position of the macro expansion, as well as macros and implicits
* that are currently in-flight.
*/
trait Enclosures {
self: BlackboxContext =>
/** The tree that undergoes macro expansion.
* Can be useful to get an offset or a range position of the entire tree being processed.
*/
def macroApplication: Tree
/** The semantic role that `macroApplication` plays in the code.
*/
type MacroRole
/** The role that represents an application of a term macro,
* e.g. `M(2)(3)` in `val x = M(2)(3)` or `M(a, b)` in `x match { case x @ M(a, b) => }`.
*/
def APPLY_ROLE: MacroRole
/** The semantic role that `macroApplication` plays in the code.
*/
def macroRole: MacroRole
/** Contexts that represent macros in-flight, including the current one. Very much like a stack trace, but for macros only.
* Can be useful for interoperating with other macros and for imposing compiler-friendly limits on macro expansion.
*
* Is also priceless for emitting sane error messages for macros that are called by other macros on synthetic (i.e. position-less) trees.
* In that dire case navigate the `enclosingMacros` stack, and it will most likely contain at least one macro with a position-ful macro application.
* See `enclosingPosition` for a default implementation of this logic.
*
* Unlike `openMacros`, this is a val, which means that it gets initialized when the context is created
* and always stays the same regardless of whatever happens during macro expansion.
*/
def enclosingMacros: List[BlackboxContext]
/** Tries to guess a position for the enclosing application.
* But that is simple, right? Just dereference `pos` of `macroApplication`? Not really.
* If we're in a synthetic macro expansion (no positions), we must do our best to infer the position of something that triggerd this expansion.
* Surprisingly, quite often we can do this by navigation the `enclosingMacros` stack.
*/
def enclosingPosition: Position
/** Tree that corresponds to the enclosing method, or EmptyTree if not applicable.
*/
@deprecated("Use enclosingDef instead, but be wary of changes in semantics", "2.10.1")
def enclosingMethod: Tree
/** Tree that corresponds to the enclosing class, or EmptyTree if not applicable.
*/
@deprecated("Use enclosingImpl instead, but be wary of changes in semantics", "2.10.1")
def enclosingClass: Tree
/** Tree that corresponds to the enclosing DefDef tree.
* Throws `EnclosureException` if there's no such enclosing tree.
*/
def enclosingDef: universe.DefDef
/** Tree that corresponds to the enclosing Template tree.
* Throws `EnclosureException` if there's no such enclosing tree.
*/
def enclosingTemplate: universe.Template
/** Tree that corresponds to the enclosing ImplDef tree (i.e. either ClassDef or ModuleDef).
* Throws `EnclosureException` if there's no such enclosing tree.
*/
def enclosingImpl: universe.ImplDef
/** Tree that corresponds to the enclosing PackageDef tree.
* Throws `EnclosureException` if there's no such enclosing tree.
*/
def enclosingPackage: universe.PackageDef
/** Compilation unit that contains this macro application.
*/
def enclosingUnit: CompilationUnit
/** Compilation run that contains this macro application.
*/
def enclosingRun: Run
/** Indicates than one of the enclosure methods failed to find a tree
* of required type among enclosing trees.
*/
case class EnclosureException(expected: Class[_], enclosingTrees: List[Tree])
extends Exception(s"Couldn't find a tree of type $expected among enclosing trees $enclosingTrees")
}
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