package scala.reflect
package macros
/** A slice of [[scala.reflect.macros.Context the Scala macros context]] that
* partially exposes the type checker to macro writers.
*/
trait Typers {
self: Context =>
import universe._
/** 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 `openMacros` 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 `enclosingMacros`, this is a def, which means that it gets recalculated on every invocation,
* so it might change depending on what is going on during macro expansion.
*/
def openMacros: List[Context]
/** Types along with corresponding trees for which implicit arguments are currently searched.
* Can be useful to get information about an application with an implicit parameter that is materialized during current macro expansion.
*
* Unlike `enclosingImplicits`, this is a def, which means that it gets recalculated on every invocation,
* so it might change depending on what is going on during macro expansion.
*/
def openImplicits: List[(Type, Tree)]
/** Typechecks the provided tree against the expected type `pt` in the macro callsite context.
*
* If `silent` is false, `TypecheckException` will be thrown in case of a typecheck error.
* If `silent` is true, the typecheck is silent and will return `EmptyTree` if an error occurs.
* Such errors don't vanish and can be inspected by turning on -Ymacro-debug-verbose.
* Unlike in `inferImplicitValue` and `inferImplicitView`, `silent` is false by default.
*
* Typechecking can be steered with the following optional parameters:
* `withImplicitViewsDisabled` recursively prohibits implicit views (though, implicit vals will still be looked up and filled in), default value is false
* `withMacrosDisabled` recursively prohibits macro expansions and macro-based implicits, default value is false
*
* @throws [[scala.reflect.macros.TypecheckException]]
*/
def typeCheck(tree: Tree, pt: Type = WildcardType, silent: Boolean = false, withImplicitViewsDisabled: Boolean = false, withMacrosDisabled: Boolean = false): Tree
/** Infers an implicit value of the expected type `pt` in the macro callsite context.
* Optional `pos` parameter provides a position that will be associated with the implicit search.
*
* If `silent` is false, `TypecheckException` will be thrown in case of an inference error.
* If `silent` is true, the typecheck is silent and will return `EmptyTree` if an error occurs.
* Such errors don't vanish and can be inspected by turning on -Xlog-implicits.
* Unlike in `typeCheck`, `silent` is true by default.
*
* @throws [[scala.reflect.macros.TypecheckException]]
*/
def inferImplicitValue(pt: Type, silent: Boolean = true, withMacrosDisabled: Boolean = false, pos: Position = enclosingPosition): Tree
/** Infers an implicit view from the provided tree `tree` of the type `from` to the type `to` in the macro callsite context.
* Optional `pos` parameter provides a position that will be associated with the implicit search.
*
* If `silent` is false, `TypecheckException` will be thrown in case of an inference error.
* If `silent` is true, the typecheck is silent and will return `EmptyTree` if an error occurs.
* Such errors don't vanish and can be inspected by turning on -Xlog-implicits.
* Unlike in `typeCheck`, `silent` is true by default.
*
* @throws [[scala.reflect.macros.TypecheckException]]
*/
def inferImplicitView(tree: Tree, from: Type, to: Type, silent: Boolean = true, withMacrosDisabled: Boolean = false, pos: Position = enclosingPosition): Tree
/** Recursively resets symbols and types in a given tree.
*
* Note that this does not revert the tree to its pre-typer shape.
* For more info, read up https://issues.scala-lang.org/browse/SI-5464.
*/
def resetAllAttrs(tree: Tree): Tree
/** Recursively resets locally defined symbols and types in a given tree.
*
* Note that this does not revert the tree to its pre-typer shape.
* For more info, read up https://issues.scala-lang.org/browse/SI-5464.
*/
def resetLocalAttrs(tree: Tree): Tree
}
/** Indicates an error during one of the methods in [[scala.reflect.macros.Typers]].
*/
case class TypecheckException(val pos: scala.reflect.api.Position, val msg: String) extends Exception(msg)
