abstract class Attachments extends AnyRef
EXPERIMENTAL
Attachments provide a way to associate custom metadata with symbols and trees.
Along with symbol
and tpe
, which represent core metadata of trees, each tree
carries the attachments
field that can store other metadata: compiler-defined (e.g. positions) or user-defined.
Same story is true for symbols, which also have extensible metadata by the virtue
of the same attachments
field.
Typically attachments just store a scala.reflect.api.Position, but they can be extended to
encompass arbitrary payloads. Payloads are stored in type-indexed slots, which can be read with get[T]
and written
with update[T]
and remove[T]
.
This API doesn't have much use in the runtime reflection API (the scala.reflect.api package), but it might be of help
for macro writers, providing a way to coordinate multiple macros operating on the same code. Therefore the attachments
field is only declared in trees and symbols belonging to scala.reflect.macros.Universe.
- Self Type
- Attachments
- Source
- Attachments.scala
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Instance Constructors
- new Attachments()
Type Members
-
abstract
type
Pos >: Null
The position type of this attachment
Abstract Value Members
-
abstract
def
pos: Pos
The underlying position
-
abstract
def
withPos(newPos: Pos): Attachments { type Pos = Attachments.this.Pos }
Creates a copy of this attachment with the position replaced by
newPos
Concrete Value Members
-
def
all: Set[Any]
The underlying payload with the guarantee that no two elements have the same type.
-
def
contains[T](implicit arg0: ClassTag[T]): Boolean
Check underlying payload contains an instance of type
T
. -
def
get[T](implicit arg0: ClassTag[T]): Option[T]
An underlying payload of the given class type
T
. - def isEmpty: Boolean
-
def
remove[T](implicit arg0: ClassTag[T]): Attachments { type Pos = Attachments.this.Pos }
Creates a copy of this attachment with the payload of the given class type
T
removed. -
def
update[T](attachment: T)(implicit arg0: ClassTag[T]): Attachments { type Pos = Attachments.this.Pos }
Creates a copy of this attachment with the payload slot of T added/updated with the provided value.
Creates a copy of this attachment with the payload slot of T added/updated with the provided value. Replaces an existing payload of the same type, if exists.