Scala Reflection Library2.12.21 < Back
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# Packages

-  package root
  Definition Classes
    root
-  package scala
  Definition Classes
    root
-  package reflect
  Definition Classes
    scala
-  package api

  EXPERIMENTAL

  EXPERIMENTAL

  The Scala Reflection API (located in scala-reflect.jar).

  In Scala 2.10.0, the Scala Reflection API and its implementation have an "experimental" status. This means that the API and the docs are not complete and can be changed in binary- and source-incompatible manner in 2.10.1. This also means that the implementation has some known issues.

  The following types are the backbone of the Scala Reflection API, and serve as a good starting point for information about Scala Reflection:

  - scala.reflect.api.Symbols
  - scala.reflect.api.Types
  - scala.reflect.api.Mirrors
  - scala.reflect.api.Universe

  For more information about Scala Reflection, see the Reflection Guide

  Definition Classes
    reflect
-  trait Trees extends AnyRef

  EXPERIMENTAL

  EXPERIMENTAL

  This trait defines the node types used in Scala abstract syntax trees (AST) and operations on them.

  Trees are the basis for Scala's abstract syntax that is used to represent programs. They are also called abstract syntax trees and commonly abbreviated as ASTs.

  In Scala reflection, APIs that produce or use `Tree`s are:

  - Annotations which use trees to represent their arguments, exposed in Annotation.scalaArgs.
  - reify, a special method on scala.reflect.api.Universe that takes an expression and returns an AST which represents the expression.
  - Macros and runtime compilation with toolboxes which both use trees as their program representation medium.

  Trees are immutable, except for three fields pos, symbol, and tpe, which are assigned when a tree is typechecked to attribute it with the information gathered by the typechecker.

  ##### Examples

  The following creates an AST representing a literal 5 in Scala source code:

      Literal(Constant(5))

  The following creates an AST representing `print("Hello World")`:

      Apply(Select(Select(This(TypeName("scala")), TermName("Predef")), TermName("print")), List(Literal(Constant("Hello World"))))

  The following creates an AST from a literal 5, and then uses `showRaw` to print it in a readable format.

      import scala.reflect.runtime.universe.{ reify, showRaw }
      print( showRaw( reify{5}.tree ) )` // prints Literal(Constant(5))

  For more information about `Tree`s, see the Reflection Guide: Symbols, Trees, Types.

  Definition Classes
    api
- Alternative
- AlternativeApi
- AlternativeExtractor
- Annotated
- AnnotatedApi
- AnnotatedExtractor
- AppliedTypeTree
- AppliedTypeTreeApi
- AppliedTypeTreeExtractor
- Apply
- ApplyApi
- ApplyExtractor
- Assign
- AssignApi
- AssignExtractor
- AssignOrNamedArg
- AssignOrNamedArgApi
- AssignOrNamedArgExtractor
- Bind
- BindApi
- BindExtractor
- Block
- BlockApi
- BlockExtractor
- CaseDef
- CaseDefApi
- CaseDefExtractor
- ClassDef
- ClassDefApi
- ClassDefExtractor
- CompoundTypeTree
- CompoundTypeTreeApi
- CompoundTypeTreeExtractor
- DefDef
- DefDefApi
- DefDefExtractor
- DefTree
- DefTreeApi
- ExistentialTypeTree
- ExistentialTypeTreeApi
- ExistentialTypeTreeExtractor
- Function
- FunctionApi
- FunctionExtractor
- GenericApply
- GenericApplyApi
- Ident
- IdentApi
- IdentExtractor
- If
- IfApi
- IfExtractor
- ImplDef
- ImplDefApi
- Import
- ImportApi
- ImportExtractor
- ImportSelector
- ImportSelectorApi
- ImportSelectorExtractor
- LabelDef
- LabelDefApi
- LabelDefExtractor
- Literal
- LiteralApi
- LiteralExtractor
- Match
- MatchApi
- MatchExtractor
- MemberDef
- MemberDefApi
- Modifiers
- ModifiersApi
- ModifiersExtractor
- ModuleDef
- ModuleDefApi
- ModuleDefExtractor
- NameTree
- NameTreeApi
- New
- NewApi
- NewExtractor
- PackageDef
- PackageDefApi
- PackageDefExtractor
- RefTree
- RefTreeApi
- RefTreeExtractor
- Return
- ReturnApi
- ReturnExtractor
- Select
- SelectApi
- SelectExtractor
- SelectFromTypeTree
- SelectFromTypeTreeApi
- SelectFromTypeTreeExtractor
- SingletonTypeTree
- SingletonTypeTreeApi
- SingletonTypeTreeExtractor
- Star
- StarApi
- StarExtractor
- Super
- SuperApi
- SuperExtractor
- SymTree
- SymTreeApi
- Template
- TemplateApi
- TemplateExtractor
- TermTree
- TermTreeApi
- This
- ThisApi
- ThisExtractor
- Throw
- ThrowApi
- ThrowExtractor
- Transformer
- Traverser
- Tree
- TreeApi
- TreeCopier
- TreeCopierOps
- Try
- TryApi
- TryExtractor
- TypTree
- TypTreeApi
- TypeApply
- TypeApplyApi
- TypeApplyExtractor
- TypeBoundsTree
- TypeBoundsTreeApi
- TypeBoundsTreeExtractor
- TypeDef
- TypeDefApi
- TypeDefExtractor
- TypeTree
- TypeTreeApi
- TypeTreeExtractor
- Typed
- TypedApi
- TypedExtractor
- UnApply
- UnApplyApi
- UnApplyExtractor
- ValDef
- ValDefApi
- ValDefExtractor
- ValOrDefDef
- ValOrDefDefApi

a

scala.reflect.api.Trees

# Literal 

###
Companion class LiteralExtractor

#### abstract type Literal >: Null <: Universe.LiteralApi with Universe.TermTree

Literal

Source
  Trees.scala

Linear Supertypes
Universe.<refinement>, Universe.<refinement>, Universe.LiteralApi, Universe.TermTreeApi, Universe.TreeApi, Product, Equals, AnyRef, Any
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Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. Literal
2. <refinement>
3. <refinement>
4. LiteralApi
5. TermTreeApi
6. TreeApi
7. Product
8. Equals
9. AnyRef
10. Any

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2. Show All

Visibility

1. Public
2. All

### Abstract Value Members

1.  abstract def canEqual(that: Any): Boolean
   Definition Classes
     Equals
2.  abstract def canHaveAttrs: Boolean

   Can this tree carry attributes (i.e.

   Can this tree carry attributes (i.e. symbols, types or positions)? Typically the answer is yes, except for the `EmptyTree` null object and two special singletons: `noSelfType` and `pendingSuperCall`.

   Definition Classes
     TreeApi
3.  abstract def children: List[Universe.Tree]

   The direct child trees of this tree.

   The direct child trees of this tree. EmptyTrees are always omitted. Lists are flattened.

   Definition Classes
     TreeApi
4.  abstract def collect[T](pf: PartialFunction[Universe.Tree, T]): List[T]

   Apply `pf` to each subtree on which the function is defined and collect the results.

   Apply `pf` to each subtree on which the function is defined and collect the results.

   Definition Classes
     TreeApi
5.  abstract def duplicate: TreeApi.this.type

   Make a copy of this tree, keeping all attributes, except that all positions are focused (so nothing in this tree will be found when searching by position).

   Make a copy of this tree, keeping all attributes, except that all positions are focused (so nothing in this tree will be found when searching by position).

   Definition Classes
     TreeApi
6.  abstract def equalsStructure(that: Universe.Tree): Boolean

   Tests whether two trees are structurally equal.

   Tests whether two trees are structurally equal. Note that `==` on trees is reference equality.

   Definition Classes
     TreeApi
7.  abstract def exists(p: (Universe.Tree) ⇒ Boolean): Boolean

   Is there exists a part of this tree which satisfies predicate `p`?

   Is there exists a part of this tree which satisfies predicate `p`?

   Definition Classes
     TreeApi
8.  abstract def filter(f: (Universe.Tree) ⇒ Boolean): List[Universe.Tree]

   Find all subtrees matching predicate `p`.

   Find all subtrees matching predicate `p`. Same as `withFilter`

   Definition Classes
     TreeApi
9.  abstract def find(p: (Universe.Tree) ⇒ Boolean): Option[Universe.Tree]

   Returns optionally first tree (in a preorder traversal) which satisfies predicate `p`, or None if none exists.

   Returns optionally first tree (in a preorder traversal) which satisfies predicate `p`, or None if none exists.

   Definition Classes
     TreeApi
10.  abstract def forAll(p: (Universe.Tree) ⇒ Boolean): Boolean

    Do all parts of this tree satisfy predicate `p`?

    Do all parts of this tree satisfy predicate `p`?

    Definition Classes
      TreeApi
11.  abstract def foreach(f: (Universe.Tree) ⇒ Unit): Unit

    Apply `f` to each subtree

    Apply `f` to each subtree

    Definition Classes
      TreeApi
12.  abstract def isDef: Boolean

    Does this tree represent a definition? (of a method, of a class, etc)

    Does this tree represent a definition? (of a method, of a class, etc)

    Definition Classes
      TreeApi
13.  abstract def isEmpty: Boolean

    Is this tree one of the empty trees?

    Is this tree one of the empty trees?

    Empty trees are: the `EmptyTree` null object and `TypeTree` instances that don't carry a type.

    Definition Classes
      TreeApi
    See also

      `canHaveAttrs`

14.  abstract def isTerm: Boolean

    The canonical way to test if a Tree represents a term.

    The canonical way to test if a Tree represents a term.

    Definition Classes
      TreeApi
15.  abstract def isType: Boolean

    The canonical way to test if a Tree represents a type.

    The canonical way to test if a Tree represents a type.

    Definition Classes
      TreeApi
16.  abstract def nonEmpty: Boolean

    Is this tree not an empty tree?

    Is this tree not an empty tree?

    Definition Classes
      TreeApi
    See also

      `isEmpty`

17.  abstract def orElse(alt: ⇒ Universe.Tree): Universe.Tree

    Provides an alternate if tree is empty

    Provides an alternate if tree is empty

    alt

      The alternate tree

    returns

      If this tree is non empty, this tree, otherwise `alt`.

    Definition Classes
      TreeApi
18.  abstract def pos: Universe.Position

    Position of the tree.

    Position of the tree.

    Definition Classes
      TreeApi
19.  abstract def productArity: Int
    Definition Classes
      Product
20.  abstract def productElement(n: Int): Any
    Definition Classes
      Product
21.  abstract def symbol: Universe.Symbol

    Symbol of the tree.

    Symbol of the tree.

    For most trees symbol is `null`. In `SymTree`s, it is overridden and implemented with a var, initialized to `NoSymbol`.

    Trees which are not `SymTree`s but which carry symbols do so by overriding `def symbol` to forward it elsewhere. Examples:

    - `Super(qual, _)` has `qual`'s symbol,
    - `Apply(fun, args)` has `fun`'s symbol,
    - `TypeApply(fun, args)` has `fun`'s symbol,
    - `AppliedTypeTree(tpt, args)` has `tpt`'s symbol,
    - `TypeTree(tpe)` has `tpe`'s `typeSymbol`, if `tpe != null`.
    Definition Classes
      TreeApi
22.  abstract def tpe: Universe.Type

    Type of the tree.

    Type of the tree.

    Upon creation most trees have their `tpe` set to `null`. Types are typically assigned to trees during typechecking. Some node factory methods set `tpe` immediately after creation.

    When the typechecker encounters a tree with a non-null tpe, it will assume it to be correct and not check it again. This means one has to be careful not to erase the `tpe` field of subtrees.

    Definition Classes
      TreeApi
23.  abstract def value: Universe.Constant

    The compile-time constant underlying the literal.

    The compile-time constant underlying the literal.

    Definition Classes
      LiteralApi
24.  abstract def withFilter(f: (Universe.Tree) ⇒ Boolean): List[Universe.Tree]

    Find all subtrees matching predicate `p`.

    Find all subtrees matching predicate `p`. Same as `filter`

    Definition Classes
      TreeApi

### Concrete Value Members

1.  final def !=(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
2.  final def ##(): Int
   Definition Classes
     AnyRef → Any
3.  final def ==(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
4.  final def asInstanceOf[T0]: T0
   Definition Classes
     Any
5.  def clone(): AnyRef
   Attributes
     protected[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( ... ) @native()
6.  final def eq(arg0: AnyRef): Boolean
   Definition Classes
     AnyRef
7.  def equals(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
8.  def finalize(): Unit
   Attributes
     protected[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( classOf[java.lang.Throwable] )
9.  final def getClass(): Class[_]
   Definition Classes
     AnyRef → Any
   Annotations
     @native()
10.  def hashCode(): Int
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
11.  final def isInstanceOf[T0]: Boolean
    Definition Classes
      Any
12.  final def ne(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
13.  final def notify(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
14.  final def notifyAll(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
15.  def productIterator: Iterator[Any]
    Definition Classes
      Product
16.  def productPrefix: String
    Definition Classes
      Product
17.  final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
      AnyRef
18.  def toString(): String

    Obtains string representation of a tree

    Obtains string representation of a tree

    Definition Classes
      TreeApi → AnyRef → Any
19.  final def wait(): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
20.  final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
21.  final def wait(arg0: Long): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... ) @native()

### Inherited from Universe.<refinement>

### Inherited from Universe.LiteralApi

### Inherited from Universe.TermTreeApi

### Inherited from Universe.TreeApi

### Inherited from Product

### Inherited from Equals

### Inherited from AnyRef

### Inherited from Any

### Ungrouped