scala.tools.nsc.transform

# TailCalls

#### abstract class TailCalls extends SubComponent with Transform

Perform tail recursive call elimination.

Source
  TailCalls.scala
Version

  1.0

Linear Supertypes
Transform, SubComponent, AnyRef, Any
Known Subclasses
tailCalls
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2. By inheritance

Inherited

1. TailCalls
2. Transform
3. SubComponent
4. AnyRef
5. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

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1. Public
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### Instance Constructors

1. #### new TailCalls()

### Type Members

1. #### class Phase extends StdPhase

   The phase defined by this transform

2. #### abstract class StdPhase extends GlobalPhase

   A standard phase template

   A standard phase template

   Definition Classes
     SubComponent

3. #### class TailCallElimination extends Global.Transformer

   A Tail Call Transformer

   A Tail Call Transformer

   Version

     1.1

     What it does:

     Finds method calls in tail-position and replaces them with jumps. A call is in a tail-position if it is the last instruction to be executed in the body of a method. This is done by recursing over the trees that may contain calls in tail-position (trees that can't contain such calls are not transformed). However, they are not that many.

     Self-recursive calls in tail-position are replaced by jumps to a label at the beginning of the method. As the JVM provides no way to jump from a method to another one, non-recursive calls in tail-position are not optimized.

     A method call is self-recursive if it calls the current method and the method is final (otherwise, it could be a call to an overridden method in a subclass). Furthermore, If the method has type parameters, the call must contain these parameters as type arguments. Recursive calls on a different instance are optimized. Since 'this' is not a local variable, a dummy local val is added and used as a label parameter. The backend knows to load the corresponding argument in the 'this' (local at index 0). This dummy local is never used and should be cleand up by dead code elimination (when enabled).

     This phase has been moved before pattern matching to catch more of the common cases of tail recursive functions. This means that more cases should be taken into account (like nested function, and pattern cases).

     If a method contains self-recursive calls, a label is added to at the beginning of its body and the calls are replaced by jumps to that label.

     Assumes: `Uncurry` has been run already, and no multiple parameter lists exit.

4. #### class TailPosLabelsTraverser extends Global.Traverser

### Abstract Value Members

1. #### abstract val global: Global

   The global environment; overridden by instantiation in Global.

   The global environment; overridden by instantiation in Global.

   Definition Classes
     SubComponent

2. #### abstract val runsAfter: List[String]

   Names of phases that must run before this phase.

   Names of phases that must run before this phase.

   Definition Classes
     SubComponent

3. #### abstract val runsRightAfter: Option[String]

   Name of the phase that this phase must follow immediately.

   Name of the phase that this phase must follow immediately.

   Definition Classes
     SubComponent

### Concrete Value Members

1. #### final def !=(arg0: Any): Boolean

   Definition Classes
     AnyRef → Any

2. #### final def ##(): Int

   Definition Classes
     AnyRef → Any

3. #### def +(other: String): String

   Implicit information
     This member is added by an implicit conversion from TailCalls to any2stringadd[TailCalls] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd

4. #### def ->[B](y: B): (TailCalls, B)

   Implicit information
     This member is added by an implicit conversion from TailCalls to ArrowAssoc[TailCalls] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()

5. #### final def ==(arg0: Any): Boolean

   Definition Classes
     AnyRef → Any

6. #### final def afterOwnPhase[T](op: ⇒ T): T

   Definition Classes
     SubComponent
   Annotations
     @inline()

7. #### final def asInstanceOf[T0]: T0

   Definition Classes
     Any

8. #### final def beforeOwnPhase[T](op: ⇒ T): T

   Definition Classes
     SubComponent
   Annotations
     @inline()

9. #### def clone(): AnyRef

   Attributes
     protected[java.lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( ... )

10. #### def enabled: Boolean

    Is this component enabled? Default is true.

    Is this component enabled? Default is true.

    Definition Classes
      SubComponent

11. #### def ensuring(cond: (TailCalls) ⇒ Boolean, msg: ⇒ Any): TailCalls

    Implicit information
      This member is added by an implicit conversion from TailCalls to Ensuring[TailCalls] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

12. #### def ensuring(cond: (TailCalls) ⇒ Boolean): TailCalls

    Implicit information
      This member is added by an implicit conversion from TailCalls to Ensuring[TailCalls] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

13. #### def ensuring(cond: Boolean, msg: ⇒ Any): TailCalls

    Implicit information
      This member is added by an implicit conversion from TailCalls to Ensuring[TailCalls] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

14. #### def ensuring(cond: Boolean): TailCalls

    Implicit information
      This member is added by an implicit conversion from TailCalls to Ensuring[TailCalls] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

15. #### final def eq(arg0: AnyRef): Boolean

    Definition Classes
      AnyRef

16. #### def equals(arg0: Any): Boolean

    Definition Classes
      AnyRef → Any

17. #### def finalize(): Unit

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )

18. #### def formatted(fmtstr: String): String

    Implicit information
      This member is added by an implicit conversion from TailCalls to StringFormat[TailCalls] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()

19. #### final def getClass(): Class[_]

    Definition Classes
      AnyRef → Any

20. #### def hashCode(): Int

    SubComponent are added to a HashSet and two phases are the same if they have the same name

    SubComponent are added to a HashSet and two phases are the same if they have the same name

    Definition Classes
      SubComponent → AnyRef → Any

21. #### val initial: Boolean

    True if this phase runs before all other phases.

    True if this phase runs before all other phases. Usually, `parser`.

    Definition Classes
      SubComponent

22. #### val internal: Boolean

    True if this phase is not provided by a plug-in.

    True if this phase is not provided by a plug-in.

    Definition Classes
      SubComponent

23. #### final def isInstanceOf[T0]: Boolean

    Definition Classes
      Any

24. #### final def ne(arg0: AnyRef): Boolean

    Definition Classes
      AnyRef

25. #### def newPhase(prev: nsc.Phase): StdPhase

    Create a new phase which applies transformer

    Create a new phase which applies transformer

    Definition Classes
      TailCalls → Transform → SubComponent

26. #### def newTransformer(unit: Global.CompilationUnit): Global.Transformer

    The transformer factory

    The transformer factory

    Definition Classes
      TailCalls → Transform

27. #### final def notify(): Unit

    Definition Classes
      AnyRef

28. #### final def notifyAll(): Unit

    Definition Classes
      AnyRef

29. #### def ownPhase: nsc.Phase

    The phase corresponding to this subcomponent in the current compiler run

    The phase corresponding to this subcomponent in the current compiler run

    Definition Classes
      SubComponent

30. #### val phaseName: String

    The name of the phase

    The name of the phase

    Definition Classes
      TailCalls → SubComponent

31. #### def phaseNewFlags: Long

    New flags defined by the phase which are not valid before

    New flags defined by the phase which are not valid before

    Definition Classes
      SubComponent

32. #### def phaseNextFlags: Long

    New flags defined by the phase which are not valid until immediately after it

    New flags defined by the phase which are not valid until immediately after it

    Definition Classes
      SubComponent

33. #### val requires: List[String]

    Names of phases required by this component.

    Names of phases required by this component. Default is `Nil`.

    Definition Classes
      SubComponent

34. #### val runsBefore: List[String]

    Names of phases that must run after this phase.

    Names of phases that must run after this phase. Default is `Nil`.

    Definition Classes
      SubComponent

35. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

36. #### val terminal: Boolean

    True if this phase runs after all other phases.

    True if this phase runs after all other phases. Usually, `terminal`.

    Definition Classes
      SubComponent

37. #### def toString(): String

    Definition Classes
      AnyRef → Any

38. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

39. #### final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

40. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

41. #### def →[B](y: B): (TailCalls, B)

    Implicit information
      This member is added by an implicit conversion from TailCalls to ArrowAssoc[TailCalls] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Inherited from Transform

### Inherited from SubComponent

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from TailCalls to any2stringadd[TailCalls]

### Inherited by implicit conversion StringFormat from TailCalls to StringFormat[TailCalls]

### Inherited by implicit conversion Ensuring from TailCalls to Ensuring[TailCalls]

### Inherited by implicit conversion ArrowAssoc from TailCalls to ArrowAssoc[TailCalls]

### Ungrouped