Scala Compiler2.12.18 < Back
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# Packages

-  package root

  The Scala compiler and reflection APIs.

  The Scala compiler and reflection APIs.

  Definition Classes
    root
-  package scala
  Definition Classes
    root
-  package tools
  Definition Classes
    scala
-  package nsc
  Definition Classes
    tools
-  package transform
  Definition Classes
    nsc
-  abstract class TailCalls extends SubComponent with Transform

  Perform tail recursive call elimination.

  Perform tail recursive call elimination.

  Definition Classes
    transform
  Version

    1.0

-  class TailCallElimination extends Global.Transformer

  A Tail Call Transformer

  A Tail Call Transformer

  Definition Classes
    TailCalls
  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 `@specialized` annotated type parameters, the recursive 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 cleaned 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 exist.

- ClonedTailContext
- DefDefTailContext
- EmptyTailContext
- TailContext

c

scala.tools.nsc.transform.TailCalls.TailCallElimination

# DefDefTailContext 

###

#### class DefDefTailContext extends TailContext

Source
  TailCalls.scala

Linear Supertypes
TailContext, AnyRef, Any
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Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. DefDefTailContext
2. TailContext
3. AnyRef
4. Any

Implicitly

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

1. Hide All
2. Show All

Visibility

1. Public
2. All

### Instance Constructors

1.  new DefDefTailContext(dd: Global.DefDef)

### 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
     This member is added by an implicit conversion from DefDefTailContext to any2stringadd[DefDefTailContext] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (DefDefTailContext, B)
   Implicit
     This member is added by an implicit conversion from DefDefTailContext to ArrowAssoc[DefDefTailContext] 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 asInstanceOf[T0]: T0
   Definition Classes
     Any
7.  def clone(): AnyRef
   Attributes
     protected[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( ... ) @native()
8.  def clonedTailContext(tailPos: Boolean): TailContext
   Attributes
     protected
   Definition Classes
     TailContext
9.  def containsRecursiveCall(t: Global.Tree): Boolean
10.  def enclosingType: Global.Type
    Definition Classes
      TailContext
11.  def ensuring(cond: (DefDefTailContext) ⇒ Boolean, msg: ⇒ Any): DefDefTailContext
    Implicit
      This member is added by an implicit conversion from DefDefTailContext to Ensuring[DefDefTailContext] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
12.  def ensuring(cond: (DefDefTailContext) ⇒ Boolean): DefDefTailContext
    Implicit
      This member is added by an implicit conversion from DefDefTailContext to Ensuring[DefDefTailContext] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
13.  def ensuring(cond: Boolean, msg: ⇒ Any): DefDefTailContext
    Implicit
      This member is added by an implicit conversion from DefDefTailContext to Ensuring[DefDefTailContext] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
14.  def ensuring(cond: Boolean): DefDefTailContext
    Implicit
      This member is added by an implicit conversion from DefDefTailContext to Ensuring[DefDefTailContext] 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[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )
18.  final def getClass(): Class[_]
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
19.  def hashCode(): Int
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
20.  def isEligible: Boolean
    Definition Classes
      TailContext
21.  final def isInstanceOf[T0]: Boolean
    Definition Classes
      Any
22.  def isMandatory: Boolean
    Definition Classes
      TailContext
23.  def isTransformed: Boolean
    Definition Classes
      TailContext
24.  lazy val label: Global.MethodSymbol
    Definition Classes
      DefDefTailContext → TailContext
25.  def method: Global.Symbol
    Definition Classes
      DefDefTailContext → TailContext
26.  def methodPos: Global.Position
    Definition Classes
      DefDefTailContext → TailContext
27.  final def ne(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
28.  def newThis(pos: Global.Position): Global.TermSymbol
    Definition Classes
      TailContext
29.  final def noTailContext(): TailContext
    Definition Classes
      TailContext
30.  final def notify(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
31.  final def notifyAll(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
32.  final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
      AnyRef
33.  lazy val tailLabels: Set[Global.Symbol]
    Definition Classes
      DefDefTailContext → TailContext
34.  def tailPos: Boolean
    Definition Classes
      DefDefTailContext → TailContext
35.  def toString(): String
    Definition Classes
      TailContext → AnyRef → Any
36.  def tparams: List[Global.Symbol]
    Definition Classes
      DefDefTailContext → TailContext
37.  final def wait(): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
38.  final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
39.  final def wait(arg0: Long): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... ) @native()
40.  final def yesTailContext(): TailContext
    Definition Classes
      TailContext
41.  def →[B](y: B): (DefDefTailContext, B)
    Implicit
      This member is added by an implicit conversion from DefDefTailContext to ArrowAssoc[DefDefTailContext] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Deprecated Value Members

1.  def formatted(fmtstr: String): String
   Implicit
     This member is added by an implicit conversion from DefDefTailContext to StringFormat[DefDefTailContext] performed by method StringFormat in scala.Predef.
   Definition Classes
     StringFormat
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.

### Inherited from TailContext

### Inherited from AnyRef

### Inherited from Any

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

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

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

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

### Ungrouped