LambdaLift

This phase performs the necessary rewritings to eliminate classes and methods nested in other methods. In detail:

  1. It adds all free variables of local functions as additional parameters (proxies).
  2. It rebinds references to free variables to the corresponding proxies,
  3. It lifts all local functions and classes out as far as possible, but at least to the enclosing class.
  4. It stores free variables of non-trait classes as additional fields of the class. The fields serve as proxies for methods in the class, which avoids the need of passing additional parameters to these methods.

A particularly tricky case are local traits. These cannot store free variables as field proxies, because LambdaLift runs after Mixin, so the fields cannot be expanded anymore. Instead, methods of local traits get free variables of the trait as additional proxy parameters. The difference between local classes and local traits is illustrated by the two rewritings below.

def f(x: Int) = { def f(x: Int) = new C(x).f2 class C { ==> class C(x$1: Int) { def f2 = x def f2 = x$1 } } new C().f2 }

def f(x: Int) = { def f(x: Int) = new C().f2(x) trait T { ==> trait T def f2 = x def f2(x$1: Int) = x$1 } } class C extends T class C extends T new C().f2 }

Companion:
object
class MiniPhase
class Phase
class Object
trait Matchable
class Any

Value members

Concrete methods

override def description: String
Definition Classes
override def initContext(ctx: FreshContext): Unit
Definition Classes
override def phaseName: String
Definition Classes
override def prepareForUnit(tree: Tree)(using Context): Context
Definition Classes
Definition Classes
Definition Classes
override def transformApply(tree: Apply)(using Context): Apply
Definition Classes
override def transformClosure(tree: Closure)(using Context): Closure
Definition Classes
override def transformDefDef(tree: DefDef)(using Context): Tree
Definition Classes
override def transformIdent(tree: Ident)(using Context): Tree
Definition Classes
override def transformReturn(tree: Return)(using Context): Tree
Definition Classes
override def transformSelect(tree: Select)(using Context): Tree
Definition Classes
override def transformTemplate(tree: Template)(using Context): Template
Definition Classes
override def transformTypeDef(tree: TypeDef)(using Context): Tree
Definition Classes

Inherited methods

final def <=(that: Phase): Boolean
Inherited from:
Phase

If set, implicit search is enabled

If set, implicit search is enabled

Inherited from:
Phase

Can this transform change the base types of a type?

Can this transform change the base types of a type?

Inherited from:
Phase

Can this transform create or delete non-private members?

Can this transform create or delete non-private members?

Inherited from:
Phase

Can this transform change the parents of a class?

Can this transform change the parents of a class?

Inherited from:
Phase
def checkPostCondition(tree: Tree)(using Context): Unit

Check what the phase achieves, to be called at any point after it is finished.

Check what the phase achieves, to be called at any point after it is finished.

Inherited from:
Phase
Inherited from:
Phase
final def erasedTypes: Boolean
Inherited from:
Phase
Inherited from:
Phase
final def flatClasses: Boolean
Inherited from:
Phase
final def hasNext: Boolean
Inherited from:
Phase
def id: Int

The sequence position of this phase in the given context where 0 is reserved for NoPhase and the first real phase is at position 1. -1 if the phase is not installed in the context.

The sequence position of this phase in the given context where 0 is reserved for NoPhase and the first real phase is at position 1. -1 if the phase is not installed in the context.

Inherited from:
Phase

Output should be checkable by TreeChecker

Output should be checkable by TreeChecker

Inherited from:
Phase
Inherited from:
Phase
Inherited from:
Phase

Is this phase the standard typerphase? True for TyperPhase, but not for other first phases (such as FromTasty or Parser). The predicate is tested in some places that perform checks and corrections. It's different from ctx.isAfterTyper (and cheaper to test).

Is this phase the standard typerphase? True for TyperPhase, but not for other first phases (such as FromTasty or Parser). The predicate is tested in some places that perform checks and corrections. It's different from ctx.isAfterTyper (and cheaper to test).

Inherited from:
Phase
final def iterator: Iterator[Phase]
Inherited from:
Phase
Inherited from:
Phase
def lastPhaseId(using Context): Int

The last phase during which the transformed denotations are valid

The last phase during which the transformed denotations are valid

Inherited from:
DenotTransformer
final def monitor(doing: String)(body: => Unit)(using Context): Unit
Inherited from:
Phase
final def next: Phase
Inherited from:
Phase
Inherited from:
Phase
Inherited from:
Phase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def prepareForBind(tree: Bind)(using Context): Context
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def prepareForIf(tree: If)(using Context): Context
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def prepareForNew(tree: New)(using Context): Context
Inherited from:
MiniPhase
def prepareForOther(tree: Tree)(using Context): Context
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def prepareForStats(trees: List[Tree])(using Context): Context
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def prepareForThis(tree: This)(using Context): Context
Inherited from:
MiniPhase
def prepareForTry(tree: Try)(using Context): Context
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
final def prev: Phase
Inherited from:
Phase
final def refChecked: Boolean
Inherited from:
Phase
final override def relaxedTyping: Boolean
Definition Classes
Inherited from:
MiniPhase
override def run(using Context): Unit
Definition Classes
Inherited from:
MiniPhase
Inherited from:
Phase

List of names of phases that should precede this phase

List of names of phases that should precede this phase

Inherited from:
Phase
Inherited from:
Phase
Inherited from:
Phase
Inherited from:
Phase
protected def singletonGroup: MegaPhase
Inherited from:
MiniPhase
def start: Int
Inherited from:
Phase
override def toString: String
Definition Classes
Phase -> Any
Inherited from:
Phase
def transformAllDeep(tree: Tree)(using Context): Tree

Transform tree using all transforms of current group (including this one)

Transform tree using all transforms of current group (including this one)

Inherited from:
MiniPhase
Inherited from:
MiniPhase
def transformAssign(tree: Assign)(using Context): Tree
Inherited from:
MiniPhase
def transformBind(tree: Bind)(using Context): Tree
Inherited from:
MiniPhase
def transformBlock(tree: Block)(using Context): Tree
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def transformFollowing(tree: Tree)(using Context): Tree

Transform single node using all transforms following the current one in this group

Transform single node using all transforms following the current one in this group

Inherited from:
MiniPhase

Transform tree using all transforms following the current one in this group

Transform tree using all transforms following the current one in this group

Inherited from:
MiniPhase
def transformIf(tree: If)(using Context): Tree
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def transformMatch(tree: Match)(using Context): Tree
Inherited from:
MiniPhase
def transformNew(tree: New)(using Context): Tree
Inherited from:
MiniPhase
def transformOther(tree: Tree)(using Context): Tree
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def transformStats(trees: List[Tree])(using Context): List[Tree]
Inherited from:
MiniPhase
def transformSuper(tree: Super)(using Context): Tree
Inherited from:
MiniPhase
def transformThis(tree: This)(using Context): Tree
Inherited from:
MiniPhase
def transformTry(tree: Try)(using Context): Tree
Inherited from:
MiniPhase
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def transformTyped(tree: Typed)(using Context): Tree
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def transformUnit(tree: Tree)(using Context): Tree
Inherited from:
MiniPhase
def transformValDef(tree: ValDef)(using Context): Tree
Inherited from:
MiniPhase
Inherited from:
MiniPhase
def validFor(using Context): Period

The validity period of the transformed denotations in the given context

The validity period of the transformed denotations in the given context

Inherited from:
DenotTransformer

Inherited fields

Inherited from:
MiniPhase