scala3-compiler-bootstrapped/dotty.tools.dotc.transform/Splicing

Splicing

class Splicing extends MacroTransform

Transforms level 1 splices into holes. To do so it transforms the contents of the splice into a lambda that receives all cross-quote references.

Cross-quote reference is a reference to a definition that is not defined in the current quote. Those references appear in quotes that are nested in a splice.

After this phase we have the invariant where all splices have the following shape

{{{ <holeIdx> | <holeType> | <captures>* | (<capturedTerms>*) => <spliceContent> 
}}}

where <spliceContent> does not contain any free references to quoted definitions and <captures>* contains the quotes with references to all cross-quote references. There are some special rules for references in the LHS of assignments and cross-quote method references.

In the following code example x1 and x2 are cross-quote references.

'{ ...
  val x1: T1 = ???
  val x2: T2 = ???
  ${ (q: Quotes) ?=> f('{ g(x1, x2) }) }: T3
}

This phase identifies cross-quote references such as x1 and replaces it with an ${x1$}. All cross-quote arguments are directly applied in the lambda.

'{ ...
   val x1: T1 = ???
   val x2: T2 = ???
{{{
 0 | T3 | x1, x2 |
     (x1$: Expr[T1], x2$: Expr[T2]) => // body of this lambda does not contain references to x1 or x2
       (q: Quotes) ?=> f('{ g(${x1$}, ${x2$}) })

}}}
 }

and then performs the same transformation on '{ g(${x1$}, ${x2$}) }.

Companion:
object
class Phase
class Object
trait Matchable
class Any

Type members

Inherited classlikes

class Transformer extends TreeMapWithPreciseStatContexts
Inherited from:
MacroTransform

Value members

Concrete methods

override def phaseName: String

A name given to the Phase that can be used to debug the compiler. For instance, it is possible to print trees after a given phase using:

A name given to the Phase that can be used to debug the compiler. For instance, it is possible to print trees after a given phase using:

$ ./bin/scalac -Xprint:<phaseNameHere> sourceFile.scala
Definition Classes
override def run(using Context): Unit
Definition Classes

Inherited methods

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

If set, implicit search is enabled

If set, implicit search is enabled

Inherited from:
Phase
def changesBaseTypes: Boolean

Can this transform change the base types of a type?

Can this transform change the base types of a type?

Inherited from:
Phase
def changesMembers: Boolean

Can this transform create or delete non-private members?

Can this transform create or delete non-private members?

Inherited from:
Phase
def changesParents: Boolean

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
def description: String
Inherited from:
Phase
def end: PhaseId
Inherited from:
Phase
final def erasedTypes: Boolean
Inherited from:
Phase
def exists: Boolean
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
def initContext(ctx: FreshContext): Unit
Inherited from:
Phase
def isCheckable: Boolean

Output should be checkable by TreeChecker

Output should be checkable by TreeChecker

Inherited from:
Phase
def isEnabled(using Context): Boolean
Inherited from:
Phase
def isRunnable(using Context): Boolean
Inherited from:
Phase
def isTyper: Boolean

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
final def lambdaLifted: Boolean
Inherited from:
Phase
final def monitor(doing: String)(body: => Unit)(using Context): Unit
Inherited from:
Phase
final def next: Phase
Inherited from:
Phase
final def patternTranslated: Boolean
Inherited from:
Phase
def period: Period
Inherited from:
Phase
final def prev: Phase
Inherited from:
Phase
final def prevMega(using Context): Phase
Inherited from:
Phase
final def refChecked: Boolean
Inherited from:
Phase
def relaxedTyping: Boolean

If set, allow missing or superfluous arguments in applications and type applications.

If set, allow missing or superfluous arguments in applications and type applications.

Inherited from:
Phase
def runOn(units: List[CompilationUnit])(using Context): List[CompilationUnit]
Inherited from:
Phase
def runsAfter: Set[String]

List of names of phases that should precede this phase

List of names of phases that should precede this phase

Inherited from:
Phase
final def sameBaseTypesStartId: Int
Inherited from:
Phase
final def sameMembersStartId: Int
Inherited from:
Phase
final def sameParentsStartId: Int
Inherited from:
Phase
def start: Int
Inherited from:
Phase
override def toString: String

Returns a string representation of the object.

Returns a string representation of the object.

The default representation is platform dependent.

Returns:

a string representation of the object.

Definition Classes
Phase -> Any
Inherited from:
Phase
protected def transformPhase(using Context): Phase

The phase in which the transformation should be run. By default this is the phase given by the this macro transformer, but it could be overridden to be the phase following that one.

The phase in which the transformation should be run. By default this is the phase given by the this macro transformer, but it could be overridden to be the phase following that one.

Inherited from:
MacroTransform