trait PatternMatching extends SubComponent with Transform with TypingTransformers with Debugging with Interface with MatchTranslation with MatchTreeMaking with MatchCodeGen with MatchCps with ScalaLogic with Solving with MatchAnalysis with MatchOptimization with MatchWarnings with PatternExpansion
Translate pattern matching.
Either into optimized if/then/else's, or virtualized as method calls (these methods form a zero-plus monad), similar in spirit to how for-comprehensions are compiled.
For each case, express all patterns as extractor calls, guards as 0-ary extractors, and sequence them using flatMap
(lifting the body of the case into the monad using one).
Cases are combined into a pattern match using the orElse combinator (the implicit failure case is expressed using the monad's zero).
TODO:
- DCE (on irrefutable patterns)
- update spec and double check it's implemented correctly (see TODO's)
(longer-term) TODO:
- user-defined unapplyProd
- recover GADT typing by locally inserting implicit witnesses to type equalities derived from the current case, and considering these witnesses during subtyping (?)
- recover exhaustivity/unreachability of user-defined extractors by partitioning the types they match on using an HList or similar type-level structure
- Source
- PatternMatching.scala
- Alphabetic
- By Inheritance
- PatternMatching
- PatternExpansion
- MatchWarnings
- MatchOptimization
- MatchAnalysis
- MatchApproximation
- Solving
- ScalaLogic
- TreeAndTypeAnalysis
- Logic
- MatchCps
- MatchTreeMaking
- MatchCodeGen
- MatchTranslation
- Interface
- TreeDSL
- Debugging
- TypingTransformers
- Transform
- SubComponent
- AnyRef
- Any
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
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- Public
- Protected
Type Members
- abstract class StdPhase extends GlobalPhase
A standard phase template
A standard phase template
- Definition Classes
- SubComponent
- class Phase extends StdPhase
The phase defined by this transform
The phase defined by this transform
- Definition Classes
- Transform
- abstract class ThicketTransformer extends TypingTransformer
A base class for typing transformers that need to perform "thicket expansion".
A base class for typing transformers that need to perform "thicket expansion". A thicket is the output of a transformation that is flattened into the enclosing block.
- Definition Classes
- TypingTransformers
- abstract class TypingTransformer extends Global.AstTransformer
- Definition Classes
- TypingTransformers
- trait MatchMonadInterface extends AnyRef
- Definition Classes
- Interface
- trait TypedSubstitution extends MatchMonadInterface
- Definition Classes
- Interface
- trait PropositionalLogic extends AnyRef
- Definition Classes
- Logic
- trait MatchAnalyzer extends MatchApproximator
- Definition Classes
- MatchAnalysis
- trait MatchApproximator extends TreeMakers with TreesAndTypesDomain
Represent a match as a formula in propositional logic that encodes whether the match matches (abstractly: we only consider types)
Represent a match as a formula in propositional logic that encodes whether the match matches (abstractly: we only consider types)
- Definition Classes
- MatchApproximation
- trait CodegenCore extends MatchMonadInterface
- Definition Classes
- MatchCodeGen
- trait OptimizedCodegen extends CodegenCore with TypedSubstitution with MatchMonadInterface
- Definition Classes
- MatchCodeGen
- trait CommonSubconditionElimination extends OptimizedCodegen with MatchApproximator
- Definition Classes
- MatchOptimization
- trait MatchOptimizer extends OptimizedCodegen with SwitchEmission with CommonSubconditionElimination
- Definition Classes
- MatchOptimization
- trait SwitchEmission extends TreeMakers with MatchMonadInterface
- Definition Classes
- MatchOptimization
- trait MatchTranslator extends PatternMatching.TreeMakers with PatternMatching.TreeMakerWarnings
- Definition Classes
- MatchTranslation
- final case class Suppression extends Product with Serializable
- Definition Classes
- MatchTreeMaking
- trait TreeMakers extends TypedSubstitution with CodegenCore
- Definition Classes
- MatchTreeMaking
- trait TreeMakerWarnings extends AnyRef
- Definition Classes
- MatchWarnings
- class ExtractorAlignment extends ExtractorSubPatternAlignment
- Definition Classes
- PatternExpansion
- trait ExtractorSubPatternAlignment extends AnyRef
The arities we can derive looking only at the subpatterns (the args of the unapply node)
The arities we can derive looking only at the subpatterns (the args of the unapply node)
- Definition Classes
- PatternExpansion
- class MatchTransformer extends TypingTransformer
- class OptimizingMatchTranslator extends MatchTranslator with MatchOptimizer with MatchAnalyzer with Solver
- trait TreesAndTypesDomain extends PropositionalLogic with CheckableTreeAndTypeAnalysis
- Definition Classes
- ScalaLogic
- trait CNF extends PropositionalLogic
- Definition Classes
- Solving
- trait Solver extends CNF
- Definition Classes
- Solving
- trait CheckableTreeAndTypeAnalysis extends AnyRef
- Definition Classes
- TreeAndTypeAnalysis
Abstract Value Members
- abstract val global: Global
- Definition Classes
- PatternExpansion
- 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
- 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
- object CODE
- Definition Classes
- TreeDSL
- object debug
- Definition Classes
- Debugging
- object Suppression extends java.io.Serializable
- Definition Classes
- MatchTreeMaking
- final def !=(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
- final def ##: Int
- Definition Classes
- AnyRef → Any
- def +(other: String): String
- Implicit
- This member is added by an implicit conversion from PatternMatching toany2stringadd[PatternMatching] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
- def ->[B](y: B): (PatternMatching, B)
- Implicit
- This member is added by an implicit conversion from PatternMatching toArrowAssoc[PatternMatching] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
- final def ==(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
- final def afterOwnPhase[T](op: => T): T
- Definition Classes
- SubComponent
- Annotations
- @inline()
- def alignAcrossRows(xss: List[List[Any]], sep: String, lineSep: String = "\n"): String
- Definition Classes
- Logic
- final def asInstanceOf[T0]: T0
- Definition Classes
- Any
- final def beforeOwnPhase[T](op: => T): T
- Definition Classes
- SubComponent
- Annotations
- @inline()
- def binderTypeImpliedByPattern(pat: Global.Tree, pt: Global.Type): Global.Type
Compute the type T implied for a value
vmatched by a patternpat(with expected typept).Compute the type T implied for a value
vmatched by a patternpat(with expected typept).Usually, this is the pattern's type because pattern matching implies instance-of checks.
However, Stable Identifier and Literal patterns are matched using
==, which does not imply a type for the binder that binds the matched value. E.g., incase x@Nil => x, all we know aboutxis that it satisfiesNil == x, which could be anything. A type pattern with a literal type works the same as the corresponding literal pattern. A literal pattern with a Boolean or Unit pattern does enforce that the respective value (true,false,()) was matched, so in those cases, the pattern type is assumed.The other patterns imply type tests, so we can safely deduce that the binder has the pattern's type when the pattern matches. Concretely, a literal, type pattern, a case class (the constructor's result type) or extractor (the unapply's argument type) all imply type tests.
See scala/bug#1503, scala/bug#5024: don't cast binders to types we're not sure they have
- Definition Classes
- TreeAndTypeAnalysis
- def clone(): AnyRef
- Attributes
- protected[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.CloneNotSupportedException]) @native()
- def enabled: Boolean
Is this component enabled? Default is true.
Is this component enabled? Default is true.
- Definition Classes
- SubComponent
- def ensuring(cond: (PatternMatching) => Boolean, msg: => Any): PatternMatching
- Implicit
- This member is added by an implicit conversion from PatternMatching toEnsuring[PatternMatching] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: (PatternMatching) => Boolean): PatternMatching
- Implicit
- This member is added by an implicit conversion from PatternMatching toEnsuring[PatternMatching] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean, msg: => Any): PatternMatching
- Implicit
- This member is added by an implicit conversion from PatternMatching toEnsuring[PatternMatching] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean): PatternMatching
- Implicit
- This member is added by an implicit conversion from PatternMatching toEnsuring[PatternMatching] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- final def eq(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
- def equals(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef → Any
- def equivalentTree(a: Global.Tree, b: Global.Tree): Boolean
- Definition Classes
- TreeAndTypeAnalysis
- def finalize(): Unit
- Attributes
- protected[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.Throwable])
- final def getClass(): Class[_ <: AnyRef]
- Definition Classes
- AnyRef → Any
- Annotations
- @native()
- def hashCode(): Int
SubComponents are added to a HashSet and two phases are the same if they have the same name.
SubComponents are added to a HashSet and two phases are the same if they have the same name.
- Definition Classes
- SubComponent → AnyRef → Any
- 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
- def instanceOfTpImplies(tp: Global.Type, tpImplied: Global.Type): Boolean
- Definition Classes
- TreeAndTypeAnalysis
- 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
- final def isInstanceOf[T0]: Boolean
- Definition Classes
- Any
- val javaClassesByUnit: HashMap[SourceFile, Set[Global.Symbol]]
Symbols to force for determining children of sealed Java classes.
- final def ne(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
- def newPhase(prev: nsc.Phase): StdPhase
Create a new phase which applies transformer
Create a new phase which applies transformer
- Definition Classes
- Transform → SubComponent
- def newRootLocalTyper(unit: Global.CompilationUnit): (analyzer)#Typer
- Attributes
- protected
- Definition Classes
- TypingTransformers
- def newTransformer(unit: Global.CompilationUnit): Global.AstTransformer
The transformer factory
The transformer factory
- Definition Classes
- PatternMatching → Transform
- final def notify(): Unit
- Definition Classes
- AnyRef
- Annotations
- @native()
- final def notifyAll(): Unit
- Definition Classes
- AnyRef
- Annotations
- @native()
- 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
- val phaseName: String
The name of the phase
The name of the phase
- Definition Classes
- PatternMatching → SubComponent
- 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
- 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
- def removeCPSFromPt(pt: Global.Type): Global.Type
- Definition Classes
- MatchCps
- val requires: List[String]
Names of phases required by this component.
Names of phases required by this component. Default is
Nil.- Definition Classes
- SubComponent
- 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
- final def synchronized[T0](arg0: => T0): T0
- Definition Classes
- AnyRef
- 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
- def toString(): String
- Definition Classes
- AnyRef → Any
- def unapplyFormals(fun: Global.Tree, args: List[Global.Tree])(context: Context): List[Global.Type]
- Definition Classes
- PatternExpansion
- final def wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
- final def wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
- final def wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException]) @native()
Deprecated Value Members
- def formatted(fmtstr: String): String
- Implicit
- This member is added by an implicit conversion from PatternMatching toStringFormat[PatternMatching] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.12.16) Use
formatString.format(value)instead ofvalue.formatted(formatString), or use thef""string interpolator. In Java 15 and later,formattedresolves to the new method in String which has reversed parameters.
- def →[B](y: B): (PatternMatching, B)
- Implicit
- This member is added by an implicit conversion from PatternMatching toArrowAssoc[PatternMatching] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use
->instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.
The Scala compiler and reflection APIs.