Scala Compiler2.12.2-20170504-135222-21d12e9 < 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
-  package patmat
  Definition Classes
    transform
-  trait MatchTranslation extends AnyRef

  Translate typed Trees that represent pattern matches into the patternmatching IR, defined by TreeMakers.

  Translate typed Trees that represent pattern matches into the patternmatching IR, defined by TreeMakers.

  Definition Classes
    patmat
- MatchTranslator

t

scala.tools.nsc.transform.patmat.MatchTranslation

# MatchTranslator 

###

#### trait MatchTranslator extends PatternMatching.TreeMakers with PatternMatching.TreeMakerWarnings

Source
  MatchTranslation.scala

Linear Supertypes
PatternMatching.TreeMakerWarnings, PatternMatching.TreeMakers, PatternMatching.CodegenCore, PatternMatching.TypedSubstitution, PatternMatching.MatchMonadInterface, AnyRef, Any
Known Subclasses
OptimizingMatchTranslator, PureMatchTranslator
Type Hierarchy
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2. By Inheritance

Inherited

1. MatchTranslator
2. TreeMakerWarnings
3. TreeMakers
4. CodegenCore
5. TypedSubstitution
6. MatchMonadInterface
7. AnyRef
8. Any

Implicitly

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

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Visibility

1. Public
2. All

### Type Members

1.  class Substitution extends AnyRef
   Definition Classes
     TypedSubstitution
2.  trait AbsCodegen extends AnyRef
   Definition Classes
     CodegenCore
3.  trait Casegen extends AbsCodegen
   Definition Classes
     CodegenCore
4.  abstract class CommonCodegen extends AbsCodegen
   Definition Classes
     CodegenCore
5.  final case class BoundTree (binder: Global.Symbol, tree: Global.Tree) extends Product with Serializable
6.  abstract class ExtractorCall extends AnyRef
7.  class ExtractorCallProd extends ExtractorCall
8.  class ExtractorCallRegular extends ExtractorCall
9.  final case class TranslationStep (makers: List[MatchTranslator.TreeMaker], subpatterns: List[BoundTree]) extends Product with Serializable
10.  case class AlternativesTreeMaker (prevBinder: Global.Symbol, altss: List[List[TreeMaker]], pos: Global.Position) extends TreeMaker with NoNewBinders with Product with Serializable
    Definition Classes
      TreeMakers
11.  case class BodyTreeMaker (body: Global.Tree, matchPt: Global.Type) extends TreeMaker with NoNewBinders with Product with Serializable
    Definition Classes
      TreeMakers
12.  sealed abstract class CondTreeMaker extends FunTreeMaker
    Definition Classes
      TreeMakers
13.  case class EqualityTestTreeMaker (prevBinder: Global.Symbol, patTree: Global.Tree, pos: Global.Position) extends CondTreeMaker with Product with Serializable
    Definition Classes
      TreeMakers
14.  case class ExtractorTreeMaker (extractor: Global.Tree, extraCond: Option[Global.Tree], nextBinder: Global.Symbol)(subPatBinders: List[Global.Symbol], subPatRefs: List[Global.Tree], potentiallyMutableBinders: Set[Global.Symbol], extractorReturnsBoolean: Boolean, checkedLength: Option[Int], prevBinder: Global.Symbol, ignoredSubPatBinders: Set[Global.Symbol]) extends FunTreeMaker with PreserveSubPatBinders with Product with Serializable

    Make a TreeMaker that will result in an extractor call specified by `extractor` the next TreeMaker (here, we don't know which it'll be) is chained after this one by flatMap'ing a function with binder `nextBinder` over our extractor's result the function's body is determined by the next TreeMaker (furthermore, the interpretation of `flatMap` depends on the codegen instance we're using).

    Make a TreeMaker that will result in an extractor call specified by `extractor` the next TreeMaker (here, we don't know which it'll be) is chained after this one by flatMap'ing a function with binder `nextBinder` over our extractor's result the function's body is determined by the next TreeMaker (furthermore, the interpretation of `flatMap` depends on the codegen instance we're using).

    The values for the subpatterns, as computed by the extractor call in `extractor`, are stored in local variables that re-use the symbols in `subPatBinders`. This makes extractor patterns more debuggable (SI-5739).

    Definition Classes
      TreeMakers
15.  sealed abstract class FunTreeMaker extends TreeMaker
    Definition Classes
      TreeMakers
16.  case class GuardTreeMaker (guardTree: Global.Tree) extends TreeMaker with NoNewBinders with Product with Serializable
    Definition Classes
      TreeMakers
17.  sealed trait NoNewBinders extends TreeMaker
    Definition Classes
      TreeMakers
18.  sealed trait PreserveSubPatBinders extends TreeMaker
    Definition Classes
      TreeMakers
19.  case class ProductExtractorTreeMaker (prevBinder: Global.Symbol, extraCond: Option[Global.Tree])(subPatBinders: List[Global.Symbol], subPatRefs: List[Global.Tree], mutableBinders: List[Global.Symbol], binderKnownNonNull: Boolean, ignoredSubPatBinders: Set[Global.Symbol]) extends FunTreeMaker with PreserveSubPatBinders with Product with Serializable

    An optimized version of ExtractorTreeMaker for Products.

    An optimized version of ExtractorTreeMaker for Products. For now, this is hard-coded to case classes, and we simply extract the case class fields.

    The values for the subpatterns, as specified by the case class fields at the time of extraction, are stored in local variables that re-use the symbols in `subPatBinders`. This makes extractor patterns more debuggable (SI-5739) as well as avoiding mutation after the pattern has been matched (SI-5158, SI-6070)

    TODO: make this user-definable as follows When a companion object defines a method `def unapply_1(x: T): U_1`, but no `def unapply` or `def unapplySeq`, the extractor is considered to match any non-null value of type T the pattern is expected to have as many sub-patterns as there are `def unapply_I(x: T): U_I` methods, and the type of the I'th sub-pattern is `U_I`. The same exception for Seq patterns applies: if the last extractor is of type `Seq[U_N]`, the pattern must have at least N arguments (exactly N if the last argument is annotated with `: _*`). The arguments starting at N (and beyond) are taken from the sequence returned by apply_N, and it is checked that that sequence has enough elements to provide values for all expected sub-patterns.

    For a case class C, the implementation is assumed to be `def unapply_I(x: C) = x._I`, and the extractor call is inlined under that assumption.

    Definition Classes
      TreeMakers
20.  case class SubstOnlyTreeMaker (prevBinder: Global.Symbol, nextBinder: Global.Symbol) extends TreeMaker with Product with Serializable
    Definition Classes
      TreeMakers
21.  abstract class TreeMaker extends AnyRef
    Definition Classes
      TreeMakers
22.  case class TrivialTreeMaker (tree: Global.Tree) extends TreeMaker with NoNewBinders with Product with Serializable
    Definition Classes
      TreeMakers
23.  case class TypeTestTreeMaker (prevBinder: Global.Symbol, testedBinder: Global.Symbol, expectedTp: Global.Type, nextBinderTp: Global.Type)(pos: Global.Position, extractorArgTypeTest: Boolean = false) extends CondTreeMaker with Product with Serializable

    implements the run-time aspects of (§8.2) (typedPattern has already done the necessary type transformations)

    implements the run-time aspects of (§8.2) (typedPattern has already done the necessary type transformations)

    Type patterns consist of types, type variables, and wildcards. A type pattern T is of one of the following forms:

    - A reference to a class C, p.C, or T#C. This type pattern matches any non-null instance of the given class. Note that the prefix of the class, if it is given, is relevant for determining class instances. For instance, the pattern p.C matches only instances of classes C which were created with the path p as prefix. The bottom types scala.Nothing and scala.Null cannot be used as type patterns, because they would match nothing in any case.
    - A singleton type p.type. This type pattern matches only the value denoted by the path p (that is, a pattern match involved a comparison of the matched value with p using method eq in class AnyRef). // TODO: the actual pattern matcher uses ==, so that's what I'm using for now // https://issues.scala-lang.org/browse/SI-4577 "pattern matcher, still disappointing us at equality time"
    - A compound type pattern T1 with ... with Tn where each Ti is a type pat- tern. This type pattern matches all values that are matched by each of the type patterns Ti.
    - A parameterized type pattern T[a1,...,an], where the ai are type variable patterns or wildcards _. This type pattern matches all values which match T for some arbitrary instantiation of the type variables and wildcards. The bounds or alias type of these type variable are determined as described in (§8.3).
    - A parameterized type pattern scala.Array[T1], where T1 is a type pattern. // TODO This type pattern matches any non-null instance of type scala.Array[U1], where U1 is a type matched by T1.
    Definition Classes
      TreeMakers

### Abstract Value Members

1.  abstract def analyzeCases(prevBinder: Global.Symbol, cases: List[List[TreeMaker]], pt: Global.Type, suppression: PatternMatching.Suppression): Unit
   Definition Classes
     TreeMakers
2.  abstract def codegen: AbsCodegen
   Definition Classes
     CodegenCore
3.  abstract def optimizeCases(prevBinder: Global.Symbol, cases: List[List[TreeMaker]], pt: Global.Type): (List[List[TreeMaker]], List[Global.Tree])
   Definition Classes
     TreeMakers
4.  abstract val typer: (analyzer)#Typer
   Definition Classes
     MatchMonadInterface

### Concrete Value Members

1.  object EmptySubstitution extends Substitution
   Definition Classes
     TypedSubstitution
2.  object Substitution
   Definition Classes
     TypedSubstitution
3.  final def !=(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
4.  final def ##(): Int
   Definition Classes
     AnyRef → Any
5.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from PatternMatching.MatchTranslator to any2stringadd[PatternMatching.MatchTranslator] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
6.  def ->[B](y: B): (PatternMatching.MatchTranslator, B)
   Implicit
     This member is added by an implicit conversion from PatternMatching.MatchTranslator to ArrowAssoc[PatternMatching.MatchTranslator] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
7.  final def ==(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
8.  final def asInstanceOf[T0]: T0
   Definition Classes
     Any
9.  def checkMatchVariablePatterns(cases: List[Global.CaseDef]): Unit
   Definition Classes
     TreeMakerWarnings
10.  def clone(): AnyRef
    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
11.  def combineCases(scrut: Global.Tree, scrutSym: Global.Symbol, casesRaw: List[List[TreeMaker]], pt: Global.Type, owner: Global.Symbol, matchFailGenOverride: Option[(Global.Tree) ⇒ Global.Tree]): Global.Tree
    Definition Classes
      TreeMakers
12.  def combineCasesNoSubstOnly(scrut: Global.Tree, scrutSym: Global.Symbol, casesNoSubstOnly: List[List[TreeMaker]], pt: Global.Type, owner: Global.Symbol, matchFailGenOverride: Option[(Global.Tree) ⇒ Global.Tree]): Global.Tree
    Definition Classes
      TreeMakers
13.  def combineExtractors(treeMakers: List[TreeMaker])(casegen: Casegen): Global.Tree
    Definition Classes
      TreeMakers
14.  val debugInfoEmitVars: Boolean
    Attributes
      protected
    Definition Classes
      TreeMakers
15.  def emitSwitch(scrut: Global.Tree, scrutSym: Global.Symbol, cases: List[List[TreeMaker]], pt: Global.Type, matchFailGenOverride: Option[(Global.Tree) ⇒ Global.Tree], unchecked: Boolean): Option[Global.Tree]
    Definition Classes
      TreeMakers
16.  def emitTypeSwitch(bindersAndCases: List[(Global.Symbol, List[TreeMaker])], pt: Global.Type): Option[List[Global.CaseDef]]
    Definition Classes
      TreeMakers
17.  def ensuring(cond: (PatternMatching.MatchTranslator) ⇒ Boolean, msg: ⇒ Any): PatternMatching.MatchTranslator
    Implicit
      This member is added by an implicit conversion from PatternMatching.MatchTranslator to Ensuring[PatternMatching.MatchTranslator] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
18.  def ensuring(cond: (PatternMatching.MatchTranslator) ⇒ Boolean): PatternMatching.MatchTranslator
    Implicit
      This member is added by an implicit conversion from PatternMatching.MatchTranslator to Ensuring[PatternMatching.MatchTranslator] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
19.  def ensuring(cond: Boolean, msg: ⇒ Any): PatternMatching.MatchTranslator
    Implicit
      This member is added by an implicit conversion from PatternMatching.MatchTranslator to Ensuring[PatternMatching.MatchTranslator] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
20.  def ensuring(cond: Boolean): PatternMatching.MatchTranslator
    Implicit
      This member is added by an implicit conversion from PatternMatching.MatchTranslator to Ensuring[PatternMatching.MatchTranslator] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
21.  final def eq(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
22.  def equals(arg0: Any): Boolean
    Definition Classes
      AnyRef → Any
23.  def finalize(): Unit
    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )
24.  def fixerUpper(origOwner: Global.Symbol, pos: Global.Position): Global.Traverser
    Attributes
      protected
    Definition Classes
      TreeMakers
25.  def formatted(fmtstr: String): String
    Implicit
      This member is added by an implicit conversion from PatternMatching.MatchTranslator to StringFormat[PatternMatching.MatchTranslator] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()
26.  def freshName(prefix: String): Global.TermName
    Definition Classes
      CodegenCore
27.  def freshSym(pos: Global.Position, tp: Global.Type = NoType, prefix: String = "x"): Global.TermSymbol
    Definition Classes
      CodegenCore
28.  final def getClass(): Class[_]
    Definition Classes
      AnyRef → Any
29.  def hashCode(): Int
    Definition Classes
      AnyRef → Any
30.  final def isInstanceOf[T0]: Boolean
    Definition Classes
      Any
31.  val matchOwner: Global.Symbol
    Definition Classes
      MatchMonadInterface
32.  final def ne(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
33.  def newBoundTree(tree: Global.Tree, pt: Global.Type): BoundTree
34.  def newSynthCaseLabel(name: String): Global.MethodSymbol
    Definition Classes
      CodegenCore
35.  final def notify(): Unit
    Definition Classes
      AnyRef
36.  final def notifyAll(): Unit
    Definition Classes
      AnyRef
37.  def propagateSubstitution(treeMakers: List[TreeMaker], initial: Substitution): List[TreeMaker]
    Definition Classes
      TreeMakers
38.  def pureType(tp: Global.Type): Global.Type
    Definition Classes
      MatchMonadInterface
39.  def removeSubstOnly(makers: List[TreeMaker]): collection.immutable.List[TreeMaker]
    Definition Classes
      TreeMakers
40.  def reportMissingCases(pos: Global.Position, counterExamples: List[String]): Unit
    Definition Classes
      MatchMonadInterface
41.  def reportUnreachable(pos: Global.Position): Unit
    Definition Classes
      MatchMonadInterface
42.  final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
      AnyRef
43.  def toString(): String
    Definition Classes
      AnyRef → Any
44.  def translateBody(body: Global.Tree, matchPt: Global.Type): TreeMaker
45.  def translateCase(scrutSym: Global.Symbol, pt: Global.Type)(caseDef: Global.CaseDef): collection.immutable.List[TreeMaker]

    The translation of `pat if guard => body` has two aspects: 1) the substitution due to the variables bound by patterns 2) the combination of the extractor calls using `flatMap`.

    The translation of `pat if guard => body` has two aspects: 1) the substitution due to the variables bound by patterns 2) the combination of the extractor calls using `flatMap`.

    2) is easy -- it looks like: `translatePattern_1.flatMap(translatePattern_2....flatMap(translatePattern_N.flatMap(translateGuard.flatMap((x_i) => success(Xbody(x_i)))))...)` this must be right-leaning tree, as can be seen intuitively by considering the scope of bound variables: variables bound by pat_1 must be visible from the function inside the left-most flatMap right up to Xbody all the way on the right 1) is tricky because translatePattern_i determines the shape of translatePattern_i+1: zoom in on `translatePattern_1.flatMap(translatePattern_2)` for example -- it actually looks more like: `translatePattern_1(x_scrut).flatMap((x_1) => {y_i -> x_1._i}translatePattern_2)`

    `x_1` references the result (inside the monad) of the extractor corresponding to `pat_1`, this result holds the values for the constructor arguments, which translatePattern_1 has extracted from the object pointed to by `x_scrut`. The `y_i` are the symbols bound by `pat_1` (in order) in the scope of the remainder of the pattern, and they must thus be replaced by:

    - (for 1-ary unapply) x_1
    - (for n-ary unapply, n > 1) selection of the i'th tuple component of `x_1`
    - (for unapplySeq) x_1.apply(i)

    in the treemakers,

    Thus, the result type of `translatePattern_i`'s extractor must conform to `M[(T_1,..., T_n)]`.

    Operationally, phase 1) is a foldLeft, since we must consider the depth-first-flattening of the transformed patterns from left to right. For every pattern ast node, it produces a transformed ast and a function that will take care of binding and substitution of the next ast (to the right).

46.  def translateGuard(guard: Global.Tree): List[TreeMaker]
47.  def translateMatch(match_: Global.Match): Global.Tree

    Implement a pattern match by turning its cases (including the implicit failure case) into the corresponding (monadic) extractors, and combining them with the `orElse` combinator.

    Implement a pattern match by turning its cases (including the implicit failure case) into the corresponding (monadic) extractors, and combining them with the `orElse` combinator.

    For `scrutinee match { case1 ... caseN }`, the resulting tree has the shape `runOrElse(scrutinee)(x => translateCase1(x).orElse(translateCase2(x)).....orElse(zero))`

    NOTE: the resulting tree is not type checked, nor are nested pattern matches transformed thus, you must typecheck the result (and that will in turn translate nested matches) this could probably optimized... (but note that the matchStrategy must be solved for each nested patternmatch)

48.  def translatePattern(bound: BoundTree): List[TreeMaker]
49.  def translateTry(caseDefs: List[Global.CaseDef], pt: Global.Type, pos: Global.Position): List[Global.CaseDef]
50.  final def wait(): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
51.  final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
52.  final def wait(arg0: Long): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
53.  def →[B](y: B): (PatternMatching.MatchTranslator, B)
    Implicit
      This member is added by an implicit conversion from PatternMatching.MatchTranslator to ArrowAssoc[PatternMatching.MatchTranslator] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc
54.  object ExtractorCall
55.  object PatternBoundToUnderscore
56.  object SymbolBound
57.  object WildcardPattern

    A conservative approximation of which patterns do not discern anything.

    A conservative approximation of which patterns do not discern anything. They are discarded during the translation.

58.  object IrrefutableExtractorTreeMaker
    Definition Classes
      TreeMakers
59.  object TypeTestTreeMaker extends Serializable
    Definition Classes
      TreeMakers

### Inherited from PatternMatching.TreeMakerWarnings

### Inherited from PatternMatching.TreeMakers

### Inherited from PatternMatching.CodegenCore

### Inherited from PatternMatching.TypedSubstitution

### Inherited from PatternMatching.MatchMonadInterface

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from PatternMatching.MatchTranslator to any2stringadd[PatternMatching.MatchTranslator]

### Inherited by implicit conversion StringFormat from PatternMatching.MatchTranslator to StringFormat[PatternMatching.MatchTranslator]

### Inherited by implicit conversion Ensuring from PatternMatching.MatchTranslator to Ensuring[PatternMatching.MatchTranslator]

### Inherited by implicit conversion ArrowAssoc from PatternMatching.MatchTranslator to ArrowAssoc[PatternMatching.MatchTranslator]

### Ungrouped