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 PatternExpansion extends AnyRef

    An 'extractor' can be a case class or an unapply or unapplySeq method.

    An 'extractor' can be a case class or an unapply or unapplySeq method.

    In a case class, the class is the unextracted type and the fixed and repeated types are derived from its constructor parameters.

    In an unapply, this is reversed: the parameter to the unapply is the unextracted type, and the other types are derived based on the return type of the unapply method.

    An extractor returns: F1, F2, ..., Fi, opt[Seq[E] or E*] A case matches: P1, P2, ..., Pj, opt[Seq[E]] Put together: P1/F1, P2/F2, ... Pi/Fi, Pi+1/E, Pi+2/E, ... Pj/E, opt[Seq[E]]

    Here Pm/Fi is the last pattern to match the fixed arity section.

    productArity: the value of i, i.e. the number of non-sequence types in the extractor nonStarArity: the value of j, i.e. the number of non-star patterns in the case definition elementArity: j - i, i.e. the number of non-star patterns which must match sequence elements starArity: 1 or 0 based on whether there is a star (sequence-absorbing) pattern totalArity: nonStarArity + starArity, i.e. the number of patterns in the case definition

    Note that productArity is a function only of the extractor, and nonStar/star/totalArity are all functions of the patterns. The key value for aligning and typing the patterns is elementArity, as it is derived from both sets of information.

    If elementArity is...

    • zero: A perfect match between extractor and the fixed patterns. If there is a star pattern it will match any sequence.
    • positive: There are more patterns than products. There will have to be a sequence which can populate at least elementArity patterns.
    • negative: There are more products than patterns: compile time error.
    Definition Classes
    patmat
  • ExtractorAlignment
  • ExtractorSubPatternAlignment
t

scala.tools.nsc.transform.patmat.PatternExpansion

ExtractorSubPatternAlignment

trait ExtractorSubPatternAlignment extends AnyRef

The arities we can derive looking only at the subpatterns (the args of the unapply node)

Source
PatternExpansion.scala
Linear Supertypes
AnyRef, Any
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Inherited
  1. ExtractorSubPatternAlignment
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. All

Abstract Value Members

  1. abstract def args: List[Global.Tree]

    Args will be broken down into the concatenation of: productArity product patterns (fixed length, corresponding to fields in case class or tuple components in classic unapply, or product selectors in product-based unapply) elementArity element patterns (explicit patterns that pick off the prefix of the final sequence-valued component of the unapply, or a repeated case constructor arg) starArity star patterns (0 or 1, absorbs the remaining variable-length components)

Concrete 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 ExtractorSubPatternAlignment toany2stringadd[ExtractorSubPatternAlignment] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (ExtractorSubPatternAlignment, B)
    Implicit
    This member is added by an implicit conversion from ExtractorSubPatternAlignment toArrowAssoc[ExtractorSubPatternAlignment] 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[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native()
  8. def ensuring(cond: (ExtractorSubPatternAlignment) => Boolean, msg: => Any): ExtractorSubPatternAlignment
    Implicit
    This member is added by an implicit conversion from ExtractorSubPatternAlignment toEnsuring[ExtractorSubPatternAlignment] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  9. def ensuring(cond: (ExtractorSubPatternAlignment) => Boolean): ExtractorSubPatternAlignment
    Implicit
    This member is added by an implicit conversion from ExtractorSubPatternAlignment toEnsuring[ExtractorSubPatternAlignment] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: Boolean, msg: => Any): ExtractorSubPatternAlignment
    Implicit
    This member is added by an implicit conversion from ExtractorSubPatternAlignment toEnsuring[ExtractorSubPatternAlignment] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean): ExtractorSubPatternAlignment
    Implicit
    This member is added by an implicit conversion from ExtractorSubPatternAlignment toEnsuring[ExtractorSubPatternAlignment] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  13. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  14. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
  15. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from ExtractorSubPatternAlignment toStringFormat[ExtractorSubPatternAlignment] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  16. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  17. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  18. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  19. val isStar: Boolean
  20. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  21. val nonStarArity: Int
  22. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  23. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  24. def starArity: Int
  25. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  26. def toString(): String
    Definition Classes
    AnyRef → Any
  27. def totalArity: Int
  28. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  29. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  30. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()

Deprecated Value Members

  1. def [B](y: B): (ExtractorSubPatternAlignment, B)
    Implicit
    This member is added by an implicit conversion from ExtractorSubPatternAlignment toArrowAssoc[ExtractorSubPatternAlignment] 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.

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd fromExtractorSubPatternAlignment to any2stringadd[ExtractorSubPatternAlignment]

Inherited by implicit conversion StringFormat fromExtractorSubPatternAlignment to StringFormat[ExtractorSubPatternAlignment]

Inherited by implicit conversion Ensuring fromExtractorSubPatternAlignment to Ensuring[ExtractorSubPatternAlignment]

Inherited by implicit conversion ArrowAssoc fromExtractorSubPatternAlignment to ArrowAssoc[ExtractorSubPatternAlignment]

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