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
Known Subclasses
ExtractorCall, ExtractorCallProd, ExtractorCallRegular, ExtractorAlignment
Type Hierarchy
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. ExtractorSubPatternAlignment
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
  1. Hide All
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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]

Ungrouped