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Diffstat (limited to 'src/xml/scala/xml/Equality.scala')
| -rw-r--r-- | src/xml/scala/xml/Equality.scala | 107 |
1 files changed, 0 insertions, 107 deletions
diff --git a/src/xml/scala/xml/Equality.scala b/src/xml/scala/xml/Equality.scala deleted file mode 100644 index 021d185812..0000000000 --- a/src/xml/scala/xml/Equality.scala +++ /dev/null @@ -1,107 +0,0 @@ -/* __ *\ -** ________ ___ / / ___ Scala API ** -** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL ** -** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** -** /____/\___/_/ |_/____/_/ | | ** -** |/ ** -\* */ - -package scala -package xml - -/** In an attempt to contain the damage being inflicted on consistency by the - * ad hoc `equals` methods spread around `xml`, the logic is centralized and - * all the `xml` classes go through the `xml.Equality trait`. There are two - * forms of `xml` comparison. - * - * 1. `'''def''' strict_==(other: scala.xml.Equality)` - * - * This one tries to honor the little things like symmetry and hashCode - * contracts. The `equals` method routes all comparisons through this. - * - * 1. `xml_==(other: Any)` - * - * This one picks up where `strict_==` leaves off. It might declare any two - * things equal. - * - * As things stood, the logic not only made a mockery of the collections - * equals contract, but also laid waste to that of case classes. - * - * Among the obstacles to sanity are/were: - * - * Node extends NodeSeq extends Seq[Node] - * MetaData extends Iterable[MetaData] - * The hacky "Group" xml node which throws exceptions - * with wild abandon, so don't get too close - * Rampant asymmetry and impossible hashCodes - * Most classes claiming to be equal to "String" if - * some specific stringification of it was the same. - * String was never going to return the favor. - */ - -object Equality { - def asRef(x: Any): AnyRef = x.asInstanceOf[AnyRef] - - /** Note - these functions assume strict equality has already failed. - */ - def compareBlithely(x1: AnyRef, x2: String): Boolean = x1 match { - case x: Atom[_] => x.data == x2 - case x: NodeSeq => x.text == x2 - case _ => false - } - def compareBlithely(x1: AnyRef, x2: Node): Boolean = x1 match { - case x: NodeSeq if x.length == 1 => x2 == x(0) - case _ => false - } - def compareBlithely(x1: AnyRef, x2: AnyRef): Boolean = { - if (x1 == null || x2 == null) - return (x1 eq x2) - - x2 match { - case s: String => compareBlithely(x1, s) - case n: Node => compareBlithely(x1, n) - case _ => false - } - } -} -import Equality._ - -trait Equality extends scala.Equals { - protected def basisForHashCode: Seq[Any] - - def strict_==(other: Equality): Boolean - def strict_!=(other: Equality) = !strict_==(other) - - /** We insist we're only equal to other `xml.Equality` implementors, - * which heads off a lot of inconsistency up front. - */ - override def canEqual(other: Any): Boolean = other match { - case x: Equality => true - case _ => false - } - - /** It's be nice to make these final, but there are probably - * people out there subclassing the XML types, especially when - * it comes to equals. However WE at least can pretend they - * are final since clearly individual classes cannot be trusted - * to maintain a semblance of order. - */ - override def hashCode() = basisForHashCode.## - override def equals(other: Any) = doComparison(other, blithe = false) - final def xml_==(other: Any) = doComparison(other, blithe = true) - final def xml_!=(other: Any) = !xml_==(other) - - /** The "blithe" parameter expresses the caller's unconcerned attitude - * regarding the usual constraints on equals. The method is thereby - * given carte blanche to declare any two things equal. - */ - private def doComparison(other: Any, blithe: Boolean) = { - val strictlyEqual = other match { - case x: AnyRef if this eq x => true - case x: Equality => (x canEqual this) && (this strict_== x) - case _ => false - } - - strictlyEqual || (blithe && compareBlithely(this, asRef(other))) - } -} |