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Diffstat (limited to 'src/library/scala/PartiallyOrdered.scala')
| -rw-r--r-- | src/library/scala/PartiallyOrdered.scala | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/src/library/scala/PartiallyOrdered.scala b/src/library/scala/PartiallyOrdered.scala new file mode 100644 index 0000000000..424e50b77d --- /dev/null +++ b/src/library/scala/PartiallyOrdered.scala @@ -0,0 +1,49 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2003-04, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +** $Id:PartiallyOrdered.scala 5359 2005-12-16 16:33:49 +0100 (Fri, 16 Dec 2005) dubochet $ +\* */ + +package scala; + + +/** A trait for partially ordered data. + * + * @author Martin Odersky + * @version 1.0, 23/04/2004 + */ +trait PartiallyOrdered[+a] { + + /** Result of comparing `this' with operand `that'. + * Returns `None' if operands are not comparable. + * If operands are comparable, returns `Some(x)' where + * <code>x < 0</code> iff <code>this < that</code> + * <code>x == 0</code> iff <code>this == that</code> + * <code>x > 0</code> iff <code>this > that</code> + */ + def tryCompareTo [b >: a <% PartiallyOrdered[b]](that: b): Option[int]; + + def < [b >: a <% PartiallyOrdered[b]](that: b): boolean = + (this tryCompareTo that) match { + case Some(x) if x < 0 => true + case _ => false + } + def > [b >: a <% PartiallyOrdered[b]](that: b): boolean = + (this tryCompareTo that) match { + case Some(x) if x > 0 => true + case _ => false + } + def <= [b >: a <% PartiallyOrdered[b]](that: b): boolean = + (this tryCompareTo that) match { + case Some(x) if x <= 0 => true + case _ => false + } + def >= [b >: a <% PartiallyOrdered[b]](that: b): boolean = + (this tryCompareTo that) match { + case Some(x) if x >= 0 => true + case _ => false + } +} |