[Assorted-commits] SF.net SVN: assorted: [749] scala-commons/trunk/src/commons/Collections. scala

[<yan...@us...>]

Revision: 749
          http://assorted.svn.sourceforge.net/assorted/?rev=749&view=rev
Author:   yangzhang
Date:     2008-05-08 12:34:26 -0700 (Thu, 08 May 2008)

Log Message:
-----------
clarified some documentation; fixed splitBy() eagerness bug

Modified Paths:
--------------
    scala-commons/trunk/src/commons/Collections.scala

Modified: scala-commons/trunk/src/commons/Collections.scala
===================================================================
--- scala-commons/trunk/src/commons/Collections.scala	2008-05-08 19:32:41 UTC (rev 748)
+++ scala-commons/trunk/src/commons/Collections.scala	2008-05-08 19:34:26 UTC (rev 749)
@@ -317,6 +317,7 @@
   /**
    * Given a list of sublists, return pairs of the first element of each
    * sublist along with the remaining elements. Empty sublists are ignored.
+   * Useful in composition with groupByHeaders.
    * <p>
    * <code>
    * separateHeads([[a,b,c],[d,e,f,g],[],[h]])
@@ -399,10 +400,10 @@
    * </code>
    */
   def splitBy[a](xs: Seq[a])(pred: a => Boolean): Stream[Seq[a]] = {
-    val consider = xs dropWhile pred
-    if (consider.length == 0) {
+    if (xs.length == 0) {
       Stream.empty
     } else {
+      val consider = xs dropWhile pred
       val (take, rest) = spanBy(consider)(not(pred))
       Stream.cons(take, splitBy(rest)(pred))
     }
@@ -500,6 +501,8 @@
    * predicate.  A reverse dropWhile.
    * <p>
    * <code>truncateWhile([1,2,3,4,5], (_ != 3)) == [1,2,3]</code>
+   * <p>
+   * <code>truncateWhile("!!hello!!", (=='!')) == "!!hello"</code>
    */
   def truncateWhile[a](seq: Seq[a])(pred: a => Boolean) =
     (seq.reverse dropWhile pred).reverse


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