[MLton-commit] r5044

[Vesa Karvonen]

Initial commit of a lib of misc utils to be refactored.
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A   mltonlib/trunk/com/ssh/misc-util/unstable/queue.sml

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Added: mltonlib/trunk/com/ssh/misc-util/unstable/queue.sml
===================================================================
--- mltonlib/trunk/com/ssh/misc-util/unstable/queue.sml	2007-01-12 12:30:48 UTC (rev 5043)
+++ mltonlib/trunk/com/ssh/misc-util/unstable/queue.sml	2007-01-12 12:31:16 UTC (rev 5044)
@@ -0,0 +1,41 @@
+(* Copyright (C) 2007 SSH Communications Security, Helsinki, Finland
+ *
+ * This code is released under the MLton license, a BSD-style license.
+ * See the LICENSE file or http://mlton.org/License for details.
+ *)
+
+(*
+ * An implementation of the {QUEUE} signature.  This is based on a space
+ * safe implementation by Stephen Weeks posted on the MLton developers
+ * mailing list.
+ *)
+
+structure Queue :> QUEUE = struct
+   structure N = Node
+
+   datatype 'a t = IN of {back : 'a N.t Ref.t,
+                          front : 'a N.t Ref.t}
+
+   fun new () = let
+      val n = N.new ()
+   in
+      IN {back = ref n, front = ref n}
+   end
+
+   fun isEmpty (IN {front, ...}) =
+       not (isSome (N.get (!front)))
+
+   fun enque (IN {back, ...}) =
+       fn a => let
+          val r = !back
+          val n = N.new ()
+       in
+          N.<- (r, SOME (a, n))
+        ; back := n
+       end
+
+   fun deque (IN {front, ...}) =
+       case N.get (!front) of
+          NONE => NONE
+        | SOME (a, n) => (front := n ; SOME a)
+end


Property changes on: mltonlib/trunk/com/ssh/misc-util/unstable/queue.sml
___________________________________________________________________
Name: svn:eol-style
   + native