[MLton-commit] r5503

[Vesa Karvonen]

Added extendl and extendr.
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U   mltonlib/trunk/com/ssh/extended-basis/unstable/detail/text/mk-text-ext.fun
U   mltonlib/trunk/com/ssh/extended-basis/unstable/public/text/substring.sig

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Modified: mltonlib/trunk/com/ssh/extended-basis/unstable/detail/text/mk-text-ext.fun
===================================================================
--- mltonlib/trunk/com/ssh/extended-basis/unstable/detail/text/mk-text-ext.fun	2007-04-11 11:59:17 UTC (rev 5502)
+++ mltonlib/trunk/com/ssh/extended-basis/unstable/detail/text/mk-text-ext.fun	2007-04-11 14:58:16 UTC (rev 5503)
@@ -94,5 +94,21 @@
       open Substring
       type t = substring
       val length = size
+      fun extendl pred ss = let
+         val (s, i, n) = base ss
+         val j = i+n
+         fun lp i = if 0 < i andalso pred (String.sub (s, i-1)) then lp (i-1)
+                    else substring (s, i, j-i)
+      in
+         lp i
+      end
+      fun extendr pred ss = let
+         val (s, i, n) = base ss
+         val m = String.size s
+         fun lp j = if j < m andalso pred (String.sub (s, j)) then lp (j+1)
+                    else substring (s, i, j-i)
+      in
+         lp (i+n)
+      end
    end
 end

Modified: mltonlib/trunk/com/ssh/extended-basis/unstable/public/text/substring.sig
===================================================================
--- mltonlib/trunk/com/ssh/extended-basis/unstable/public/text/substring.sig	2007-04-11 11:59:17 UTC (rev 5502)
+++ mltonlib/trunk/com/ssh/extended-basis/unstable/public/text/substring.sig	2007-04-11 14:58:16 UTC (rev 5503)
@@ -16,4 +16,18 @@
     * Returns the size of the given substring.  This is equivalent to
     * {size}.
     *)
+
+   val extendl : char UnPr.t -> t UnOp.t
+   val extendr : char UnPr.t -> t UnOp.t
+   (**
+    * These extend the substring with characters satisfying the predicate
+    * as far as possible within the underlying string either to the left
+    * or to the right.  For example,
+    *
+    *> "aa" = string |< extendr (eq #"a") |< substring ("aabb", 0, 0)
+    *
+    * and
+    *
+    *> "aabb" = string |< extendr (const true) |< substring ("aabb", 0, 0)
+    *)
 end