Conditional inclusion

1 files changed, 17 insertions, 0 deletions

diff --git a/stream.sml b/stream.sml
index fd5932a..4ea7f08 100644
--- a/stream.sml
+++ b/stream.sml
@@ -52,6 +52,23 @@ structure Stream :> STREAM = struct
   fun getSubstr startOff endOff ({ contents, ... }: t) =
       String.substring (contents, startOff, endOff - startOff)
 
+  fun getLine (S as { contents, off, ... }: t) =
+  let
+    fun find off =
+      if off = size contents then
+        NONE
+      else
+        if String.sub (contents, off) = #"\n" then
+          SOME off
+        else
+          find (off + 1)
+  in
+    case find off of
+      SOME off' =>
+        (SOME $ getSubstr off off' S, updateStream S s#off off' %)
+    | NONE => (NONE, S)
+  end
+
   fun getFname ({ fname, ... }: t) = fname
 
   fun createFromInstream fname instream =