Fix off by one error in getPos.

src/lexer/newline.sig

@@ -2,22 +2,12 @@ signature NEWLINE =
 sig
     type yypos = int
 
-    (*
-    Resets the internal state for this structure.
-    *)
+    (* Resets the internal state for this structure. *)
     val reset : unit -> unit
-    (*
-    Adds a newline at the given yypos.
-    *)
+    (* Adds a newline at the given yypos. *)
     val add : yypos -> unit
-    (*
-    Returns the line number which the given yypos is in. Newlines
-    themselves are considered to be the 0th character of a line.
-    *)
+    (* Returns the line number which the given yypos is in. *)
     val getLine : yypos -> int
-    (*
-    Returns the character position relative to the given yypos's line.
-    Newlines themselves are considered to be the 0th character of a line.
-    *)
+    (* Returns the character position relative to the given yypos's line. *)
     val getPos : yypos -> int
 end

src/lexer/newline.sml

@@ -1,11 +1,11 @@
 structure Newline :> NEWLINE =
 struct
-    val lines = ref [1]
+    val lines = ref [0]
 
     type yypos = int
 
     fun reset () =
-        lines := [1]
+        lines := [0]
 
     fun add yypos =
         lines := yypos :: !lines
@@ -18,9 +18,9 @@ struct
         end
 
     fun getPos yypos =
-        let fun look (p::ps, n) = if p <= yypos then yypos - p else look(ps, n-1)
-            |   look _ = 0
+        let fun look (p::ps) = if p <= yypos then yypos - p else look(ps)
+            |   look [] = 0
         in
-            look(!lines, List.length(!lines))
+            look(!lines)
         end
 end

test/newline.sml

@@ -20,8 +20,8 @@ Test.test(fn () =>
 Test.test(fn () =>
     (Newline.reset();
      Newline.add(5);
-     Test.assertEq(0, Newline.getPos(1), Int.toString);
-     Test.assertEq(3, Newline.getPos(4), Int.toString);
+     Test.assertEq(1, Newline.getPos(1), Int.toString);
+     Test.assertEq(4, Newline.getPos(4), Int.toString);
      Test.assertEq(0, Newline.getPos(5), Int.toString);
      Test.assertEq(1, Newline.getPos(6), Int.toString);
      Newline.add(20);