replaced Source.of_list_limited by slightly more economic Source.of_string_limited;

--- a/src/Pure/General/source.ML	Wed Jul 21 20:32:08 2010 +0200
+++ b/src/Pure/General/source.ML	Wed Jul 21 21:08:40 2010 +0200
@@ -16,9 +16,9 @@
   val map_filter: ('a -> 'b option) -> ('a, 'c) source -> ('b, ('a, 'c) source) source
   val filter: ('a -> bool) -> ('a, 'b) source -> ('a, ('a, 'b) source) source
   val of_list: 'a list -> ('a, 'a list) source
-  val of_list_limited: int -> 'a list -> ('a, 'a list) source
+  val exhausted: ('a, 'b) source -> ('a, 'a list) source
   val of_string: string -> (string, string list) source
-  val exhausted: ('a, 'b) source -> ('a, 'a list) source
+  val of_string_limited: int -> string -> (string, substring) source
   val tty: (string, unit) source
   val source': 'a -> 'b Scan.stopper -> ('a * 'b list -> 'c list * ('a * 'b list)) ->
     (bool * (string -> 'a * 'b list -> 'c list * ('a * 'b list))) option ->
@@ -101,11 +101,21 @@
 (* list source *)
 
 fun of_list xs = make_source [] xs default_prompt (fn _ => fn xs => (xs, []));
-fun of_list_limited n xs = make_source [] xs default_prompt (fn _ => chop n);
+
+fun exhausted src = of_list (exhaust src);
+
+
+(* string source *)
 
 val of_string = of_list o explode;
 
-fun exhausted src = of_list (exhaust src);
+fun of_string_limited limit str =
+  make_source [] (Substring.full str) default_prompt
+    (fn _ => fn s =>
+      let
+        val (s1, s2) = Substring.splitAt (s, Int.min (Substring.size s, limit));
+        val cs = map String.str (Substring.explode s1);
+      in (cs, s2) end);
 
 
 (* stream source *)

--- a/src/Pure/Thy/thy_load.ML	Wed Jul 21 20:32:08 2010 +0200
+++ b/src/Pure/Thy/thy_load.ML	Wed Jul 21 21:08:40 2010 +0200
@@ -116,7 +116,7 @@
     val master as (path, _) = check_thy dir name;
     val text = File.read path;
     val (name', imports, uses) =
-      Thy_Header.read (Path.position path) (Source.of_list_limited 8000 (explode text));
+      Thy_Header.read (Path.position path) (Source.of_string_limited 8000 text);
     val _ = check_name name name';
     val uses = map (Path.explode o #1) uses;
   in {master = master, text = text, imports = imports, uses = uses} end;