diff -r f44ab3108202 -r d4fda7d05ce5 src/HOL/Tools/string_syntax.ML
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/string_syntax.ML	Sat Dec 23 22:50:19 2000 +0100
@@ -0,0 +1,84 @@
+(*  Title:      HOL/Tools/string_syntax.ML
+    ID:         $Id$
+    Author:     Markus Wenzel, TU Muenchen
+    License:    GPL (GNU GENERAL PUBLIC LICENSE)
+
+Concrete syntax for hex chars and strings.  Assumes consts and syntax
+of theory HOL/String.
+*)
+
+signature STRING_SYNTAX =
+sig
+  val setup: (theory -> theory) list
+end;
+
+structure StringSyntax: STRING_SYNTAX =
+struct
+
+
+(* chars *)
+
+fun syntax_xstr x = Syntax.const "_xstr" $ Syntax.free x;
+
+
+val zero = ord "0";
+val ten = ord "A" - 10;
+
+fun mk_nib n =
+  Syntax.const ("H0" ^ chr (n + (if n <= 9 then zero else ten)));
+
+fun dest_nib (Const (c, _)) =
+      (case explode c of
+        ["H", "0", h] => ord h - (if h <= "9" then zero else ten)
+      | _ => raise Match)
+  | dest_nib _ = raise Match;
+
+fun dest_nibs t1 t2 = chr (dest_nib t1 * 16 + dest_nib t2);
+
+
+fun mk_char c =
+  Syntax.const "Char" $ mk_nib (ord c div 16) $ mk_nib (ord c mod 16);
+
+fun dest_char (Const ("Char", _) $ t1 $ t2) = dest_nibs t1 t2
+  | dest_char _ = raise Match;
+
+
+fun char_tr (*"_Char"*) [Free (xstr, _)] =
+      (case Syntax.explode_xstr xstr of
+        [c] => mk_char c
+      | _ => error ("Single character expected: " ^ xstr))
+  | char_tr (*"_Char"*) ts = raise TERM ("char_tr", ts);
+
+fun char_tr' (*"Char"*) [t1, t2] =
+      Syntax.const "_Char" $ syntax_xstr (Syntax.implode_xstr [dest_nibs t1 t2])
+  | char_tr' (*"Char"*) _ = raise Match;
+
+
+(* strings *)
+
+fun mk_string [] = Syntax.const Syntax.constrainC $ Syntax.const "Nil" $ Syntax.const "string"
+  | mk_string (t :: ts) = Syntax.const "Cons" $ t $ mk_string ts;
+
+fun dest_string (Const ("Nil", _)) = []
+  | dest_string (Const ("Cons", _) $ c $ cs) = dest_char c :: dest_string cs
+  | dest_string _ = raise Match;
+
+
+fun string_tr (*"_String"*) [Free (xstr, _)] =
+      mk_string (map mk_char (Syntax.explode_xstr xstr))
+  | string_tr (*"_String"*) ts = raise TERM ("string_tr", ts);
+
+fun cons_tr' (*"Cons"*) [c, cs] =
+      Syntax.const "_String" $
+        syntax_xstr (Syntax.implode_xstr (dest_char c :: dest_string cs))
+  | cons_tr' (*"Cons"*) ts = raise Match;
+
+
+(* theory setup *)
+
+val setup =
+  [Theory.add_trfuns
+    ([], [("_Char", char_tr), ("_String", string_tr)],
+    [("Char", char_tr'), ("Cons", cons_tr')], [])];
+
+end;