deffilter grows in power: it can take quasistrings.

* lib.c (cdr_f): New global variable.
(funcall1, funcall2, funcall3, funcall4): Fix unterminated
arguments in uw_throwf call by using uw_throw instead.
(do_or): New static function.
(orf): New function.
(obj_init): gc_protect and initialize cdr_f.

* lib.h (cdr_f, orf): Declared.

* match.c (v_deffilter): Treat the table as forms to be evaluated which
must reduce to strings, rather than literal strings.

* txr.1: Documented.

1 files changed, 6 insertions, 3 deletions

diff --git a/txr.1 b/txr.1
index 33f21df7..cd30c208 100644
--- a/txr.1
+++ b/txr.1
@@ -3564,9 +3564,10 @@ This directive's syntax is illustrated in this example:
 
 
 The deffilter symbol must be followed by the name of the filter to be defined,
-followed by tuples of strings. Each tuple specifies one or more texts
-which are mapped to a replacement text. For instance, the following specifies
-a telephone keypad mapping from upper case letters to digits.
+followed by tuples of forms which evaluate to strings. Each tuple specifies one
+or more texts which are mapped to a replacement text. For instance, the
+following specifies a telephone keypad mapping from upper case letters to
+digits.  Quasiliterals may be used.
  
   @(deffilter alpha_to_phone ("E" "0") 
                              ("J" "N" "Q" "1")
@@ -3579,6 +3580,8 @@ a telephone keypad mapping from upper case letters to digits.
                              ("L" "O" "P" "8")
                              ("G" "H" "Z" "9"))
 
+  @(deffilter foo (`@a` `@b`) ("c" `->@d`))
+
 Filtering works using a longest match algorithm. The input is scanned from left
 to right, and the longest piece of text is identified at every character
 position which matches a string on the left hand side, and that text is