txr: support variable in postive match.

In the @{var mod} syntax in the pattern language, allow mod to
be a variable which contains a regex or integer, not just an
integer or regex literal.

* match.c (h_var): Check for modifier being a variable, and
resolve it.

* parser.y (modifiers): Allow a SYMTOK phrase.

* txr.1: Documented.

1 files changed, 1 insertions, 0 deletions

diff --git a/parser.y b/parser.y
index abc12d1c..a64d489b 100644
--- a/parser.y
+++ b/parser.y
@@ -788,6 +788,7 @@ modifiers : NUMBER              { $$ = cons($1, nil); }
                                   rlc($$, $1); }
           | compound            { $$ = rlc(cons(expand_meta($1, nil),
                                                  nil), $1); }
+          | SYMTOK              { $$ = cons(symhlpr($1, nil), nil); }
           ;
 
 o_var : SYMTOK                  { val expr = symhlpr($1, nil);