* parser.y (text): Allow the EMPTY token (the @(empty) syntax)

to be a text.

* txr.1: Documented @(empty).

3 files changed, 14 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index dd4e6787..491b7884 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-03-15  Kaz Kylheku  <kaz@kylheku.com>
+
+	* parser.y (text): Allow the EMPTY token (the @(empty) syntax)
+	to be a text.
+
+	* txr.1: Documented @(empty).
+
 2014-03-14  Kaz Kylheku  <kaz@kylheku.com>
 
 	* parser.l (regex_parse, lisp_parse): Fix neglected handling of
diff --git a/parser.y b/parser.y
index efbc485b..19332684 100644
--- a/parser.y
+++ b/parser.y
@@ -334,7 +334,6 @@ else_clause_opt : ELSE newl
                   |                  { $$ = nil; }
                   ;
 
-
 line : elems_opt '\n'           { $$ = $1; }
      ;
 
@@ -363,6 +362,7 @@ text : TEXT                     { $$ = rl(string_own($1), num(lineno)); }
      | regex                    { $$ = cons(regex_compile(rest($1), nil),
                                             rest($1));
                                   rl($$, num(lineno)); }
+     | EMPTY                    { $$ = null_string; }
      ;
 
 texts : text %prec LOW          { $$ = rlcp(cons($1, nil), $1); }
diff --git a/txr.1 b/txr.1
index 86b30e8d..0c86dd5d 100644
--- a/txr.1
+++ b/txr.1
@@ -1315,6 +1315,12 @@ which translates to a combination of @(cases) and @(require)
 Multiple clauses are applied to the same input. The one whose effect persists
 is the one which maximizes or minimizes the length of a particular variable.
 
+.IP @(empty)
+The @(empty) directive matches the empty string. It is useful in certain
+situations, such as expressing an empty match in a directive that doesn't
+accept an empty clause. The @(empty) syntax has another meaning in
+@(output) clauses, in conjunctio with @(repeat).
+
 .IP "@(define NAME ( ARGUMENTS ...))"
 Introduces a function. Functions are discussed in the FUNCTIONS section below.