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commit 8c1b7dcf132204dc18122aabdccbc7e1139f04c5
parent 8ac38f4a3a2e5a8dedbefe4f48980b953e200016
Author: Georges Dupéron <georges.duperon@gmail.com>
Date:   Mon, 19 Sep 2016 21:00:39 +0200

Put 'none back as a result for ~global-and with no matches.

Diffstat:
M
private/global.rkt
 | 
12
+++++++-----
M
scribblings/extensible-parser-specifications.scrbl
 | 
9
+++++++--

2 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/private/global.rkt b/private/global.rkt
@@ -44,11 +44,13 @@
   (make-~global #'aggregate-global-or #'#t))
 
 (define (aggregate-global-and . bs)
-  (true? ;; force the result to be a boolean, the order of terms is unimportant
-   (andmap unbox ;; remove the layer of protection
-           (cons (box-immutable 'none) ;; default value when no bindings matched
-                 (filter identity ;; remove failed bindings
-                         (flatten bs)))))) ;; don't care about ellipsis nesting
+  (let ([matches (filter identity ;; remove failed bindings
+                         (flatten bs))])
+    (if (null? matches)
+        'none ;; no matches occurred
+        (true? ;; coerce to boolean, so that the order of terms is unimportant
+         (andmap unbox ;; remove the layer of protection
+                 matches))))) ;; don't care about ellipsis nesting
 (define-eh-mixin-expander ~global-and
   (make-~global #'aggregate-global-and))
 
diff --git a/scribblings/extensible-parser-specifications.scrbl b/scribblings/extensible-parser-specifications.scrbl
@@ -262,8 +262,13 @@ the notion of order irrelevant.
  matches of a global pattern using the same @racket[#,tribute-name]. See above
  for a description of how global operations work.
 
- The result is always transformed into a boolean, so @racket[_attribute-name] is
- always bound to either @racket[#t] or @racket[#f].}
+ If there is at least one occurrence of @racket[~global-and] for that
+ @racket[_attribute-name] which successfully matches, the result of the
+ @racket[(and valueᵢ ...)] is always coerced to a boolean, so
+ @racket[_attribute-name] is always bound to either @racket[#t] or @racket[#f].
+
+ If there are no matches at all, the special value @racket['none] is used
+ instead of @racket[#t] as would be produced by @racket[(and)].}
 
 @defform[(~global-counter attribute-name+value #,ntax-pattern ...)
          #:grammar