diff options
Diffstat (limited to 'share')
| -rw-r--r-- | share/txr/stdlib/tagbody.tl | 24 |
1 files changed, 5 insertions, 19 deletions
diff --git a/share/txr/stdlib/tagbody.tl b/share/txr/stdlib/tagbody.tl index a0e41a7c..535c5ea1 100644 --- a/share/txr/stdlib/tagbody.tl +++ b/share/txr/stdlib/tagbody.tl @@ -51,25 +51,11 @@ ((set ,next-var (block* ,tb-id (sys:switch ,next-var #(,*codes)) - nil)))))) - ;; pass one: expand inner forms, including tagbody forms. - ;; if any inner tagbody forms leave (go ...) forms unexpanded, - ;; protect those (go ...)forms from falling victim to the - ;; global macro, by wrapping this with a harmless local go macro. - (pass-one (sys:expand ^(macrolet ((go (:form form label) form)) - ,basic-code) env))) - ;; pass two: now expand the remaining go forms at this level, against - ;; this tagbody. If any go forms remain, they must refer to nonexistent - ;; labels. By calling sys:expand one more time, we flush these out - ;; using the global go macro --- unless we are nested inside the - ;; pass-one expansion of outer tagbody, which protects them! - ;; Thus, the outermost tagbody flushes out the undefined labels. - (sys:expand ^(macrolet ((go (:form form label) - (let ((index (posql label ',lbls))) - (cond - ((null index) form) - (t ^(return* ,',tb-id ,index)))))) - ,pass-one) env))))))) + nil))))))) + ^(macrolet ((go (:form form label) + (let ((index (posql label ',lbls))) + (if index ^(return* ,',tb-id ,index) form)))) + ,basic-code))))))) (defmacro go (label) (if [[orf symbolp integerp chrp] label] |