diff options
Diffstat (limited to 'features.lisp')
| -rw-r--r-- | features.lisp | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/features.lisp b/features.lisp new file mode 100644 index 0000000000..67348dbba4 --- /dev/null +++ b/features.lisp @@ -0,0 +1,14 @@ +(in-package :alexandria) + +(defun featurep (feature-expression) + "Returns T if the argument matches the state of the *FEATURES* +list and NIL if it does not. FEATURE-EXPRESSION can be any atom +or list acceptable to the reader macros #+ and #-." + (etypecase feature-expression + (symbol (not (null (member feature-expression *features*)))) + (cons (check-type (first feature-expression) symbol) + (eswitch ((first feature-expression) :test 'string=) + (:and (every #'featurep (rest feature-expression))) + (:or (some #'featurep (rest feature-expression))) + (:not (assert (= 2 (length feature-expression))) + (not (featurep (second feature-expression)))))))) |