root/trunk/thirdparty/alexandria/features.lisp

Revision 3201, 0.7 kB (checked in by hans, 8 months ago)

add missing files

Line 
1 (in-package :alexandria)
2
3 (defun featurep (feature-expression)
4   "Returns T if the argument matches the state of the *FEATURES*
5 list and NIL if it does not. FEATURE-EXPRESSION can be any atom
6 or list acceptable to the reader macros #+ and #-."
7   (etypecase feature-expression
8     (symbol (not (null (member feature-expression *features*))))
9     (cons (check-type (first feature-expression) symbol)
10           (eswitch ((first feature-expression) :test 'string=)
11             (:and (every #'featurep (rest feature-expression)))
12             (:or  (some #'featurep (rest feature-expression)))
13             (:not (assert (= 2 (length feature-expression)))
14                   (not (featurep (second feature-expression))))))))
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