added tags-from-oneliner function

1 files changed, 12 insertions, 5 deletions

diff --git a/src/lib.lisp b/src/lib.lisp
index ec65d13..d1b8db6 100644
--- a/src/lib.lisp
+++ b/src/lib.lisp
@@ -63,13 +63,20 @@
   (when (uiop:file-exists-p (last-search-file))
     (nth n (uiop:read-file-form (last-search-file)))))
 
-(defun command-on-system (cmd)
-  )
+(defun executable-on-system-p (name)
+  "A hack that heuristically determins whether or not an executable
+with the provided name is on the system. It is not perfect. It
+consults the environment PATH, and looks for the command in any of
+the directories that appear in the value of that variable."
+  #+(unix)
+  (loop for path in (str:split ":" (uiop:getenv "PATH"))
+        for directory = (cons :absolute
+                              (cdr (str:split "/" path)))
+          thereis (uiop:file-exists-p
+                   (make-pathname :name name :directory directory))))
 
 (defun tags-from-oneliner (oneliner)
-  (loop for cmd? in (ppcre:split " +" oneliner)
-        when (command-on-system cmd?)
-          collect cmd?))
+  (remove-if-not #'executable-on-system-p (ppcre:split " +" oneliner)))
 
 (defun prompt (prompt &key (out-stream *standard-output*) (in-stream *standard-input*))
   (princ prompt out-stream)