branch: externals/taxy
commit d682c3727521db91d7c517bf56a91b38d8f7855d
Author: Adam Porter <a...@alphapapa.net>
Commit: Adam Porter <a...@alphapapa.net>
Add: (taxy-make-take-function)
---
taxy.el | 47 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 45 insertions(+), 2 deletions(-)
diff --git a/taxy.el b/taxy.el
index 3fbbb5d..40b66e3 100644
--- a/taxy.el
+++ b/taxy.el
@@ -263,9 +263,11 @@ KEY is passed to `cl-sort', which see."
(defalias 'taxy-sort* #'taxy-sort-taxys)
-;;;; Defining key functions
+;;;; Key functions
-;; Utilities to define key functions and helpers in a standard way.
+;; Utilities to define key and take functions in a standard way.
+
+;; TODO: Document these.
(defmacro taxy-define-key-definer (name variable prefix docstring)
"Define a macro NAME that defines a key-function-defining macro.
@@ -304,6 +306,47 @@ item being tested, bound within the function to `item'."
(fset ',fn-symbol ,fn)
(setf (map-elt ,variable ',name) ',fn-symbol))))))
+(defun taxy-make-take-function (keys aliases)
+ "Return a `taxy' \"take\" function for KEYS.
+Each of KEYS should be a function alias defined in ALIASES, or a
+list of such KEY-FNS (recursively, ad infinitum, approximately).
+ALIASES should be an alist mapping aliases to functions (such as
+defined with a definer defined by `taxy-define-key-definer')."
+ (let ((macrolets (cl-loop for (name . fn) in aliases
+ collect `(,name ',fn))))
+ (cl-labels ((expand-form
+ ;; Is using (cadr (macroexpand-all ...)) really better than
`eval'?
+ (form) (cadr (macroexpand-all
+ `(cl-symbol-macrolet (,@macrolets)
+ ,form))))
+ (quote-fn
+ (fn) (pcase fn
+ ((pred symbolp) (expand-form fn))
+ (`(,(and (or 'and 'or 'not) boolean) . ,(and args (map
:name :keys)))
+ ;; Well, that pcase expression isn't confusing at
all... ;)
+ ;; (cl-assert name t "Boolean key functions require
a NAME")
+ ;; (cl-assert keys t "Boolean key functions require
KEYS")
+ `(lambda (buffer)
+ (when (cl-loop for fn in ',(mapcar #'quote-fn (or
keys args))
+ ,(pcase boolean
+ ('and 'always)
+ ('or 'thereis)
+ ('not 'never))
+ (funcall fn buffer))
+ (or ,name ""))))
+ (`(,(and (pred symbolp) fn)
+ . ,(and args (guard (cl-typecase (car args)
+ ((or keyword (and atom (not
symbol)))
+ t)))))
+ ;; Key with args: replace with a lambda that
+ ;; calls that key's function with given args.
+ `(lambda (element)
+ (,(expand-form fn) element ,@args)))
+ ((pred listp) (mapcar #'quote-fn fn)))))
+ (setf keys (mapcar #'quote-fn keys))
+ `(lambda (item taxy)
+ (taxy-take-keyed ',keys item taxy)))))
+
;;;; Footer
(provide 'taxy)
