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New function seq-map-indexed

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* lisp/emacs-lisp/seq.el (seq-map-indexed): New function.
* test/lisp/emacs-lisp/seq-tests.el: Add tests for seq-map-indexed.
This commit is contained in:
Nicolas Petton 2016-02-14 10:25:10 +01:00
parent d9bf0c1c6a
commit 30fe90fa3c
2 changed files with 22 additions and 0 deletions
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12
lisp/emacs-lisp/seq.el
View File

@ -144,6 +144,18 @@ if positive or too small if negative)."
sequence)
(nreverse result)))
(defun seq-map-indexed (function sequence)
"Return the result of applying FUNCTION to each element of SEQUENCE.
Unlike `seq-map', FUNCTION takes two arguments: the element of
the sequence, and its index within the sequence."
(let ((index 0))
(seq-map (lambda (elt)
(prog1
(funcall function elt index)
(setq index (1+ index))))
sequence)))
;; faster implementation for sequences (sequencep)
(cl-defmethod seq-map (function (sequence sequence))
(mapcar function sequence))

10
test/lisp/emacs-lisp/seq-tests.el
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@ -97,6 +97,16 @@ Evaluate BODY for each created sequence.
(with-test-sequences (seq '())
(should (seq-empty-p (seq-take-while #'test-sequences-oddp seq)))))
(ert-deftest test-seq-map-indexed ()
(should (equal (seq-map-indexed (lambda (elt i)
(list elt i))
nil)
nil))
(should (equal (seq-map-indexed (lambda (elt i)
(list elt i))
'(a b c d))
'((a 0) (b 1) (c 2) (d 3)))))
(ert-deftest test-seq-filter ()
(with-test-sequences (seq '(6 7 8 9 10))
(should (equal (seq-filter #'test-sequences-evenp seq) '(6 8 10)))