Question

有没有人在Emacs Lisp中实现自然顺序排序？我知道写作并不难，但借用别人的工作更容易。

（是的，我无法相信我只是搜索了一个Emacs功能而无法找到它。）

Answer 1

此代码提供了'dictionary-lessp，可用于排序算法。到目前为止似乎在我的测试中工作：

(defun dictionary-lessp (str1 str2)
  "return t if STR1 is < STR2 when doing a dictionary compare
(splitting the string at numbers and doing numeric compare with them)"
  (let ((str1-components (dict-split str1))
        (str2-components (dict-split str2)))
    (dict-lessp str1-components str2-components)))

(defun dict-lessp (slist1 slist2)
  "compare the two lists of strings & numbers"
  (cond ((null slist1)
         (not (null slist2)))
        ((null slist2)
         nil)
        ((and (numberp (car slist1))
              (stringp (car slist2)))
         t)
        ((and (numberp (car slist2))
              (stringp (car slist1)))
         nil)
        ((and (numberp (car slist1))
              (numberp (car slist2)))
         (or (< (car slist1) (car slist2))
             (and (= (car slist1) (car slist2))
                  (dict-lessp (cdr slist1) (cdr slist2)))))
        (t
         (or (string-lessp (car slist1) (car slist2))
             (and (string-equal (car slist1) (car slist2))
                  (dict-lessp (cdr slist1) (cdr slist2)))))))

(defun dict-split (str)
  "split a string into a list of number and non-number components"
  (save-match-data 
    (let ((res nil))
      (while (and str (not (string-equal "" str)))
        (let ((p (string-match "[0-9]*\\.?[0-9]+" str)))
          (cond ((null p)
                 (setq res (cons str res))
                 (setq str nil))
                ((= p 0)
                 (setq res (cons (string-to-number (match-string 0 str)) res))
                 (setq str (substring str (match-end 0))))
                (t
                 (setq res (cons (substring str 0 (match-beginning 0)) res))
                 (setq str (substring str (match-beginning 0)))))))
      (reverse res))))

这是我的测试：

(and (dictionary-lessp "a" "b")
     (null (dictionary-lessp "b" "a"))
     (null (dictionary-lessp "a" "a"))
     (dictionary-lessp "1" "2")
     (null (dictionary-lessp "2" "1"))
     (null (dictionary-lessp "1" "1"))
     (dictionary-lessp "1" "a")
     (null (dictionary-lessp "a" "1"))
     (dictionary-lessp "" "a")
     (null (dictionary-lessp "a" ""))

     (dictionary-lessp "ab12" "ab34")
     (dictionary-lessp "ab12" "ab123")
     (dictionary-lessp "ab12" "ab12d")
     (dictionary-lessp "ab132" "ab132z")


     (dictionary-lessp "132zzzzz" "ab132z")
     (null (dictionary-lessp "1.32" "1ab")))

示例用法是：

(sort '("b" "a" "1" "f19" "f" "f2" "f1can") 'dictionary-lessp)

产量

("1" "a" "b" "f" "f1can" "f2" "f19")

Emacs Lisp的自然排序

1 个答案: