Subject: bug#13946: 24.3; [PATCH] fix of apropos with words

From: Shigeru Fukaya <[email-masked]>
Date: Thu, 14 Mar 2013 00:21:29 +0900

Hello,

`apropos' family with plural words returns unexpected symbols and are
annoying.  It is because `apropos-words-to-regexp' doesn't work as
documented/expected.

The following is revised `apropos-words-to-regexp'.

(defun apropos-words-to-regexp (words wild)
  "Make regexp matching any two of the words in WORDS."
  (if (null (cdr words))
      (car words)
    ;; assure all words are independent objects for delq
    (setq words (mapcar 'copy-sequence words))
    (mapconcat
     (lambda (w)
       (concat "\\(?:" w "\\)" ;; parens for synonyms
               wild
               "\\(?:"
               (mapconcat
                'identity
                (delete-dups (delq w (copy-sequence words)))
                "\\|")
               "\\)"))
     (delete-dups (copy-sequence words))
     "\\|")))

results:

(apropos-words-to-regexp '("A" "B") ".*?")
"\\(?:A\\).*?\\(?:B\\)\\|\\(?:B\\).*?\\(?:A\\)"

(apropos-words-to-regexp '("A" "B" "C") ".*?")
"\\(?:A\\).*?\\(?:B\\|C\\)\\|\\(?:B\\).*?\\(?:A\\|C\\)\\|\\(?:C\\).*?\\(?:A\\|B\\)"

(apropos-words-to-regexp '("A" "B" "B") ".*?")
"\\(?:A\\).*?\\(?:B\\)\\|\\(?:B\\).*?\\(?:A\\|B\\)"

(apropos-words-to-regexp '("A" "A" "B" "C" "C") ".*?")
"\\(?:A\\).*?\\(?:A\\|B\\|C\\)\\|\\(?:B\\).*?\\(?:A\\|C\\)\\|\\(?:C\\).*?\\(?:A\\|B\\|C\\)"

Additionally, in `apropos-parse-pattern', ".+" passed to
`apropos-words-to-regexp' wolud be better if ".+?".

Regards,
Shigeru.