;-*- coding: utf-8 -*-
; some elisp string replacement functions
; used for regex replace operations

; 2007-06
;   Xah Lee
; ∑ http://xahlee.org/

(defun wikipedia-link-replacement ()
  "Returns a canonical form of Wikipedia link from a regex match.

This function is used for query-replace-regexp, to turn the
following forms of links:

<a href=\"http://en.wikipedia.org/wiki/event\">event</a>
<a href=\"http://en.wikipedia.org/wiki/Middle_distance\">Middle_distance↗</a>
<a href=\"http://en.wikipedia.org/wiki/Middle_distance_track_event\">Middle_distance_track_event↗</a>
<a href=\"http://en.wikipedia.org/wiki/Sapir-Whorf_Hypothesis\">Sapir-Whorf_Hypothesis↗</a>

into a cannonical form. Basically, the link text needs to have
“_” replaced by space, and should have a “↗” at the end. Also, it
shouldn't match links that's already in canonical form, nor
matching non-wikipedia link texts.

The regex to be used for this function is:
<a href=\"http://\\(..\\)\\.wikipedia.org/wiki/\\([^\"]+\\)\">\\(\\([-.A-Za-z0-9]+_\\)+[-.A-Za-z0-9]+ ?↗*\\)</a>

To use a function in query-replace-regexp, do “\\,(wikipedia-link-replacement)”.
."
  (let (langCode articlePath linkText linkText2 returnText)
    (setq langCode (buffer-substring (match-beginning 1) (match-end 1)))
    (setq articlePath (buffer-substring (match-beginning 2) (match-end 2)))
    (setq linkText (buffer-substring (match-beginning 3) (match-end 3)))
    (setq linkText2
          (concat 
           (replace-regexp-in-string "_" " " articlePath)
           "↗"))
    (setq returnText
          (concat "<a href=\"http://"
                  langCode ".wikipedia.org/wiki/"
                  articlePath "\">" linkText2 "</a>" ))
    returnText
    )
  )

(defun get-html-h1 ()
  "Returns the current buffer's first <h1></h1> tag content.

This function is used to get a set of HTML page's <title> tag
content in sync with the <h1> tag content. This function is used
for dired-do-query-replace-regex.

The search regex should be: 
<title>\([^<]+\)</title>

The replace string should be:
<title>\,(get-html-h1)</title>"
  (interactive)
  (let (pos1 pos2)
; move to the beginning
; search for <h1>, get position
; search for </h1>, get position
; get the text between positions
    (save-excursion
      (goto-char (point-min))
      (search-forward "<h1>" nil t)
      (setq pos1 (point))
      (search-forward "</h1>" nil t)
      (search-backward "</h1>" nil t)
      (setq pos2 (point))
      )
    (buffer-substring-no-properties pos1 pos2)
    )
  )