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How can I write an Emacs Lisp function to find all hrefs in an HTML file and extract all of the links?
Input:
<html> <a href="http://www.stackoverflow.com" _target="_blank">StackOverFlow</a> <h1>Emacs Lisp</h1> <a href="http://news.ycombinator.com" _target="_blank">Hacker News</a> </html>
Output:
http://www.stackoverflow.com|StackOverFlow http://news.ycombinator.com|Hacker News
I've seen the re-search-forward function mentioned several times during my search. Here's what I think that I need to do based on what I've read so far.
(defun extra-urls (file)
...
(setq buffer (...
(while
(re-search-forward "http://" nil t)
(when (match-string 0)
...
))
I took Heinzi's solution and came up with the final solution that I needed. I can now take a list of files, extract all URL's and titles, and place the results in one output buffer.
(defun extract-urls (fname)
"Extract HTML href url's,titles to buffer 'new-urls.csv' in | separated format."
(setq in-buf (set-buffer (find-file fname))); Save for clean up
(beginning-of-buffer); Need to do this in case the buffer is already open
(setq u1 '())
(while
(re-search-forward "^.*<a href=\"\\([^\"]+\\)\"[^>]+>\\([^<]+\\)</a>" nil t)
(when (match-string 0) ; Got a match
(setq url (match-string 1) ) ; URL
(setq title (match-string 2) ) ; Title
(setq u1 (cons (concat url "|" title "\n") u1)) ; Build the list of URLs
)
)
(kill-buffer in-buf) ; Don't leave a mess of buffers
(progn
(with-current-buffer (get-buffer-create "new-urls.csv"); Send results to new buffer
(mapcar 'insert u1))
(switch-to-buffer "new-urls.csv"); Finally, show the new buffer
)
)
;; Create a list of files to process
;;
(mapcar 'extract-urls '(
"/tmp/foo.html"
"/tmp/bar.html"
))
If there is at most one link per line and you don't mind some very ugly regular expression hacking, run the following code on your buffer:
(defun getlinks ()
(beginning-of-buffer)
(replace-regexp "^.*<a href=\"\\([^\"]+\\)\"[^>]+>\\([^<]+\\)</a>.*$" "LINK:\\1|\\2")
(beginning-of-buffer)
(replace-regexp "^\\([^L]\\|\\(L[^I]\\)\\|\\(LI[^N]\\)\\|\\(LIN[^K]\\)\\).*$" "")
(beginning-of-buffer)
(replace-regexp "
+" "
")
(beginning-of-buffer)
(replace-regexp "^LINK:\\(.*\\)$" "\\1")
)
It replaces all links with LINK:url|description, deletes all lines containing anything else, deletes empty lines, and finally removes the "LINK:".
Detailed HOWTO: (1) Correct the bug in your example html file by replacing <href with <a href, (2) copy the above function into Emacs scratch, (3) hit C-x C-e after the final ")" to load the function, (4) load your example HTML file, (5) execute the function with M-: (getlinks).
Note that the linebreaks in the third replace-regexp are important. Don't indent those two lines.
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