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Re: [ANN] faster org-table-to-lisp
From: |
tbanelwebmin |
Subject: |
Re: [ANN] faster org-table-to-lisp |
Date: |
Thu, 30 Apr 2020 22:28:58 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 |
Le 30/04/2020 à 10:09, Nicolas Goaziou a écrit :
> Hello,
>
> tbanelwebmin <address@hidden> writes:
>
>> Here is an alternative, faster version of org-table-to-lisp. It can be
>> more than 100 times faster.
> Great! Thank you!
>
>> #+BEGIN_SRC elisp
>> (defun org-table-to-lisp-faster (&optional org-table-at-p-done)
>> "Convert the table at point to a Lisp structure.
>> The structure will be a list. Each item is either the symbol `hline'
>> for a horizontal separator line, or a list of field values as strings.
>> The table is taken from the buffer at point.
>> When the optional ORG-TABLE-AT-P-DONE parameter is not nil, it is
>> assumed that (org-at-table-p) was already called."
> Since you're changing the signature, I suggest to provide the table
> element instead of ORG-AT-TABLE-P. AFAICT, `org-babel-read-element',
> through `org-babel-read-table', would greatly benefit from this.
>
> Or, to be backward compatible, I suggest
>
> &optional TEXT TABLE
>
>> (or org-table-at-p-done (org-at-table-p) (user-error "No table at point"))
>> (save-excursion
>> (goto-char (org-table-begin))
>> (let ((end (org-table-end))
>> (row)
>> (table))
> Nitpick:
>
> (row nil)
> (table nil)
>
>> (while (< (point) end)
>> (setq row nil)
>> (search-forward "|" end)
>> (if (looking-at "-")
>> (progn
>> (search-forward "\n" end)
> (forward-line)
>
>> (push 'hline table))
>> (while (not (search-forward-regexp "\\=\n" end t))
> (unless (eolp)
> ...)
>
>> (unless (search-forward-regexp "\\=\\s-*\\([^|]*\\)" end t)
>> (user-error "Malformed table at char %s" (point)))
> A row may not be properly ended. It doesn't warrant an error. Could you
> make it more tolerant?
>
> Also `search-forward-regexp' -> `re-search-forward', i.e., use the
> original.
>
>> (let ((b (match-beginning 1))
>> (e (match-end 1)))
> Nitpick: spurious spaces.
>
>> (and (search-backward-regexp "[^ \t]" b t)
>> (forward-char 1))
> (skip-chars-backward " \t")
>
>> It is faster because it operates directly on the buffer with
>> (search-forward-regexp). Whereas the standard function splits a string
>> extracted from the buffer.
> You are right. I guess the initial implementation didn't have these
> monster tables in mind.
>
>> This function is a drop-in replacement for the standard one. It can
>> benefit to Babel and Gnuplot.
>>
>> Would it make sense to upgrade Org Mode code base?
> Certainly. Could you add an entry in ORG-NEWS, in "Miscellaneous"?
>
> Regards,
>
Thanks Nicolas for your nice suggestions. I've taken them into
account. Particularly, the use of (skip-chars-backward " \t") gave a
small additional speedup, and simplified the code.
I found a way to ensure full backward compatibility. I keep the same
signature. When a table is given as a string parameter, it is inserted
into a temporary buffer, which is then parsed. Overall, the resulting
speed is quite satisfactory.
I also made the function more tolerant to ill-formed tables: missing
"|" or excess of spaces at the end of a row are now gracefully
accepted.
Regards
Thierry
#+BEGIN_SRC elisp
(defun org-table-to-lisp (&optional txt)
"Convert the table at point to a Lisp structure.
The structure will be a list. Each item is either the symbol `hline'
for a horizontal separator line, or a list of field values as strings.
The table is taken from the parameter TXT, or from the buffer at point."
(if txt
(with-temp-buffer
(insert txt)
(goto-char (point-min))
(org-table-to-lisp))
(unless (org-at-table-p) (user-error "No table at point"))
(save-excursion
(goto-char (org-table-begin))
(let ((end (org-table-end))
(row nil)
(table nil))
(while (< (point) end)
(setq row nil)
(search-forward "|" end)
(if (looking-at "-")
(progn
(forward-line)
(push 'hline table))
(while (not (re-search-forward "\\=\\s-*\n" end t))
(unless (re-search-forward "\\=\\s-*\\([^|\n]*\\)\\(|?\\)" end t)
(user-error "Malformed table at char %s" (point)))
(goto-char (match-end 1))
(skip-chars-backward " \t" (match-beginning 1))
(push
(buffer-substring-no-properties (match-beginning 1) (point))
row)
(goto-char (match-end 2)))
(push (nreverse row) table)))
(nreverse table)))))
#+END_SRC
* Version 9.4 (not yet released)
** Miscellaneous
*** Faster org-table-to-lisp
The new implementation can be more than 100 times faster. This enhances
responsiveness of Babel or Gnuplot blocks handling thousands long tables.