From: Carsten Dominik <carsten.dominik@gmail.com>
To: Thorsten Jolitz <tjolitz@gmail.com>
Cc: emacs-orgmode@gnu.org
Subject: Re: [BUG] in org-property-drawer-re?
Date: Tue, 1 Oct 2013 20:17:08 +0200 [thread overview]
Message-ID: <AF619789-B5B0-4904-A1DD-F89DE121D74F@gmail.com> (raw)
In-Reply-To: <87r4c4519w.fsf@gmail.com>
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On 1.10.2013, at 19:50, Thorsten Jolitz <tjolitz@gmail.com> wrote:
>
> Hi List,
>
> for the navi-mode keyword-search for complete property drawers I copied
>
> ,-----------------------
> | org-property-drawer-re
> `-----------------------
>
> from org.el:
>
> #+begin_src emacs-lisp
> (concat "\\(" org-property-start-re "\\)[^\000]*\\("
> org-property-end-re "\\)\n?")
> #+end_src
>
> #+results:
> : \(^[ ]*:PROPERTIES:[ ]*$\)[^\\000]*\(^[ ]*:END:[ ]*$\)
> : ?
>
> A bit unreadable, but you get the message ... here is my hopefully equivalent
> version:
>
> ,--------------------------------------------------------------
> | (:propertydrawer
> | . (concat "\\(^[\\s\\t]*:PROPERTIES:[\\s\\t]*$\\)[^\\000]*"
> | "\\(^[\\s\\t]*:END:[\\s\\t]*$\\)\\n?"))
> `--------------------------------------------------------------
>
> But this did not match correctly in Bernt Hansens tutorial:
Indeed, this is a bad regular expression, it is too greedy and will
match all the way to the last :END: line it can find. also, \\s is
wrong, it should be just a space, so "[ \t]". Luckily
this regular expression does not seem to be used in Org as far
as I can see....
>
> ,--------------------------------------------------------------------------
> | 43::PROPERTIES:
> | ::CUSTOM_ID: Setup
> | ::END:
> | 131::PROPERTIES:
> | ::CUSTOM_ID: OrgFiles
> | ::END:
> | 185::PROPERTIES:
> | ::CUSTOM_ID: AgendaSetup
> | ::END:
> | :
> | :Here is my current =org-agenda-files= setup.
> | :#+begin_src emacs-lisp :tangle no
> | : (setq org-agenda-files (quote ("~/git/org"
> | : "~/git/org/client1"
> | : "~/git/org/bzflag"
> | : "~/git/client2")))
> | :#+end_src
> | :
> | :#+begin_src emacs-lisp :tangle yes :exports none
> | : ;; The following setting is different from the document so that you
> | : ;; can override the document org-agenda-files by setting your
> | : ;; org-agenda-files in the variable org-user-agenda-files
> | : ;;
> | : (if (boundp 'org-user-agenda-files)
> | : (setq org-agenda-files org-user-agenda-files)
> | : (setq org-agenda-files (quote ("~/git/org"
> | : "~/git/org/client1"
> | : "~/git/org/bzflag"
> | : "~/git/client2"))))
> | :
> | :#+end_src
> `--------------------------------------------------------------------------
>
> I had to add two ?
You only need the first - the second is OK.
> after the * and delete the final \n
>
> ,-------------------------------------------------------------
> | (:propertydrawer
> | . (concat "\\(^[\\s\\t]*:PROPERTIES:[\\s\\t]*$\\)[^\\000]*?"
> | "\\(^[\\s\\t]*:END:[\\s\\t]*?$\\)"))
> `-------------------------------------------------------------
Yes, you need the star to make it non-greedy.
However, you can leave the \n after you have corrected the
character class to "[ \t]" - it just means that
the \n will be part of the match, but still allow
for the possibility that the last line hits the end
of the buffer.
Ahhhh, regular expressions. I think in my entire history
as a programmer, learning about regular expressions was
the biggest braintrip I ever had - still love them.
>
> to get the desired results:
>
> ,---------------------------------
> | 43::PROPERTIES:
> | ::CUSTOM_ID: Setup
> | ::END:
> | 131::PROPERTIES:
> | ::CUSTOM_ID: OrgFiles
> | ::END:
> | 185::PROPERTIES:
> | ::CUSTOM_ID: AgendaSetup
> | ::END:
> | 234::PROPERTIES:
> | ::CUSTOM_ID: OrgFileStructure
> | ::END:
> `---------------------------------
>
> A bug in the regexp?
>
> PS
> Can anybody explain this marvelous construct in the regexp:
>
> ,---------
> | [^\\000]
> `---------
This is just a cheep way to match any character at all, because \000 should
not be part of any string (in C it indicates the end of a string).
In principle you could put any character you are sure will not turn up,
but \000 seems to be the safest choice. It is
faster (I think) than "\\(.\\|\n\\)*" because the first will
just run fast and streight with a table lookup while the
latter need to always alternate between two alternatives.
I have not timed it, though.
>
> I often pondered about how to achieve its effect with other means, since
> I did not find it in the Emacs Lisp manual.
There you go - sometimes a brain is better than the Emacs manual :)
Regards
- Carsten
>
> --
> cheers,
> Thorsten
>
>
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next prev parent reply other threads:[~2013-10-01 18:17 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-01 17:50 [BUG] in org-property-drawer-re? Thorsten Jolitz
2013-10-01 18:17 ` Carsten Dominik [this message]
2013-10-01 18:36 ` Thorsten Jolitz
2013-10-01 18:44 ` Carsten Dominik
2013-10-02 9:55 ` Nicolas Goaziou
2013-10-02 11:05 ` Carsten Dominik
2013-10-02 11:14 ` Nicolas Goaziou
2013-10-02 11:37 ` Carsten Dominik
2013-10-02 11:38 ` Thorsten Jolitz
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