Re: Usage of org-element api

[Dieter Van Eessen <dieter.van.eessen@gmail.com>]

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Hello Rasmus,

Thank you for the fast reply, the link you've given on interpreting is very
useful ! Also didn't know there existed such thing as the org-dp library to
manipulate org-elements, I'll sure check it out.

More about question number 3:
>> 3) How can the output of (org-element-parse-secondary-string ...) be
used.
>> When I give a heading and bit of text as input (output of
>> buffer-substring), it looks like it returns the 'content' of the region.
>> Though I can't seem to use it anyway as 'CONTENT' for the functions
>> requiring this.

The reason I've tried this (and the internal org-element--parse-elements)
is because I'd prefer not having to parse the whole buffer and still get
the contents. The local parsing functions (org-element-at-point) and
(org-element-context) don't contain content (stated in the org-element api,
also tried it ).

Now I'm not sure IF I really NEED it? I could actually get the contents
using the  :content-begin and :content-end and other properties from
(org-elemen-at-point)  BUT I don't know the exact syntax the content should
have and how to merge it with the element-list I get from
(org-element-at-point) before feeding it to the org-element-interpret-data.

I don't actually know how 'content' looks like...  When applying a small
function
" (defun test
()

    (interactive)

(debug)

    (setq content (org-element-contents (org-element-parse-buffer))))"
on a simple headline with some text,
" * woot
     And a bit of text "
I can see in debugger (returned values) that 'content' is actually
(org-data nil ('content'). See output below. Thus concluding that content
is also just an <element>. Then why do all the
org-element-<element>-interpreters require both the <element>  AND
'content', since to me, it seems logical that all this information is
already inside <element>.

At first I thought that the things behind #  were 'content' (for example in
the output below. These don't show up in (org-element-at-point), thus
explaining why they returned nil when asked for content. The
org-element-parse-secondary-string also returns all things behind #. If
this is NOT content, then how to manipulate this data (behind the #) whilst
assuring that syntax and position remains valid for
org-element-interpret-data to understand?

OUTPUT:
 (org-data nil (headline (:raw-value "woot" :begin 1 :end 29 :pre-blank 0
:contents-begin 8 ...) (section (:begin 8 :end 29 :contents-begin
  8 :contents-end 26 :post-blank 2 ...) (paragraph (:begin 8 :end 26
:contents-begin 8 :contents-end 26 :post-blank 0 ...) #("And a bit of
  text  " 0 18 (:parent #3))))))

  ((headline (:raw-value "woot" :begin 1 :end 29 :pre-blank 0
:contents-begin 8 ...) (section (:begin 8 :end 29 :contents-begin 8
  :contents-end 26 :post-blank 2 ...) (paragraph (:begin 8 :end 26
:contents-begin 8 :contents-end 26 :post-blank 0 ...) #("And a bit of text
  " 0 18 (:parent #3))))))

Perhaps my view is completely wrong, so please correct me if possible.
Thanks for the time,
Dieter





On Fri, Jan 16, 2015 at 8:35 PM, Rasmus <rasmus@gmx.us> wrote:

> Hi Dieter,
>
> Nicolas will probably reply at some point and he has much greater (∞ more)
> insight in this topics.  None the less, I hope the below message will
> help a bit.
>
> Dieter Van Eessen <dieter.van.eessen@gmail.com> writes:
>
> > 1) How to use org-element-content? Returns nil when used on elements
> parsed
> > by org-element-<element>-parser (because they operate locally)  When used
> > globally, it only seems to remove the car of the list (org-data ....)
>
> Don't use org-element-<element>-parser directly.
>
> Use org-element-at-point or org-element-contents.  The former is for
> elements, the latter is for contents, such as scripts, bold, etc.  See the
> head of org-element.el.
>
> > 2) What is actually a normal workflow if you wish to interactive
> manipulate
> > only some of the elements? Is it something like:
> >  a)  Define the region in which you wish to manipulate things (using
> :begin
> > and :extract from  org-element-at-point)
>
> Org-element is a parser and manipulation might not be super efficient with
> org-element, but it can be done.
>
> OTOH Org-syntax is great for manipulation.  E.g. to insert a heading you
> can do (insert (format "* %s" "my-heading")).
>
> >  b) Parse the region: Get TREE and CONTENT
> >      (Are they always separated for manipulation?)
>
> See org-element-map for operating on a subset of the consents.  You could
> also use narrowing to operate only on a subset of the buffer.
>
> >  c) Manipulate tree AND/OR manipulate content
>
>
> Manipulate whatever you have as you want.  Org-elements are plists.  Check
> org-element-type, org-element-property, org-element-contents,
> org-element-put-property, org-element-set-contents.  See also
> ";;; Accessors and Setters" in org-element.el.
>
> org-element-interpret-data is the way to go from an element to
> org-syntax.  Here's an example:
>
>
> http://emacs.stackexchange.com/questions/2869/turn-a-list-or-data-structure-into-an-org-document/
>
> >  d) Interpret (the org-element-<element>interpreters seem to require
> > <element> and content whilst the org-element-interpret-data only
> requires a
> > single 'data'. Why?)
>
> Don't use org-element-<element>interpreters.  Use
> org-element-interpret-data for transforming org-element→org-syntax.
>
> >  e) See the manipulated stuff appear in the buffer.
>
> There's insert for that.
>
> > 3) How can the output of (org-element-parse-secondary-string ...) be
> used.
> > When I give a heading and bit of text as input (output of
> > buffer-substring), it looks like it returns the 'content' of the region.
> > Though I can't seem to use it anyway as 'CONTENT' for the functions
> > requiring this.
>
> I don't get this.
>
> > 4) How to use org-element--parse-elements? Whilst it is running i notice
> > that it uses (org-element--current-element) and some of the
> > (org-element-<element>-parser) functions. Thought it could be nice to use
> > this one, but no matter how use it, all I get is nil. For example:
>
> In Emacs-lisp typically "--" indicates that it's a private function.
> Don't use it.
>
> > 5) What is org-element--current-element for? It also seems to be called
> by
> > org-element--parse-element.The properties :begin, :end and :title  seem
> > different than when parsing with org-element-at-point.
> Org-element-contents
> > also nill when applied on the output. Why can't I use
> >     this function (org-element--current-element) on plainlists/items
> > (returns error with point within a plain-list/item)?
>
> See above.
>
> > I know the basic answer to most of these question is: Why don't you use
> > (org-element-parse-buffer). Well simply because I don't need everything.
> in
> > first implementation I only need:
> > OR HEADLINE under point and it's subtree
> >   (HEADLINE (plainlist (item,item,item)),(subheadline),...)
> > OR the headline of an ITEM under point and subtree
> >  (headline (plainlist (item, ITEM,item)),(subheadline),...).
>
> So use org-element-map and org-element-parse-buffer.
>
> Hope it helps,
> Rasmus
>
> --
> The second rule of Fight Club is: You do not talk about Fight Club
>
>
>


-- 
gtz,
Dieter VE

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