Re: Org-element once again

[Thorsten Jolitz <tjolitz@gmail.com>]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> Marcin Borkowski <mbork@wmi.amu.edu.pl> writes:
>
>> Hi list,
>>
>> does there exist any place I could find the specs of the org-element
>> data structure?  From what I can see, it is a list whose car is the type
>> of the element, then a (somewhat mysterious or me) plist follows, and
>> then the children.  Where could I find more info?  If the answer is
>> "read the source, Luke" ;-) , which functions should I start with?
>>
>> Best,
>
> Have you looked at this page?
>
> http://orgmode.org/worg/dev/org-element-api.html
>
> That and the pages linked from it seem to cover most of what's going on.
>
> The mysterious plist holds all the properties for a given element. Most
> are generated by the parsing process (eg :contents-begin and
> :contents-end, see the link above for all the different properties the
> various elements/objects might get), while headlines will also have
> their actual property-drawer properties put into the list.
>
> The only thing that remains a little opaque to me is the "section"
> element, which apparently gets wrapped around a heading's subtree. I
> don't know what it does, but it's never gotten in my way so I haven't
> worried about it.

in simple terms, the data structure is just:

,----
| (element-typ (plist) (section))
`----

i.e. the plist describes the element itself, the section is its
content. 


* TODO Test :@home:
  DEADLINE: <2014-10-09 Do>
  :PROPERTIES:
  :ARCHIVE:  foo
  :END:


org-element-at-point does not parse the contents of an element, it
thus simply returns

,----
| (element-typ (plist))
`----


#+NAME: foo
#+BEGIN_SRC emacs-lisp
 (save-excursion
 (outline-previous-heading)
 (org-element-at-point))
#+END_SRC

# [:results pp]
#+results:
: (headline
:  (:raw-value "Test" :begin 1432 :end 2214 :pre-blank 0 :contents-begin 1452 :contents-end 2214 :level 1 :priority nil :tags
: 	     ("@home")
: 	     :todo-keyword "TODO" :todo-type todo :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 1432 :deadline
: 	     (timestamp
: 	      (:type active :raw-value "<2014-10-09 Do>" :year-start 2014 :month-start 10 :day-start 9 :hour-start nil :minute-start nil :year-end 2014 :month-end 10 :day-end 9 :hour-end nil :minute-end nil :begin 1464 :end 1479 :post-blank 0))
: 	     :ARCHIVE "foo" :title "Test"))

#+NAME: bar
#+BEGIN_SRC emacs-lisp :var x=foo 
 (org-element-interpret-data x) 
#+END_SRC

#+results: bar
: * TODO Test :@home:

so this is (just) the element (headline) as specified by its plist.

You can get the contents e.g. with 

#+BEGIN_SRC emacs-lisp :results wrap
(require 'org-dp-lib)
 (save-excursion
 (outline-previous-heading)
 (org-dp-contents nil t)))
#+END_SRC

#+results:
:RESULTS:
DEADLINE: <2014-10-09 Do>
:PROPERTIES:
:ARCHIVE:  foo
:END:

[...]
:END:

but the default org-element-parse-buffer parses everything (when specified), the
contents too, so it would give you 

,----
| (element-typ (plist) (section))
`----

with section recursively containing other elements with the same
structure -> a nested list.

-- 
cheers,
Thorsten