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Problems with Emacs print syntax
From: |
Thorsten Jolitz |
Subject: |
Problems with Emacs print syntax |
Date: |
Tue, 10 Sep 2013 09:12:32 +0200 |
User-agent: |
Gnus/5.130002 (Ma Gnus v0.2) Emacs/24.3 (gnu/linux) |
Hi List,
this is a question about the org-element parse-tree, but its actually
about reading 'unreadable' Emacs print syntax, so I ask it here too (in
a slightly different formulation).
How do I get the printed representation of an org-file parse-tree that can be
reverted to the original org-file with `'org-element-interpret-data'?
Elisp manual says:
,-------------------------------------------------------------------------
| Reading and printing are more or less inverse operations: [...]
|
| However, these two operations are not precisely inverse to each other.
| There are three kinds of exceptions:
|
| Printing can produce text that cannot be read. For example, buffers,
| windows, frames, subprocesses and markers print as text that starts
| with ‘#’; if you try to read this text, you get an error. There is
| no way to read those data types. [...]
`-------------------------------------------------------------------------
E.g. given file tmp.org:
,-------------------
| #+options: toc:nil
| * A
| B
`-------------------
#+begin_src emacs-lisp
(with-current-buffer "tmp.org"
(org-element-interpret-data (org-element-parse-buffer)))
#+end_src
yields what is expected:
,--------------------
| "#+OPTIONS: toc:nil
| * A
| B
| "
`--------------------
but, e.g., this
#+begin_src emacs-lisp
(with-current-buffer "tmp.org"
(print (org-element-parse-buffer)))
#+end_src
yields:
#+begin_src emacs-lisp
(org-data nil (section (:begin 1 :end 20 :contents-begin
1 :contents-end 20 :post-blank 0 :parent
#0) (keyword (:key "OPTIONS" :value "toc:nil" :begin 1 :end
20 :post-blank 0 :post-affiliated 1 :parent
#1))) (headline (:raw-value "A" :begin 20 :end 26 :pre-blank
0 :hiddenp nil :contents-begin 24 :contents-end 26 :level
1 :priority nil :tags nil :todo-keyword nil :todo-type
nil :post-blank 0 :footnote-section-p nil :archivedp
nil :commentedp nil :quotedp nil :CATEGORY nil :title (#("A" 0
1 (:parent #1))) :parent #0) (section (:begin 24 :end
26 :contents-begin 24 :contents-end 26 :post-blank 0 :parent
#1) (paragraph (:begin 24 :end 26 :contents-begin
24 :contents-end 26 :post-blank 0 :post-affiliated 24 :parent #2)
#("B" 0 2 (:parent #3))))))
#+end_src
what can't be used with `org-element-interpret-data' directly, but can't
be read first with `read-from-string' or so either because of unreadble
parts like this:
,---------------------------------------------
| :title (#("A" 0 1 (:parent #1))) :parent #0)
`---------------------------------------------
I think it would be great if one could produce a 'readable' printed
representation of such a parse-tree programmatically, read it as Lisp
object, and then interpret that Lisp object with
`org-element-interpret-data' to produce the specified textual Org
element (or Org file).
How could one achieve that given that Org-mode parser employs
circular lists and strings are stored with text-properties?
--
cheers,
Thorsten
- Problems with Emacs print syntax,
Thorsten Jolitz <=