Emacs org: Promote all headings of a subtree during export? - emacs

Question

I use emacs org a lot to export parts of org documents to latex/pdf. I was wondering whether there is a way to promote all headings of the selected parts during the export process. For instance, suppose the file looks like this:
* Project 1
** Task 1 :export:
*** Introduction
Text text text.
*** Results
Text text text.
* Project 2
The emacs org export to latex would produce a tex file of the following structure:
\section{Project 1}
\subsection{Task 1}
\subsubsection{Introduction}
Text text text.
\subsubsection{Results}
Text text text.
But because there is not highest level in the part to be exported, it would make more sense to have the following structure:
\section{Task 1}
\subsection{Introduction}
Text text text.
\subsection{Results}
Text text text.
Or, even better:
\title{Task 1}
\maketitle
\section{Introduction}
Text text text.
\section{Results}
Text text text.
I was wondering whether anyone has an idea how to go about this? My lisp skills are unfortunately very rudimentary, seems like it should not be too hard.
Thanks!
Stephan

Answer 1

The first behavior you describe can be achieved by adding the following to your .emacs:
;; Define a function for turning a single subtree into a top-level tree
;; (:export: headings might be located at an arbitrary nesting level,
;; so a single call to "org-promote-subtree" is not enough):
(defun org-promote-to-top-level ()
"Promote a single subtree to top-level."
(let ((cur-level (org-current-level)))
(loop repeat (/ (- cur-level 1) (org-level-increment))
do (org-promote-subtree))))
;; Define a function that applies "org-promote-to-top-level"
;; to each :export: subtree:
(defun org-export-trees-to-top-level (backend)
"Promote all subtrees tagged :export: to top-level.
BACKEND is the export back-end being used, as a symbol."
(org-map-entries 'org-promote-to-top-level "+export"))
;; Make org-mode run "org-export-subtrees-to-top-level" as part of the export
;; process:
(add-hook 'org-export-before-parsing-hook 'org-export-trees-to-top-level)
Implementing the second behavior is a bit trickier but you can use theorg-export-trees-to-top-level function as a starting point if that's what you ultimately need. I'd like to point out, however, that this will not work for files with more than one :export: subtree (unless you also come up with a way to decide which headline would become the \title in these cases).
Sources:
Logic of org-promote-to-top-level based on source code of org-cycle-level command
Using the org-mode mapping API
Relevant information about export hooks