#+Title: Org-Docco
#+Author: Eric Schulte
#+Style: <link rel="stylesheet" href="docco.css" type="text/css">
#+Property: tangle yes

The =docco= tool (see http://jashkenas.github.com/docco/) generates
HTML from JavaScript source code providing an attractive side-by-side
display of source code and comments.  This file (see [[https://orgmode.org/cgit.cgi/org-mode.git/plain/contrib/scripts/org-docco.org][org-docco.org]])
generates the same type of output from Org-mode documents with code
embedded in code blocks.

The way this works is an Org-mode document with embedded code blocks
is exported to html using the standard Org-mode export functions.
This file defines a new function named =org-docco-buffer= which, when
added to the =org-export-html-final-hook=, will be run automatically
as part of the Org-mod export process doccoizing your Org-mode
document.

A pure source code file can be extracted (or "/tangled/") from the
Org-mode document using the normal =org-babel-tangle= function.  See
[[https://orgmode.org/manual/Working-With-Source-Code.html][Working With Source Code]] chapter of the Org-mode manual for more
information on using code blocks in Org-mode files.

*Disclaimer*: this currently only works on /very/ simple Org-mode
files which have no headings but rather are just a collection of
alternating text and code blocks.  It wouldn't be difficult to
generalize the following code so that it could be run in particular
sub-trees but I simply don't have the time to do so myself, and this
version perfectly satisfies my own limit needs.  I make no promises to
support this code moving forward.  /Caveat Emptor/

#+begin_src emacs-lisp :padline no
;;; org-docco.el --- docco type html generation from Org-mode

;; Copyright (C) 2012 Eric Schulte

;; Author: Eric Schulte
;; Keywords: org-mode, literate programming, html
;; Homepage: https://orgmode.org/worg/org-contrib/org-mime.php
;; Version: 0.01

;; This file is not part of GNU Emacs.

;;; License:

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 3, or (at your option)
;; any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; <- look over there
#+end_src

The =cl= package provides all of the state-changing functions used
below e.g., =push= and =incf=.  It looks like a namespace-safe version
of =cl= may soon be permissible for use in official Emacs packages.
#+begin_src emacs-lisp
;;; Code:
(require 'cl-lib)
#+end_src

This is a function which returns the buffer positions of matching
regular expressions.  It has two special features...
1. It only counts matched instances of =beg-re= and =end-re= which are
   properly nested, so for example if =beg-re= and =end-re= are set to
   =(= and =)= respectively and we run this against the following,
   : 1    2       3 4   5     6
   : |    |       | |   |     |
   : v    v       v v   v     v
   : (foo (bar baz) (qux) quux)
   it will return 1 and 6 rather than 1 and 3.
2. It uses [[www.gnu.org/s/emacs/manual/html_node/elisp/Markers.html][markers]] which save their position in a buffer even as the
   buffer is changed (e.g., by me adding in extra HTML text).
#+begin_src emacs-lisp
(defun org-docco-balanced-re (beg-re end-re)
  "Return the beginning and of a balanced regexp."
  (save-excursion
    (save-match-data
      (let ((both-re (concat "\\(" beg-re "\\|" end-re "\\)"))
            (beg-count 0) (end-count 0)
            beg end)
        (when (re-search-forward beg-re nil t)
          (goto-char (match-beginning 0))
          (setq beg (point-marker))
          (cl-incf beg-count)
          (goto-char (match-end 0))
          (while (and (not end) (re-search-forward both-re nil t))
            (goto-char (match-beginning 0))
            (cond ((looking-at beg-re) (cl-incf beg-count))
                  ((looking-at end-re) (cl-incf end-count))
                  (:otherwise (error "miss-matched")))
            (goto-char (match-end 0))
            (when (= beg-count end-count) (setq end (point-marker))))
          (when end (cons beg end)))))))
#+end_src

This ugly large function does the actual conversion.  It wraps the
entire main content =div= of the exported Org-mode html into a single
large table.  Each row of the table has documentation on the left side
and code on the right side.  This function has two parts.
1. We use =(org-docco-balanced-re "<div" "</div>")= to find the
   beginning and end of the main content div.  We then break up this
   div at =<pre></pre>= boundaries with multiple calls to
   =(org-docco-balanced-re "<pre class\"src" "</pre>")=.
2. With all documentation/code boundaries in hand we step through the
   buffer inserting the table html code at boundary locations.
#+begin_src emacs-lisp
(defun org-docco-buffer ()
  "Call from within an HTML buffer to doccoize it."
  (interactive)
  (let ((table-start "<table>\n")
        (doc-row-start  "<tr><th class=\"docs\">\n") (doc-row-end  "</th>\n")
        (code-row-start "    <td class=\"code\">\n") (code-row-end "</td></tr>\n")
        (table-end "</table>" )
        pair transition-points next)
    (save-excursion
      (save-match-data
        (goto-char (point-min))
        (when (re-search-forward "<div id=\"content\">" nil t)
          (goto-char (match-end 0))
          (push (point-marker) transition-points)
          (goto-char (match-beginning 0))
          (setq pair (org-docco-balanced-re "<div" "</div>"))
          (while (setq next (org-docco-balanced-re "<pre class=\"src" "</pre>"))
            (goto-char (cdr next))
            (push (car next) transition-points)
            (push (cdr next) transition-points))
          (goto-char (cdr pair))
          (push (and (re-search-backward "</div>" nil t) (point-marker))
                transition-points)
          ;; collected transitions, so build the table
          (setq transition-points (nreverse transition-points))
          (goto-char (pop transition-points))
          (insert table-start doc-row-start)
          (while (> (length transition-points) 1)
            (goto-char (pop transition-points))
            (insert doc-row-end code-row-start)
            (goto-char (pop transition-points))
            (insert code-row-end doc-row-start))
          (goto-char (pop transition-points))
          (insert code-row-end table-end)
          (unless (null transition-points)
            (error "leftover points")))))))
#+end_src

We'll use Emacs [[http://www.gnu.org/software/emacs/manual/html_node/emacs/Specifying-File-Variables.html][File Local Variables]] and the
=org-export-html-final-hook= to control which buffers have
=org-docco-buffer= run as part of their export process.
#+begin_src emacs-lisp
  (defvar org-docco-doccoize-me nil
    "File local variable controlling if html export should be doccoized.")
  (make-local-variable 'org-docco-doccoize-me)
#+end_src

A simple function will conditionally process HTML output based on the
value of this variable.
#+begin_src emacs-lisp
  (defun org-docco-buffer-maybe ()
    (when org-docco-doccoize-me (org-docco-buffer)))
#+end_src

Finally this function is added to the =org-export-html-final-hook=.
#+begin_src emacs-lisp
  (add-hook 'org-export-html-final-hook #'org-docco-buffer-maybe)
#+end_src

That's it.  To use this simply;
1. Checkout this file from https://github.com/eschulte/org-docco,
   : git clone git://github.com/eschulte/org-docco.git
   and open it using Emacs.
2. Tangle =org-docco.el= out of this file by calling
   =org-babel-tangle= or =C-c C-v t=.
3. Load the resulting Emacs Lisp file.
4. Execute the following in any Org-mode buffer to add file local
   variable declarations which will enable post-processed with
   =org-docco-buffer=.
   : (add-file-local-variable 'org-export-html-postamble nil)
   : (add-file-local-variable 'org-export-html-style-include-default nil)
   : (add-file-local-variable 'org-docco-doccoize-me t)
   And add the following style declaration to make use of the
   =docco.css= style sheet taken directly from
   https://github.com/jashkenas/docco.
   : #+Style: <link rel="stylesheet" href="docco.css" type="text/css">

#+begin_src emacs-lisp
(provide 'org-docco)
;;; org-docco.el ends here
#+end_src

# Local Variables:
# org-export-html-postamble: nil
# org-export-html-style-include-default: nil
# org-docco-doccoize-me: t
# End: