;;; org-md.el --- Markdown Back-End for Org Export Engine
;; Copyright (C) 2012 Free Software Foundation, Inc.
;; Author: Nicolas Goaziou <n.goaziou@gmail.com>
;; Keywords: org, wp, tex
;; 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 of the License, 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 this program. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;; This library implements a Markdown back-end (vanilla flavour) for
;; Org exporter, based on `e-html'.
;;
;; It provides two commands for export, depending on the desired
;; output: `org-md-export-as-markdown' (temporary buffer) and
;; `org-md-export-to-markdown' ("md" file).
;;; Code:
(require 'org-e-html)
;;; User-Configurable Variables
(defgroup org-export-md nil
"Options specific to Markdown export back-end."
:tag "Org Markdown"
:group 'org-export
:version "24.2")
(defcustom org-md-headline-style 'atx
"Style used to format headlines.
This variable can be set to either `atx' or `setext'."
:group 'org-export-md
:type '(choice
(const :tag "Use \"atx\" style" atx)
(const :tag "Use \"Setext\" style" setext)))
;;; Define Back-End
(org-export-define-derived-backend md e-html
:export-block ("MD" "MARKDOWN")
:filters-alist ((:filter-parse-tree . org-md-separate-elements))
:menu-entry
(?m "Export to Markdown"
((?M "To temporary buffer"
(lambda (s v b) (org-md-export-as-markdown s v)))
(?m "To file" (lambda (s v b) (org-md-export-to-markdown s v)))
(?o "To file and open"
(lambda (s v b) (org-open-file (org-md-export-to-markdown s v))))))
:translate-alist ((bold . org-md-bold)
(code . org-md-verbatim)
(example-block . org-md-example-block)
(footnote-definition . ignore)
(footnote-reference . ignore)
(headline . org-md-headline)
(horizontal-rule . org-md-horizontal-rule)
(inline-src-block . org-md-verbatim)
(italic . org-md-italic)
(item . org-md-item)
(line-break . org-md-line-break)
(link . org-md-link)
(paragraph . org-md-paragraph)
(plain-list . org-md-plain-list)
(plain-text . org-md-plain-text)
(quote-block . org-md-quote-block)
(quote-section . org-md-example-block)
(section . org-md-section)
(src-block . org-md-example-block)
(template . org-md-template)
(verbatim . org-md-verbatim)))
;;; Filters
(defun org-md-separate-elements (tree backend info)
"Make sure elements are separated by at least one blank line.
TREE is the parse tree being exported. BACKEND is the export
back-end used. INFO is a plist used as a communication channel.
Assume BACKEND is `md'."
(org-element-map
tree org-element-all-elements
(lambda (elem)
(unless (eq (org-element-type elem) 'org-data)
(org-element-put-property
elem :post-blank
(let ((post-blank (org-element-property :post-blank elem)))
(if (not post-blank) 1 (max 1 post-blank)))))))
;; Return updated tree.
tree)
;;; Transcode Functions
;;;; Bold
(defun org-md-bold (bold contents info)
"Transcode BOLD object into Markdown format.
CONTENTS is the text within bold markup. INFO is a plist used as
a communication channel."
(format "**%s**" contents))
;;;; Code and Verbatim
(defun org-md-verbatim (verbatim contents info)
"Transcode VERBATIM object into Markdown format.
CONTENTS is nil. INFO is a plist used as a communication
channel."
(let ((value (org-element-property :value verbatim)))
(format (cond ((not (string-match "`" value)) "`%s`")
((or (string-match "\\``" value)
(string-match "`\\'" value))
"`` %s ``")
(t "``%s``"))
value)))
;;;; Example Block and Src Block
(defun org-md-example-block (example-block contents info)
"Transcode EXAMPLE-BLOCK element into Markdown format.
CONTENTS is nil. INFO is a plist used as a communication
channel."
(replace-regexp-in-string
"^" " "
(org-remove-indentation
(org-element-property :value example-block))))
;;;; Headline
(defun org-md-headline (headline contents info)
"Transcode HEADLINE element into Markdown format.
CONTENTS is the headline contents. INFO is a plist used as
a communication channel."
(unless (org-element-property :footnote-section-p headline)
(let* ((level (org-export-get-relative-level headline info))
(title (org-export-data (org-element-property :title headline) info))
(todo (and (plist-get info :with-todo-keywords)
(let ((todo (org-element-property :todo-keyword
headline)))
(and todo (concat (org-export-data todo info) " ")))))
(tags (and (plist-get info :with-tags)
(let ((tag-list (org-export-get-tags headline info)))
(and tag-list
(format " :%s:"
(mapconcat 'identity tag-list ":"))))))
(priority
(and (plist-get info :with-priority)
(let ((char (org-element-property :priority headline)))
(and char (format "[#%c] " char)))))
;; Headline text without tags.
(heading (concat todo priority title)))
(cond
;; Cannot create an headline. Fall-back to a list.
((or (org-export-low-level-p headline info)
(not (memq org-md-headline-style '(atx setext)))
(and (eq org-md-headline-style 'atx) (> level 6))
(and (eq org-md-headline-style 'setext) (> level 2)))
(let ((bullet
(if (not (org-export-numbered-headline-p headline info)) "-"
(concat (number-to-string
(car (last (org-export-get-headline-number
headline info))))
"."))))
(concat bullet (make-string (- 4 (length bullet)) ? ) heading tags
"\n\n"
(and contents
(replace-regexp-in-string "^" " " contents)))))
;; Use "Setext" style.
((eq org-md-headline-style 'setext)
(concat heading tags "\n"
(make-string (length heading) (if (= level 1) ?= ?-))
"\n\n"
contents))
;; Use "atx" style.
(t (concat (make-string level ?#) " " heading tags "\n\n" contents))))))
;;;; Horizontal Rule
(defun org-md-horizontal-rule (horizontal-rule contents info)
"Transcode HORIZONTAL-RULE element into Markdown format.
CONTENTS is the horizontal rule contents. INFO is a plist used
as a communication channel."
"---")
;;;; Italic
(defun org-md-italic (italic contents info)
"Transcode ITALIC object into Markdown format.
CONTENTS is the text within italic markup. INFO is a plist used
as a communication channel."
(format "*%s*" contents))
;;;; Item
(defun org-md-item (item contents info)
"Transcode ITEM element into Markdown format.
CONTENTS is the item contents. INFO is a plist used as
a communication channel."
(let* ((type (org-element-property :type (org-export-get-parent item)))
(struct (org-element-property :structure item))
(bullet (if (not (eq type 'ordered)) "-"
(concat (number-to-string
(car (last (org-list-get-item-number
(org-element-property :begin item)
struct
(org-list-prevs-alist struct)
(org-list-parents-alist struct)))))
"."))))
(concat bullet
(make-string (- 4 (length bullet)) ? )
(case (org-element-property :checkbox item)
(on "[X] ")
(trans "[-] ")
(off "[ ] "))
(let ((tag (org-element-property :tag item)))
(and tag (format "**%s:** "(org-export-data tag info))))
(org-trim (replace-regexp-in-string "^" " " contents)))))
;;;; Line Break
(defun org-md-line-break (line-break contents info)
"Transcode LINE-BREAK object into Markdown format.
CONTENTS is nil. INFO is a plist used as a communication
channel."
" ")
;;;; Link
(defun org-md-link (link contents info)
"Transcode LINE-BREAK object into Markdown format.
CONTENTS is the link's description. INFO is a plist used as
a communication channel."
(let ((--link-org-files-as-html-maybe
(function
(lambda (raw-path info)
;; Treat links to `file.org' as links to `file.html', if
;; needed. See `org-e-html-link-org-files-as-html'.
(cond
((and org-e-html-link-org-files-as-html
(string= ".org"
(downcase (file-name-extension raw-path "."))))
(concat (file-name-sans-extension raw-path) "."
(plist-get info :html-extension)))
(t raw-path)))))
(type (org-element-property :type link)))
(cond ((member type '("custom-id" "id"))
(let ((destination (org-export-resolve-id-link link info)))
(if (stringp destination) ; External file.
(let ((path (funcall --link-org-files-as-html-maybe
destination info)))
(if (not contents) (format "<%s>" path)
(format "[%s](%s)" contents path)))
(concat
(and contents (concat contents " "))
(format "(%s)"
(format (org-export-translate "See section %s" :html info)
(mapconcat 'number-to-string
(org-export-get-headline-number
destination info)
".")))))))
((org-export-inline-image-p link org-e-html-inline-image-rules)
(format ""
(let ((caption (org-export-get-caption
(org-export-get-parent-element link))))
(when caption (org-export-data caption info)))
path))
((string= type "coderef")
(let ((ref (org-element-property :path link)))
(format (org-export-get-coderef-format ref contents)
(org-export-resolve-coderef ref info))))
((equal type "radio")
(let ((destination (org-export-resolve-radio-link link info)))
(org-export-data (org-element-contents destination) info)))
((equal type "fuzzy")
(let ((destination (org-export-resolve-fuzzy-link link info)))
;; Ignore invisible "#+TARGET: path".
(unless (eq (org-element-type destination) 'keyword)
(if (org-string-nw-p contents) contents
(when destination
(let ((number (org-export-get-ordinal destination info)))
(when number
(if (atom number) (number-to-string number)
(mapconcat 'number-to-string number ".")))))))))
(t (let* ((raw-path (org-element-property :path link))
(path (cond
((member type '("http" "https" "ftp"))
(concat type ":" raw-path))
((equal type "file")
;; Treat links to ".org" files as ".html",
;; if needed.
(setq raw-path
(funcall --link-org-files-as-html-maybe
raw-path info))
;; If file path is absolute, prepend it
;; with protocol component - "file://".
(if (not (file-name-absolute-p raw-path)) raw-path
(concat "file://" (expand-file-name raw-path))))
(t raw-path))))
(if (not contents) (format "<%s>" path)
(format "[%s](%s)" contents path)))))))
;;;; Paragraph
(defun org-md-paragraph (paragraph contents info)
"Transcode PARAGRAPH element into Markdown format.
CONTENTS is the paragraph contents. INFO is a plist used as
a communication channel."
(let ((first-object (car (org-element-contents paragraph))))
;; If paragraph starts with a #, protect it.
(if (and (stringp first-object) (string-match "\\`#" first-object))
(replace-regexp-in-string "\\`#" "\\#" contents nil t)
contents)))
;;;; Plain List
(defun org-md-plain-list (plain-list contents info)
"Transcode PLAIN-LIST element into Markdown format.
CONTENTS is the plain-list contents. INFO is a plist used as
a communication channel."
contents)
;;;; Plain Text
(defun org-md-plain-text (text info)
"Transcode a TEXT string into Markdown format.
TEXT is the string to transcode. INFO is a plist holding
contextual information."
(when (plist-get info :with-smart-quotes)
(setq text (org-export-activate-smart-quotes text :html info)))
;; Protect ambiguous #. This will protect # at the beginning of
;; a line, but not at the beginning of a paragraph. See
;; `org-md-paragraph'.
(setq text (replace-regexp-in-string "\n#" "\n\\\\#" text))
;; Protect ambiguous !
(setq text (replace-regexp-in-string "\\(!\\)\\[" "\\\\!" text nil nil 1))
;; Protect `, *, _ and \
(setq text (replace-regexp-in-string "[`*_\\]" "\\\\\\&" text))
;; Handle special strings, if required.
(when (plist-get info :with-special-strings)
(setq text (org-e-html-convert-special-strings text)))
;; Handle break preservation, if required.
(when (plist-get info :preserve-breaks)
(setq text (replace-regexp-in-string "[ \t]*\n" " \n" text)))
;; Return value.
text)
;;;; Quote Block
(defun org-md-quote-block (quote-block contents info)
"Transcode QUOTE-BLOCK element into Markdown format.
CONTENTS is the quote-block contents. INFO is a plist used as
a communication channel."
(replace-regexp-in-string
"^" "> "
(replace-regexp-in-string "\n\\'" "" contents)))
;;;; Section
(defun org-md-section (section contents info)
"Transcode SECTION element into Markdown format.
CONTENTS is the section contents. INFO is a plist used as
a communication channel."
contents)
;;;; Template
(defun org-md-template (contents info)
"Return complete document string after Markdown conversion.
CONTENTS is the transcoded contents string. INFO is a plist used
as a communication channel."
contents)
;;; Interactive function
;;;###autoload
(defun org-md-export-as-markdown (&optional subtreep visible-only)
"Export current buffer to a text buffer.
If narrowing is active in the current buffer, only export its
narrowed part.
If a region is active, export that region.
When optional argument SUBTREEP is non-nil, export the sub-tree
at point, extracting information from the headline properties
first.
When optional argument VISIBLE-ONLY is non-nil, don't export
contents of hidden elements.
Export is done in a buffer named \"*Org MD Export*\", which will
be displayed when `org-export-show-temporary-export-buffer' is
non-nil."
(interactive)
(let ((outbuf (org-export-to-buffer
'md "*Org MD Export*" subtreep visible-only)))
(with-current-buffer outbuf (text-mode))
(when org-export-show-temporary-export-buffer
(switch-to-buffer-other-window outbuf))))
;;;###autoload
(defun org-md-export-to-markdown (&optional subtreep visible-only)
"Export current buffer to a Markdown file.
If narrowing is active in the current buffer, only export its
narrowed part.
If a region is active, export that region.
When optional argument SUBTREEP is non-nil, export the sub-tree
at point, extracting information from the headline properties
first.
When optional argument VISIBLE-ONLY is non-nil, don't export
contents of hidden elements.
Return output file's name."
(interactive)
(let ((outfile (org-export-output-file-name ".md" subtreep)))
(org-export-to-file 'md outfile subtreep visible-only)))
(provide 'org-md)
;;; org-md.el ends here