lisp/ox-md.el

   1 ;;; ox-md.el --- Markdown Back-End for Org Export Engine
   2
   3 ;; Copyright (C) 2012-2014 Free Software Foundation, Inc.
   4
   5 ;; Author: Nicolas Goaziou <n.goaziou@gmail.com>
   6 ;; Keywords: org, wp, markdown
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software: you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation, either version 3 of the License, or
  13 ;; (at your option) any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 ;;; Commentary:
  24
  25 ;; This library implements a Markdown back-end (vanilla flavor) for
  26 ;; Org exporter, based on `html' back-end.  See Org manual for more
  27 ;; information.
  28
  29 ;;; Code:
  30
  31 (eval-when-compile (require 'cl))
  32 (require 'ox-html)
  33 (require 'ox-publish)
  34
  35 \f
  36 ;;; User-Configurable Variables
  37
  38 (defgroup org-export-md nil
  39   "Options specific to Markdown export back-end."
  40   :tag "Org Markdown"
  41   :group 'org-export
  42   :version "24.4"
  43   :package-version '(Org . "8.0"))
  44
  45 (defcustom org-md-headline-style 'atx
  46   "Style used to format headlines.
  47 This variable can be set to either `atx' or `setext'."
  48   :group 'org-export-md
  49   :type '(choice
  50           (const :tag "Use \"atx\" style" atx)
  51           (const :tag "Use \"Setext\" style" setext)))
  52
  53
  54 \f
  55 ;;; Define Back-End
  56
  57 (org-export-define-derived-backend 'md 'html
  58   :export-block '("MD" "MARKDOWN")
  59   :filters-alist '((:filter-parse-tree . org-md-separate-elements))
  60   :menu-entry
  61   '(?m "Export to Markdown"
  62        ((?M "To temporary buffer"
  63             (lambda (a s v b) (org-md-export-as-markdown a s v)))
  64         (?m "To file" (lambda (a s v b) (org-md-export-to-markdown a s v)))
  65         (?o "To file and open"
  66             (lambda (a s v b)
  67               (if a (org-md-export-to-markdown t s v)
  68                 (org-open-file (org-md-export-to-markdown nil s v)))))))
  69   :translate-alist '((bold . org-md-bold)
  70                      (code . org-md-verbatim)
  71                      (comment . (lambda (&rest args) ""))
  72                      (comment-block . (lambda (&rest args) ""))
  73                      (example-block . org-md-example-block)
  74                      (export-block . org-md-export-block)
  75                      (fixed-width . org-md-example-block)
  76                      (headline . org-md-headline)
  77                      (horizontal-rule . org-md-horizontal-rule)
  78                      (inline-src-block . org-md-verbatim)
  79                      (inner-template . org-md-inner-template)
  80                      (italic . org-md-italic)
  81                      (item . org-md-item)
  82                      (keyword . org-md-keyword)
  83                      (line-break . org-md-line-break)
  84                      (link . org-md-link)
  85                      (node-property . org-md-node-property)
  86                      (paragraph . org-md-paragraph)
  87                      (plain-list . org-md-plain-list)
  88                      (plain-text . org-md-plain-text)
  89                      (property-drawer . org-md-property-drawer)
  90                      (quote-block . org-md-quote-block)
  91                      (section . org-md-section)
  92                      (src-block . org-md-example-block)
  93                      (template . org-md-template)
  94                      (verbatim . org-md-verbatim))
  95   :options-alist '((:md-headline-style nil nil org-md-headline-style)))
  96
  97 \f
  98 ;;; Filters
  99
 100 (defun org-md-separate-elements (tree backend info)
 101   "Fix blank lines between elements.
 102
 103 TREE is the parse tree being exported.  BACKEND is the export
 104 back-end used.  INFO is a plist used as a communication channel.
 105
 106 Enforce a blank line between elements.  There are two exceptions
 107 to this rule:
 108
 109   1. Preserve blank lines between sibling items in a plain list,
 110
 111   2. In an item, remove any blank line before the very first
 112      paragraph and the next sub-list.
 113
 114 Assume BACKEND is `md'."
 115   (org-element-map tree (remq 'item org-element-all-elements)
 116     (lambda (e)
 117       (org-element-put-property
 118        e :post-blank
 119        (if (and (eq (org-element-type e) 'paragraph)
 120                 (eq (org-element-type (org-element-property :parent e)) 'item)
 121                 (eq (org-element-type (org-export-get-next-element e info))
 122                     'plain-list)
 123                 (not (org-export-get-previous-element e info)))
 124            0
 125          1))))
 126   ;; Return updated tree.
 127   tree)
 128
 129
 130 \f
 131 ;;; Transcode Functions
 132
 133 ;;;; Bold
 134
 135 (defun org-md-bold (bold contents info)
 136   "Transcode BOLD object into Markdown format.
 137 CONTENTS is the text within bold markup.  INFO is a plist used as
 138 a communication channel."
 139   (format "**%s**" contents))
 140
 141
 142 ;;;; Code and Verbatim
 143
 144 (defun org-md-verbatim (verbatim contents info)
 145   "Transcode VERBATIM object into Markdown format.
 146 CONTENTS is nil.  INFO is a plist used as a communication
 147 channel."
 148   (let ((value (org-element-property :value verbatim)))
 149     (format (cond ((not (string-match "`" value)) "`%s`")
 150                   ((or (string-match "\\``" value)
 151                        (string-match "`\\'" value))
 152                    "`` %s ``")
 153                   (t "``%s``"))
 154             value)))
 155
 156
 157 ;;;; Example Block, Src Block and export Block
 158
 159 (defun org-md-example-block (example-block contents info)
 160   "Transcode EXAMPLE-BLOCK element into Markdown format.
 161 CONTENTS is nil.  INFO is a plist used as a communication
 162 channel."
 163   (replace-regexp-in-string
 164    "^" "    "
 165    (org-remove-indentation
 166     (org-export-format-code-default example-block info))))
 167
 168 (defun org-md-export-block (export-block contents info)
 169   "Transcode a EXPORT-BLOCK element from Org to Markdown.
 170 CONTENTS is nil.  INFO is a plist holding contextual information."
 171   (if (member (org-element-property :type export-block) '("MARKDOWN" "MD"))
 172       (org-remove-indentation (org-element-property :value export-block))
 173     ;; Also include HTML export blocks.
 174     (org-export-with-backend 'html export-block contents info)))
 175
 176
 177 ;;;; Headline
 178
 179 (defun org-md-headline (headline contents info)
 180   "Transcode HEADLINE element into Markdown format.
 181 CONTENTS is the headline contents.  INFO is a plist used as
 182 a communication channel."
 183   (unless (org-element-property :footnote-section-p headline)
 184     (let* ((level (org-export-get-relative-level headline info))
 185            (title (org-export-data (org-element-property :title headline) info))
 186            (todo (and (plist-get info :with-todo-keywords)
 187                       (let ((todo (org-element-property :todo-keyword
 188                                                         headline)))
 189                         (and todo (concat (org-export-data todo info) " ")))))
 190            (tags (and (plist-get info :with-tags)
 191                       (let ((tag-list (org-export-get-tags headline info)))
 192                         (and tag-list
 193                              (format "     :%s:"
 194                                      (mapconcat 'identity tag-list ":"))))))
 195            (priority
 196             (and (plist-get info :with-priority)
 197                  (let ((char (org-element-property :priority headline)))
 198                    (and char (format "[#%c] " char)))))
 199            (anchor
 200             (when (plist-get info :with-toc)
 201               (org-html--anchor
 202                (or (org-element-property :CUSTOM_ID headline)
 203                    (org-export-get-headline-id headline info))
 204                nil nil info)))
 205            ;; Headline text without tags.
 206            (heading (concat todo priority title))
 207            (style (plist-get info :md-headline-style)))
 208       (cond
 209        ;; Cannot create a headline.  Fall-back to a list.
 210        ((or (org-export-low-level-p headline info)
 211             (not (memq style '(atx setext)))
 212             (and (eq style 'atx) (> level 6))
 213             (and (eq style 'setext) (> level 2)))
 214         (let ((bullet
 215                (if (not (org-export-numbered-headline-p headline info)) "-"
 216                  (concat (number-to-string
 217                           (car (last (org-export-get-headline-number
 218                                       headline info))))
 219                          "."))))
 220           (concat bullet (make-string (- 4 (length bullet)) ? ) heading tags
 221                   "\n\n"
 222                   (and contents
 223                        (replace-regexp-in-string "^" "    " contents)))))
 224        ;; Use "Setext" style.
 225        ((eq style 'setext)
 226         (concat heading tags anchor "\n"
 227                 (make-string (length heading) (if (= level 1) ?= ?-))
 228                 "\n\n"
 229                 contents))
 230        ;; Use "atx" style.
 231        (t (concat (make-string level ?#) " " heading tags anchor "\n\n" contents))))))
 232
 233
 234 ;;;; Horizontal Rule
 235
 236 (defun org-md-horizontal-rule (horizontal-rule contents info)
 237   "Transcode HORIZONTAL-RULE element into Markdown format.
 238 CONTENTS is the horizontal rule contents.  INFO is a plist used
 239 as a communication channel."
 240   "---")
 241
 242
 243 ;;;; Italic
 244
 245 (defun org-md-italic (italic contents info)
 246   "Transcode ITALIC object into Markdown format.
 247 CONTENTS is the text within italic markup.  INFO is a plist used
 248 as a communication channel."
 249   (format "*%s*" contents))
 250
 251
 252 ;;;; Item
 253
 254 (defun org-md-item (item contents info)
 255   "Transcode ITEM element into Markdown format.
 256 CONTENTS is the item contents.  INFO is a plist used as
 257 a communication channel."
 258   (let* ((type (org-element-property :type (org-export-get-parent item)))
 259          (struct (org-element-property :structure item))
 260          (bullet (if (not (eq type 'ordered)) "-"
 261                    (concat (number-to-string
 262                             (car (last (org-list-get-item-number
 263                                         (org-element-property :begin item)
 264                                         struct
 265                                         (org-list-prevs-alist struct)
 266                                         (org-list-parents-alist struct)))))
 267                            "."))))
 268     (concat bullet
 269             (make-string (- 4 (length bullet)) ? )
 270             (case (org-element-property :checkbox item)
 271               (on "[X] ")
 272               (trans "[-] ")
 273               (off "[ ] "))
 274             (let ((tag (org-element-property :tag item)))
 275               (and tag (format "**%s:** "(org-export-data tag info))))
 276             (and contents
 277                  (org-trim (replace-regexp-in-string "^" "    " contents))))))
 278
 279
 280
 281 ;;;; Keyword
 282
 283 (defun org-md-keyword (keyword contents info)
 284   "Transcode a KEYWORD element into Markdown format.
 285 CONTENTS is nil.  INFO is a plist used as a communication
 286 channel."
 287   (if (member (org-element-property :key keyword) '("MARKDOWN" "MD"))
 288       (org-element-property :value keyword)
 289     (org-export-with-backend 'html keyword contents info)))
 290
 291
 292 ;;;; Line Break
 293
 294 (defun org-md-line-break (line-break contents info)
 295   "Transcode LINE-BREAK object into Markdown format.
 296 CONTENTS is nil.  INFO is a plist used as a communication
 297 channel."
 298   "  \n")
 299
 300
 301 ;;;; Link
 302
 303 (defun org-md-link (link contents info)
 304   "Transcode LINE-BREAK object into Markdown format.
 305 CONTENTS is the link's description.  INFO is a plist used as
 306 a communication channel."
 307   (let ((link-org-files-as-md
 308          (function
 309           (lambda (raw-path)
 310             ;; Treat links to `file.org' as links to `file.md'.
 311             (if (string= ".org" (downcase (file-name-extension raw-path ".")))
 312                 (concat (file-name-sans-extension raw-path) ".md")
 313               raw-path))))
 314         (type (org-element-property :type link)))
 315     (cond
 316      ;; Link type is handled by a special function.
 317      ((org-export-custom-protocol-maybe link contents info))
 318      ((member type '("custom-id" "id"))
 319       (let ((destination (org-export-resolve-id-link link info)))
 320         (if (stringp destination)       ; External file.
 321             (let ((path (funcall link-org-files-as-md destination)))
 322               (if (not contents) (format "<%s>" path)
 323                 (format "[%s](%s)" contents path)))
 324           (concat
 325            (and contents (concat contents " "))
 326            (format "(%s)"
 327                    (format (org-export-translate "See section %s" :html info)
 328                            (if (org-export-numbered-headline-p destination info)
 329                                (mapconcat #'number-to-string
 330                                           (org-export-get-headline-number
 331                                            destination info)
 332                                           ".")
 333                              (org-export-data
 334                               (org-element-property :title destination) info))))))))
 335      ((org-export-inline-image-p link org-html-inline-image-rules)
 336       (let ((path (let ((raw-path (org-element-property :path link)))
 337                     (if (not (file-name-absolute-p raw-path)) raw-path
 338                       (expand-file-name raw-path))))
 339             (caption (org-export-data
 340                       (org-export-get-caption
 341                        (org-export-get-parent-element link)) info)))
 342         (format "![img](%s)"
 343                 (if (not (org-string-nw-p caption)) path
 344                   (format "%s \"%s\"" path caption)))))
 345      ((string= type "coderef")
 346       (let ((ref (org-element-property :path link)))
 347         (format (org-export-get-coderef-format ref contents)
 348                 (org-export-resolve-coderef ref info))))
 349      ((equal type "radio") contents)
 350      ((equal type "fuzzy")
 351       (let ((destination (org-export-resolve-fuzzy-link link info)))
 352         (if (org-string-nw-p contents) contents
 353           (when destination
 354             (let ((number (org-export-get-ordinal destination info)))
 355               (if number
 356                   (if (atom number) (number-to-string number)
 357                     (mapconcat #'number-to-string number "."))
 358                 ;; Unnumbered headline.
 359                 (and (eq 'headline (org-element-type destination))
 360                      ;; BUG: shouldn't headlines have a form like [ref](name) in md?
 361                      (org-export-data
 362                       (org-element-property :title destination) info))))))))
 363      (t (let* ((raw-path (org-element-property :path link))
 364                (path
 365                 (cond
 366                  ((member type '("http" "https" "ftp"))
 367                   (concat type ":" raw-path))
 368                  ((string= type "file")
 369                   (let ((path (funcall link-org-files-as-md raw-path)))
 370                     (if (not (file-name-absolute-p path)) path
 371                       ;; If file path is absolute, prepend it
 372                       ;; with "file:" component.
 373                       (concat "file:" path))))
 374                  (t raw-path))))
 375           (if (not contents) (format "<%s>" path)
 376             (format "[%s](%s)" contents path)))))))
 377
 378
 379 ;;;; Node Property
 380
 381 (defun org-md-node-property (node-property contents info)
 382   "Transcode a NODE-PROPERTY element into Markdown syntax.
 383 CONTENTS is nil.  INFO is a plist holding contextual
 384 information."
 385   (format "%s:%s"
 386           (org-element-property :key node-property)
 387           (let ((value (org-element-property :value node-property)))
 388             (if value (concat " " value) ""))))
 389
 390
 391 ;;;; Paragraph
 392
 393 (defun org-md-paragraph (paragraph contents info)
 394   "Transcode PARAGRAPH element into Markdown format.
 395 CONTENTS is the paragraph contents.  INFO is a plist used as
 396 a communication channel."
 397   (let ((first-object (car (org-element-contents paragraph))))
 398     ;; If paragraph starts with a #, protect it.
 399     (if (and (stringp first-object) (string-match "\\`#" first-object))
 400         (replace-regexp-in-string "\\`#" "\\#" contents nil t)
 401       contents)))
 402
 403
 404 ;;;; Plain List
 405
 406 (defun org-md-plain-list (plain-list contents info)
 407   "Transcode PLAIN-LIST element into Markdown format.
 408 CONTENTS is the plain-list contents.  INFO is a plist used as
 409 a communication channel."
 410   contents)
 411
 412
 413 ;;;; Plain Text
 414
 415 (defun org-md-plain-text (text info)
 416   "Transcode a TEXT string into Markdown format.
 417 TEXT is the string to transcode.  INFO is a plist holding
 418 contextual information."
 419   (when (plist-get info :with-smart-quotes)
 420     (setq text (org-export-activate-smart-quotes text :html info)))
 421   ;; Protect ambiguous #.  This will protect # at the beginning of
 422   ;; a line, but not at the beginning of a paragraph.  See
 423   ;; `org-md-paragraph'.
 424   (setq text (replace-regexp-in-string "\n#" "\n\\\\#" text))
 425   ;; Protect ambiguous !
 426   (setq text (replace-regexp-in-string "\\(!\\)\\[" "\\\\!" text nil nil 1))
 427   ;; Protect `, *, _ and \
 428   (setq text (replace-regexp-in-string "[`*_\\]" "\\\\\\&" text))
 429   ;; Handle special strings, if required.
 430   (when (plist-get info :with-special-strings)
 431     (setq text (org-html-convert-special-strings text)))
 432   ;; Handle break preservation, if required.
 433   (when (plist-get info :preserve-breaks)
 434     (setq text (replace-regexp-in-string "[ \t]*\n" "  \n" text)))
 435   ;; Return value.
 436   text)
 437
 438
 439 ;;;; Property Drawer
 440
 441 (defun org-md-property-drawer (property-drawer contents info)
 442   "Transcode a PROPERTY-DRAWER element into Markdown format.
 443 CONTENTS holds the contents of the drawer.  INFO is a plist
 444 holding contextual information."
 445   (and (org-string-nw-p contents)
 446        (replace-regexp-in-string "^" "    " contents)))
 447
 448
 449 ;;;; Quote Block
 450
 451 (defun org-md-quote-block (quote-block contents info)
 452   "Transcode QUOTE-BLOCK element into Markdown format.
 453 CONTENTS is the quote-block contents.  INFO is a plist used as
 454 a communication channel."
 455   (replace-regexp-in-string
 456    "^" "> "
 457    (replace-regexp-in-string "\n\\'" "" contents)))
 458
 459
 460 ;;;; Section
 461
 462 (defun org-md-section (section contents info)
 463   "Transcode SECTION element into Markdown format.
 464 CONTENTS is the section contents.  INFO is a plist used as
 465 a communication channel."
 466   contents)
 467
 468
 469 ;;;; Template
 470
 471 (defun org-md-inner-template (contents info)
 472   "Return body of document after converting it to Markdown syntax.
 473 CONTENTS is the transcoded contents string.  INFO is a plist
 474 holding export options."
 475   ;; Make sure CONTENTS is separated from table of contents and
 476   ;; footnotes with at least a blank line.
 477   (org-trim (org-html-inner-template (concat "\n" contents "\n") info)))
 478
 479 (defun org-md-template (contents info)
 480   "Return complete document string after Markdown conversion.
 481 CONTENTS is the transcoded contents string.  INFO is a plist used
 482 as a communication channel."
 483   contents)
 484
 485
 486 \f
 487 ;;; Interactive function
 488
 489 ;;;###autoload
 490 (defun org-md-export-as-markdown (&optional async subtreep visible-only)
 491   "Export current buffer to a Markdown buffer.
 492
 493 If narrowing is active in the current buffer, only export its
 494 narrowed part.
 495
 496 If a region is active, export that region.
 497
 498 A non-nil optional argument ASYNC means the process should happen
 499 asynchronously.  The resulting buffer should be accessible
 500 through the `org-export-stack' interface.
 501
 502 When optional argument SUBTREEP is non-nil, export the sub-tree
 503 at point, extracting information from the headline properties
 504 first.
 505
 506 When optional argument VISIBLE-ONLY is non-nil, don't export
 507 contents of hidden elements.
 508
 509 Export is done in a buffer named \"*Org MD Export*\", which will
 510 be displayed when `org-export-show-temporary-export-buffer' is
 511 non-nil."
 512   (interactive)
 513   (org-export-to-buffer 'md "*Org MD Export*"
 514     async subtreep visible-only nil nil (lambda () (text-mode))))
 515
 516 ;;;###autoload
 517 (defun org-md-convert-region-to-md ()
 518   "Assume the current region has org-mode syntax, and convert it to Markdown.
 519 This can be used in any buffer.  For example, you can write an
 520 itemized list in org-mode syntax in a Markdown buffer and use
 521 this command to convert it."
 522   (interactive)
 523   (org-export-replace-region-by 'md))
 524
 525
 526 ;;;###autoload
 527 (defun org-md-export-to-markdown (&optional async subtreep visible-only)
 528   "Export current buffer to a Markdown file.
 529
 530 If narrowing is active in the current buffer, only export its
 531 narrowed part.
 532
 533 If a region is active, export that region.
 534
 535 A non-nil optional argument ASYNC means the process should happen
 536 asynchronously.  The resulting file should be accessible through
 537 the `org-export-stack' interface.
 538
 539 When optional argument SUBTREEP is non-nil, export the sub-tree
 540 at point, extracting information from the headline properties
 541 first.
 542
 543 When optional argument VISIBLE-ONLY is non-nil, don't export
 544 contents of hidden elements.
 545
 546 Return output file's name."
 547   (interactive)
 548   (let ((outfile (org-export-output-file-name ".md" subtreep)))
 549     (org-export-to-file 'md outfile async subtreep visible-only)))
 550
 551 ;;;###autoload
 552 (defun org-md-publish-to-md (plist filename pub-dir)
 553   "Publish an org file to Markdown.
 554
 555 FILENAME is the filename of the Org file to be published.  PLIST
 556 is the property list for the given project.  PUB-DIR is the
 557 publishing directory.
 558
 559 Return output file name."
 560   (org-publish-org-to 'md filename ".md" plist pub-dir))
 561
 562 (provide 'ox-md)
 563
 564 ;; Local variables:
 565 ;; generated-autoload-file: "org-loaddefs.el"
 566 ;; End:
 567
 568 ;;; ox-md.el ends here