ox-gfm/ox-gfm.el
2018-12-13 04:08:33 +00:00

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;;; ox-gfm.el --- Github Flavored Markdown Back-End for Org Export Engine
;; Copyright (C) 2014-2017 Lars Tveito
;; Copyright (C) 2012-2018 Free Software Foundation, Inc.
;; Copyright (C) 2018 Aaron Muir Hamilton
;; Author: Lars Tveito
;; Keywords: org, wp, markdown, github
;; This file is not part of GNU Emacs.
;; 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 (github flavor) for Org
;; exporter, based on the `md' back-end.
;;; Code:
(require 'ox-md)
(require 'ox-publish)
;;; User-Configurable Variables
(defgroup org-export-gfm nil
"Options specific to Markdown export back-end."
:tag "Org Github Flavored Markdown"
:group 'org-export
:version "24.4"
:package-version '(Org . "8.0"))
;;; Define Back-End
(org-export-define-derived-backend 'gfm 'md
:filters-alist '((:filter-parse-tree . org-md-separate-elements))
:menu-entry
'(?g "Export to Github Flavored Markdown"
((?G "To temporary buffer"
(lambda (a s v b) (org-gfm-export-as-markdown a s v)))
(?g "To file" (lambda (a s v b) (org-gfm-export-to-markdown a s v)))
(?o "To file and open"
(lambda (a s v b)
(if a (org-gfm-export-to-markdown t s v)
(org-open-file (org-gfm-export-to-markdown nil s v)))))))
:translate-alist '((headline . org-gfm-headline)
(inner-template . org-gfm-inner-template)
(paragraph . org-gfm-paragraph)
(strike-through . org-gfm-strike-through)
(src-block . org-gfm-src-block)
(table-cell . org-gfm-table-cell)
(table-row . org-gfm-table-row)
(table . org-gfm-table)))
;;; Transcode Functions
;;;; Headline
(defun org-gfm-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))
(style (plist-get info :md-headline-style)))
(cond
;; Cannot create a headline. Fall-back to a list.
((or (org-export-low-level-p headline info)
(not (memq style '(atx setext)))
(and (eq style 'atx) (> level 6))
(and (eq 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)) ?\s) heading tags "\n\n"
(and contents (replace-regexp-in-string "^" " " contents)))))
(t
(concat (org-md--headline-title style level heading tags) contents))))))
;;;; Paragraph
(defun org-gfm-paragraph (paragraph contents info)
"Transcode PARAGRAPH element into Github Flavoured Markdown format.
CONTENTS is the paragraph contents. INFO is a plist used as a
communication channel."
(unless (plist-get info :preserve-breaks)
(setq contents (concat (mapconcat 'identity (split-string contents) " ") "\n")))
(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)))
;;;; Src Block
(defun org-gfm-src-block (src-block contents info)
"Transcode SRC-BLOCK element into Github Flavored Markdown
format. CONTENTS is nil. INFO is a plist used as a communication
channel."
(let* ((lang (org-element-property :language src-block))
(code (org-export-format-code-default src-block info))
(prefix (concat "```" lang "\n"))
(suffix "```"))
(concat prefix code suffix)))
;;;; Strike-Through
(defun org-gfm-strike-through (strike-through contents info)
"Transcode STRIKE-THROUGH from Org to Markdown (GFM).
CONTENTS is the text with strike-through markup. INFO is a plist
holding contextual information."
(format "~~%s~~" contents))
;;;; Table-Common
(defvar width-cookies nil)
(defvar width-cookies-table nil)
(defconst gfm-table-left-border "|")
(defconst gfm-table-right-border " |")
(defconst gfm-table-separator " |")
(defun org-gfm-table-col-width (table column info)
"Return width of TABLE at given COLUMN. INFO is a plist used as
communication channel. Width of a column is determined either by
inquerying `width-cookies' in the column, or by the maximum cell with in
the column."
(let ((cookie (when (hash-table-p width-cookies)
(gethash column width-cookies))))
(if (and (eq table width-cookies-table)
(not (eq nil cookie)))
cookie
(progn
(unless (and (eq table width-cookies-table)
(hash-table-p width-cookies))
(setq width-cookies (make-hash-table))
(setq width-cookies-table table))
(let ((max-width 0)
(specialp (org-export-table-has-special-column-p table)))
(org-element-map
table
'table-row
(lambda (row)
(setq max-width
(max (length
(org-export-data
(org-element-contents
(elt (if specialp (car (org-element-contents row))
(org-element-contents row))
column))
info))
max-width)))
info)
(puthash column max-width width-cookies))))))
(defun org-gfm-make-hline-builder (table info char)
"Return a function to build horizontal line in TABLE with given
CHAR. INFO is a plist used as a communication channel."
`(lambda (col)
(let ((max-width (max 3 (org-gfm-table-col-width table col info))))
(when (< max-width 1)
(setq max-width 1))
(make-string max-width ,char))))
;;;; Table-Cell
(defun org-gfm-table-cell (table-cell contents info)
"Transcode TABLE-CELL element from Org into GFM. CONTENTS is content
of the cell. INFO is a plist used as a communication channel."
(let* ((table (org-export-get-parent-table table-cell))
(column (cdr (org-export-table-cell-address table-cell info)))
(width (org-gfm-table-col-width table column info))
(left-border (if (org-export-table-cell-starts-colgroup-p table-cell info) "| " " "))
(right-border " |")
(data (or contents "")))
(setq contents
(concat data
(make-string (max 0 (- width (string-width data)))
?\s)))
(concat left-border contents right-border)))
;;;; Table-Row
(defun org-gfm-table-row (table-row contents info)
"Transcode TABLE-ROW element from Org into GFM. CONTENTS is cell
contents of TABLE-ROW. INFO is a plist used as a communication
channel."
(let ((table (org-export-get-parent-table table-row)))
(when (and (eq 'rule (org-element-property :type table-row))
;; In GFM, rule is valid only at second row.
(eq 1 (cl-position
table-row
(org-element-map table 'table-row 'identity info))))
(let* ((table (org-export-get-parent-table table-row))
(header-p (org-export-table-row-starts-header-p table-row info))
(build-rule (org-gfm-make-hline-builder table info ?-))
(cols (cdr (org-export-table-dimensions table info))))
(setq contents
(concat gfm-table-left-border
(mapconcat (lambda (col) (funcall build-rule col))
(number-sequence 0 (- cols 1))
gfm-table-separator)
gfm-table-right-border))))
contents))
;;;; Table
(defun org-gfm-table (table contents info)
"Transcode TABLE element into Github Flavored Markdown table.
CONTENTS is the contents of the table. INFO is a plist holding
contextual information."
(let* ((rows (org-element-map table 'table-row 'identity info))
(no-header (or (<= (length rows) 1)))
(cols (cdr (org-export-table-dimensions table info)))
(build-dummy-header
(function
(lambda ()
(let ((build-empty-cell (org-gfm-make-hline-builder table info ?\s))
(build-rule (org-gfm-make-hline-builder table info ?-))
(columns (number-sequence 0 (- cols 1))))
(concat gfm-table-left-border
(mapconcat (lambda (col) (funcall build-empty-cell col))
columns
gfm-table-separator)
gfm-table-right-border "\n" gfm-table-left-border
(mapconcat (lambda (col) (funcall build-rule col))
columns
gfm-table-separator)
gfm-table-right-border "\n"))))))
(concat (when no-header (funcall build-dummy-header))
(replace-regexp-in-string "\n\n" "\n" contents))))
;;;; Table of contents
(defun org-gfm-anchor-from-title (title)
(replace-regexp-in-string "[^a-z\-_]" "" (downcase (replace-regexp-in-string "[ ]" "-" title))))
(defun org-gfm-anchor-from-headline (headline)
(org-gfm-anchor-from-title (org-export-data (org-export-get-alt-title headline info) info)))
(defun org-gfm-put-headline-dup (acc headline anchor counter)
(if (assoc (concat anchor "-" (number-to-string counter)) acc)
(org-gfm-put-headline-dup acc headline anchor (1+ counter))
(cons (cons (concat anchor "-" (number-to-string counter)) headline) acc)))
(defun org-gfm-put-headline (acc headline)
(let* ((anchor (org-gfm-anchor-from-headline headline)))
(if (assoc anchor acc)
(org-gfm-put-headline-dup acc headline anchor 1)
(cons (cons anchor headline) acc))))
(defun org-gfm-format-toc (anchor-and-headline)
"Return an appropriate table of contents entry for HEADLINE. INFO is a
plist used as a communication channel."
(let* ((headline (cdr anchor-and-headline))
(title (org-export-data
(org-export-get-alt-title headline info) info))
(level (1- (org-element-property :level headline)))
(indent (concat (make-string (* level 2) ? )))
(anchor (car anchor-and-headline)))
(concat indent "- [" title "]" "(#" anchor ")")))
;;;; Footnote section
(defun org-gfm-footnote-section (info)
"Format the footnote section.
INFO is a plist used as a communication channel."
(let* ((fn-alist (org-export-collect-footnote-definitions info))
(fn-alist
(cl-loop for (n type raw) in fn-alist collect
(cons n (org-trim (org-export-data raw info))))))
(when fn-alist
(format
"## %s\n%s"
"Footnotes"
(format
"\n%s\n"
(mapconcat
(lambda (fn)
(let ((n (car fn)) (def (cdr fn)))
(format
"%s %s\n"
(format
(plist-get info :html-footnote-format)
(org-html--anchor
(format "fn.%d" n)
n
(format " class=\"footnum\" href=\"#fnr.%d\"" n)
info))
def)))
fn-alist
"\n"))))))
;;;; Template
(defun org-gfm-inner-template (contents info)
"Return body of document after converting it to Markdown syntax.
CONTENTS is the transcoded contents string. INFO is a plist
holding export options."
(let* ((depth (plist-get info :with-toc))
(headlines (and depth (org-export-collect-headlines info depth)))
(anchors-to-headlines (reverse (seq-reduce 'org-gfm-put-headline headlines '())))
(toc-string (or (mapconcat 'org-gfm-format-toc anchors-to-headlines "\n") ""))
(toc-tail (if headlines "\n\n" "")))
(org-trim (concat toc-string toc-tail contents "\n" (org-gfm-footnote-section info)))))
;;; Interactive function
;;;###autoload
(defun org-gfm-export-as-markdown (&optional async subtreep visible-only)
"Export current buffer to a Github Flavored Markdown buffer.
If narrowing is active in the current buffer, only export its
narrowed part.
If a region is active, export that region.
A non-nil optional argument ASYNC means the process should happen
asynchronously. The resulting buffer should be accessible
through the `org-export-stack' interface.
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 GFM Export*\", which will
be displayed when `org-export-show-temporary-export-buffer' is
non-nil."
(interactive)
(org-export-to-buffer 'gfm "*Org GFM Export*"
async subtreep visible-only nil nil (lambda () (text-mode))))
;;;###autoload
(defun org-gfm-convert-region-to-md ()
"Assume the current region has org-mode syntax, and convert it
to Github Flavored Markdown. This can be used in any buffer.
For example, you can write an itemized list in org-mode syntax in
a Markdown buffer and use this command to convert it."
(interactive)
(org-export-replace-region-by 'gfm))
;;;###autoload
(defun org-gfm-export-to-markdown (&optional async subtreep visible-only)
"Export current buffer to a Github Flavored Markdown file.
If narrowing is active in the current buffer, only export its
narrowed part.
If a region is active, export that region.
A non-nil optional argument ASYNC means the process should happen
asynchronously. The resulting file should be accessible through
the `org-export-stack' interface.
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 'gfm outfile async subtreep visible-only)))
;;;###autoload
(defun org-gfm-publish-to-gfm (plist filename pub-dir)
"Publish an org file to Markdown.
FILENAME is the filename of the Org file to be published. PLIST
is the property list for the given project. PUB-DIR is the
publishing directory.
Return output file name."
(org-publish-org-to 'gfm filename ".md" plist pub-dir))
(provide 'ox-gfm)
;;; ox-gfm.el ends here