org-mode/contrib/lisp/ox-rss.el

409 lines
14 KiB
EmacsLisp

;;; ox-rss.el --- RSS 2.0 Back-End for Org Export Engine
;; Copyright (C) 2013 Bastien Guerry
;; Author: Bastien Guerry <bzg@gnu.org>
;; Keywords: org, wp, blog, feed, rss
;; This file is not yet 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 GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;; This library implements a RSS 2.0 back-end for Org exporter, based on
;; the `html' back-end.
;;
;; It requires Emacs 24.1 at least.
;;
;; It provides two commands for export, depending on the desired output:
;; `org-rss-export-as-rss' (temporary buffer) and `org-rss-export-to-rss'
;; (as a ".xml" file).
;;
;; This backend understands two new option keywords:
;;
;; #+RSS_EXTENSION: xml
;; #+RSS_IMAGE_URL: http://myblog.org/mypicture.jpg
;;
;; It uses #+HTML_LINK_HOME: to set the base url of the feed.
;;
;; Exporting an Org file to RSS modifies each top-level entry by adding a
;; PUBDATE property. If `org-rss-use-entry-url-as-guid', it will also add
;; an ID property, later used as the guid for the feed's item.
;;
;; You typically want to use it within a publishing project like this:
;;
;; (add-to-list
;; 'org-publish-project-alist
;; '("homepage_rss"
;; :base-directory "~/myhomepage/"
;; :base-extension "org"
;; :rss-image-url "http://lumiere.ens.fr/~guerry/images/faces/15.png"
;; :html-link-home "http://lumiere.ens.fr/~guerry/"
;; :html-link-use-abs-url t
;; :rss-extension "xml"
;; :publishing-directory "/home/guerry/public_html/"
;; :publishing-function (org-rss-publish-to-rss)
;; :section-numbers nil
;; :exclude ".*" ;; To exclude all files...
;; :include ("index.org") ;; ... except index.org.
;; :table-of-contents nil))
;;
;; ... then rsync /home/guerry/public_html/ with your server.
;;
;; By default, the permalink for a blog entry points to the headline.
;; You can specify a different one by using the :RSS_PERMALINK:
;; property within an entry.
;;; Code:
(require 'ox-html)
(declare-function url-encode-url "url-util" (url))
;;; Variables and options
(defgroup org-export-rss nil
"Options specific to RSS export back-end."
:tag "Org RSS"
:group 'org-export
:version "24.4"
:package-version '(Org . "8.0"))
(defcustom org-rss-image-url "http://orgmode.org/img/org-mode-unicorn-logo.png"
"The URL of the an image for the RSS feed."
:group 'org-export-rss
:type 'string)
(defcustom org-rss-extension "xml"
"File extension for the RSS 2.0 feed."
:group 'org-export-rss
:type 'string)
(defcustom org-rss-categories 'from-tags
"Where to extract items category information from.
The default is to extract categories from the tags of the
headlines. When set to another value, extract the category
from the :CATEGORY: property of the entry."
:group 'org-export-rss
:type '(choice
(const :tag "From tags" from-tags)
(const :tag "From the category property" from-category)))
(defcustom org-rss-use-entry-url-as-guid t
"Use the URL for the <guid> metatag?
When nil, Org will create ids using `org-icalendar-create-uid'."
:group 'org-export-rss
:type 'boolean)
;;; Define backend
(org-export-define-derived-backend 'rss 'html
:menu-entry
'(?r "Export to RSS"
((?R "As RSS buffer"
(lambda (a s v b) (org-rss-export-as-rss a s v)))
(?r "As RSS file" (lambda (a s v b) (org-rss-export-to-rss a s v)))
(?o "As RSS file and open"
(lambda (a s v b)
(if a (org-rss-export-to-rss t s v)
(org-open-file (org-rss-export-to-rss nil s v)))))))
:options-alist
'((:with-toc nil nil nil) ;; Never include HTML's toc
(:rss-extension "RSS_EXTENSION" nil org-rss-extension)
(:rss-image-url "RSS_IMAGE_URL" nil org-rss-image-url)
(:rss-categories nil nil org-rss-categories))
:filters-alist '((:filter-final-output . org-rss-final-function))
:translate-alist '((headline . org-rss-headline)
(comment . (lambda (&rest args) ""))
(comment-block . (lambda (&rest args) ""))
(timestamp . (lambda (&rest args) ""))
(plain-text . org-rss-plain-text)
(section . org-rss-section)
(template . org-rss-template)))
;;; Export functions
;;;###autoload
(defun org-rss-export-as-rss (&optional async subtreep visible-only)
"Export current buffer to a RSS 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 RSS Export*\", which will
be displayed when `org-export-show-temporary-export-buffer' is
non-nil."
(interactive)
(let ((file (buffer-file-name (buffer-base-buffer))))
(org-icalendar-create-uid file 'warn-user)
(org-rss-add-pubdate-property))
(org-export-to-buffer 'rss "*Org RSS Export*"
async subtreep visible-only nil nil (lambda () (text-mode))))
;;;###autoload
(defun org-rss-export-to-rss (&optional async subtreep visible-only)
"Export current buffer to a RSS 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 ((file (buffer-file-name (buffer-base-buffer))))
(org-icalendar-create-uid file 'warn-user)
(org-rss-add-pubdate-property))
(let ((outfile (org-export-output-file-name
(concat "." org-rss-extension) subtreep)))
(org-export-to-file 'rss outfile async subtreep visible-only)))
;;;###autoload
(defun org-rss-publish-to-rss (plist filename pub-dir)
"Publish an org file to RSS.
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."
(let ((bf (get-file-buffer filename)))
(if bf
(progn
(org-icalendar-create-uid filename 'warn-user)
(with-current-buffer bf
(org-rss-add-pubdate-property)
(write-file filename)))
(find-file filename)
(org-icalendar-create-uid filename 'warn-user)
(org-rss-add-pubdate-property)
(write-file filename) (kill-buffer)))
(org-publish-org-to
'rss filename (concat "." org-rss-extension) plist pub-dir))
;;; Main transcoding functions
(defun org-rss-headline (headline contents info)
"Transcode HEADLINE element into RSS format.
CONTENTS is the headline contents. INFO is a plist used as a
communication channel."
(unless (or (org-element-property :footnote-section-p headline)
;; Only consider first-level headlines
(> (org-export-get-relative-level headline info) 1))
(let* ((author (and (plist-get info :with-author)
(let ((auth (plist-get info :author)))
(and auth (org-export-data auth info)))))
(htmlext (plist-get info :html-extension))
(hl-number (org-export-get-headline-number headline info))
(hl-home (file-name-as-directory (plist-get info :html-link-home)))
(hl-pdir (plist-get info :publishing-directory))
(hl-perm (org-element-property :RSS_PERMALINK headline))
(anchor
(org-export-solidify-link-text
(or (org-element-property :CUSTOM_ID headline)
(concat "sec-" (mapconcat 'number-to-string hl-number "-")))))
(category (org-rss-plain-text
(or (org-element-property :CATEGORY headline) "") info))
(pubdate
(let ((system-time-locale "C"))
(format-time-string
"%a, %d %b %Y %H:%M:%S %z"
(org-time-string-to-time
(or (org-element-property :PUBDATE headline)
(error "Missing PUBDATE property"))))))
(title (org-element-property :raw-value headline))
(publink
(or (and hl-perm (concat (or hl-home hl-pdir) hl-perm))
(concat
(or hl-home hl-pdir)
(file-name-nondirectory
(file-name-sans-extension
(plist-get info :input-file))) "." htmlext "#" anchor)))
(guid (if org-rss-use-entry-url-as-guid
publink
(org-rss-plain-text
(or (org-element-property :ID headline)
(org-element-property :CUSTOM_ID headline)
publink)
info))))
(format
(concat
"<item>\n"
"<title>%s</title>\n"
"<link>%s</link>\n"
"<author>%s</author>\n"
"<guid isPermaLink=\"false\">%s</guid>\n"
"<pubDate>%s</pubDate>\n"
(org-rss-build-categories headline info) "\n"
"<description><![CDATA[%s]]></description>\n"
"</item>\n")
title publink author guid pubdate contents))))
(defun org-rss-build-categories (headline info)
"Build categories for the RSS item."
(if (eq (plist-get info :rss-categories) 'from-tags)
(mapconcat
(lambda (c) (format "<category><![CDATA[%s]]></category>" c))
(org-element-property :tags headline)
"\n")
(let ((c (org-element-property :CATEGORY headline)))
(format "<category><![CDATA[%s]]></category>" c))))
(defun org-rss-template (contents info)
"Return complete document string after RSS conversion.
CONTENTS is the transcoded contents string. INFO is a plist used
as a communication channel."
(concat
(format "<?xml version=\"1.0\" encoding=\"%s\"?>"
(symbol-name org-html-coding-system))
"\n<rss version=\"2.0\"
xmlns:content=\"http://purl.org/rss/1.0/modules/content/\"
xmlns:wfw=\"http://wellformedweb.org/CommentAPI/\"
xmlns:dc=\"http://purl.org/dc/elements/1.1/\"
xmlns:atom=\"http://www.w3.org/2005/Atom\"
xmlns:sy=\"http://purl.org/rss/1.0/modules/syndication/\"
xmlns:slash=\"http://purl.org/rss/1.0/modules/slash/\"
xmlns:georss=\"http://www.georss.org/georss\"
xmlns:geo=\"http://www.w3.org/2003/01/geo/wgs84_pos#\"
xmlns:media=\"http://search.yahoo.com/mrss/\">"
"<channel>"
(org-rss-build-channel-info info) "\n"
contents
"</channel>\n"
"</rss>"))
(defun org-rss-build-channel-info (info)
"Build the RSS channel information."
(let* ((system-time-locale "C")
(title (plist-get info :title))
(email (org-export-data (plist-get info :email) info))
(author (and (plist-get info :with-author)
(let ((auth (plist-get info :author)))
(and auth (org-export-data auth info)))))
(date (format-time-string "%a, %d %b %Y %H:%M:%S %z")) ;; RFC 882
(description (org-export-data (plist-get info :description) info))
(lang (plist-get info :language))
(keywords (plist-get info :keywords))
(rssext (plist-get info :rss-extension))
(blogurl (or (plist-get info :html-link-home)
(plist-get info :publishing-directory)))
(image (url-encode-url (plist-get info :rss-image-url)))
(ifile (plist-get info :input-file))
(publink
(concat (file-name-as-directory blogurl)
(file-name-nondirectory
(file-name-sans-extension ifile))
"." rssext)))
(format
"\n<title>%s</title>
<atom:link href=\"%s\" rel=\"self\" type=\"application/rss+xml\" />
<link>%s</link>
<description><![CDATA[%s]]></description>
<language>%s</language>
<pubDate>%s</pubDate>
<lastBuildDate>%s</lastBuildDate>
<generator>%s</generator>
<webMaster>%s (%s)</webMaster>
<image>
<url>%s</url>
<title>%s</title>
<link>%s</link>
</image>
"
title publink blogurl description lang date date
(concat (format "Emacs %d.%d"
emacs-major-version
emacs-minor-version)
" Org-mode " (org-version))
email author image title blogurl)))
(defun org-rss-section (section contents info)
"Transcode SECTION element into RSS format.
CONTENTS is the section contents. INFO is a plist used as
a communication channel."
contents)
(defun org-rss-timestamp (timestamp contents info)
"Transcode a TIMESTAMP object from Org to RSS.
CONTENTS is nil. INFO is a plist holding contextual
information."
(org-html-encode-plain-text
(org-timestamp-translate timestamp)))
(defun org-rss-plain-text (contents info)
"Convert plain text into RSS encoded text."
(let (output)
(setq output (org-html-encode-plain-text contents)
output (org-export-activate-smart-quotes
output :html info))))
;;; Filters
(defun org-rss-final-function (contents backend info)
"Prettify the RSS output."
(with-temp-buffer
(xml-mode)
(insert contents)
(indent-region (point-min) (point-max))
(buffer-substring-no-properties (point-min) (point-max))))
;;; Miscellaneous
(defun org-rss-add-pubdate-property ()
"Set the PUBDATE property for top-level headlines."
(let (msg)
(org-map-entries
(lambda ()
(let* ((entry (org-element-at-point))
(level (org-element-property :level entry)))
(when (= level 1)
(unless (org-entry-get (point) "PUBDATE")
(setq msg t)
(org-set-property
"PUBDATE" (format-time-string
(cdr org-time-stamp-formats)))))))
nil nil 'comment 'archive)
(when msg
(message "Property PUBDATE added to top-level entries in %s"
(buffer-file-name))
(sit-for 2))))
(provide 'ox-rss)
;;; ox-rss.el ends here