409 lines
14 KiB
EmacsLisp
409 lines
14 KiB
EmacsLisp
;;; ox-rss.el --- RSS 2.0 Back-End for Org Export Engine
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;; Copyright (C) 2013 Bastien Guerry
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;; Author: Bastien Guerry <bzg@gnu.org>
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;; Keywords: org, wp, blog, feed, rss
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;; This file is not yet part of GNU Emacs.
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;; This program is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This library implements a RSS 2.0 back-end for Org exporter, based on
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;; the `html' back-end.
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;;
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;; It requires Emacs 24.1 at least.
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;;
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;; It provides two commands for export, depending on the desired output:
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;; `org-rss-export-as-rss' (temporary buffer) and `org-rss-export-to-rss'
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;; (as a ".xml" file).
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;;
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;; This backend understands two new option keywords:
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;;
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;; #+RSS_EXTENSION: xml
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;; #+RSS_IMAGE_URL: http://myblog.org/mypicture.jpg
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;;
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;; It uses #+HTML_LINK_HOME: to set the base url of the feed.
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;;
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;; Exporting an Org file to RSS modifies each top-level entry by adding a
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;; PUBDATE property. If `org-rss-use-entry-url-as-guid', it will also add
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;; an ID property, later used as the guid for the feed's item.
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;;
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;; You typically want to use it within a publishing project like this:
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;;
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;; (add-to-list
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;; 'org-publish-project-alist
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;; '("homepage_rss"
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;; :base-directory "~/myhomepage/"
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;; :base-extension "org"
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;; :rss-image-url "http://lumiere.ens.fr/~guerry/images/faces/15.png"
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;; :html-link-home "http://lumiere.ens.fr/~guerry/"
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;; :html-link-use-abs-url t
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;; :rss-extension "xml"
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;; :publishing-directory "/home/guerry/public_html/"
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;; :publishing-function (org-rss-publish-to-rss)
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;; :section-numbers nil
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;; :exclude ".*" ;; To exclude all files...
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;; :include ("index.org") ;; ... except index.org.
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;; :table-of-contents nil))
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;;
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;; ... then rsync /home/guerry/public_html/ with your server.
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;;
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;; By default, the permalink for a blog entry points to the headline.
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;; You can specify a different one by using the :RSS_PERMALINK:
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;; property within an entry.
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;;; Code:
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(require 'ox-html)
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(declare-function url-encode-url "url-util" (url))
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;;; Variables and options
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(defgroup org-export-rss nil
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"Options specific to RSS export back-end."
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:tag "Org RSS"
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:group 'org-export
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:version "24.4"
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:package-version '(Org . "8.0"))
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(defcustom org-rss-image-url "http://orgmode.org/img/org-mode-unicorn-logo.png"
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"The URL of the an image for the RSS feed."
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:group 'org-export-rss
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:type 'string)
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(defcustom org-rss-extension "xml"
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"File extension for the RSS 2.0 feed."
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:group 'org-export-rss
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:type 'string)
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(defcustom org-rss-categories 'from-tags
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"Where to extract items category information from.
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The default is to extract categories from the tags of the
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headlines. When set to another value, extract the category
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from the :CATEGORY: property of the entry."
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:group 'org-export-rss
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:type '(choice
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(const :tag "From tags" from-tags)
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(const :tag "From the category property" from-category)))
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(defcustom org-rss-use-entry-url-as-guid t
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"Use the URL for the <guid> metatag?
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When nil, Org will create ids using `org-icalendar-create-uid'."
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:group 'org-export-rss
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:type 'boolean)
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;;; Define backend
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(org-export-define-derived-backend 'rss 'html
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:menu-entry
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'(?r "Export to RSS"
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((?R "As RSS buffer"
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(lambda (a s v b) (org-rss-export-as-rss a s v)))
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(?r "As RSS file" (lambda (a s v b) (org-rss-export-to-rss a s v)))
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(?o "As RSS file and open"
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(lambda (a s v b)
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(if a (org-rss-export-to-rss t s v)
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(org-open-file (org-rss-export-to-rss nil s v)))))))
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:options-alist
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'((:with-toc nil nil nil) ;; Never include HTML's toc
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(:rss-extension "RSS_EXTENSION" nil org-rss-extension)
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(:rss-image-url "RSS_IMAGE_URL" nil org-rss-image-url)
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(:rss-categories nil nil org-rss-categories))
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:filters-alist '((:filter-final-output . org-rss-final-function))
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:translate-alist '((headline . org-rss-headline)
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(comment . (lambda (&rest args) ""))
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(comment-block . (lambda (&rest args) ""))
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(timestamp . (lambda (&rest args) ""))
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(plain-text . org-rss-plain-text)
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(section . org-rss-section)
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(template . org-rss-template)))
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;;; Export functions
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;;;###autoload
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(defun org-rss-export-as-rss (&optional async subtreep visible-only)
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"Export current buffer to a RSS buffer.
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If narrowing is active in the current buffer, only export its
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narrowed part.
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If a region is active, export that region.
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A non-nil optional argument ASYNC means the process should happen
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asynchronously. The resulting buffer should be accessible
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through the `org-export-stack' interface.
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When optional argument SUBTREEP is non-nil, export the sub-tree
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at point, extracting information from the headline properties
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first.
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When optional argument VISIBLE-ONLY is non-nil, don't export
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contents of hidden elements.
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Export is done in a buffer named \"*Org RSS Export*\", which will
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be displayed when `org-export-show-temporary-export-buffer' is
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non-nil."
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(interactive)
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(let ((file (buffer-file-name (buffer-base-buffer))))
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(org-icalendar-create-uid file 'warn-user)
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(org-rss-add-pubdate-property))
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(org-export-to-buffer 'rss "*Org RSS Export*"
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async subtreep visible-only nil nil (lambda () (text-mode))))
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;;;###autoload
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(defun org-rss-export-to-rss (&optional async subtreep visible-only)
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"Export current buffer to a RSS file.
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If narrowing is active in the current buffer, only export its
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narrowed part.
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If a region is active, export that region.
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A non-nil optional argument ASYNC means the process should happen
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asynchronously. The resulting file should be accessible through
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the `org-export-stack' interface.
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When optional argument SUBTREEP is non-nil, export the sub-tree
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at point, extracting information from the headline properties
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first.
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When optional argument VISIBLE-ONLY is non-nil, don't export
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contents of hidden elements.
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Return output file's name."
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(interactive)
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(let ((file (buffer-file-name (buffer-base-buffer))))
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(org-icalendar-create-uid file 'warn-user)
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(org-rss-add-pubdate-property))
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(let ((outfile (org-export-output-file-name
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(concat "." org-rss-extension) subtreep)))
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(org-export-to-file 'rss outfile async subtreep visible-only)))
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;;;###autoload
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(defun org-rss-publish-to-rss (plist filename pub-dir)
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"Publish an org file to RSS.
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FILENAME is the filename of the Org file to be published. PLIST
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is the property list for the given project. PUB-DIR is the
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publishing directory.
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Return output file name."
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(let ((bf (get-file-buffer filename)))
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(if bf
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(progn
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(org-icalendar-create-uid filename 'warn-user)
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(with-current-buffer bf
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(org-rss-add-pubdate-property)
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(write-file filename)))
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(find-file filename)
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(org-icalendar-create-uid filename 'warn-user)
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(org-rss-add-pubdate-property)
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(write-file filename) (kill-buffer)))
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(org-publish-org-to
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'rss filename (concat "." org-rss-extension) plist pub-dir))
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;;; Main transcoding functions
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(defun org-rss-headline (headline contents info)
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"Transcode HEADLINE element into RSS format.
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CONTENTS is the headline contents. INFO is a plist used as a
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communication channel."
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(unless (or (org-element-property :footnote-section-p headline)
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;; Only consider first-level headlines
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(> (org-export-get-relative-level headline info) 1))
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(let* ((author (and (plist-get info :with-author)
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(let ((auth (plist-get info :author)))
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(and auth (org-export-data auth info)))))
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(htmlext (plist-get info :html-extension))
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(hl-number (org-export-get-headline-number headline info))
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(hl-home (file-name-as-directory (plist-get info :html-link-home)))
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(hl-pdir (plist-get info :publishing-directory))
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(hl-perm (org-element-property :RSS_PERMALINK headline))
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(anchor
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(org-export-solidify-link-text
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(or (org-element-property :CUSTOM_ID headline)
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(concat "sec-" (mapconcat 'number-to-string hl-number "-")))))
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(category (org-rss-plain-text
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(or (org-element-property :CATEGORY headline) "") info))
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(pubdate
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(let ((system-time-locale "C"))
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(format-time-string
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"%a, %d %b %Y %H:%M:%S %z"
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(org-time-string-to-time
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(or (org-element-property :PUBDATE headline)
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(error "Missing PUBDATE property"))))))
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(title (org-element-property :raw-value headline))
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(publink
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(or (and hl-perm (concat (or hl-home hl-pdir) hl-perm))
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(concat
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(or hl-home hl-pdir)
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(file-name-nondirectory
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(file-name-sans-extension
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(plist-get info :input-file))) "." htmlext "#" anchor)))
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(guid (if org-rss-use-entry-url-as-guid
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publink
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(org-rss-plain-text
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(or (org-element-property :ID headline)
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(org-element-property :CUSTOM_ID headline)
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publink)
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info))))
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(format
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(concat
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"<item>\n"
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"<title>%s</title>\n"
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"<link>%s</link>\n"
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"<author>%s</author>\n"
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"<guid isPermaLink=\"false\">%s</guid>\n"
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"<pubDate>%s</pubDate>\n"
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(org-rss-build-categories headline info) "\n"
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"<description><![CDATA[%s]]></description>\n"
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"</item>\n")
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title publink author guid pubdate contents))))
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(defun org-rss-build-categories (headline info)
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"Build categories for the RSS item."
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(if (eq (plist-get info :rss-categories) 'from-tags)
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(mapconcat
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(lambda (c) (format "<category><![CDATA[%s]]></category>" c))
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(org-element-property :tags headline)
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"\n")
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(let ((c (org-element-property :CATEGORY headline)))
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(format "<category><![CDATA[%s]]></category>" c))))
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(defun org-rss-template (contents info)
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"Return complete document string after RSS conversion.
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CONTENTS is the transcoded contents string. INFO is a plist used
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as a communication channel."
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(concat
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(format "<?xml version=\"1.0\" encoding=\"%s\"?>"
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(symbol-name org-html-coding-system))
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"\n<rss version=\"2.0\"
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xmlns:content=\"http://purl.org/rss/1.0/modules/content/\"
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xmlns:wfw=\"http://wellformedweb.org/CommentAPI/\"
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xmlns:dc=\"http://purl.org/dc/elements/1.1/\"
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xmlns:atom=\"http://www.w3.org/2005/Atom\"
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xmlns:sy=\"http://purl.org/rss/1.0/modules/syndication/\"
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xmlns:slash=\"http://purl.org/rss/1.0/modules/slash/\"
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xmlns:georss=\"http://www.georss.org/georss\"
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xmlns:geo=\"http://www.w3.org/2003/01/geo/wgs84_pos#\"
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xmlns:media=\"http://search.yahoo.com/mrss/\">"
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"<channel>"
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(org-rss-build-channel-info info) "\n"
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contents
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"</channel>\n"
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"</rss>"))
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(defun org-rss-build-channel-info (info)
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"Build the RSS channel information."
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(let* ((system-time-locale "C")
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(title (plist-get info :title))
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(email (org-export-data (plist-get info :email) info))
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(author (and (plist-get info :with-author)
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(let ((auth (plist-get info :author)))
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(and auth (org-export-data auth info)))))
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(date (format-time-string "%a, %d %b %Y %H:%M:%S %z")) ;; RFC 882
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(description (org-export-data (plist-get info :description) info))
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(lang (plist-get info :language))
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(keywords (plist-get info :keywords))
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(rssext (plist-get info :rss-extension))
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(blogurl (or (plist-get info :html-link-home)
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(plist-get info :publishing-directory)))
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(image (url-encode-url (plist-get info :rss-image-url)))
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(ifile (plist-get info :input-file))
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(publink
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(concat (file-name-as-directory blogurl)
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(file-name-nondirectory
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(file-name-sans-extension ifile))
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"." rssext)))
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(format
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"\n<title>%s</title>
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<atom:link href=\"%s\" rel=\"self\" type=\"application/rss+xml\" />
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<link>%s</link>
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<description><![CDATA[%s]]></description>
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<language>%s</language>
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<pubDate>%s</pubDate>
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<lastBuildDate>%s</lastBuildDate>
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<generator>%s</generator>
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<webMaster>%s (%s)</webMaster>
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<image>
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<url>%s</url>
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<title>%s</title>
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<link>%s</link>
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</image>
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"
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title publink blogurl description lang date date
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(concat (format "Emacs %d.%d"
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emacs-major-version
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emacs-minor-version)
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" Org-mode " (org-version))
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email author image title blogurl)))
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(defun org-rss-section (section contents info)
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"Transcode SECTION element into RSS format.
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CONTENTS is the section contents. INFO is a plist used as
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a communication channel."
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contents)
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(defun org-rss-timestamp (timestamp contents info)
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"Transcode a TIMESTAMP object from Org to RSS.
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CONTENTS is nil. INFO is a plist holding contextual
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information."
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(org-html-encode-plain-text
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(org-timestamp-translate timestamp)))
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(defun org-rss-plain-text (contents info)
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"Convert plain text into RSS encoded text."
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(let (output)
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(setq output (org-html-encode-plain-text contents)
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output (org-export-activate-smart-quotes
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output :html info))))
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;;; Filters
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(defun org-rss-final-function (contents backend info)
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"Prettify the RSS output."
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(with-temp-buffer
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(xml-mode)
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(insert contents)
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(indent-region (point-min) (point-max))
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(buffer-substring-no-properties (point-min) (point-max))))
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;;; Miscellaneous
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(defun org-rss-add-pubdate-property ()
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"Set the PUBDATE property for top-level headlines."
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(let (msg)
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(org-map-entries
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(lambda ()
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(let* ((entry (org-element-at-point))
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(level (org-element-property :level entry)))
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(when (= level 1)
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(unless (org-entry-get (point) "PUBDATE")
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(setq msg t)
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(org-set-property
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"PUBDATE" (format-time-string
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(cdr org-time-stamp-formats)))))))
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nil nil 'comment 'archive)
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(when msg
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(message "Property PUBDATE added to top-level entries in %s"
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(buffer-file-name))
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(sit-for 2))))
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(provide 'ox-rss)
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;;; ox-rss.el ends here
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