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-rw-r--r--Makefile.am1
-rw-r--r--haunt/builder/rss.scm107
2 files changed, 108 insertions, 0 deletions
diff --git a/Makefile.am b/Makefile.am
index 1389cfb..b30753a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -54,6 +54,7 @@ SOURCES = \
haunt/builder/assets.scm \
haunt/builder/atom.scm \
haunt/builder/blog.scm \
+ haunt/builder/rss.scm \
haunt/reader.scm \
haunt/reader/texinfo.scm \
haunt/ui.scm \
diff --git a/haunt/builder/rss.scm b/haunt/builder/rss.scm
new file mode 100644
index 0000000..1d988a7
--- /dev/null
+++ b/haunt/builder/rss.scm
@@ -0,0 +1,107 @@
+;;; Haunt --- Static site generator for GNU Guile
+;;; Copyright © 2018 Christopher Lemmer Webber <cwebber@dustycloud.org>
+;;;
+;;; This file is part of Haunt.
+;;;
+;;; Haunt 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.
+;;;
+;;; Haunt 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 Haunt. If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; RSS feed builder.
+;;
+;;; Code:
+
+(define-module (haunt builder rss)
+ #:use-module (srfi srfi-19)
+ #:use-module (srfi srfi-26)
+ #:use-module (ice-9 match)
+ #:use-module (sxml simple)
+ #:use-module (haunt site)
+ #:use-module (haunt post)
+ #:use-module (haunt page)
+ #:use-module (haunt utils)
+ #:use-module (haunt html)
+ #:use-module (haunt serve mime-types)
+ #:use-module (haunt builder atom)
+ #:export (rss-feed))
+
+;; Reader beware: this isn't as nice as atom.scm, because rss isn't
+;; as nice as atom. Worse beats better on the play field again...
+
+;; RFC 822 dates are inferior to ISO 8601, but it's
+;; what RSS wants, so...
+(define (date->rfc822-str date)
+ (date->string date "~a, ~d ~b ~Y ~T ~z"))
+
+(define (sxml->xml* sxml port)
+ "Write SXML to PORT, preceded by an <?xml> tag."
+ (display "<?xml version=\"1.0\" encoding=\"utf-8\"?>" port)
+ (sxml->xml sxml port))
+
+(define* (post->rss-item site post #:key (blog-prefix ""))
+ "Convert POST into an RSS <item> node."
+ `(item
+ (title ,(post-ref post 'title))
+ ;; Looks like: <author>lawyer@boyer.net (Lawyer Boyer)</author>
+ (author
+ ,(let ((email (post-ref post 'email))
+ (author (post-ref post 'author)))
+ (string-append (if email
+ (string-append email " ")
+ "")
+ (if author
+ (string-append "(" author ")")
+ ""))))
+ (pubDate ,(date->rfc822-str (post-date post)))
+ (link (@ (href ,(string-append blog-prefix "/"
+ (site-post-slug site post) ".html"))
+ (rel "alternate")))
+ (description ,(sxml->html-string (post-sxml post)))
+ ,@(map (lambda (enclosure)
+ `(enclosure (@ (title ,(enclosure-title enclosure))
+ (url ,(enclosure-url enclosure))
+ (type ,(enclosure-mime-type enclosure))
+ ,@(map (match-lambda
+ ((key . value)
+ (list key value)))
+ (enclosure-extra enclosure)))))
+ (post-ref-all post 'enclosure))))
+
+(define* (rss-feed #:key
+ (file-name "rss-feed.xml")
+ (subtitle "Recent Posts")
+ (filter posts/reverse-chronological)
+ (max-entries 20)
+ (blog-prefix ""))
+ "Return a builder procedure that renders a list of posts as an RSS
+feed. All arguments are optional:
+
+FILE-NAME: The page file name
+SUBTITLE: The feed subtitle
+FILTER: The procedure called to manipulate the posts list before rendering
+MAX-ENTRIES: The maximum number of posts to render in the feed"
+ (lambda (site posts)
+ (make-page file-name
+ `(rss (@ (version "2.0"))
+ (channel
+ (title ,(site-title site))
+ ;; It looks like RSS's description and atom's subtitle
+ ;; are equivalent?
+ (description ,subtitle)
+ (pubDate ,(date->rfc822-str (current-date)))
+ (link (@ (href ,(site-domain site))))
+ ,@(map (cut post->rss-item site <>
+ #:blog-prefix blog-prefix)
+ (take-up-to max-entries (filter posts)))))
+ sxml->xml*)))