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;;; Haunt --- Static site generator for GNU Guile
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2016 Christopher Allan 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:
;;
;; Atom feed builder.
;;
;;; Code:
(define-module (haunt builder atom)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-19)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:use-module (sxml simple)
#:use-module (haunt artifact)
#: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 (web uri)
#:export (make-enclosure
enclosure?
enclosure-title
enclosure-url
enclosure-extra
enclosure-mime-type
atom-feed
atom-feeds-by-tag))
(define-record-type <enclosure>
(make-enclosure title url extra)
enclosure?
(title enclosure-title)
(url enclosure-url)
(extra enclosure-extra))
(define (enclosure-mime-type enclosure)
(mime-type (enclosure-url enclosure)))
(define char-set:enclosure-key
(char-set-union char-set:letter+digit
(char-set-delete char-set:punctuation #\: #\")
(char-set-delete char-set:symbol #\=)))
(define (parse-enclosure s)
(call-with-input-string s
(lambda (port)
(define (assert-char char)
(let ((c (read-char port)))
(unless (eqv? c char)
(error "enclosure: parse: expected" char "got" c))))
(define (whitespace? char)
(char-set-contains? char-set:whitespace char))
(define (consume-whitespace)
(match (peek-char port)
((? eof-object?) *unspecified*)
((? whitespace?)
(read-char port)
(consume-whitespace))
(_ *unspecified*)))
(define (read-escape-character)
(match (read-char port)
(#\" #\")
(#\\ #\\)
(char (error "enclosure: parse: invalid escape character:" char))))
(define (read-unquoted-string)
(list->string
(let loop ()
(let ((c (peek-char port)))
(cond
((eof-object? c)
'())
((char-set-contains? char-set:enclosure-key c)
(read-char port)
(cons c (loop)))
(else
'()))))))
(define (read-string)
(if (eqv? (peek-char port) #\")
(begin
(assert-char #\")
(list->string
(let loop ()
(match (read-char port)
((? eof-object?)
(error "enclosure: parse: EOF while reading string"))
(#\" '())
(#\\ (cons (read-escape-character) (loop)))
(char (cons char (loop)))))))
(read-unquoted-string)))
(define (read-key)
(string->symbol (read-unquoted-string)))
(let loop ((attrs '()))
(consume-whitespace)
(if (eof-object? (peek-char port))
(make-enclosure (assq-ref attrs 'title)
(assq-ref attrs 'url)
(let loop ((attrs attrs))
(match attrs
(() '())
((((or 'title 'url) . _) . rest)
(loop rest))
((attr . rest)
(cons attr (loop rest))))))
(let ((key (read-key)))
(assert-char #\:)
(loop (cons (cons key (read-string)) attrs))))))))
(register-metadata-parser! 'enclosure parse-enclosure)
(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 (date->string* date)
"Convert date to RFC-3339 formatted string."
(date->string date "~Y-~m-~dT~H:~M:~SZ"))
(define* (post->atom-entry site post #:key (blog-prefix ""))
"Convert POST into an Atom <entry> XML node."
(let ((uri (uri->string
(build-uri (site-scheme site)
#:host (site-domain site)
#:path (string-append blog-prefix "/"
(site-post-slug site post)
".html")))))
`(entry
(title ,(post-ref post 'title))
(id ,uri)
(author
(name ,(post-ref post 'author))
,(let ((email (post-ref post 'email)))
(if email `(email ,email) '())))
(updated ,(date->string* (post-date post)))
(link (@ (href ,uri) (rel "alternate")))
(summary (@ (type "html"))
,(sxml->html-string (post-sxml post)))
,@(map (lambda (enclosure)
`(link (@ (rel "enclosure")
(title ,(enclosure-title enclosure))
(href ,(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* (atom-feed #:key
(file-name "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 Atom
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)
(let ((uri (uri->string
(build-uri (site-scheme site)
#:host (site-domain site)
#:path (string-append "/" file-name)))))
(serialized-artifact file-name
`(feed (@ (xmlns "http://www.w3.org/2005/Atom"))
(title ,(site-title site))
(id ,uri)
(subtitle ,subtitle)
(updated ,(date->string* (current-date)))
(link (@ (href ,(string-append (site-domain site)
"/" file-name))
(rel "self")))
(link (@ (href ,(site-domain site))))
,@(map (cut post->atom-entry site <>
#:blog-prefix blog-prefix)
(take-up-to max-entries (filter posts))))
sxml->xml*))))
(define* (atom-feeds-by-tag #:key
(prefix "feeds/tags")
(filter posts/reverse-chronological)
(max-entries 20)
(blog-prefix ""))
"Return a builder procedure that renders an atom feed for every tag
used in a post. All arguments are optional:
PREFIX: The directory in which to write the feeds
FILTER: The procedure called to manipulate the posts list before rendering
MAX-ENTRIES: The maximum number of posts to render in each feed"
(lambda (site posts)
(let ((tag-groups (posts/group-by-tag posts)))
(map (match-lambda
((tag . posts)
((atom-feed #:file-name (string-append prefix "/" tag ".xml")
#:subtitle (string-append "Tag: " tag)
#:filter filter
#:max-entries max-entries
#:blog-prefix blog-prefix)
site posts)))
tag-groups))))
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