haunt/haunt/post.scm

146 lines
4.4 KiB
Scheme

;;; 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:
;;
;; Post data type.
;;
;;; Code:
(define-module (haunt post)
#:use-module (ice-9 match)
#:use-module (ice-9 rdelim)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-19)
#:use-module (haunt utils)
#:export (make-post
post?
post-file-name
post-sxml
post-metadata
post-ref
post-ref-all
post-slug
%default-date
post-date
posts/reverse-chronological
posts/group-by-tag
register-metadata-parser!
parse-metadata
read-metadata-headers))
(define-record-type <post>
(make-post file-name metadata sxml)
post?
(file-name post-file-name)
(metadata post-metadata)
(sxml post-sxml))
(define (post-ref post key)
"Return the metadata corresponding to KEY within POST."
(assq-ref (post-metadata post) key))
(define (post-ref-all post key)
"Return a list of all metadata values for KEY within POST."
(filter-map (match-lambda
((k . v)
(and (eq? key k) v)))
(post-metadata post)))
(define char-set:slug
(char-set-union char-set:letter+digit (char-set #\-)))
(define (post-slug post)
"Transform the title of POST into a URL slug."
(or (post-ref post 'slug)
(string-join (map (lambda (s)
(string-filter char-set:slug s))
(string-split (string-downcase (post-ref post 'title))
char-set:whitespace))
"-")))
(define %default-date
(make-date 0 0 0 0 1 1 1970 0)) ; UNIX epoch
(define (post-date post)
"Return the date for POST, or '%default-date' if no date is
specified."
(or (post-ref post 'date) %default-date))
(define (post-time post)
(date->time-utc (post-ref post 'date)))
(define (posts/reverse-chronological posts)
"Returns POSTS sorted in reverse chronological order."
(sort posts
(lambda (a b)
(time>? (post-time a) (post-time b)))))
(define (posts/group-by-tag posts)
"Return an alist of tags mapped to the posts that used them."
(let ((table (make-hash-table)))
(for-each (lambda (post)
(for-each (lambda (tag)
(let ((current (hash-ref table tag)))
(if current
(hash-set! table tag (cons post current))
(hash-set! table tag (list post)))))
(or (post-ref post 'tags) '())))
posts)
(hash-fold alist-cons '() table)))
;;;
;;; Metadata
;;;
(define %metadata-parsers
(make-hash-table))
(define (metadata-parser key)
(or (hash-ref %metadata-parsers key) identity))
(define (register-metadata-parser! name parser)
(hash-set! %metadata-parsers name parser))
(define (parse-metadata key value)
((metadata-parser key) value))
(define (read-metadata-headers port)
(let loop ((metadata '()))
(let ((line (read-line port)))
(cond
((eof-object? line)
(error "end of file while reading metadata: " (port-filename port)))
((string=? line "---")
metadata)
(else
(match (map string-trim-both (string-split-at line #\:))
(((= string->symbol key) value)
(loop (alist-cons key (parse-metadata key value) metadata)))
(_ (error "invalid metadata format: " line))))))))
(register-metadata-parser!
'tags
(lambda (str)
(map string-trim-both (string-split str #\,))))
(register-metadata-parser! 'date string->date*)