haunt/haunt/reader.scm

126 lines
4.1 KiB
Scheme

;;; Haunt --- Static site generator for GNU Guile
;;; Copyright © 2015 David Thompson <davet@gnu.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 readers.
;;
;;; Code:
(define-module (haunt reader)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
#:use-module (ice-9 ftw)
#:use-module (ice-9 match)
#:use-module (ice-9 regex)
#:use-module (ice-9 rdelim)
#:use-module (sxml simple)
#:use-module (haunt post)
#:use-module (haunt utils)
#:export (make-reader
reader?
reader-matcher
reader-proc
reader-match?
read-post
read-posts
make-file-extension-matcher
sxml-reader
html-reader))
(define-record-type <reader>
(make-reader matcher proc)
reader?
(matcher reader-matcher)
(proc reader-proc))
(define (reader-match? reader file-name)
"Return #t if FILE-NAME is a file supported by READER."
((reader-matcher reader) file-name))
(define* (read-post reader file-name #:optional (default-metadata '()))
"Read a post object from FILE-NAME using READER, merging its
metadata with DEFAULT-METADATA."
(let-values (((metadata sxml) ((reader-proc reader) file-name)))
(make-post file-name
(append metadata default-metadata)
sxml)))
(define* (read-posts directory keep? readers #:optional (default-metadata '()))
"Read all of the files in DIRECTORY that match KEEP? as post
objects. The READERS list must contain a matching reader for every
post."
(define enter? (const #t))
(define (leaf file-name stat memo)
(if (keep? file-name)
(let ((reader (find (cut reader-match? <> file-name) readers)))
(if reader
(cons (read-post reader file-name default-metadata) memo)
(error "no reader available for post: " file-name)))
memo))
(define (noop file-name stat result)
result)
(define (err file-name stat errno result)
(error "file processing failed with errno: " file-name errno))
(file-system-fold enter? leaf noop noop noop err '() directory))
;;;
;;; Simple readers
;;;
(define (make-file-extension-matcher ext)
"Return a procedure that returns #t when a file name ends with
'.EXT'."
(let ((regexp (make-regexp (string-append "\\." ext "$"))))
(lambda (file-name)
(regexp-match? (regexp-exec regexp file-name)))))
(define sxml-reader
(make-reader (make-file-extension-matcher "sxml")
(lambda (file-name)
(let ((contents (load (absolute-file-name file-name))))
(values (alist-delete 'content contents eq?)
(assq-ref contents 'content))))))
(define (read-html-post 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 "---")
(values metadata
(match (xml->sxml port)
(('*TOP* sxml) sxml))))
(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))))))))
(define html-reader
(make-reader (make-file-extension-matcher "html")
(cut call-with-input-file <> read-html-post)))