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;;; Haunt --- Static site generator for GNU Guile
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2024 Daniel Meißner <dan_m@posteo.de>
;;;
;;; 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:
;;
;; SXML to HTML conversion.
;;
;;; Code:
(define-module (haunt html)
#:use-module (sxml simple)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:use-module (ice-9 format)
#:use-module (ice-9 hash-table)
#:export (sxml->html
sxml->html-string))
(define %void-elements
'(area
base
br
col
command
embed
hr
img
input
keygen
link
meta
param
source
track
wbr))
(define (void-element? tag)
"Return #t if TAG is a void element."
(pair? (memq tag %void-elements)))
(define %raw-elements
'(script style))
(define (raw-element? tag)
"Return #t if TAG is a raw element."
(pair? (memq tag %raw-elements)))
(define %escape-chars
(alist->hash-table
'((#\" . "quot")
(#\& . "amp")
(#\< . "lt")
(#\> . "gt"))))
(define (string->escaped-html s port)
"Write the HTML escaped form of S to PORT."
(define (escape c)
(let ((escaped (hash-ref %escape-chars c)))
(if escaped
(format port "&~a;" escaped)
(display c port))))
(string-for-each escape s))
(define (object->escaped-html obj port)
"Write the HTML escaped form of OBJ to PORT."
(string->escaped-html
(call-with-output-string (cut display obj <>))
port))
(define (attribute-value->html value port)
"Write the HTML escaped form of VALUE to PORT."
(if (string? value)
(string->escaped-html value port)
(object->escaped-html value port)))
(define (attribute->html attr value port)
"Write ATTR and VALUE to PORT."
(format port "~a=\"" attr)
(attribute-value->html value port)
(display #\" port))
(define (element->html tag attrs body port)
"Write the HTML TAG to PORT, where TAG has the attributes in the
list ATTRS and the child nodes in BODY."
(format port "<~a" tag)
(for-each (match-lambda
((attr value)
(display #\space port)
(attribute->html attr value port)))
attrs)
(cond
((and (null? body) (void-element? tag))
(display " />" port))
((raw-element? tag)
(display #\> port)
(for-each (lambda (node) (display node port)) body)
(format port "</~a>" tag))
(else
(display #\> port)
(for-each (cut sxml->html <> port) body)
(format port "</~a>" tag))))
(define (doctype->html doctype port)
(format port "<!DOCTYPE ~a>" doctype))
(define* (sxml->html tree #:optional (port (current-output-port)))
"Write the serialized HTML form of TREE to PORT."
(match tree
(() *unspecified*)
(('doctype type)
(doctype->html type port))
(((? symbol? tag) ('@ attrs ...) body ...)
(element->html tag attrs body port))
(((? symbol? tag) body ...)
(element->html tag '() body port))
((nodes ...)
(for-each (cut sxml->html <> port) nodes))
((? string? text)
(string->escaped-html text port))
;; Render arbitrary Scheme objects, too.
(obj (object->escaped-html obj port))))
(define (sxml->html-string sxml)
"Render SXML as an HTML string."
(call-with-output-string
(lambda (port)
(sxml->html sxml port))))
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