給博客添加純文本版本
看了 wiwi 的 偷偷加入的功能 (另見 Zine#54) 我也給博客的文章添加了純文本版本，你可以在每篇文章的底部找到純文本版本的連結，也可以將頁面 URL 的 .html 換成 .txt 訪問純文本版本 (如果換成 .org 就能看到文章的原始文件)。最近看到 Wiwi.Blog 純文字版，我也跟著做了一個 純文本版本的索引頁。
純文本的好处是極簡，基本上就是文字，沒有其它干擾元素，其次是體積小，在網絡不好時也能較快的加載 (不過網絡條件不好，和服務器建立連結也需要時間，能節省的是頁面需要的流量)。
製作純文本版本，只要將原始文件想辦法轉成 txt 版本就好了 (現在只是轉換成了 HTML)，然後給所有的 txt 文件做一個索引頁 (建議掛載在 /txt 這個路徑下)，基本上就够用了。
我的博客是用 org-publish 和 denote 構建的，接下來我會分享我是如何通過它們給博客添加純文本版本的，包擴：
- 將原始 org 文件轉換出一個 txt 版本
- 給每個頁面添加對應的純文本版本連結
- 製作索引頁
相關代碼可以在 init-org-publish.el 和 init-denote.el 找到。
將原始 org 文件轉換出一個 txt 版本
因為我是用 org-publish 構建的，要構建純文本版本，可以向 org-publish-project-alist 添加一個 project 來實現。
(setq org-publish-project-alist
`(
;; 省略其它
("plain-text-all"
:base-directory "~/git/taxodium/posts"
:base-extension "org"
:exclude ".*"
:with-toc nil
:include ,(spike-leung/get-file-list-from-denote-silo "~/git/taxodium/posts" (rx (or "_blackhole" "_published")))
:publishing-directory ,spike-leung/org-publish-default-publishing-directory
:publishing-function spike-leung/org-publish-plain-text)
;; 省略其它
))
這個 project 做的事就是 ，用 spike-leung/org-publish-plain-text 处理成純文本版本。
(defun spike-leung/org-publish-plain-text (_plist filename pub-dir)
"Publish a org file and use export_file_name as filename.
FILENAME is the filename of the Org file to be published. PLIST
is the property list for the given project. PUB-DIR is the
publishing directory.
Return output file name."
(unless (file-directory-p pub-dir)
(make-directory pub-dir t))
(let* ((export-file-name
(or (spike-leung/org-publish-get-org-keyword nil nil "export_file_name" filename) filename))
(base-filename (expand-file-name (file-name-nondirectory export-file-name) pub-dir))
(org-file (file-name-with-extension base-filename "org"))
(text-file (file-name-with-extension base-filename "txt")))
;; generate .txt file
(org-publish-org-to 'ascii filename ".txt" _plist pub-dir)
;; copy original org file to pub-dir
(copy-file filename org-file t)
;; Return file name.
org-file))
spike-leung/org-publish-plain-text 會從文章的 org 文件裡找到 URL ()，然後用 org-publish-org-to 导出一個 ascii 版本到用於發布的目录󠄃，這樣就很到了每篇文章對應的純文本版本了。
另外為了讓純文本版本的內容看起來更簡洁，我還覆盖了 ox-ascii 的一些實現，移除了加粗等標記。
ox-ascii 的改動
(use-package ox-ascii
:straight nil
:custom
(org-ascii-text-width 88)
(org-ascii-quote-margin 2)
(org-ascii-charset 'ascii)
(org-ascii-links-to-notes t)
:config
;; do not interpret *word*, /word/, _word_ and +word+
(defun org-ascii-bold (_bold contents _info) contents)
(defun org-ascii-italic (_italic contents _info) contents)
(defun org-ascii-underline (_underline contents _info) contents)
(defun org-ascii-strike-through (_strike-through contents _info) contents)
;; override `org-ascii-template--document-title', change center align to left align
(defun org-ascii-template--document-title (info)
"Return document title, as a string.
INFO is a plist used as a communication channel."
(let* ((text-width (plist-get info :ascii-text-width))
;; Links in the title will not be resolved later, so we make
;; sure their path is located right after them.
(info (org-combine-plists info '(:ascii-links-to-notes nil)))
(with-title (plist-get info :with-title))
(title (org-export-data
(when with-title (plist-get info :title)) info))
(subtitle (org-export-data
(when with-title (plist-get info :subtitle)) info))
(author (and (plist-get info :with-author)
(let ((auth (plist-get info :author)))
(and auth (org-export-data auth info)))))
(email (and (plist-get info :with-email)
(org-export-data (plist-get info :email) info)))
(date (and (plist-get info :with-date)
(org-export-data (org-export-get-date info) info))))
;; There are two types of title blocks depending on the presence
;; of a title to display.
(if (string= title "")
;; Title block without a title. DATE is positioned at the top
;; right of the document, AUTHOR to the top left and EMAIL
;; just below.
(cond
((and (org-string-nw-p date) (org-string-nw-p author))
(concat
author
(make-string (- text-width (string-width date) (string-width author))
?\s)
date
(when (org-string-nw-p email) (concat "\n" email))
"\n\n\n"))
((and (org-string-nw-p date) (org-string-nw-p email))
(concat
email
(make-string (- text-width (string-width date) (string-width email))
?\s)
date "\n\n\n"))
((org-string-nw-p date)
(concat
(org-ascii--justify-lines date text-width 'right)
"\n\n\n"))
((and (org-string-nw-p author) (org-string-nw-p email))
(concat author "\n" email "\n\n\n"))
((org-string-nw-p author) (concat author "\n\n\n"))
((org-string-nw-p email) (concat email "\n\n\n")))
;; Title block with a title. Document's TITLE, along with the
;; AUTHOR and its EMAIL are both overlined and an underlined,
;; centered. Date is just below, also centered.
(let* ((utf8p (eq (plist-get info :ascii-charset) 'utf-8))
;; Format TITLE. It may be filled if it is too wide,
;; that is wider than the two thirds of the total width.
(title-len (min (apply #'max
(mapcar #'string-width
(org-split-string
(concat title "\n" subtitle) "\n")))
(/ (* 2 text-width) 3)))
(formatted-title (org-ascii--fill-string title title-len info))
(formatted-subtitle (when (org-string-nw-p subtitle)
(org-ascii--fill-string subtitle title-len info)))
(line
(make-string
(min (+ (max title-len
(string-width (or author ""))
(string-width (or email "")))
2)
text-width) (if utf8p ?━ ?_))))
(org-ascii--justify-lines
(concat (upcase formatted-title)
(and formatted-subtitle (concat " - " formatted-subtitle))
(when (org-string-nw-p date) (concat "\n\n" date))
"\n" line "\n\n")
text-width 'left))))))
給每個頁面添加對應的純文本版本連結
接下來要給文章添加純文本連結，只要获取到文章的 URL，然後加上 .txt 後輟就行。連結我放在了頁脚，頁脚的內容是通過 :html-postamble spike-leung/html-postamble 指定的 (:html-postamble 是 org-publish-project-alist 裡的一個配置項，用於配置頁脚)。
spike-leung/html-postamble 是一個函數：
spike-leung/html-postamble
(defun spike-leung/html-postamble (info)
"Return a string for html-postamble.
INFO is a plist holding contextual information."
(let* ((timestamp-format "%Y-%m-%d %a %H:%M")
(display-timestamp-format "%Y-%m-%d")
(input-file (plist-get info :input-file))
(output-file (plist-get info :output-file))
(title (org-export-data (plist-get info :title) info))
(subtitle (org-export-data (plist-get info :subtitle) info))
(create-date (org-export-data (org-export-get-date info timestamp-format) info))
(modified-date (format-time-string timestamp-format
(and input-file (file-attribute-modification-time
(file-attributes input-file)))))
(create-date-display (org-export-data (org-export-get-date info display-timestamp-format) info))
(modified-date-display (format-time-string display-timestamp-format
(and input-file (file-attribute-modification-time
(file-attributes input-file)))))
(output-filename (file-name-base output-file)))
(concat
;; webmention
"
Webmentions (加载中...)
如果你想回应这篇文章，可以在你的文章或社交媒体帖子中链接这篇文章，然后提交你的 URL，你的回应随后会显示在此页面上。
(关于 Webmention)
"
;; microformat
"
Spike Leung
Spike Leung
"
;; footer
(format-spec "
感谢你的阅读！(´｡• ᵕ •｡`) ♡
文章创建於 %C，更新於 %M，
所有原创內容均遵循 署名、非商业性使用、相同方式共享，
所有源代碼以及内联文檔遵循 AGPL v3。
如果你有什么想说的，尽管给 Spike Leung 发一封 純文本邮件 :)
如果文章对你有帮助，请考虑 用你喜欢的方式 支持我。
純文本版本 原始 org 文件
"
`((?c . ,create-date)
(?C . ,create-date-display)
(?m . ,modified-date)
(?M . ,modified-date-display)
(?t . ,title)
(?s . ,subtitle)
(?u . ,output-filename)))
;; scripts
"
")))
函數的參數 info 是一個包含了 org-publish 相關上下文的 plist，其中的 :output-file 對應的就是最終导出的文件名字，也就是 URL，用這個 URL 拼接上 .txt ，展示成一個 元素，就得到了文章的純文本版本連結。
製作索引頁
純文本索引頁 和 首頁 基本是一樣的，都是用 Denote Org 获取文章的 denote 連結 (denote:)，不同之处在於，首頁是將 denote 的的連結轉換成 .html 的連結，而純文本索引頁需要轉換成 .txt 的連結，這需要覆盖 denote: 連結的导出函數。
denote 相關改動
;;; make denote-link-ol-export support #+export_file_name
;; see also: https://jiewawa.me/2024/03/blogging-with-denote-and-hugo/
(defun spike-leung/my-denote--get-export-file-name (file)
"Find #+export_file_name in FILE and return its value.
Return nil if not found or FILE does not exist."
(when (and file (file-exists-p file))
(with-temp-buffer
(insert-file-contents file)
(goto-char (point-min))
(when (re-search-forward "^#\\+export_file_name: \\(.*\\)$" nil t)
(string-trim (match-string-no-properties 1))))))
(defun spike-leung/denote-link-ol-export (link description format)
"Export a `denote:' link from Org files.
The LINK, DESCRIPTION, and FORMAT are handled by the export
backend."
(pcase-let* ((`(,path ,query ,file-search) (denote-link--ol-resolve-link-to-target link :full-data))
(export-file-name (when path (spike-leung/my-denote--get-export-file-name path)))
(anchor (if export-file-name
export-file-name
(when path (file-relative-name (file-name-sans-extension path)))))
(desc (cond
(description)
(file-search (format "denote:%s::%s" query file-search))
(t (concat "denote:" query))))
(ext org-html-extension))
(if path
(pcase format
('html (if file-search
(format "%s" (url-encode-url anchor) ext file-search desc)
(format "%s" (url-encode-url anchor) ext desc)))
('latex (format "\\href{%s}{%s}" (replace-regexp-in-string "[\\{}$%&_#~^]" "\\\\\\&" path) desc))
('texinfo (format "@uref{%s,%s}" path desc))
('ascii (if file-search
(format "[%s] <https://taxodium.ink/%s.html%s>" desc (url-encode-url anchor) file-search ) (format "[%s] <https://taxodium.ink/%s.html>" desc (url-encode-url anchor))))
('md (format "[%s](%s)" desc path))
(_ path))
(format-message "[[Denote query for `%s']]" query))))
;; 修改 `denote:' 链接的导出，使其读取 `#+export_file_name'
(add-hook 'org-export-before-processing-hook
#'(lambda (backend)
(org-link-set-parameters "denote" :export #'spike-leung/denote-link-ol-export)))
更多見： init-denote.el。
主要的改動是讓 denote: 在导出時讀取 org-html-extension 作為後輟，默認是 html ，在純文本索引頁我會添加一個 File Variables：
# Local Variables:
# org-html-extension: "txt"
# End:
將 org-html-extension 的默認值覆盖為 txt ，然後將索引頁用 org-publish 导出就行。
除此之外就是移除了頁頭、頁脚和樣式，讓索引頁盡可能精簡一些，索引頁目前資源大小只有 35K，HTML 只有 8K，應該足够小了，網絡不好時應該也能較快地加載。
如果你是博客作者，也可以考慮加一下純文本版本。如果你是讀者，要是在網絡不好時你還想看我的博客，你可以訪問 https://taxodium.ink/txt.html ；至於頁面，網絡不好時，你可以將 URL 上的 .html 換成 .txt ，先湊合看著。
感谢你的阅读！
欢迎 邮件 跟我分享你的想法 :)
你也可以 我的博客，保持更新 :P
祝好，素未某面的读者。
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