Fixed #461. Support for in-buffer external plugin specification

Readme.org

@@ -55,8 +55,6 @@
 #+REVEAL: split:t
     - [[Initialization options][Initialization options]]([[https://github.com/yjwen/org-reveal#initialization-options][gh]])
     - [[Third-Party Plugins][Third-Party Plugins]]([[https://github.com/yjwen/org-reveal#third-party-plugins][gh]])
-      - [[By Defining Variable][By Defining Variable]]([[https://github.com/yjwen/org-reveal#by-defining-variable][gh]])
-      - [[By Local Option Line][By Local Option Line]]([[https://github.com/yjwen/org-reveal#by-local-option-line][gh]])
     - [[Highlight Source Code][Highlight Source Code]]([[https://github.com/yjwen/org-reveal#highlight-source-code][gh]])
       - [[Using highlight.js][Using highlight.js]]([[https://github.com/yjwen/org-reveal#using-highlightjs][gh]])
     - [[Auto-Animate]] ([[https://github.com/yjwen/org-reveal#auto-animate][gh]])
@@ -67,7 +65,6 @@
       - [[Generating Pre/Postamble by Emacs-Lisp Functions][Generating Pre/Postamble by Emacs-Lisp Functions]]([[https://github.com/yjwen/org-reveal#generating-pre/postamble-by-emacs-lisp-functions][gh]])
     - [[Raw HTML in Slides][Raw HTML in Slides]]([[https://github.com/yjwen/org-reveal#raw-html-in-slides][gh]])
     - [[Speaker Notes][Speaker Notes]]([[https://github.com/yjwen/org-reveal#speaker-notes][gh]])
-      - [[Easy-Template for Speaker Notes][Easy-Template for Speaker Notes]]([[https://github.com/yjwen/org-reveal#easy-template-for-speaker-notes][gh]])
     - [[Multiplexing][Multiplexing]]([[https://github.com/yjwen/org-reveal#multiplexing][gh]])
     - [[Extra Stylesheets][Extra Stylesheets]]([[https://github.com/yjwen/org-reveal#extra-stylesheets][gh]])
     - [[Select Built-In Scripts][Select Built-In Scripts]]([[https://github.com/yjwen/org-reveal#select-built-in-scripts][gh]])
@@ -573,14 +570,27 @@ Reveal.js is also extensible through third-party plugins. Org-reveal
 provides a customizable variable ~org-reveal-external-plugins~ for
 defining available third-party plugins. This variable is an
 associative list. The first element of each Assoc cell is a symbol
-same as the name of the plugin and the second is a string specifying
-the location of the plugin script. The string can have ONE optional
+same as the name of the plugin and the second is either a string
+specifying the location of the plugin script or a list of string in
+case of multiple scripts. Each script string can have ONE optional
 ~%s~, which will be replaced by `reveal-root`. Code below is an
 example.
 #+begin_src lisp
 (setq org-reveal-external-plugins '((RevealMenu . "path/to/reveal.js-menu/menu.js"))
 #+end_src
 
+#+REVEAL: split:t
+
+Plugins can be specified in buffer by one or more
+~#+REVEAL_EXTERNAL_PLUGINS~ options. Each option can have one or more
+plugin specifications of the same format as in
+~org-reveal-external-plugins~. Below is an example.
+
+#+begin_src org
+  ,#+REVEAL_EXTERNAL_PLUGINS: (plugin1 . "ex/plugin1.js") (plugin2 . "ex/plugin2.js")
+  ,#+REVEAL_EXTERNAL_PLUGINS: (plugin3 "ex/plugin3-1.js" "ex/plugin3-2.js")
+#+end_src
+
 ** Highlight Source Code
 
    There are two ways to highlight source code.

ox-reveal.el

@@ -96,7 +96,7 @@
     (:reveal-slide-header "REVEAL_SLIDE_HEADER" nil org-reveal-slide-header t)
     (:reveal-slide-footer "REVEAL_SLIDE_FOOTER" nil org-reveal-slide-footer t)
     (:reveal-plugins "REVEAL_PLUGINS" nil nil t)
-    (:reveal-external-plugins "REVEAL_EXTERNAL_PLUGINS" nil nil newline)
+    (:reveal-external-plugins "REVEAL_EXTERNAL_PLUGINS" nil nil space)
     (:reveal-default-frag-style "REVEAL_DEFAULT_FRAG_STYLE" nil org-reveal-default-frag-style t)
     (:reveal-single-file nil "reveal_single_file" org-reveal-single-file t)
     (:reveal-init-script "REVEAL_INIT_SCRIPT" nil org-reveal-init-script space)
@@ -820,6 +820,15 @@ Reveal.initialize({
                (or (plist-get info :reveal-extra-script) "")))
 )))
 
+(defun org-reveal--read-sexps-from-string (s)
+  (let ((s (string-trim s)))
+    (and (not (string-empty-p s))
+      (let ((r (read-from-string s)))
+        (let ((obj (car r))
+              (remain-index (cdr r)))
+          (and obj
+               (cons obj (read-sexps-from-string (substring s remain-index)))))))))
+
 (defun org-reveal-plugin-scripts-4 (plugins info)
   "Return scripts for initializing reveal.js 4.x builtin scripts"
   ;; Return a tuple (represented as a list), the first value is a list of script
@@ -849,7 +858,11 @@ Reveal.initialize({
                         (RevealNotes . "%splugin/notes/notes.js")
                         (RevealMath . "%splugin/math/math.js")
                         (RevealZoom . "%splugin/zoom/zoom.js"))
-                      org-reveal-external-plugins))
+                      org-reveal-external-plugins
+                      ;; Buffer local plugins
+                      (let ((local-plugins (plist-get info :reveal-external-plugins)))
+                        (and local-plugins
+                             (org-reveal--read-sexps-from-string local-plugins)))))
              (plugin-js (seq-filter 'identity ;; Filter out nil
                                     (mapcar (lambda (p)
                                               (cdr (assoc p available-plugins)))
@@ -864,10 +877,10 @@ Reveal.initialize({
                   (cond
                    ((listp p)
                     (mapconcat (lambda (pi)
-                                 (format "<script src=\"%s\"></script>"
+                                 (format "<script src=\"%s\"></script>\n"
                                          (format pi root-path)))
                                p
-                               "\n"))
+                               ""))
                    ;; when it is a single string, create a single script tag
                    (t (format "<script src=\"%s\"></script>\n"
                               (format p root-path)))))