Re: c47b535bb origin/main org-element: Remove dependency on ‘org-emphasis-regexp-components’

[Ihor Radchenko <yantar92@gmail.com>]

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Max Nikulin <manikulin@gmail.com> writes:

> These regexps will always fail under some conditions, since it is not 
> strict markup. An example is emphasis terminated inside link target
>
> /A link [[https://orgmode.org/?oops=true][Org Mode]]

Your example actually reveals a much bigger issue with current element
parser. Even though the link is fontified by Org, if you run
org-element-context on the link, it will return nil. The parsed sentence
will look like:

<begin italic>/A link [[https://orgmode.org/<end italic><begin ordinary
text - it is not a link!>?oops=true][Org Mode]]<end of ordinary text>

The reason behind is partially regexps used to detect emphasised text
and partially the way our parser works - no intersected objects are
allowed.

My intuition says that the current parser behaviour is not correct. It
would make more sense to prioritise link over italics. However, it would
require a major change in the parser - instead of a single pass, the
parser may parse different types of objects sequentially. The emphasis
objects should come last avoiding the markers to have different parents.

Nicolas, WDYT?

>> Maybe something like the attached?
>
> Thank you, Ihor. Another reason why I have not tried to do it myself is 
> that it is necessary to test behavior for users who customized markers. 
> The change should not be fatal for them. I have not checked it with you 
> patch yet.
>
> I was considering some way to warn users if improper customization is 
> detected (unexpected marker is noticed). It should be noticeable to make 
> user aware of export issues but not too annoying.
>
>> +The characters in the alist must not be changed.  They do not affect
>> +the actual Org syntax, just fontification.
>
> Since this is known point of abuses, maybe stronger words are appropriate.
>
> Do not change makers and do not add new ones to use custom markers for 
> existing styles or to introduce new styles. Org syntax is not meant to 
> be configurable and such modifications will not work with export. If you 
> are interested in fontification of custom markup inside Emacs only, 
> there are other ways to achieve desired effect.
> ...
> In addition, I do not like the following phrase in the manual:
>
>> To narrow down the list of available markup syntax, you can customize org-emphasis-alist.

I updated the patch dropping your last suggested sentence in the
docstring. I find it not very helpful for the user. We should either say
nothing (as in the patch) or give a concrete reference how to "achieve
the desired effect".

Best,
Ihor

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From c950768bc08b4cae07ba3cb451d8af0abfec7dc8 Mon Sep 17 00:00:00 2001
Message-Id: <c950768bc08b4cae07ba3cb451d8af0abfec7dc8.1637237807.git.yantar92@gmail.com>
From: Ihor Radchenko <yantar92@gmail.com>
Date: Tue, 16 Nov 2021 15:40:35 +0800
Subject: [PATCH] org-emphasis-alist: Update defcustom making emphasis
 characters constant

* lisp/org.el (org-emphasis-alist): Mention that emphasis characters
should not be changed by user.  Update the defcustom type accordingly.
* doc/org-manual.org (Emphasis and Monospace): Update the referece to
`org-emphasis-alist'.
---
 doc/org-manual.org |  5 +++--
 lisp/org.el        | 41 ++++++++++++++++++++++++++++++++++++-----
 2 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/doc/org-manual.org b/doc/org-manual.org
index c4bb7ef30..9fea2c42e 100644
--- a/doc/org-manual.org
+++ b/doc/org-manual.org
@@ -10814,9 +10814,10 @@ ** Emphasis and Monospace
 exported verbatim.
 
 #+vindex: org-fontify-emphasized-text
+#+vindex: org-emphasis-alist
 To turn off fontification for marked up text, you can set
-~org-fontify-emphasized-text~ to ~nil~.  To narrow down the list of
-available markup syntax, you can customize ~org-emphasis-alist~.
+~org-fontify-emphasized-text~ to ~nil~.  For more fine-tuned
+fontification, you can customize ~org-emphasis-alist~.
 
 ** Subscripts and Superscripts
 :PROPERTIES:
diff --git a/lisp/org.el b/lisp/org.el
index 603b57279..00ac00ab3 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -3833,18 +3833,49 @@ (defcustom org-emphasis-alist
 marker characters and the face to be used by font-lock for highlighting
 in Org buffers.
 
+Do not change the characters and do not add new ones to use custom
+markers for existing styles or to introduce new styles.  Org syntax is
+not meant to be configurable and such modifications will not work with
+export.
+
 You need to reload Org or to restart Emacs after customizing this."
   :group 'org-appearance
   :set 'org-set-emph-re
   :version "24.4"
   :package-version '(Org . "8.0")
-  :type '(repeat
+  :type '(list
 	  (list
-	   (string :tag "Marker character")
+	   (const "*")
+	   (choice
+	    (face :tag "Bold emphasis face")
+	    (plist :tag "Bold emphasis face property list")))
+          (list
+	   (const "/")
+	   (choice
+	    (face :tag "Italic emphasis face")
+	    (plist :tag "Italic emphasis face property list")))
+          (list
+	   (const "_")
+	   (choice
+	    (face :tag "Underline emphasis face")
+	    (plist :tag "Underline emphasis face property list")))
+          (list
+	   (const "=")
+	   (choice
+	    (face :tag "Verbatim emphasis face")
+	    (plist :tag "Verbatim emphasis face property list"))
+	   (const verbatim))
+          (list
+	   (const "~")
+	   (choice
+	    (face :tag "Code emphasis face")
+	    (plist :tag "Code emphasis face property list"))
+	   (const verbatim))
+          (list
+	   (const "+")
 	   (choice
-	    (face :tag "Font-lock-face")
-	    (plist :tag "Face property list"))
-	   (option (const verbatim)))))
+	    (face :tag "Strike-through emphasis face")
+	    (plist :tag "Strike-through emphasis face property list")))))
 
 (defvar org-protecting-blocks '("src" "example" "export")
   "Blocks that contain text that is quoted, i.e. not processed as Org syntax.
-- 
2.32.0