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Re: [O] Inline LaTeX formulae

From: Titus von der Malsburg
Subject: Re: [O] Inline LaTeX formulae
Date: Fri, 08 May 2015 15:25:06 -0700

On 2015-05-08 Fri 14:40, Nicolas Goaziou wrote:
> Titus von der Malsburg <address@hidden> writes:
>> Both are fixed in the patch below.
> Thank you.
>> I also included opening parentheses. It’s an unlikely case but for
>> consistency they should be included.
> If there's no need to exclude opening parenthesis, I suggest to use
>   "\\([[:punct:][:space:]]\\|$\\)"

This looks indeed much nicer but it’s not what we want.  The Emacs
documentation says:

    This matches any punctuation character. (At present, for multibyte
    characters, it matches anything that has non-word syntax.)

If this matches any non-word multibyte character, it also matches things
like the multiplication sign along with a lot of other non-punctuation
characters.  So if we’d use [:punct:] we would incorrectly detect a
latex fragment in the following example:


The patch with commit message is below.  I did the FSF copyright
paperwork a while ago (for a contribution to Emacs) so the TINYCHANGE
tag may not be required.

> instead of
>   "\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|$\\)"
> It is shorter and clearer.
>> I also updated org.texi.  Dashes are punctuation and don’t need special
>> mention.  I also clarified that quotes and parentheses are considered to
>> be punctuation (although Emacs has separate syntax classes for them).
> OK.
> Could you provide a commit message for this patch and send it again,
> with change above?

Fix detection of latex fragments

* org-element.el (org-element-latex-fragment-parser):
* org.el (org-latex-regexps): Fix the detection of latex
  fragments.  Uses syntax tables to detect whitespaces and punctuation
  marks following the final $ sign.

In order to qualify as a math delimiter, the final $ sign of a LaTeX
fragment has to be followed by a whitespace or punctuation mark but the
regexp used in the previous code matched only a small number of
punctuation marks and therefore missed some latex fragments.

diff --git a/doc/org.texi b/doc/org.texi
index 7b78417..d926de4 100644
--- a/doc/org.texi
+++ b/doc/org.texi
@@ -10347,9 +10347,10 @@ Text within the usual @LaTeX{} math delimiters.  To 
avoid conflicts with
 currency specifications, single @samp{$} characters are only recognized as
 math delimiters if the enclosed text contains at most two line breaks, is
 directly attached to the @samp{$} characters with no whitespace in between,
-and if the closing @samp{$} is followed by whitespace, punctuation or a dash.
-For the other delimiters, there is no such restriction, so when in doubt, use
address@hidden(...\)} as inline math delimiters.
+and if the closing @samp{$} is followed by whitespace or punctuation
+(parentheses and quotes are considered to be punctuation in this
+context).  For the other delimiters, there is no such restriction, so when in
+doubt, use @samp{\(...\)} as inline math delimiters.
 @end itemize
 @noindent For example:
diff --git a/lisp/org-element.el b/lisp/org-element.el
index 7aab9f6..8f57c90 100644
--- a/lisp/org-element.el
+++ b/lisp/org-element.el
@@ -2963,7 +2963,7 @@ Assume point is at the beginning of the LaTeX fragment."
                         (search-forward "$" nil t 2)
                         (not (memq (char-before (match-beginning 0))
                                    '(?\s ?\t ?\n ?, ?.)))
-                        (looking-at "\\([- \t.,?;:'\"]\\|$\\)")
+                        (looking-at 
                (case (char-after (1+ (point)))
                  (?\( (search-forward "\\)" nil t))
diff --git a/lisp/org.el b/lisp/org.el
index 6139876..46a73b6 100755
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -540,8 +540,8 @@ An entry can be toggled between COMMENT and normal with
   '(("begin" "^[ 
\t]*\\(\\\\begin{\\([a-zA-Z0-9\\*]+\\)[^\000]+?\\\\end{\\2}\\)" 1 t)
     ;; ("$" "\\([      (]\\|^\\)\\(\\(\\([$]\\)\\([^   
\r\n,.$].*?\\(\n.*?\\)\\{0,5\\}[^       \r\n,.$]\\)\\4\\)\\)\\([        
.,?;:'\")]\\|$\\)" 2 nil)
     ;; \000 in the following regex is needed for org-inside-LaTeX-fragment-p
-    ("$1" "\\([^$]\\|^\\)\\(\\$[^      \r\n,;.$]\\$\\)\\([-    
.,?;:'\")\000]\\|$\\)" 2 nil)
-    ("$" "\\([^$]\\|^\\)\\(\\(\\$\\([^         
\r\n,.$]\\)\\$\\)\\)\\([-       .,?;:'\")\000]\\|$\\)" 2 nil)
+    ("$1" "\\([^$]\\|^\\)\\(\\$[^      
\r\n,;.$]\\$\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|$\\)" 2 nil)
+    ("$"  "\\([^$]\\|^\\)\\(\\(\\$\\([^        
\r\n,.$]\\)\\$\\)\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|$\\)" 2 nil)
     ("\\(" "\\\\([^\000]*?\\\\)" 0 nil)
     ("\\[" "\\\\\\[[^\000]*?\\\\\\]" 0 nil)
     ("$$" "\\$\\$[^\000]*?\\$\\$" 0 nil))

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