[elpa] externals/org 981f250: ox-md: Use TeX-style $ math wrapping

[ELPA Syncer]

branch: externals/org
commit 981f25031dd17ceb4dec69e307815438ed095648
Author: Timothy <tecosaur@gmail.com>
Commit: TEC <tec@tecosaur.com>

    ox-md: Use TeX-style $ math wrapping
    
    * lisp/ox-md.el (org-md-latex-environment, org-md-latex-fragment):
    These two new filters wrap LaTeX maths in $ / $$ TeX-style notation.
    While ox-md endeavours to adhere to the original Markdown specification,
    and not any particular variant, the original specification does not deal
    with LaTeX fragments at all, and so this change does not reduce how
    faithfully the original specification is followed.
    There is a major upside to this though. Of the many Markdown variants
    that have emerged, those that support LaTeX very often exclusively
    support TeX style notation.  This change thus improves the utility of
    the Markdown export for many use cases, and deviates no more from the
    original specification that the current method.
---
 lisp/ox-md.el | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/lisp/ox-md.el b/lisp/ox-md.el
index 8a13231..a19664a 100644
--- a/lisp/ox-md.el
+++ b/lisp/ox-md.el
@@ -101,6 +101,8 @@ The %s will be replaced by the footnote reference itself."
                     (italic . org-md-italic)
                     (item . org-md-item)
                     (keyword . org-md-keyword)
+                     (latex-environment . org-md-latex-environment)
+                     (latex-fragment . org-md-latex-fragment)
                     (line-break . org-md-line-break)
                     (link . org-md-link)
                     (node-property . org-md-node-property)
@@ -461,6 +463,35 @@ channel."
     (_ (org-export-with-backend 'html keyword contents info))))
 
 
+;;;; Latex Environment
+
+(defun org-md-latex-environment (latex-environment contents info)
+  "Transcode a LATEX-ENVIRONMENT object from Org to Markdown.
+CONTENTS is nil.  INFO is a plist holding contextual information."
+  (when (plist-get info :with-latex)
+    (let ((latex-frag (org-remove-indentation
+                       (org-element-property :value latex-environment)))
+          (label (org-html--reference latex-environment info t)))
+      (if (org-string-nw-p label)
+          (replace-regexp-in-string "\\`.*"
+                                    (format "\\&\n\\\\label{%s}" label)
+                                    latex-frag)
+        latex-frag))))
+
+;;;; Latex Fragment
+
+(defun org-md-latex-fragment (latex-fragment contents info)
+  "Transcode a LATEX-FRAGMENT object from Org to Markdown.
+CONTENTS is nil.  INFO is a plist holding contextual information."
+  (when (plist-get info :with-latex)
+    (let ((frag (org-element-property :value latex-fragment)))
+      (cond
+       ((string-match-p "^\\\\(" frag)
+        (concat "$" (substring frag 2 -2) "$"))
+       ((string-match-p "^\\\\\\[" frag)
+        (concat "$$" (substring frag 2 -2) "$$"))
+       (t frag))))) ; either already $-deliminated or a macro
+
 ;;;; Line Break
 
 (defun org-md-line-break (_line-break _contents _info)