Re: Bug: HTML export of equations leads to error [8.3.3 (8.3.3-17-gce80a0-elpaplus @ /home/dfeich/.emacs.d/elpa/org-plus-contrib-20160118/)]

[Derek Feichtinger <dfeich@gmail.com>]

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Hi

I was able to repair the problem by setting the temp buffer that is created
within ort-html-format-latex to org-mode. I put the function with the
added line marked by PATCH here:

#+BEGIN_SRC elisp
  (defun org-html-format-latex (latex-frag processing-type info)
    "Format a LaTeX fragment LATEX-FRAG into HTML.
  PROCESSING-TYPE designates the tool used for conversion.  It is
  a symbol among `mathjax', `dvipng', `imagemagick', `verbatim' nil
  and t.  See `org-html-with-latex' for more information.  INFO is
  a plist containing export properties."
    (let ((cache-relpath "") (cache-dir ""))
      (unless (eq processing-type 'mathjax)
        (let ((bfn (or (buffer-file-name)
                       (make-temp-name
                        (expand-file-name "latex"
temporary-file-directory))))
              (latex-header
               (let ((header (plist-get info :latex-header)))
                 (and header
                      (concat (mapconcat
                               (lambda (line) (concat "#+LATEX_HEADER: "
line))
                               (org-split-string header "\n")
                               "\n")
                              "\n")))))
          (setq cache-relpath
                (concat "ltxpng/"
                        (file-name-sans-extension
                         (file-name-nondirectory bfn)))
                cache-dir (file-name-directory bfn))
          ;; Re-create LaTeX environment from original buffer in
          ;; temporary buffer so that dvipng/imagemagick can properly
          ;; turn the fragment into an image.
          (setq latex-frag (concat latex-header latex-frag))))
      (with-temp-buffer
        (insert latex-frag)
        (org-mode) ; <---  PATCH
        (org-format-latex cache-relpath cache-dir nil "Creating LaTeX
Image..."
                          nil processing-type)
        (buffer-string))))
#+END_SRC

Best regards,
Derek


On Sun, Jan 24, 2016 at 11:24 AM, Derek Feichtinger <dfeich@gmail.com>
wrote:

> Dear Org maintainers
>
> HTML export of equations leads to an error since my last update from
> MELPA, yesterday. I can trace it back to the invocation of
> org-element-context in a temporary buffer in fundamental mode. A more
> exact analysis follows.
>
> Emacs  : GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
>  of 2015-05-04 on dflt1w
> Package: Org-mode version 8.3.3 (8.3.3-17-gce80a0-elpaplus @
> /home/dfeich/.emacs.d/elpa/org-plus-contrib-20160118/)
>
>
> The error can be reproduced using a minimal org file with these contents:
>
> #+BEGIN_EXAMPLE
> * Equation export error
>
>   This equation produces an error on html export
>
>   $$
>     U = R \cdot I
>   $$
>
> #+END_EXAMPLE
>
> Upon export to html the following error and backtrace result (I took
> the liberty of cutting the lines to avoid special characters).
>
> #+BEGIN_EXAMPLE
> Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>   looking-at(nil)
>   byte-code("\212\214~\210...
>   org-element-context()
>   org-format-latex("" "" nil "Creating LaTeX Image..." nil mathjax)
>   org-html-format-latex("$$\n ...
>   org-html-latex-fragment((latex-fragment ...
>   org-export-data((latex-fragment ...
>   #[(element)...
>   mapconcat(#[(element)...
>   org-export-data((paragraph...
>   #[(element) "\302...
>   mapconcat(#[(element)...
>   org-export-data((section...
>   #[(element) "\302...
>   mapconcat(#[(element)...
>   org-export-data((headline...
>   #[(element) "\302...
>   mapconcat(#[(element) "\302...
>   org-export-data((org-data nil (headline (:raw-value "Equation export
> error" :begin 1 :end 108 :pre-blank 1 :contents-begin 26 :contents-end 104
> :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil
> :post-blank 2 :footnote-section-p nil :archivedp nil :commentedp nil
> :post-affiliated 1 :title (#("Equation export error" 0 21 (:parent #1)))
> :parent #0) (section (:begin 26 :end 108 :contents-begin 26 :contents-end
> 104 :post-blank 2 :post-affiliated 26 :parent #1) (paragraph (:begin 26
> :end 76 :contents-begin 26 :contents-end 75 :post-blank 1 :post-affiliated
> 26 :parent #2) #("This equation produces an error on html export\n" 0 47
> (:parent #3))) (paragraph (:begin 76 :end 104 :contents-begin 76
> :contents-end 104 :post-blank 0 :post-affiliated 76 :parent #2) ""
> (latex-fragment (:value "$$\n    U = R \\cdot I\n  $$" :begin 78 :end 103
> :post-blank 0 :parent #3)) #("\n" 0 1 (:parent #3)))))) (:export-options
> nil :input-buffer "err-example.org" :input-file "/tmp/html-exp-error/
> err-example.org" :html-doctype "xhtml-strict" :html-container "div"
> :description nil :keywords nil :html-html5-fancy nil :html-link-use-abs-url
> nil :html-link-home "" :html-link-up "" :html-mathjax "" :html-postamble
> auto :html-preamble t :html-head "" :html-head-extra "" :subtitle nil
> :html-head-include-default-style t :html-head-include-scripts t
> :html-allow-name-attribute-in-anchors nil :html-divs ((preamble "div"
> "preamble") (content "div" "content") (postamble "div" "postamble"))
> :html-checkbox-type ascii :html-extension "html" :html-footnote-format
> "<sup>%s</sup>" :html-footnote-separator "<sup>, </sup>" ...))
>   org-export-as(html nil nil nil (:output-file "./err-example.html"))
>   org-export-to-file(html "./err-example.html" nil nil nil nil nil)
>   org-html-export-to-html(nil nil nil nil)
>   org-export-dispatch(nil)
>   call-interactively(org-export-dispatch nil nil)
>   command-execute(org-export-dispatch)
> #+END_EXAMPLE
>
> From the debugger I can see that the org-element-context is executed in a
> temporary buffer:
>
> : Debugger Eval ((point)): 1
> : Debugger Eval (major-mode): fundamental-mode
> : Debugger Eval ((buffer-name)):  *temp*-831342
> : Debugger Eval ((buffer-string)): $$
> :     U = R \cdot I
> :   $$
>
>
> I can reproduce the error by creating a file and filling it with the
> contents
> that "buffer-string" yielded and opening it in fundamental mode.
> #+BEGIN_EXAMPLE
> $$
>     U = R \cdot I
> $$
> #+END_EXAMPLE
>
> When I now execute "org-element-context" with point at 1 then I get the
> same error:
>
> Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>   looking-at(nil)
>   byte-code("\212\214~\210...
>   org-element-context()
>   eval((org-element-context) nil)
>   eval-expression((org-element-context) nil)
>   call-interactively(eval-expression nil nil)
>   command-execute(eval-expression)
>
> If the buffer is set to org-mode, the error does not appear, and
> org-element-context
> correctly recognizes the text as a latex-fragment.
>
>
> Best regards,
> Derek
>
>

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