Brute-foce the dependencies on undo-tree and px for emacs-25.

At least until I can figure out why 25.1 breaks here and not elsewhere.

.travis.yml

@@ -33,7 +33,7 @@ matrix:
       env: EVM_EMACS=emacs-25.1-travis IPYTHON=5.8.0
     - dist: xenial
       python: 3.6
-      env: EVM_EMACS=emacs-26.3-travis-linux-xenial IPYTHON=6.5.0
+      env: EVM_EMACS=emacs-26.1-travis-linux-xenial IPYTHON=6.5.0
     - dist: xenial
       python: 3.7
       env: EVM_EMACS=emacs-26.3-travis-linux-xenial IPYTHON=7.8.0

Cask

@@ -23,8 +23,10 @@
  (depends-on "polymode" "0.2")
  (depends-on "markdown-mode" "2.3")
  (depends-on "julia-mode") ;; See https://github.com/JuliaEditorSupport/julia-emacs/issues/46
- (depends-on "undo-tree") ;; Specifying a version breaks emacs 25 environment.
  (depends-on "ess" "18.10.2")
- ;; (depends-on "px") ;; Not in melpa stable
  (depends-on "f" "0.20.0")
  (depends-on "s" "1.12.0"))
+
+
+;; (depends-on "px") ;; Not in melpa stable
+;; (depends-on "undo-tree") ;; Specifying emacs 25 environment.

lisp/px.el

@@ -0,0 +1,150 @@
+;;; px.el --- preview inline latex in any mode
+
+;; Copyright (C) 2014 Aurélien Aptel <aurelien.aptel@gmail.com>
+;; Copyright (C) 2013 Rüdiger Sonderfeld <ruediger@c-plusplus.de>
+
+;; Author: Aurélien Aptel <aurelien.aptel@gmail.com>
+;; URL: http://github.com/aaptel/preview-latex
+;; Version: 1.1
+
+
+;;; Commentary:
+
+;; Provides functions to preview LaTeX codes like $x^2$ in any
+;; buffer/mode.
+
+;; Use `px-preview-region' to preview LaTeX codes delimited by $ pairs
+;; in the region.
+;; Use `px-preview' to process the whole buffer.
+;; Use `px-remove' to remove all images and restore the text back.
+;; Use `px-toggle' to toggle between images and text on the whole
+;; buffer.
+
+;; Most of this code comes from weechat-latex.el which in turn uses
+;; org-mode previewer.
+
+
+;;; License:
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'org)
+
+(defvar px-temp-file-prefix "px-"
+  "Prefix for temporary files.")
+
+(defvar px-temp-directory-prefix "px-"
+  "Prefix for temporary directory.")
+
+(defvar px-image-program org-latex-create-formula-image-program
+  "Program to convert LaTeX fragments.
+See `org-latex-create-formula-image-program'")
+
+(defvar px-temp-dir nil
+  "The temporary directory used for preview images.")
+
+(defvar px--active nil)
+(make-variable-buffer-local 'px--active)
+
+(defun px--create-preview (&optional beg end)
+  "Wrapper for `org-format-latex'.
+The parameter AT should be nil or in (TYPE . POINT) format.  With TYPE being a
+string showing the matched LaTeX statement (e.g., ``$'') and POINT being the
+POINT to replace.  If AT is nil replace statements everywhere."
+  (if (version< "9" org-version)
+      (org-format-latex px-temp-file-prefix
+                        beg end
+                        temporary-file-directory
+                        'overlays
+                        "Creating images...%s"
+                        'forbuffer
+                        px-image-program)
+    (condition-case e
+        (org-format-latex px-temp-file-prefix
+                          px-temp-dir
+                          'overlays
+                          "Creating images...%s"
+                          (if beg (cons "$" beg) nil)
+                          'forbuffer
+                          px-image-program)
+
+      ;; if wrong arity, try with one less argument (cf. issue #1)
+      (wrong-number-of-arguments
+       (org-format-latex px-temp-file-prefix
+                         px-temp-dir
+                         'overlays
+                         "Creating images...%s"
+                         'forbuffer
+                         px-image-program)))))
+
+
+(defun px--set-temp-dir ()
+  "Set `px-temp-dir' unless it is already set."
+  (unless px-temp-dir
+    (setq px-temp-dir
+          (make-temp-file px-temp-directory-prefix
+                          'directory))))
+
+;;;###autoload
+(defun px-preview ()
+  "Preview LaTeX fragments in the current buffer."
+  (interactive)
+  (save-excursion
+    (let ((inhibit-read-only t))
+      (px--set-temp-dir)
+      (px-remove)
+      (px--create-preview)
+      (setq px--active t))))
+
+;;;###autoload
+(defun px-preview-region (beg end)
+  "Preview LaTeX fragments in region."
+  (interactive "r")
+  (let* ((math-regex (assoc "$" org-latex-regexps))
+         (regex (nth 1 math-regex))
+         (n (nth 2 math-regex))
+         matches)
+    (save-excursion
+      (goto-char beg)
+      (while (re-search-forward regex end t)
+        (setq matches (cons (cons (match-beginning n) (match-end n)) matches)))
+      (let ((inhibit-read-only t))
+        (px--set-temp-dir)
+        (dolist (i matches)
+          (px--create-preview i))))))
+
+;;;###autoload
+(defun px-remove ()
+  "Remove LaTeX preview images in current buffer."
+  (interactive)
+  (let ((inhibit-read-only t))
+    (if (version< "9" org-version)
+        (delete-all-overlays)
+      (org-remove-latex-fragment-image-overlays)))
+  (setq px--active nil))
+
+;;;###autoload
+(defun px-toggle ()
+  "Toggle display of LaTeX preview in the current buffer."
+  (interactive)
+  (if px--active
+      (px-remove)
+    (px-preview)))
+
+
+(provide 'px)
+
+;;; px.el ends here