[elpa] externals/auctex 4d9b411 08/10: Check engine before running LaTeX command.

[Tassilo Horn]

branch: externals/auctex
commit 4d9b411216083d4aa3529d65af00adf27c8dee16
Author: Mosè Giordano <address@hidden>
Commit: Tassilo Horn <address@hidden>

    Check engine before running LaTeX command.
    
    * tex-buf.el (TeX-check-engine): New customizable variable.
    (TeX-check-engine-list): New variable.
    (TeX-check-engine-add-engines): New function.
    (TeX-check-engine): New function.
    (TeX-command): Use `TeX-check-engine' and update docstring
    accordingly.
    
    * style/fontspec.el ("fontspec"): Add engine restrictions.
    
    * doc/auctex.texi (Processor Options): Document
    `TeX-check-engine'.
    
    * doc/changes.texi: Mention `TeX-check-engine'.
---
 ChangeLog         |   16 +++++++++
 doc/auctex.texi   |   14 ++++++++
 doc/changes.texi  |    5 +++
 style/fontspec.el |    1 +
 tex-buf.el        |   97 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 132 insertions(+), 1 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c3acdb1..e52c015 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2015-08-21  Mos� Giordano  <address@hidden>
+
+       * tex-buf.el (TeX-check-engine): New customizable variable.
+       (TeX-check-engine-list): New variable.
+       (TeX-check-engine-add-engines): New function.
+       (TeX-check-engine): New function.
+       (TeX-command): Use `TeX-check-engine' and update docstring
+       accordingly.
+
+       * style/fontspec.el ("fontspec"): Add engine restrictions.
+
+       * doc/auctex.texi (Processor Options): Document
+       `TeX-check-engine'.
+
+       * doc/changes.texi: Mention `TeX-check-engine'.
+
 2015-08-20  Mos� Giordano  <address@hidden>
 
        * tex-buf.el (TeX-error-overview-jump-to-source)
diff --git a/doc/auctex.texi b/doc/auctex.texi
index 09935c9..141afff 100644
--- a/doc/auctex.texi
+++ b/doc/auctex.texi
@@ -2950,6 +2950,20 @@ command can either be a variable or a string.  An empty 
string or nil
 means there is no command available.
 @end defopt
 
+Some @LaTeX{} packages requires the document to be compiled with a
+specific engine.  Notably examples are fontspec and polyglossia
+packages, which require address@hidden and address@hidden engines.  If you try 
to
+compile a document which loads one of such packages and the set engine
+is not one of those allowed you will be asked to select a different
+engine before running the @LaTeX{} command.  If you do not want to be
+warned by @AUCTeX{} in these cases, customize the option
address@hidden
+
address@hidden TeX-check-engine
+This boolean option controls whether @AUCTeX{} should check the correct
+engine has been set before running @LaTeX{} commands.
address@hidden defopt
+
 As shown above, @AUCTeX{} handles in a special way most of the main
 options that can be given to the @TeX{} processors.  When you need to
 pass to the @TeX{} processor arbitrary options not handled by @AUCTeX{},
diff --git a/doc/changes.texi b/doc/changes.texi
index 1dd552d..2178387 100644
--- a/doc/changes.texi
+++ b/doc/changes.texi
@@ -34,6 +34,11 @@ Indent @samp{\[...\]} math mode as a regular environment by 
default.
 @item
 @code{TeX-view-program-list} can contain, as third optional element of
 each item, the name of the executable(s) needed to open the viewer.
+
address@hidden
+When new option @code{TeX-check-engine} is non-nil, before running
address@hidden commands @AUCTeX{} will check whether the correct engine has
+been set, based upon known restrictions posed by @LaTeX{} packages.
 @end itemize
 
 @heading News in 11.88
diff --git a/style/fontspec.el b/style/fontspec.el
index 144b976..5ec7bb4 100644
--- a/style/fontspec.el
+++ b/style/fontspec.el
@@ -166,6 +166,7 @@ to retrieve the list of fonts."
 (TeX-add-style-hook
  "fontspec"
  (lambda ()
+   (TeX-check-engine-add-engines 'luatex 'xetex)
    (TeX-run-style-hooks "expl3" "xparse")
    (TeX-add-symbols
     ;; Font selection
diff --git a/tex-buf.el b/tex-buf.el
index cdd5fe2..3be47d7 100644
--- a/tex-buf.el
+++ b/tex-buf.el
@@ -332,6 +332,96 @@ This works only with TeX commands and if the
 (defconst TeX-error-overview-buffer-name "*TeX errors*"
   "Name of the buffer in which to show error list.")
 
+(defcustom TeX-check-engine t
+  "Whether AUCTeX should check the correct engine has been set before running 
LaTeX commands."
+  :group 'TeX-command
+  :type 'boolean)
+
+(defvar TeX-check-engine-list '(default luatex omega xetex)
+  "List of engines required by the loaded TeX packages.
+
+Do not set this variable directly, use
+`TeX-check-engine-add-engines' to specify required engines.")
+(make-variable-buffer-local 'TeX-check-engine-list)
+
+(defun TeX-check-engine-add-engines (&rest engines)
+  "Add ENGINES to list of required engines.
+
+Set `TeX-check-engine-list' to the intersection between the list
+itself and the list of provided engines.
+
+See for example style/fontspec.el"
+  (let ((list TeX-check-engine-list)
+       (res nil))
+    (setq TeX-check-engine-list
+         ;; The following is based on the definition of `cl-intersection' of
+         ;; GNU Emacs.
+         (and list engines
+              (if (equal list engines) list
+                (or (>= (length list) (length engines))
+                    (setq list (prog1 engines (setq engines list))))
+                (while engines
+                  (if (memq (car engines) list)
+                      (push (car engines) res))
+                  (pop engines))
+                res)))))
+
+(defun TeX-check-engine (name)
+  "Check the correct engine has been set.
+
+Look into `TeX-check-engine-list' for the required engines.
+
+NAME is the command to be run.  Actually do the check only if the
+variable `TeX-check-engine' is non-nil and LaTeX is the command
+to be run."
+  (and
+   (string= name "LaTeX")
+   TeX-check-engine
+   TeX-check-engine-list
+   (null (memq TeX-engine TeX-check-engine-list))
+   (memq TeX-engine '(default luatex omega xetex))
+   ;; The set engine is not listed in `TeX-check-engine-list'.  We check only
+   ;; builtin engines because we can't take care of custom ones.  Do nothing if
+   ;; there is no allowed engine, we don't know what to do in that case.
+   (let ((length (length TeX-check-engine-list))
+        (name-alist '((default . "TeX")
+                      (luatex  . "LuaTeX")
+                      (omega   . "Omega")
+                      (xetex   . "XeTeX")))
+        (completion-ignore-case t)
+        (engine nil))
+     (when
+        (cond
+         ;; There is exactly one allowed engine.
+         ((= length 1)
+          (setq engine (car TeX-check-engine-list))
+          (y-or-n-p (format "%s is required to build this document.
+Do you want to use this engine?" (cdr (assoc engine name-alist)))))
+         ;; More than one engine is allowed.
+         ((> length 1)
+          (if (y-or-n-p (format "%s are required to build this document.
+Do you want to select one of these engines?"
+                                (mapconcat
+                                 (lambda (elt) (cdr (assoc elt name-alist)))
+                                 TeX-check-engine-list ", ")))
+              (setq engine
+                    (car (rassoc
+                          (completing-read
+                           (format
+                            "Choose between %s: "
+                            (mapconcat
+                             (lambda (elt) (cdr (assoc elt name-alist)))
+                             TeX-check-engine-list ", "))
+                           (mapcar
+                            (lambda (elt) (cdr (assoc elt name-alist)))
+                            TeX-check-engine-list))
+                          name-alist))))))
+       (TeX-engine-set engine)
+       (when (and (fboundp 'add-file-local-variable)
+                 (y-or-n-p "Do you want to remember the choice?"))
+        (add-file-local-variable 'TeX-engine engine)
+        (save-buffer))))))
+
 (defun TeX-command (name file &optional override-confirm)
   "Run command NAME on the file returned by calling FILE.
 
@@ -343,7 +433,12 @@ Use the information in `TeX-command-list' to determine how 
to run
 the command.
 
 If OVERRIDE-CONFIRM is a prefix argument, confirmation will be
-asked if it is positive, and suppressed if it is not."
+asked if it is positive, and suppressed if it is not.
+
+Run function `TeX-check-engine' to check the correct engine has
+been set."
+  (TeX-check-engine name)
+
   (cond ((eq file 'TeX-region-file)
         (setq TeX-current-process-region-p t))
        ((eq file 'TeX-master-file)