* lisp/progmodes/prolog.el: Replace by a whole new file.

lisp/ChangeLog

+2011-01-11  Stefan Bruda  <stefan@bruda.ca>
+
+	* progmodes/prolog.el: Replace by a whole new file.
+
 2011-01-11  Stefan Monnier  <monnier@iro.umontreal.ca>
 	* subr.el (eval-after-load): Fix timing for features (bug#7769).

lisp/progmodes/prolog.el

-;;; prolog.el --- major mode for editing and running Prolog under Emacs
+;; prolog.el --- major mode for editing and running Prolog (and Mercury) code
 
-;; Copyright (C) 1986, 1987, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
-;;   2008, 2009, 2010  Free Software Foundation, Inc.
+;; Copyright (C) 1986, 1987, 1997, 1998, 1999, 2002, 2003 Free Software Foundation, Inc.
 
-;; Author: Masanobu UMEDA <umerin@mse.kyutech.ac.jp>
-;; Keywords: languages
+;; Authors: Emil Åström <emil_astrom(at)hotmail(dot)com>
+;;          Milan Zamazal <pdm(at)freesoft(dot)cz>
+;;          Stefan Bruda <stefan(at)bruda(dot)ca>  (current maintainer)
+;;          * See below for more details
+;; Keywords: prolog major mode sicstus swi mercury
 
-;; This file is part of GNU Emacs.
+(defvar prolog-mode-version "1.22"
+  "Prolog mode version number")
 
-;; GNU Emacs is free software: you can redistribute it and/or modify
+;; 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.
+;; the Free Software Foundation; either version 2, or (at your option)
+;; any later version.
 
-;; GNU Emacs is distributed in the hope that it will be useful,
+;; 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+;; along with GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;; Original author: Masanobu UMEDA <umerin(at)mse(dot)kyutech(dot)ac(dot)jp>
+;; Parts of this file was taken from a modified version of the original
+;; by Johan Andersson, Peter Olin, Mats Carlsson, Johan Bevemyr, Stefan
+;; Andersson, and Per Danielsson (all SICS people), and Henrik Båkman
+;; at Uppsala University, Sweden.
+;;
+;; Some ideas and also a few lines of code have been borrowed (not stolen ;-)
+;; from Oz.el, the Emacs major mode for the Oz programming language,
+;; Copyright (C) 1993 DFKI GmbH, Germany, with permission.
+;; Authors: Ralf Scheidhauer and Michael Mehl ([scheidhr|mehl](at)dfki(dot)uni-sb(dot)de)
+;;
+;; More ideas and code have been taken from the SICStus debugger mode
+;; (http://www.csd.uu.se/~perm/source_debug/index.shtml -- broken link
+;; as of Mon May 5 08:23:48 EDT 2003) by Per Mildner.
+;;
+;; Additions for ECLiPSe and other helpful suggestions: Stephan Heuel
+;; <heuel(at)ipb(dot)uni-bonn(dot)de>
 
 ;;; Commentary:
+;;
+;; This package provides a major mode for editing Prolog code, with
+;; all the bells and whistles one would expect, including syntax
+;; highlighting and auto indentation.  It can also send regions to an
+;; inferior Prolog process.
+;;
+;; The code requires the comint, easymenu, info, imenu, and font-lock
+;; libraries. These are normally distributed with GNU Emacs and
+;; XEmacs.
+
+;;; Installation:
+;;
+;; Insert the following lines in your init file--typically ~/.emacs
+;; (GNU Emacs and XEmacs <21.4), or ~/.xemacs/init.el (XEmacs
+;; 21.4)--to use this mode when editing Prolog files under Emacs:
+;;
+;; (setq load-path (cons "/usr/lib/xemacs/site-lisp" load-path))
+;; (autoload 'run-prolog "prolog" "Start a Prolog sub-process." t)
+;; (autoload 'prolog-mode "prolog" "Major mode for editing Prolog programs." t)
+;; (autoload 'mercury-mode "prolog" "Major mode for editing Mercury programs." t)
+;; (setq prolog-system 'swi)  ; optional, the system you are using;
+;;                            ; see `prolog-system' below for possible values
+;; (setq auto-mode-alist (append '(("\\.pl$" . prolog-mode)
+;;                                 ("\\.m$" . mercury-mode))
+;;                                auto-mode-alist))
+;;
+;; where the path in the first line is the file system path to this file.
+;; MSDOS paths can be written like "d:/programs/emacs-19.34/site-lisp". 
+;; Note: In XEmacs, either `/usr/lib/xemacs/site-lisp' (RPM default in
+;; Red Hat-based distributions) or `/usr/local/lib/xemacs/site-lisp'
+;; (default when compiling from sources) are automatically added to
+;; `load-path', so the first line is not necessary provided that you
+;; put this file in the appropriate place.
+;;
+;; The last s-expression above makes sure that files ending with .pl
+;; are assumed to be Prolog files and not Perl, which is the default
+;; Emacs setting. If this is not wanted, remove this line. It is then
+;; necessary to either
+;;
+;;  o  insert in your Prolog files the following comment as the first line:
+;;
+;;       % -*- Mode: Prolog -*-
+;;
+;;     and then the file will be open in Prolog mode no matter its 
+;;     extension, or
+;;
+;;  o  manually switch to prolog mode after opening a Prolog file, by typing 
+;;     M-x prolog-mode.
+;;
+;; If the command to start the prolog process ('sicstus', 'pl' or
+;; 'swipl' for SWI prolog, etc.) is not available in the default path,
+;; then it is necessary to set the value of the environment variable
+;; EPROLOG to a shell command to invoke the prolog process.  In XEmacs
+;; and Emacs 20+ you can also customize the variable
+;; `prolog-program-name' (in the group `prolog-inferior') and provide
+;; a full path for your Prolog system (swi, scitus, etc.).
+;;
+;; Note: I (Stefan, the current maintainer) work under XEmacs.  Future
+;;   developments will thus be biased towards XEmacs (OK, I admit it,
+;;   I am biased towards XEmacs in general), though I will do my best
+;;   to keep the GNU Emacs compatibility.  So if you work under Emacs
+;;   and see something that does not work do drop me a line, as I have
+;;   a smaller chance to notice this kind of bugs otherwise.
 
-;; This package provides a major mode for editing Prolog.  It knows
-;; about Prolog syntax and comments, and can send regions to an inferior
-;; Prolog interpreter process.  Font locking is tuned towards GNU Prolog.
+;; Changelog:
 
+;; Version 1.22:
+;;  o  Allowed both 'swipl' and 'pl' as names for the SWI Prolog
+;;     interpreter.
+;;  o  Atoms that start a line are not blindly coloured as
+;;     predicates.  Instead we check that they are followed by ( or
+;;     :- first.  Patch suggested by Guy Wiener.
+;; Version 1.21:
+;;  o  Cleaned up the code that defines faces.  The missing face
+;;     warnings on some Emacsen should disappear.
+;; Version 1.20:
+;;  o  Improved the handling of clause start detection and multi-line
+;;     comments: `prolog-clause-start' no longer finds non-predicate
+;;     (e.g., capitalized strings) beginning of clauses.
+;;     `prolog-tokenize' recognizes when the end point is within a
+;;     multi-line comment.
+;; Version 1.19:
+;;  o  Minimal changes for Aquamacs inclusion and in general for
+;;     better coping with finding the Prolog executable.  Patch
+;;     provided by David Reitter 
+;; Version 1.18:
+;;  o  Fixed syntax highlighting for clause heads that do not begin at
+;;     the beginning of the line.
+;;  o  Fixed compilation warnings under Emacs.
+;;  o  Updated the email address of the current maintainer.
+;; Version 1.17:
+;;  o  Minor indentation fix (patch by Markus Triska)
+;;  o  `prolog-underscore-wordchar-flag' defaults now to nil (more
+;;     consistent to other Emacs modes)
+;; Version 1.16:
+;;  o  Eliminated a possible compilation warning.
+;; Version 1.15:
+;;  o  Introduced three new customizable variables: electric colon
+;;     (`prolog-electric-colon-flag', default nil), electric dash
+;;     (`prolog-electric-dash-flag', default nil), and a possibility
+;;     to prevent the predicate template insertion from adding commata
+;;     (`prolog-electric-dot-full-predicate-template', defaults to t
+;;     since it seems quicker to me to just type those commata).  A
+;;     trivial adaptation of a patch by Markus Triska.
+;;  o  Improved the behaviour of electric if-then-else to only skip
+;;     forward if the parenthesis/semicolon is preceded by
+;;     whitespace.  Once more a trivial adaptation of a patch by
+;;     Markus Triska.
+;; Version 1.14:
+;;  o  Cleaned up align code. `prolog-align-flag' is eliminated (since
+;;     on a second thought it does not do anything useful).  Added key
+;;     binding (C-c C-a) and menu entry for alignment.
+;;  o  Condensed regular expressions for lower and upper case
+;;     characters (GNU Emacs seems to go over the regexp length limit
+;;     with the original form).  My code on the matter was improved
+;;     considerably by Markus Triska.
+;;  o  Fixed `prolog-insert-spaces-after-paren' (which used an
+;;     unitialized variable).
+;;  o  Minor changes to clean up the code and avoid some implicit
+;;     package requirements.
+;; Version 1.13:
+;;  o  Removed the use of `map-char-table' in `prolog-build-case-strings'
+;;     which appears to cause prblems in (at least) Emacs 23.0.0.1.
+;;  o  Added if-then-else indentation + corresponding electric
+;;     characters.  New customization: `prolog-electric-if-then-else-flag'
+;;  o  Align support (requires `align').  New customization:
+;;     `prolog-align-flag'.
+;;  o  Temporary consult files have now the same name throughout the
+;;     session.  This prevents issues with reconsulting a buffer
+;;     (this event is no longer passed to Prolog as a request to
+;;     consult a new file).
+;;  o  Adaptive fill mode is now turned on.  Comment indentation is
+;;     still worse than it could be though, I am working on it.
+;;  o  Improved filling and auto-filling capabilities.  Now block
+;;     comments should be [auto-]filled correctly most of the time;
+;;     the following pattern in particular is worth noting as being
+;;     filled correctly:
+;;         <some code here> % some comment here that goes beyond the
+;;                          % rightmost column, possibly combined with
+;;                          % subsequent comment lines
+;;  o  `prolog-char-quote-workaround' now defaults to nil.
+;;  o  Note: Many of the above improvements have been suggested by
+;;     Markus Triska, who also provided useful patches on the matter
+;;     when he realized that I was slow in responding.  Many thanks.
+;; Version 1.11 / 1.12
+;;  o  GNU Emacs compatibility fix for paragraph filling (fixed
+;;     incorrectly in 1.11, fix fixed in 1.12).
+;; Version 1.10
+;;  o  Added paragraph filling in comment blocks and also correct auto
+;;     filling for comments.
+;;  o  Fixed the possible "Regular expression too big" error in
+;;     `prolog-electric-dot'.
+;; Version 1.9
+;;  o  Parenthesis expressions are now indented by default so that
+;;     components go one underneath the other, just as for compound
+;;     terms.  You can use the old style (the second and subsequent
+;;     lines being indented to the right in a parenthesis expression)
+;;     by setting the customizable variable `prolog-paren-indent-p'
+;;     (group "Prolog Indentation") to t.
+;;  o  (Somehow awkward) handling of the 0' character escape
+;;     sequence. I am looking into a better way of doing it but
+;;     prospects look bleak.  If this breaks things for you please let
+;;     me know and also set the `prolog-char-quote-workaround' (group
+;;     "Prolog Other") to nil.
+;; Version 1.8
+;;  o  Key binding fix.
+;; Version 1.7
+;;  o  Fixed a number of issues with the syntax of single quotes,
+;;     including Debian bug #324520.
+;; Version 1.6
+;;  o  Fixed mercury mode menu initialization (Debian bug #226121).
+;;  o  Fixed (i.e., eliminated) Delete remapping (Debian bug #229636).
+;;  o  Corrected indentation for clauses defining quoted atoms.
+;; Version 1.5:
+;;  o  Keywords fontifying should work in console mode so this is
+;;     enabled everywhere.
+;; Version 1.4:
+;;  o  Now supports GNU Prolog--minor adaptation of a patch by Stefan
+;;     Moeding.
+;; Version 1.3:
+;;  o  Info-follow-nearest-node now called correctly under Emacs too
+;;     (thanks to Nicolas Pelletier).  Should be implemented more
+;;     elegantly (i.e., without compilation warnings) in the future.
+;; Version 1.2:
+;;  o  Another prompt fix, still in SWI mode (people seem to have
+;;     changed the prompt of SWI Prolog).
+;; Version 1.1:
+;;  o  Fixed dots in the end of line comments causing indentation
+;;     problems.  The following code is now correctly indented (note
+;;     the dot terminating the comment):
+;;        a(X) :- b(X),                   
+;;            c(X).                  % comment here.
+;;        a(X).
+;;     and so is this (and variants):
+;;        a(X) :- b(X),                   
+;;            c(X).                  /* comment here. */
+;;        a(X).
+;; Version 1.0:
+;;  o  Revamped the menu system.
+;;  o  Yet another prompt recognition fix (SWI mode).
+;;  o  This is more of a renumbering than a new edition.  I promoted
+;;     the mode to version 1.0 to emphasize the fact that it is now
+;;     mature and stable enough to be considered production (in my
+;;     opinion anyway).
+;; Version 0.1.41:
+;;  o  GNU Emacs compatibility fixes.
+;; Version 0.1.40:
+;;  o  prolog-get-predspec is now suitable to be called as
+;;     imenu-extract-index-name-function.  The predicate index works.
+;;  o  Since imenu works now as advertised, prolog-imenu-flag is t
+;;     by default.
+;;  o  Eliminated prolog-create-predicate-index since the imenu
+;;     utilities now work well.  Actually, this function is also
+;;     buggy, and I see no reason to fix it since we do not need it
+;;     anyway.
+;;  o  Fixed prolog-pred-start, prolog-clause-start, prolog-clause-info.
+;;  o  Fix for prolog-build-case-strings; now prolog-upper-case-string
+;;     and prolog-lower-case-string are correctly initialized, 
+;;  o  Various font-lock changes; most importantly, block comments (/*
+;;     ... */) are now correctly fontified in XEmacs even when they
+;;     extend on multiple lines.
+;; Version 0.1.36: 
+;;  o  The debug prompt of SWI Prolog is now correctly recognized.
+;; Version 0.1.35: 
+;;  o  Minor font-lock bug fixes.
+
+
 ;;; Code:
 
-(defvar comint-prompt-regexp)
-(defvar comint-process-echoes)
-(require 'smie)
+(eval-when-compile
+  (require 'compile)
+  (require 'font-lock)
+  ;; We need imenu everywhere because of the predicate index!
+  (require 'imenu)
+  ;)
+  (require 'info)
+  (require 'shell)
+  )
+
+(require 'comint)
+(require 'easymenu)
+(require 'align)
+
 
 (defgroup prolog nil
-  "Major mode for editing and running Prolog under Emacs."
-  :link '(custom-group-link :tag "Font Lock Faces group" font-lock-faces)
+  "Major modes for editing and running Prolog and Mercury files."
   :group 'languages)
 
+(defgroup prolog-faces nil
+  "Prolog mode specific faces."
+  :group 'font-lock)
 
-(defcustom prolog-program-name
-  (let ((names '("prolog" "gprolog" "swipl")))
-    (while (and names
-		(not (executable-find (car names))))
-      (setq names (cdr names)))
-    (or (car names) "prolog"))
-  "Program name for invoking an inferior Prolog with `run-prolog'."
-  :type 'string
+(defgroup prolog-indentation nil
+  "Prolog mode indentation configuration."
   :group 'prolog)
 
-(defcustom prolog-consult-string "reconsult(user).\n"
-  "(Re)Consult mode (for C-Prolog and Quintus Prolog). "
-  :type 'string
+(defgroup prolog-font-lock nil
+  "Prolog mode font locking patterns."
   :group 'prolog)
 
-(defcustom prolog-compile-string "compile(user).\n"
-  "Compile mode (for Quintus Prolog)."
-  :type 'string
+(defgroup prolog-keyboard nil
+  "Prolog mode keyboard flags."
   :group 'prolog)
 
-(defcustom prolog-eof-string "end_of_file.\n"
-  "String that represents end of file for Prolog.
-When nil, send actual operating system end of file."
-  :type 'string
+(defgroup prolog-inferior nil
+  "Inferior Prolog mode options."
+  :group 'prolog)
+
+(defgroup prolog-other nil
+  "Other Prolog mode options."
   :group 'prolog)
 
-(defcustom prolog-indent-width 4
-  "Level of indentation in Prolog buffers."
-  :type 'integer
+
+;;-------------------------------------------------------------------
+;; User configurable variables
+;;-------------------------------------------------------------------
+
+;; General configuration
+
+(defcustom prolog-system nil
+  "*Prolog interpreter/compiler used.
+The value of this variable is nil or a symbol.
+If it is a symbol, it determines default values of other configuration
+variables with respect to properties of the specified Prolog
+interpreter/compiler.
+
+Currently recognized symbol values are:
+eclipse - Eclipse Prolog
+mercury - Mercury
+sicstus - SICStus Prolog
+swi     - SWI Prolog
+gnu     - GNU Prolog"
+  :group 'prolog
+  :type '(choice (const :tag "SICStus" :value sicstus)
+                 (const :tag "SWI Prolog" :value swi)
+                 (const :tag "Default" :value nil)))
+(make-variable-buffer-local 'prolog-system)
+
+;; NB: This alist can not be processed in prolog-mode-variables to
+;; create a prolog-system-version-i variable since it is needed
+;; prior to the call to prolog-mode-variables.
+(defcustom prolog-system-version
+  '((sicstus  (3 . 6))
+    (swi      (0 . 0))
+    (mercury  (0 . 0))
+    (eclipse  (3 . 7))
+    (gnu      (0 . 0)))
+  "*Alist of Prolog system versions.
+The version numbers are of the format (Major . Minor)."
   :group 'prolog)
 
-(defvar prolog-font-lock-keywords
-  '(("\\(#[<=]=>\\|:-\\)\\|\\(#=\\)\\|\\(#[#<>\\/][=\\/]*\\|!\\)"
-     0 font-lock-keyword-face)
-    ("\\<\\(is\\|write\\|nl\\|read_\\sw+\\)\\>"
-     1 font-lock-keyword-face)
-    ("^\\(\\sw+\\)\\s-*\\((\\(.+\\))\\)*"
-     (1 font-lock-function-name-face)
-     (3 font-lock-variable-name-face)))
-  "Font-lock keywords for Prolog mode.")
-
-(defvar prolog-mode-syntax-table
+;; Indentation
+
+(defcustom prolog-indent-width tab-width
+  "*The indentation width used by the editing buffer."
+  :group 'prolog-indentation
+  :type 'integer)  
+
+(defcustom prolog-align-comments-flag t
+  "*Non-nil means automatically align comments when indenting."
+  :group 'prolog-indentation
+  :type 'boolean)
+
+(defcustom prolog-indent-mline-comments-flag t
+  "*Non-nil means indent contents of /* */ comments.
+Otherwise leave such lines as they are."
+  :group 'prolog-indentation
+  :type 'boolean)
+
+(defcustom prolog-object-end-to-0-flag t
+  "*Non-nil means indent closing '}' in SICStus object definitions to level 0.
+Otherwise indent to `prolog-indent-width'."
+  :group 'prolog-indentation
+  :type 'boolean)
+
+(defcustom prolog-left-indent-regexp "\\(;\\|\\*?->\\)"
+  "*Regexp for character sequences after which next line is indented.
+Next line after such a regexp is indented to the opening paranthesis level."
+  :group 'prolog-indentation
+  :type 'regexp)
+
+(defcustom prolog-paren-indent-p nil
+  "*If non-nil, increase indentation for parenthesis expressions.
+The second and subsequent line in a parenthesis expression other than
+a compound term can either be indented `prolog-paren-indent' to the
+right (if this variable is non-nil) or in the same way as for compound
+terms (if this variable is nil, default)."
+  :group 'prolog-indentation
+  :type 'boolean)
+
+(defcustom prolog-paren-indent 4
+  "*The indentation increase for parenthesis expressions.
+Only used in ( If -> Then ; Else) and ( Disj1 ; Disj2 ) style expressions."
+  :group 'prolog-indentation
+  :type 'integer)
+
+(defcustom prolog-parse-mode 'beg-of-clause
+  "*The parse mode used (decides from which point parsing is done).
+Legal values:
+'beg-of-line   - starts parsing at the beginning of a line, unless the
+                 previous line ends with a backslash. Fast, but has
+                 problems detecting multiline /* */ comments.
+'beg-of-clause - starts parsing at the beginning of the current clause.
+                 Slow, but copes better with /* */ comments."
+  :group 'prolog-indentation
+  :type '(choice (const :value beg-of-line)
+                 (const :value beg-of-clause)))
+
+;; Font locking
+
+(defcustom prolog-keywords
+  '((eclipse
+     ("use_module" "begin_module" "module_interface" "dynamic"
+      "external" "export" "dbgcomp" "nodbgcomp" "compile"))
+    (mercury
+     ("all" "else" "end_module" "equality" "external" "fail" "func" "if"
+      "implementation" "import_module" "include_module" "inst" "instance"
+      "interface" "mode" "module" "not" "pragma" "pred" "some" "then" "true"
+      "type" "typeclass" "use_module" "where"))
+    (sicstus
+     ("block" "dynamic" "mode" "module" "multifile" "meta_predicate"
+      "parallel" "public" "sequential" "volatile"))
+    (swi
+     ("discontiguous" "dynamic" "ensure_loaded" "export" "export_list" "import"
+      "meta_predicate" "module" "module_transparent" "multifile" "require"
+      "use_module" "volatile"))
+    (gnu
+     ("built_in" "char_conversion" "discontiguous" "dynamic" "ensure_linked"
+      "ensure_loaded" "foreign" "include" "initialization" "multifile" "op"
+      "public" "set_prolog_flag"))
+    (t
+     ("dynamic" "module")))
+  "*Alist of Prolog keywords which is used for font locking of directives."
+  :group 'prolog-font-lock
+  :type 'sexp)
+
+(defcustom prolog-types
+  '((mercury
+     ("char" "float" "int" "io__state" "string" "univ"))
+    (t nil))
+  "*Alist of Prolog types used by font locking."
+  :group 'prolog-font-lock
+  :type 'sexp)
+
+(defcustom prolog-mode-specificators
+  '((mercury
+     ("bound" "di" "free" "ground" "in" "mdi" "mui" "muo" "out" "ui" "uo"))
+    (t nil))
+  "*Alist of Prolog mode specificators used by font locking."
+  :group 'prolog-font-lock
+  :type 'sexp)
+
+(defcustom prolog-determinism-specificators
+  '((mercury
+     ("cc_multi" "cc_nondet" "det" "erroneous" "failure" "multi" "nondet"
+      "semidet"))
+    (t nil))
+  "*Alist of Prolog determinism specificators used by font locking."
+  :group 'prolog-font-lock
+  :type 'sexp)
+
+(defcustom prolog-directives
+  '((mercury
+     ("^#[0-9]+"))
+    (t nil))
+  "*Alist of Prolog source code directives used by font locking."
+  :group 'prolog-font-lock
+  :type 'sexp)
+
+
+;; Keyboard
+
+(defcustom prolog-electric-newline-flag t
+  "*Non-nil means automatically indent the next line when the user types RET."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-hungry-delete-key-flag nil
+  "*Non-nil means delete key consumes all preceding spaces."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-electric-dot-flag nil
+  "*Non-nil means make dot key electric.
+Electric dot appends newline or inserts head of a new clause.
+If dot is pressed at the end of a line where at least one white space
+precedes the point, it inserts a recursive call to the current predicate.
+If dot is pressed at the beginning of an empty line, it inserts the head
+of a new clause for the current predicate. It does not apply in strings
+and comments. 
+It does not apply in strings and comments."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-electric-dot-full-predicate-template nil
+  "*If nil, electric dot inserts only the current predicate's name and `(' 
+for recursive calls or new clause heads. Non-nil means to also 
+insert enough commata to cover the predicate's arity and `)', 
+and dot and newline for recursive calls."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-electric-underscore-flag nil
+  "*Non-nil means make underscore key electric.
+Electric underscore replaces the current variable with underscore.
+If underscore is pressed not on a variable then it behaves as usual."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-electric-tab-flag nil
+  "*Non-nil means make TAB key electric.
+Electric TAB inserts spaces after parentheses, ->, and ;
+in ( If -> Then ; Else) and ( Disj1 ; Disj2 ) style expressions."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-electric-if-then-else-flag nil
+  "*Non-nil makes `(', `>' and `;' electric 
+to automatically indent if-then-else constructs."
+  :group 'prolog-keyboard
+  :type 'boolean)
+ 
+(defcustom prolog-electric-colon-flag nil
+  "*Makes `:' electric (inserts `:-' on a new line).
+If non-nil, pressing `:' at the end of a line that starts in 
+the first column (i.e., clause heads) inserts ` :-' and newline."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-electric-dash-flag nil
+  "*Makes `-' electric (inserts a `-->' on a new line).
+If non-nil, pressing `-' at the end of a line that starts in
+the first column (i.e., DCG heads) inserts ` -->' and newline."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+(defcustom prolog-old-sicstus-keys-flag nil
+  "*Non-nil means old SICStus Prolog mode keybindings are used."
+  :group 'prolog-keyboard
+  :type 'boolean)
+
+;; Inferior mode
+
+(defcustom prolog-program-name
+  `(((getenv "EPROLOG") (eval (getenv "EPROLOG")))
+    (eclipse "eclipse")
+    (mercury nil)
+    (sicstus "sicstus")
+    (swi ,(if (not (executable-find "swipl")) "pl" "swipl"))
+    (gnu "gprolog")
+    (t ,(let ((names '("prolog" "gprolog" "swipl" "pl")))
+ 	  (while (and names
+ 		      (not (executable-find (car names))))
+ 	    (setq names (cdr names)))
+ 	  (or (car names) "prolog"))))
+  "*Alist of program names for invoking an inferior Prolog with `run-prolog'."
+  :group 'prolog-inferior
+  :type 'sexp)
+
+(defcustom prolog-program-switches
+  '((sicstus ("-i"))
+    (t nil))
+  "*Alist of switches given to inferior Prolog run with `run-prolog'."
+  :group 'prolog-inferior
+  :type 'sexp)
+
+(defcustom prolog-consult-string
+  '((eclipse "[%f].")