;; proof-compat.el   Operating system and Emacs version compatibility
;;
;; Copyright (C) 2000-2010 LFCS Edinburgh.
;; Author:      David Aspinall <David.Aspinall@ed.ac.uk> and others
;; License:     GPL (GNU GENERAL PUBLIC LICENSE)
;;
;; $Id$
;;
;; This file collects together compatibility hacks for different
;; operating systems and Emacs versions.  This is to help keep
;; track of them.
;;
;; The development policy for Proof General (since v3.7) is for the
;; main codebase to be written for the latest stable version of
;; GNU Emacs, following GNU Emacs advice on obsolete function calls.
;;
;; Since Proof General 4.0, XEmacs is not supported at all.
;;

(eval-when-compile
  (require 'easymenu))

(require 'cl)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;
;;; Architecture flags
;;;

;; can use eval-and-compile to allow optimisation, but that would
;; require recompilation for Windows
(defvar proof-running-on-win32 (memq system-type '(win32 windows-nt cygwin))
  "Non-nil if Proof General is running on a windows variant system.")


;; Workaround a small bug in Carbon Emacs Winter 2008 (at least)
;; Menu presses query this variable, but it's not bound unless
;; mode engaged.  Not noticeable in normal use, but it is as soon
;; as debug-on-error is engaged.
(with-no-warnings
  (if (and (boundp 'carbon-emacs-package-version)
	   (not (boundp 'mac-key-mode)))
      (setq mac-key-mode nil)))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;
;;; Modifications and adjustments
;;;

;; Remove a custom setting.  Needed to support dynamic reconfiguration.
;; (We'd prefer that repeated defcustom calls acted like repeated
;;  "defvar treated as defconst" in XEmacs)
(defun pg-custom-undeclare-variable (symbol)
  "Remove a custom setting SYMBOL.
Done by `makunbound' and removing all properties mentioned by custom library."
  (mapc (lambda (prop) (remprop symbol prop))
	  '(default
	     standard-value
	     force-value
	     variable-comment
	     saved-variable-comment
	     variable-documentation
	     group-documentation
	     custom-set
	     custom-get
	     custom-options
	     custom-requests
	     custom-group
	     custom-prefix
	     custom-tag
	     custom-links
	     custom-version
	     saved-value
	     theme-value
	     theme-face))
  (makunbound symbol))


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;
;;; GNU Emacs compatibility with XEmacs
;;;

(unless (fboundp 'save-selected-frame)
(defmacro save-selected-frame (&rest body)
  "Execute forms in BODY, then restore the selected frame.
The value returned is the value of the last form in BODY."
  (let ((old-frame (gensym "ssf")))
    `(let ((,old-frame (selected-frame)))
       (unwind-protect
	   (progn ,@body)
	 (select-frame ,old-frame))))))

;; These functions are used in the intricate logic around
;; shrink-to-fit.

;; window-leftmost-p, window-rightmost-p: my implementations
(or (fboundp 'window-leftmost-p)
    (defun window-leftmost-p (window)
      (zerop (car (window-edges window)))))

(or (fboundp 'window-rightmost-p)
    (defun window-rightmost-p (window)
      (>= (nth 2 (window-edges window))
	  (frame-width (window-frame window)))))

(or (fboundp 'window-bottom-p)
    (defun window-bottom-p (window)
      (>= (nth 3 (window-edges window))
	  (frame-height (window-frame window)))))

;; find-coding-system emulation for GNU Emacs
(unless (fboundp 'find-coding-system)
  (defun find-coding-system (name)
    "Retrieve the coding system of the given name, or nil if non-such."
    (condition-case nil
	(check-coding-system name)
      (error nil))))


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;
;;; A naughty hack to completion.el
;;;
;;; At the moment IMO completion too eagerly adds stuff to
;;; its database: the completion-before-command function
;;; makes every suffix be added as a completion!

(eval-after-load "completion"
'(defun completion-before-command ()
  (if (and (symbolp this-command) (get this-command 'completion-function))
	(funcall (get this-command 'completion-function)))))


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;
;;; Backward compatibility for Emacs 22
;;;

(or (fboundp 'characterp)
    (defun characterp (obj)
      (with-no-warnings (char-valid-p obj))))


(or (fboundp 'declare-function)
;; taken from Emacs 22.2, not present in 22.1:
(defmacro declare-function (&rest args)
  "In Emacs 22, does nothing.  In 23, it will suppress byte-compiler warnings.
This definition is so that packages may take advantage of the
Emacs 23 feature and still remain compatible with Emacs 22."
  nil))

;; End of proof-compat.el
(provide 'proof-compat)