python-mode.el

;;; python-mode.el --- Major mode for editing Python programs

;; Copyright (C) 1992,1993,1994  Tim Peters

;; Author: 1995-1998 Barry A. Warsaw
;;         1992-1994 Tim Peters
;; Maintainer: python-mode@python.org
;; Created:    Feb 1992
;; Keywords:   python languages oop

(defconst py-version "$Revision$"
  "`python-mode' version number.")

;; This software is provided as-is, without express or implied
;; warranty.  Permission to use, copy, modify, distribute or sell this
;; software, without fee, for any purpose and by any individual or
;; organization, is hereby granted, provided that the above copyright
;; notice and this paragraph appear in all copies.

;;; Commentary:

;; This is a major mode for editing Python programs.  It was developed
;; by Tim Peters after an original idea by Michael A. Guravage.  Tim
;; subsequently left the net; in 1995, Barry Warsaw inherited the mode
;; and is the current maintainer.  Tim's now back but disavows all
;; responsibility for the mode.  Smart Tim :-)

;; This version of python-mode.el is no longer compatible with Emacs
;; 18.  I am striving to maintain compatibility with the X/Emacs 19
;; lineage but as time goes on that becomes more and more difficult.
;; I current recommend that you upgrade to the latest stable released
;; version of your favorite branch: Emacs 20.3 or better, or XEmacs
;; 20.4 or better (XEmacs 21.0 is in beta testing as of this writing
;; 27-Oct-1998 appears to work fine with this version of
;; python-mode.el).  Even Windows users should be using at least
;; NTEmacs 20.3, and XEmacs 21.0 will work very nicely on Windows when
;; it is released.

;; FOR MORE INFORMATION:

;; For more information on installing python-mode.el, especially with
;; respect to compatibility information, please see
;;
;;     http://www.python.org/emacs/python-mode/
;;
;; This site also contains links to other packages that you might find 
;; useful, such as pdb interfaces, OO-Browser links, etc.

;; BUG REPORTING:

;; To submit bug reports, use C-c C-b.  Please include a complete, but
;; concise code sample and a recipe for reproducing the bug.  Send
;; suggestions and other comments to python-mode@python.org.

;; When in a Python mode buffer, do a C-h m for more help.  It's
;; doubtful that a texinfo manual would be very useful, but if you
;; want to contribute one, I'll certainly accept it!

;; TO DO LIST:

;; - Better integration with pdb.py and gud-mode for debugging.
;; - Rewrite according to GNU Emacs Lisp standards.
;; - have py-execute-region on indented code act as if the region is
;;   left justified.  Avoids syntax errors.
;; - add a py-goto-block-down, bound to C-c C-d

;;; Code:

(require 'comint)
(require 'custom)
(eval-when-compile
  (require 'cl)
  (if (not (and (condition-case nil
		    (require 'custom)
		  (error nil))
		;; Stock Emacs 19.34 has a broken/old Custom library
		;; that does more harm than good.  Fortunately, it is
		;; missing defcustom
		(fboundp 'defcustom)))
      (error "STOP! STOP! STOP! STOP!

The Custom library was not found or is out of date.  A more current
version is required.  Please download and install the latest version
of the Custom library from:

    <http://www.dina.kvl.dk/~abraham/custom/>

See the Python Mode home page for details:

    <http://www.python.org/emacs/python-mode>
")))



;; user definable variables
;; vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

(defgroup python nil
  "Support for the Python programming language, <http://www.python.org/>"
  :group 'languages
  :prefix "py-")

(defcustom py-python-command "python"
  "*Shell command used to start Python interpreter."
  :type 'string
  :group 'python)

(defcustom py-jpython-command "jpython"
  "*Shell command used to start the JPython interpreter."
  :type 'string
  :group 'python
  :tag "JPython Command")

(defcustom py-default-interpreter 'cpython
  "*Which Python interpreter is used by default.
The value for this variable can be either `cpython' or `jpython'.

When the value is `cpython', the variables `py-python-command' and
`py-python-command-args' are consulted to determine the interpreter
and arguments to use.

When the value is `jpython', the variables `py-jpython-command' and
`py-jpython-command-args' are consulted to determine the interpreter
and arguments to use.

Note that this variable is consulted only the first time that a Python
mode buffer is visited during an Emacs session.  After that, use
\\[py-toggle-shells] to change the interpreter shell."
  :type '(choice (const :tag "Python (a.k.a. CPython)" cpython)
		 (const :tag "JPython" jpython))
  :group 'python)

(defcustom py-python-command-args '("-i")
  "*List of string arguments to be used when starting a Python shell."
  :type '(repeat string)
  :group 'python)

(defcustom py-jpython-command-args '("-i")
  "*List of string arguments to be used when starting a JPython shell."
  :type '(repeat string)
  :group 'python
  :tag "JPython Command Args")

(defcustom py-indent-offset 4
  "*Amount of offset per level of indentation.
`\\[py-guess-indent-offset]' can usually guess a good value when
you're editing someone else's Python code."
  :type 'integer
  :group 'python)

(defcustom py-smart-indentation t
  "*Should `python-mode' try to automagically set some indentation variables?
When this variable is non-nil, two things happen when a buffer is set
to `python-mode':

    1. `py-indent-offset' is guessed from existing code in the buffer.
       Only guessed values between 2 and 8 are considered.  If a valid
       guess can't be made (perhaps because you are visiting a new
       file), then the value in `py-indent-offset' is used.

    2. `indent-tabs-mode' is turned off if `py-indent-offset' does not
       equal `tab-width' (`indent-tabs-mode' is never turned on by
       Python mode).  This means that for newly written code, tabs are
       only inserted in indentation if one tab is one indentation
       level, otherwise only spaces are used.

Note that both these settings occur *after* `python-mode-hook' is run,
so if you want to defeat the automagic configuration, you must also
set `py-smart-indentation' to nil in your `python-mode-hook'."
  :type 'boolean
  :group 'python)

(defcustom py-align-multiline-strings-p t
  "*Flag describing how multi-line triple quoted strings are aligned.
When this flag is non-nil, continuation lines are lined up under the
preceding line's indentation.  When this flag is nil, continuation
lines are aligned to column zero."
  :type '(choice (const :tag "Align under preceding line" t)
		 (const :tag "Align to column zero" nil))
  :group 'python)

(defcustom py-block-comment-prefix "##"
  "*String used by \\[comment-region] to comment out a block of code.
This should follow the convention for non-indenting comment lines so
that the indentation commands won't get confused (i.e., the string
should be of the form `#x...' where `x' is not a blank or a tab, and
`...' is arbitrary).  However, this string should not end in whitespace."
  :type 'string
  :group 'python)

(defcustom py-honor-comment-indentation t
  "*Controls how comment lines influence subsequent indentation.

When nil, all comment lines are skipped for indentation purposes, and
if possible, a faster algorithm is used (i.e. X/Emacs 19 and beyond).

When t, lines that begin with a single `#' are a hint to subsequent
line indentation.  If the previous line is such a comment line (as
opposed to one that starts with `py-block-comment-prefix'), then its
indentation is used as a hint for this line's indentation.  Lines that
begin with `py-block-comment-prefix' are ignored for indentation
purposes.

When not nil or t, comment lines that begin with a `#' are used as
indentation hints, unless the comment character is in column zero."
  :type '(choice
	  (const :tag "Skip all comment lines (fast)" nil)
	  (const :tag "Single # `sets' indentation for next line" t)
	  (const :tag "Single # `sets' indentation except at column zero"
		 other)
	  )
  :group 'python)

(defcustom py-temp-directory
  (let ((ok '(lambda (x)
	       (and x
		    (setq x (expand-file-name x)) ; always true
		    (file-directory-p x)
		    (file-writable-p x)
		    x))))
    (or (funcall ok (getenv "TMPDIR"))
	(funcall ok "/usr/tmp")
	(funcall ok "/tmp")
	(funcall ok  ".")
	(error
	 "Couldn't find a usable temp directory -- set `py-temp-directory'")))
  "*Directory used for temp files created by a *Python* process.
By default, the first directory from this list that exists and that you
can write into:  the value (if any) of the environment variable TMPDIR,
/usr/tmp, /tmp, or the current directory."
  :type 'string
  :group 'python)

(defcustom py-beep-if-tab-change t
  "*Ring the bell if `tab-width' is changed.
If a comment of the form

  \t# vi:set tabsize=<number>:

is found before the first code line when the file is entered, and the
current value of (the general Emacs variable) `tab-width' does not
equal <number>, `tab-width' is set to <number>, a message saying so is
displayed in the echo area, and if `py-beep-if-tab-change' is non-nil
the Emacs bell is also rung as a warning."
  :type 'boolean
  :group 'python)

(defcustom py-jump-on-exception t
  "*Jump to innermost exception frame in *Python Output* buffer.
When this variable is non-nil and an exception occurs when running
Python code synchronously in a subprocess, jump immediately to the
source code of the innermost traceback frame."
  :type 'boolean
  :group 'python)

(defcustom py-ask-about-save t
  "If not nil, ask about which buffers to save before executing some code.
Otherwise, all modified buffers are saved without asking."
  :type 'boolean
  :group 'python)

(defcustom py-backspace-function 'backward-delete-char-untabify
  "*Function called by `py-electric-backspace' when deleting backwards."
  :type 'function
  :group 'python)

(defcustom py-delete-function 'delete-char
  "*Function called by `py-electric-delete' when deleting forwards."
  :type 'function
  :group 'python)

(defcustom py-imenu-show-method-args-p nil 
  "*Controls echoing of arguments of functions & methods in the Imenu buffer.
When non-nil, arguments are printed."
  :type 'boolean
  :group 'python)
(make-variable-buffer-local 'py-indent-offset)

;; Not customizable
(defvar py-master-file nil
  "If non-nil, execute the named file instead of the buffer's file.
The intent is to allow you to set this variable in the file's local
variable section, e.g.:

    # Local Variables:
    # py-master-file: \"master.py\"
    # End:

so that typing \\[py-execute-buffer] in that buffer executes the named
master file instead of the buffer's file.  If the file name has a
relative path, the value of variable `default-directory' for the
buffer is prepended to come up with a file name.")
(make-variable-buffer-local 'py-master-file)



;; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
;; NO USER DEFINABLE VARIABLES BEYOND THIS POINT

(defconst py-emacs-features
  (let (features)
   ;; NTEmacs 19.34.6 has a broken make-temp-name; it always returns
   ;; the same string.
   (let ((tmp1 (make-temp-name ""))
	 (tmp2 (make-temp-name "")))
     (if (string-equal tmp1 tmp2)
	 (push 'broken-temp-names features)))
   ;; return the features
   features)
  "A list of features extant in the Emacs you are using.
There are many flavors of Emacs out there, with different levels of
support for features needed by `python-mode'.")

(defvar python-font-lock-keywords
  (let ((kw1 (mapconcat 'identity
			'("and"      "assert"   "break"   "class"
			  "continue" "def"      "del"     "elif"
			  "else"     "except"   "exec"    "for"
			  "from"     "global"   "if"      "import"
			  "in"       "is"       "lambda"  "not"
			  "or"       "pass"     "print"   "raise"
			  "return"   "while"
			  )
			"\\|"))
	(kw2 (mapconcat 'identity
			'("else:" "except:" "finally:" "try:")
			"\\|"))
	)
    (list
     ;; keywords
     (cons (concat "\\b\\(" kw1 "\\)\\b[ \n\t(]") 1)
     ;; block introducing keywords with immediately following colons.
     ;; Yes "except" is in both lists.
     (cons (concat "\\b\\(" kw2 "\\)[ \n\t(]") 1)
     ;; classes
     '("\\bclass[ \t]+\\([a-zA-Z_]+[a-zA-Z0-9_]*\\)"
       1 font-lock-type-face)
     ;; functions
     '("\\bdef[ \t]+\\([a-zA-Z_]+[a-zA-Z0-9_]*\\)"
       1 font-lock-function-name-face)
     ))
  "Additional expressions to highlight in Python mode.")
(put 'python-mode 'font-lock-defaults '(python-font-lock-keywords))

;; have to bind py-file-queue before installing the kill-emacs-hook
(defvar py-file-queue nil
  "Queue of Python temp files awaiting execution.
Currently-active file is at the head of the list.")


;; Constants

(defconst py-stringlit-re
  (concat
   ;; These fail if backslash-quote ends the string (not worth
   ;; fixing?).  They precede the short versions so that the first two
   ;; quotes don't look like an empty short string.
   ;;
   ;; (maybe raw), long single quoted triple quoted strings (SQTQ),
   ;; with potential embedded single quotes
   "[rR]?'''[^']*\\(\\('[^']\\|''[^']\\)[^']*\\)*'''"
   "\\|"
   ;; (maybe raw), long double quoted triple quoted strings (DQTQ),
   ;; with potential embedded double quotes
   "[rR]?\"\"\"[^\"]*\\(\\(\"[^\"]\\|\"\"[^\"]\\)[^\"]*\\)*\"\"\""
   "\\|"
   "[rR]?'\\([^'\n\\]\\|\\\\.\\)*'"	; single-quoted
   "\\|"				; or
   "[rR]?\"\\([^\"\n\\]\\|\\\\.\\)*\""	; double-quoted
   )
  "Regular expression matching a Python string literal.")

(defconst py-continued-re
  ;; This is tricky because a trailing backslash does not mean
  ;; continuation if it's in a comment
  (concat
   "\\(" "[^#'\"\n\\]" "\\|" py-stringlit-re "\\)*"
   "\\\\$")
  "Regular expression matching Python backslash continuation lines.")
  
(defconst py-blank-or-comment-re "[ \t]*\\($\\|#\\)"
  "Regular expression matching a blank or comment line.")

(defconst py-outdent-re
  (concat "\\(" (mapconcat 'identity
			   '("else:"
			     "except\\(\\s +.*\\)?:"
			     "finally:"
			     "elif\\s +.*:")
			   "\\|")
	  "\\)")
  "Regular expression matching statements to be dedented one level.")
  
(defconst py-block-closing-keywords-re
  "\\(return\\|raise\\|break\\|continue\\|pass\\)"
  "Regular expression matching keywords which typically close a block.")

(defconst py-no-outdent-re
  (concat
   "\\("
   (mapconcat 'identity
	      (list "try:"
		    "except\\(\\s +.*\\)?:"
		    "while\\s +.*:"
		    "for\\s +.*:"
		    "if\\s +.*:"
		    "elif\\s +.*:"
		    (concat py-block-closing-keywords-re "[ \t\n]")
		    )
	      "\\|")
	  "\\)")
  "Regular expression matching lines not to dedent after.")

(defconst py-defun-start-re
  "^\\([ \t]*\\)def[ \t]+\\([a-zA-Z_0-9]+\\)\\|\\(^[a-zA-Z_0-9]+\\)[ \t]*="
  ;; If you change this, you probably have to change py-current-defun
  ;; as well.  This is only used by py-current-defun to find the name
  ;; for add-log.el.
  "Regular expression matching a function, method, or variable assignment.")

(defconst py-class-start-re "^class[ \t]*\\([a-zA-Z_0-9]+\\)"
  ;; If you change this, you probably have to change py-current-defun
  ;; as well.  This is only used by py-current-defun to find the name
  ;; for add-log.el.
  "Regular expression for finding a class name.")

(defconst py-traceback-line-re
  "[ \t]+File \"\\([^\"]+\\)\", line \\([0-9]+\\)"
  "Regular expression that describes tracebacks.")



;; Major mode boilerplate

;; define a mode-specific abbrev table for those who use such things
(defvar python-mode-abbrev-table nil
  "Abbrev table in use in `python-mode' buffers.")
(define-abbrev-table 'python-mode-abbrev-table nil)

(defvar python-mode-hook nil
  "*Hook called by `python-mode'.")

;; In previous version of python-mode.el, the hook was incorrectly
;; called py-mode-hook, and was not defvar'd.  Deprecate its use.
(and (fboundp 'make-obsolete-variable)
     (make-obsolete-variable 'py-mode-hook 'python-mode-hook))

(defvar py-mode-map ()
  "Keymap used in `python-mode' buffers.")
(if py-mode-map
    nil
  (setq py-mode-map (make-sparse-keymap))
  ;; electric keys
  (define-key py-mode-map ":" 'py-electric-colon)
  ;; indentation level modifiers
  (define-key py-mode-map "\C-c\C-l"  'py-shift-region-left)
  (define-key py-mode-map "\C-c\C-r"  'py-shift-region-right)
  (define-key py-mode-map "\C-c<"     'py-shift-region-left)
  (define-key py-mode-map "\C-c>"     'py-shift-region-right)
  ;; subprocess commands
  (define-key py-mode-map "\C-c\C-c"  'py-execute-buffer)
  (define-key py-mode-map "\C-c\C-m"  'py-execute-import-or-reload)
  (define-key py-mode-map "\C-c\C-s"  'py-execute-string)
  (define-key py-mode-map "\C-c|"     'py-execute-region)
  (define-key py-mode-map "\e\C-x"    'py-execute-def-or-class)
  (define-key py-mode-map "\C-c!"     'py-shell)
  (define-key py-mode-map "\C-c\C-t"  'py-toggle-shells)
  ;; Caution!  Enter here at your own risk.  We are trying to support
  ;; several behaviors and it gets disgusting. :-( This logic ripped
  ;; largely from CC Mode.
  ;;
  ;; In XEmacs 19, Emacs 19, and Emacs 20, we use this to bind
  ;; backwards deletion behavior to DEL, which both Delete and
  ;; Backspace get translated to.  There's no way to separate this
  ;; behavior in a clean way, so deal with it!  Besides, it's been
  ;; this way since the dawn of time.
  (if (not (boundp 'delete-key-deletes-forward))
      (define-key py-mode-map "\177" 'py-electric-backspace)
    ;; However, XEmacs 20 actually achieved enlightenment.  It is
    ;; possible to sanely define both backward and forward deletion
    ;; behavior under X separately (TTYs are forever beyond hope, but
    ;; who cares?  XEmacs 20 does the right thing with these too).
    (define-key py-mode-map [delete]    'py-electric-delete)
    (define-key py-mode-map [backspace] 'py-electric-backspace))
  ;; Separate M-BS from C-M-h.  The former should remain
  ;; backward-kill-word.
  (define-key py-mode-map [(control meta h)] 'py-mark-def-or-class)
  (define-key py-mode-map "\C-c\C-k"  'py-mark-block)
  ;; Miscellaneous
  (define-key py-mode-map "\C-c:"     'py-guess-indent-offset)
  (define-key py-mode-map "\C-c\t"    'py-indent-region)
  (define-key py-mode-map "\C-c\C-n"  'py-next-statement)
  (define-key py-mode-map "\C-c\C-p"  'py-previous-statement)
  (define-key py-mode-map "\C-c\C-u"  'py-goto-block-up)
  (define-key py-mode-map "\C-c#"     'py-comment-region)
  (define-key py-mode-map "\C-c?"     'py-describe-mode)
  (define-key py-mode-map "\C-c\C-hm" 'py-describe-mode)
  (define-key py-mode-map "\e\C-a"    'py-beginning-of-def-or-class)
  (define-key py-mode-map "\e\C-e"    'py-end-of-def-or-class)
  (define-key py-mode-map "\C-c-"     'py-up-exception)
  (define-key py-mode-map "\C-c="     'py-down-exception)
  ;; stuff that is `standard' but doesn't interface well with
  ;; python-mode, which forces us to rebind to special commands
  (define-key py-mode-map "\C-xnd"    'py-narrow-to-defun)
  ;; information
  (define-key py-mode-map "\C-c\C-b" 'py-submit-bug-report)
  (define-key py-mode-map "\C-c\C-v" 'py-version)
  ;; shadow global bindings for newline-and-indent w/ the py- version.
  ;; BAW - this is extremely bad form, but I'm not going to change it
  ;; for now.
  (mapcar #'(lambda (key)
	      (define-key py-mode-map key 'py-newline-and-indent))
	  (where-is-internal 'newline-and-indent))
  ;; Force RET to be py-newline-and-indent even if it didn't get
  ;; mapped by the above code.  motivation: Emacs' default binding for
  ;; RET is `newline' and C-j is `newline-and-indent'.  Most Pythoneers
  ;; expect RET to do a `py-newline-and-indent' and any Emacsers who
  ;; dislike this are probably knowledgeable enough to do a rebind.
  ;; However, we do *not* change C-j since many Emacsers have already
  ;; swapped RET and C-j and they don't want C-j bound to `newline' to 
  ;; change.
  (define-key py-mode-map "\C-m" 'py-newline-and-indent)
  )

(defvar py-mode-output-map nil
  "Keymap used in *Python Output* buffers.")
(if py-mode-output-map
    nil
  (setq py-mode-output-map (make-sparse-keymap))
  (define-key py-mode-output-map [button2]  'py-mouseto-exception)
  (define-key py-mode-output-map "\C-c\C-c" 'py-goto-exception)
  ;; TBD: Disable all self-inserting keys.  This is bogus, we should
  ;; really implement this as *Python Output* buffer being read-only
  (mapcar #' (lambda (key)
	       (define-key py-mode-output-map key
		 #'(lambda () (interactive) (beep))))
	     (where-is-internal 'self-insert-command))
  )

(defvar py-shell-map nil
  "Keymap used in *Python* shell buffers.")
(if py-shell-map
    nil
  (setq py-shell-map (copy-keymap comint-mode-map))
  (define-key py-shell-map [tab]   'tab-to-tab-stop)
  (define-key py-shell-map "\C-c-" 'py-up-exception)
  (define-key py-shell-map "\C-c=" 'py-down-exception)
  )

(defvar py-mode-syntax-table nil
  "Syntax table used in `python-mode' buffers.")
(if py-mode-syntax-table
    nil
  (setq py-mode-syntax-table (make-syntax-table))
  (modify-syntax-entry ?\( "()" py-mode-syntax-table)
  (modify-syntax-entry ?\) ")(" py-mode-syntax-table)
  (modify-syntax-entry ?\[ "(]" py-mode-syntax-table)
  (modify-syntax-entry ?\] ")[" py-mode-syntax-table)
  (modify-syntax-entry ?\{ "(}" py-mode-syntax-table)
  (modify-syntax-entry ?\} "){" py-mode-syntax-table)
  ;; Add operator symbols misassigned in the std table
  (modify-syntax-entry ?\$ "."  py-mode-syntax-table)
  (modify-syntax-entry ?\% "."  py-mode-syntax-table)
  (modify-syntax-entry ?\& "."  py-mode-syntax-table)
  (modify-syntax-entry ?\* "."  py-mode-syntax-table)
  (modify-syntax-entry ?\+ "."  py-mode-syntax-table)
  (modify-syntax-entry ?\- "."  py-mode-syntax-table)
  (modify-syntax-entry ?\/ "."  py-mode-syntax-table)
  (modify-syntax-entry ?\< "."  py-mode-syntax-table)
  (modify-syntax-entry ?\= "."  py-mode-syntax-table)
  (modify-syntax-entry ?\> "."  py-mode-syntax-table)
  (modify-syntax-entry ?\| "."  py-mode-syntax-table)
  ;; For historical reasons, underscore is word class instead of
  ;; symbol class.  GNU conventions say it should be symbol class, but
  ;; there's a natural conflict between what major mode authors want
  ;; and what users expect from `forward-word' and `backward-word'.
  ;; Guido and I have hashed this out and have decided to keep
  ;; underscore in word class.  If you're tempted to change it, try
  ;; binding M-f and M-b to py-forward-into-nomenclature and
  ;; py-backward-into-nomenclature instead.  This doesn't help in all
  ;; situations where you'd want the different behavior
  ;; (e.g. backward-kill-word).
  (modify-syntax-entry ?\_ "w"  py-mode-syntax-table)
  ;; Both single quote and double quote are string delimiters
  (modify-syntax-entry ?\' "\"" py-mode-syntax-table)
  (modify-syntax-entry ?\" "\"" py-mode-syntax-table)
  ;; backquote is open and close paren
  (modify-syntax-entry ?\` "$"  py-mode-syntax-table)
  ;; comment delimiters
  (modify-syntax-entry ?\# "<"  py-mode-syntax-table)
  (modify-syntax-entry ?\n ">"  py-mode-syntax-table)
  )



;; Utilities

(defmacro py-safe (&rest body)
  "Safely execute BODY, return nil if an error occurred."
  (` (condition-case nil
	 (progn (,@ body))
       (error nil))))

(defsubst py-keep-region-active ()
  "Keep the region active in XEmacs."
  ;; Ignore byte-compiler warnings you might see.  Also note that
  ;; FSF's Emacs 19 does it differently; its policy doesn't require us
  ;; to take explicit action.
  (and (boundp 'zmacs-region-stays)
       (setq zmacs-region-stays t)))

(defsubst py-point (position)
  "Returns the value of point at certain commonly referenced POSITIONs.
POSITION can be one of the following symbols:

  bol  -- beginning of line
  eol  -- end of line
  bod  -- beginning of def or class
  eod  -- end of def or class
  bob  -- beginning of buffer
  eob  -- end of buffer
  boi  -- back to indentation
  bos  -- beginning of statement

This function does not modify point or mark."
  (let ((here (point)))
    (cond
     ((eq position 'bol) (beginning-of-line))
     ((eq position 'eol) (end-of-line))
     ((eq position 'bod) (py-beginning-of-def-or-class))
     ((eq position 'eod) (py-end-of-def-or-class))
     ;; Kind of funny, I know, but useful for py-up-exception.
     ((eq position 'bob) (beginning-of-buffer))
     ((eq position 'eob) (end-of-buffer))
     ((eq position 'boi) (back-to-indentation))
     ((eq position 'bos) (py-goto-initial-line))
     (t (error "Unknown buffer position requested: %s" position))
     )
    (prog1
	(point)
      (goto-char here))))

(defsubst py-highlight-line (from to file line)
  (cond
   ((fboundp 'make-extent)
    ;; XEmacs
    (let ((e (make-extent from to)))
      (set-extent-property e 'mouse-face 'highlight)
      (set-extent-property e 'py-exc-info (cons file line))
      (set-extent-property e 'keymap py-mode-output-map)))
   (t
    ;; Emacs -- Please port this!
    )
   ))

(defun py-in-literal (&optional lim)
  "Return non-nil if point is in a Python literal (a comment or string).
Optional argument LIM indicates the beginning of the containing form,
i.e. the limit on how far back to scan."
  ;; This is the version used for non-XEmacs, which has a nicer
  ;; interface.
  ;;
  ;; WARNING: Watch out for infinite recursion.
  (let* ((lim (or lim (py-point 'bod)))
	 (state (parse-partial-sexp lim (point))))
    (cond
     ((nth 3 state) 'string)
     ((nth 4 state) 'comment)
     (t nil))))

;; XEmacs has a built-in function that should make this much quicker.
;; In this case, lim is ignored
(defun py-fast-in-literal (&optional lim)
  "Fast version of `py-in-literal', used only by XEmacs.
Optional LIM is ignored."
  ;; don't have to worry about context == 'block-comment
  (buffer-syntactic-context))

(if (fboundp 'buffer-syntactic-context)
    (defalias 'py-in-literal 'py-fast-in-literal))



;; Menu definitions, only relevent if you have the easymenu.el package
;; (standard in the latest Emacs 19 and XEmacs 19 distributions).
(defvar py-menu nil
  "Menu for Python Mode.
This menu will get created automatically if you have the `easymenu'
package.  Note that the latest X/Emacs releases contain this package.")

(and (py-safe (require 'easymenu) t)
     (easy-menu-define
      py-menu py-mode-map "Python Mode menu"
      '("Python"
	["Comment Out Region"   py-comment-region  (mark)]
	["Uncomment Region"     (py-comment-region (point) (mark) '(4)) (mark)]
	"-"
	["Mark current block"   py-mark-block t]
	["Mark current def"     py-mark-def-or-class t]
	["Mark current class"   (py-mark-def-or-class t) t]
	"-"
	["Shift region left"    py-shift-region-left (mark)]
	["Shift region right"   py-shift-region-right (mark)]
	"-"
	["Import/reload file"   py-execute-import-or-reload t]
	["Execute buffer"       py-execute-buffer t]
	["Execute region"       py-execute-region (mark)]
	["Execute def or class" py-execute-def-or-class (mark)]
	["Execute string"       py-execute-string t]
	["Start interpreter..." py-shell t]
	"-"
	["Go to start of block" py-goto-block-up t]
	["Go to start of class" (py-beginning-of-def-or-class t) t]
	["Move to end of class" (py-end-of-def-or-class t) t]
	["Move to start of def" py-beginning-of-def-or-class t]
	["Move to end of def"   py-end-of-def-or-class t]
	"-"
	["Describe mode"        py-describe-mode t]
	)))



;; Imenu definitions
(defvar py-imenu-class-regexp
  (concat				; <<classes>>
   "\\("				;
   "^[ \t]*"				; newline and maybe whitespace
   "\\(class[ \t]+[a-zA-Z0-9_]+\\)"	; class name
					; possibly multiple superclasses
   "\\([ \t]*\\((\\([a-zA-Z0-9_,. \t\n]\\)*)\\)?\\)"
   "[ \t]*:"				; and the final :
   "\\)"				; >>classes<<
   )
  "Regexp for Python classes for use with the Imenu package."
  )

(defvar py-imenu-method-regexp
  (concat                               ; <<methods and functions>>
   "\\("                                ; 
   "^[ \t]*"                            ; new line and maybe whitespace
   "\\(def[ \t]+"                       ; function definitions start with def
   "\\([a-zA-Z0-9_]+\\)"                ;   name is here
					;   function arguments...
;;   "[ \t]*(\\([-+/a-zA-Z0-9_=,\* \t\n.()\"'#]*\\))"
   "[ \t]*(\\([^:#]*\\))"
   "\\)"                                ; end of def
   "[ \t]*:"                            ; and then the :
   "\\)"                                ; >>methods and functions<<
   )
  "Regexp for Python methods/functions for use with the Imenu package."
  )

(defvar py-imenu-method-no-arg-parens '(2 8)
  "Indices into groups of the Python regexp for use with Imenu.

Using these values will result in smaller Imenu lists, as arguments to
functions are not listed.

See the variable `py-imenu-show-method-args-p' for more
information.")

(defvar py-imenu-method-arg-parens '(2 7)
  "Indices into groups of the Python regexp for use with imenu.
Using these values will result in large Imenu lists, as arguments to
functions are listed.

See the variable `py-imenu-show-method-args-p' for more
information.")

;; Note that in this format, this variable can still be used with the
;; imenu--generic-function. Otherwise, there is no real reason to have
;; it.
(defvar py-imenu-generic-expression
  (cons
   (concat 
    py-imenu-class-regexp
    "\\|"				; or...
    py-imenu-method-regexp
    )
   py-imenu-method-no-arg-parens)
  "Generic Python expression which may be used directly with Imenu.
Used by setting the variable `imenu-generic-expression' to this value.
Also, see the function \\[py-imenu-create-index] for a better
alternative for finding the index.")

;; These next two variables are used when searching for the Python
;; class/definitions. Just saving some time in accessing the
;; generic-python-expression, really.
(defvar py-imenu-generic-regexp nil)
(defvar py-imenu-generic-parens nil)


(defun py-imenu-create-index-function ()
  "Python interface function for the Imenu package.
Finds all Python classes and functions/methods. Calls function
\\[py-imenu-create-index-engine].  See that function for the details
of how this works."
  (setq py-imenu-generic-regexp (car py-imenu-generic-expression)
	py-imenu-generic-parens (if py-imenu-show-method-args-p
				    py-imenu-method-arg-parens
				  py-imenu-method-no-arg-parens))
  (goto-char (point-min))
  ;; Warning: When the buffer has no classes or functions, this will
  ;; return nil, which seems proper according to the Imenu API, but
  ;; causes an error in the XEmacs port of Imenu.  Sigh.
  (py-imenu-create-index-engine nil))

(defun py-imenu-create-index-engine (&optional start-indent)
  "Function for finding Imenu definitions in Python.

Finds all definitions (classes, methods, or functions) in a Python
file for the Imenu package.

Returns a possibly nested alist of the form

	(INDEX-NAME . INDEX-POSITION)

The second element of the alist may be an alist, producing a nested
list as in

	(INDEX-NAME . INDEX-ALIST)

This function should not be called directly, as it calls itself
recursively and requires some setup.  Rather this is the engine for
the function \\[py-imenu-create-index-function].

It works recursively by looking for all definitions at the current
indention level.  When it finds one, it adds it to the alist.  If it
finds a definition at a greater indentation level, it removes the
previous definition from the alist. In its place it adds all
definitions found at the next indentation level.  When it finds a
definition that is less indented then the current level, it returns
the alist it has created thus far.

The optional argument START-INDENT indicates the starting indentation
at which to continue looking for Python classes, methods, or
functions.  If this is not supplied, the function uses the indentation
of the first definition found."
  (let (index-alist
	sub-method-alist
	looking-p
	def-name prev-name
	cur-indent def-pos
	(class-paren (first  py-imenu-generic-parens)) 
	(def-paren   (second py-imenu-generic-parens)))
    (setq looking-p
	  (re-search-forward py-imenu-generic-regexp (point-max) t))
    (while looking-p
      (save-excursion
	;; used to set def-name to this value but generic-extract-name
	;; is new to imenu-1.14. this way it still works with
	;; imenu-1.11
	;;(imenu--generic-extract-name py-imenu-generic-parens))
	(let ((cur-paren (if (match-beginning class-paren)
			     class-paren def-paren)))
	  (setq def-name
		(buffer-substring-no-properties (match-beginning cur-paren)
						(match-end cur-paren))))
	(save-match-data
	  (py-beginning-of-def-or-class 'either))
	(beginning-of-line)
	(setq cur-indent (current-indentation)))
      ;; HACK: want to go to the next correct definition location.  We
      ;; explicitly list them here but it would be better to have them
      ;; in a list.
      (setq def-pos
	    (or (match-beginning class-paren)
		(match-beginning def-paren)))
      ;; if we don't have a starting indent level, take this one
      (or start-indent
	  (setq start-indent cur-indent))
      ;; if we don't have class name yet, take this one
      (or prev-name
	  (setq prev-name def-name))
      ;; what level is the next definition on?  must be same, deeper
      ;; or shallower indentation
      (cond
       ;; at the same indent level, add it to the list...
       ((= start-indent cur-indent)
	(push (cons def-name def-pos) index-alist))
       ;; deeper indented expression, recurse
       ((< start-indent cur-indent)
	;; the point is currently on the expression we're supposed to
	;; start on, so go back to the last expression. The recursive
	;; call will find this place again and add it to the correct
	;; list
	(re-search-backward py-imenu-generic-regexp (point-min) 'move)
	(setq sub-method-alist (py-imenu-create-index-engine cur-indent))
	(if sub-method-alist
	    ;; we put the last element on the index-alist on the start
	    ;; of the submethod alist so the user can still get to it.
	    (let ((save-elmt (pop index-alist)))
	      (push (cons prev-name
			  (cons save-elmt sub-method-alist))
		    index-alist))))
       ;; found less indented expression, we're done.
       (t 
	(setq looking-p nil)
	(re-search-backward py-imenu-generic-regexp (point-min) t)))
      ;; end-cond
      (setq prev-name def-name)
      (and looking-p
	   (setq looking-p
		 (re-search-forward py-imenu-generic-regexp
				    (point-max) 'move))))
    (nreverse index-alist)))


;;;###autoload
(defun python-mode ()
  "Major mode for editing Python files.
To submit a problem report, enter `\\[py-submit-bug-report]' from a
`python-mode' buffer.  Do `\\[py-describe-mode]' for detailed
documentation.  To see what version of `python-mode' you are running,
enter `\\[py-version]'.

This mode knows about Python indentation, tokens, comments and
continuation lines.  Paragraphs are separated by blank lines only.

COMMANDS
\\{py-mode-map}
VARIABLES

py-indent-offset\t\tindentation increment
py-block-comment-prefix\t\tcomment string used by `comment-region'
py-python-command\t\tshell command to invoke Python interpreter
py-temp-directory\t\tdirectory used for temp files (if needed)
py-beep-if-tab-change\t\tring the bell if `tab-width' is changed"
  (interactive)
  ;; set up local variables
  (kill-all-local-variables)
  (make-local-variable 'font-lock-defaults)
  (make-local-variable 'paragraph-separate)
  (make-local-variable 'paragraph-start)
  (make-local-variable 'require-final-newline)
  (make-local-variable 'comment-start)
  (make-local-variable 'comment-end)
  (make-local-variable 'comment-start-skip)
  (make-local-variable 'comment-column)
  (make-local-variable 'comment-indent-function)
  (make-local-variable 'indent-region-function)
  (make-local-variable 'indent-line-function)
  (make-local-variable 'add-log-current-defun-function)
  ;;
  (set-syntax-table py-mode-syntax-table)
  (setq major-mode              'python-mode
	mode-name               "Python"
	local-abbrev-table      python-mode-abbrev-table
	font-lock-defaults      '(python-font-lock-keywords)
	paragraph-separate      "^[ \t]*$"
	paragraph-start         "^[ \t]*$"
	require-final-newline   t
	comment-start           "# "
	comment-end             ""
	comment-start-skip      "# *"
	comment-column          40
	comment-indent-function 'py-comment-indent-function
	indent-region-function  'py-indent-region
	indent-line-function    'py-indent-line
	;; tell add-log.el how to find the current function/method/variable
	add-log-current-defun-function 'py-current-defun
	)
  (use-local-map py-mode-map)
  ;; add the menu
  (if py-menu
      (easy-menu-add py-menu))
  ;; Emacs 19 requires this
  (if (boundp 'comment-multi-line)
      (setq comment-multi-line nil))
  ;; Install Imenu if available
  (when (py-safe (require 'imenu))
    (setq imenu-create-index-function #'py-imenu-create-index-function)
    (setq imenu-generic-expression py-imenu-generic-expression)
    (if (fboundp 'imenu-add-to-menubar)
	(imenu-add-to-menubar (format "%s-%s" "IM" mode-name)))
    )
  ;; Run the mode hook.  Note that py-mode-hook is deprecated.
  (if python-mode-hook
      (run-hooks 'python-mode-hook)
    (run-hooks 'py-mode-hook))
  ;; Now do the automagical guessing
  (if py-smart-indentation
    (let ((offset py-indent-offset))
      ;; It's okay if this fails to guess a good value
      (if (and (py-safe (py-guess-indent-offset))
	       (<= py-indent-offset 8)
	       (>= py-indent-offset 2))
	  (setq offset py-indent-offset))
      (setq py-indent-offset offset)
      ;; Only turn indent-tabs-mode off if tab-width !=
      ;; py-indent-offset.  Never turn it on, because the user must
      ;; have explicitly turned it off.
      (if (/= tab-width py-indent-offset)
	  (setq indent-tabs-mode nil))
      ))
  ;; Set the default shell if not already set
  (when (null py-which-shell)
    (py-toggle-shells py-default-interpreter))
  )