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;;; python.el --- silly walks for Python  -*- coding: iso-8859-1 -*-
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;; Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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;;   Free Software Foundation, Inc.
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;; Author: Dave Love <fx@gnu.org>
;; Maintainer: FSF
;; Created: Nov 2003
;; Keywords: languages

;; This file is part of GNU Emacs.

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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
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;; GNU Emacs 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
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;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:

;; Major mode for editing Python, with support for inferior processes.

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;; There is another Python mode, python-mode.el:
;; http://launchpad.net/python-mode
;; used by XEmacs, and originally maintained with Python.
;; That isn't covered by an FSF copyright assignment (?), unlike this
;; code, and seems not to be well-maintained for Emacs (though I've
;; submitted fixes).  This mode is rather simpler and is better in
;; other ways.  In particular, using the syntax functions with text
;; properties maintained by font-lock makes it more correct with
;; arbitrary string and comment contents.
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;; This doesn't implement all the facilities of python-mode.el.  Some
;; just need doing, e.g. catching exceptions in the inferior Python
;; buffer (but see M-x pdb for debugging).  [Actually, the use of
;; `compilation-shell-minor-mode' now is probably enough for that.]
;; Others don't seem appropriate.  For instance,
;; `forward-into-nomenclature' should be done separately, since it's
;; not specific to Python, and I've installed a minor mode to do the
;; job properly in Emacs 23.  [CC mode 5.31 contains an incompatible
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;; feature, `subword-mode' which is intended to have a similar
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;; effect, but actually only affects word-oriented keybindings.]

;; Other things seem more natural or canonical here, e.g. the
;; {beginning,end}-of-defun implementation dealing with nested
;; definitions, and the inferior mode following `cmuscheme'.  (The
;; inferior mode can find the source of errors from
;; `python-send-region' & al via `compilation-shell-minor-mode'.)
;; There is (limited) symbol completion using lookup in Python and
;; Eldoc support also using the inferior process.  Successive TABs
;; cycle between possible indentations for the line.

;; Even where it has similar facilities, this mode is incompatible
;; with python-mode.el in some respects.  For instance, various key
;; bindings are changed to obey Emacs conventions.

;; TODO: See various Fixmes below.

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;; Fixme: This doesn't support (the nascent) Python 3 .

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;;; Code:

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(require 'comint)

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(eval-when-compile
  (require 'compile)
  (require 'hippie-exp))

(autoload 'comint-mode "comint")

(defgroup python nil
  "Silly walks in the Python language."
  :group 'languages
  :version "22.1"
  :link '(emacs-commentary-link "python"))

;;;###autoload
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(add-to-list 'interpreter-mode-alist (cons (purecopy "jython") 'jython-mode))
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;;;###autoload
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(add-to-list 'interpreter-mode-alist (cons (purecopy "python") 'python-mode))
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;;;###autoload
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(add-to-list 'auto-mode-alist (cons (purecopy "\\.py\\'")  'python-mode))
(add-to-list 'same-window-buffer-names (purecopy "*Python*"))
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;;;; Font lock

(defvar python-font-lock-keywords
  `(,(rx symbol-start
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	 ;; From v 2.7 reference, § keywords.
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	 ;; def and class dealt with separately below
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	 (or "and" "as" "assert" "break" "continue" "del" "elif" "else"
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	     "except" "exec" "finally" "for" "from" "global" "if"
	     "import" "in" "is" "lambda" "not" "or" "pass" "print"
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	     "raise" "return" "try" "while" "with" "yield"
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             ;; Not real keywords, but close enough to be fontified as such
             "self" "True" "False")
	 symbol-end)
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    (,(rx symbol-start "None" symbol-end)	; see § Keywords in 2.7 manual
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     . font-lock-constant-face)
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    ;; Definitions
    (,(rx symbol-start (group "class") (1+ space) (group (1+ (or word ?_))))
     (1 font-lock-keyword-face) (2 font-lock-type-face))
    (,(rx symbol-start (group "def") (1+ space) (group (1+ (or word ?_))))
     (1 font-lock-keyword-face) (2 font-lock-function-name-face))
    ;; Top-level assignments are worth highlighting.
    (,(rx line-start (group (1+ (or word ?_))) (0+ space) "=")
     (1 font-lock-variable-name-face))
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    ;; Decorators.
    (,(rx line-start (* (any " \t")) (group "@" (1+ (or word ?_))
					    (0+ "." (1+ (or word ?_)))))
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     (1 font-lock-type-face))
    ;; Built-ins.  (The next three blocks are from
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    ;; `__builtin__.__dict__.keys()' in Python 2.7)  These patterns
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    ;; are debateable, but they at least help to spot possible
    ;; shadowing of builtins.
    (,(rx symbol-start (or
	  ;; exceptions
	  "ArithmeticError" "AssertionError" "AttributeError"
	  "BaseException" "DeprecationWarning" "EOFError"
	  "EnvironmentError" "Exception" "FloatingPointError"
	  "FutureWarning" "GeneratorExit" "IOError" "ImportError"
	  "ImportWarning" "IndentationError" "IndexError" "KeyError"
	  "KeyboardInterrupt" "LookupError" "MemoryError" "NameError"
	  "NotImplemented" "NotImplementedError" "OSError"
	  "OverflowError" "PendingDeprecationWarning" "ReferenceError"
	  "RuntimeError" "RuntimeWarning" "StandardError"
	  "StopIteration" "SyntaxError" "SyntaxWarning" "SystemError"
	  "SystemExit" "TabError" "TypeError" "UnboundLocalError"
	  "UnicodeDecodeError" "UnicodeEncodeError" "UnicodeError"
	  "UnicodeTranslateError" "UnicodeWarning" "UserWarning"
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	  "ValueError" "Warning" "ZeroDivisionError"
	  ;; Python 2.7
	  "BufferError" "BytesWarning" "WindowsError") symbol-end)
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     . font-lock-type-face)
    (,(rx (or line-start (not (any ". \t"))) (* (any " \t")) symbol-start
	  (group (or
	  ;; callable built-ins, fontified when not appearing as
	  ;; object attributes
	  "abs" "all" "any" "apply" "basestring" "bool" "buffer" "callable"
	  "chr" "classmethod" "cmp" "coerce" "compile" "complex"
	  "copyright" "credits" "delattr" "dict" "dir" "divmod"
	  "enumerate" "eval" "execfile" "exit" "file" "filter" "float"
	  "frozenset" "getattr" "globals" "hasattr" "hash" "help"
	  "hex" "id" "input" "int" "intern" "isinstance" "issubclass"
	  "iter" "len" "license" "list" "locals" "long" "map" "max"
	  "min" "object" "oct" "open" "ord" "pow" "property" "quit"
	  "range" "raw_input" "reduce" "reload" "repr" "reversed"
	  "round" "set" "setattr" "slice" "sorted" "staticmethod"
	  "str" "sum" "super" "tuple" "type" "unichr" "unicode" "vars"
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	  "xrange" "zip"
	  ;; Python 2.7.
	  "bin" "bytearray" "bytes" "format" "memoryview" "next" "print"
	  )) symbol-end)
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     (1 font-lock-builtin-face))
    (,(rx symbol-start (or
	  ;; other built-ins
	  "True" "False" "None" "Ellipsis"
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	  "_" "__debug__" "__doc__" "__import__" "__name__" "__package__")
          symbol-end)
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     . font-lock-builtin-face)))
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(defconst python-font-lock-syntactic-keywords
  ;; Make outer chars of matching triple-quote sequences into generic
  ;; string delimiters.  Fixme: Is there a better way?
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  ;; First avoid a sequence preceded by an odd number of backslashes.
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  `((,(concat "\\(?:\\([RUru]\\)[Rr]?\\|^\\|[^\\]\\(?:\\\\.\\)*\\)" ;Prefix.
              "\\(?:\\('\\)'\\('\\)\\|\\(?2:\"\\)\"\\(?3:\"\\)\\)")
     (1 (python-quote-syntax 1) nil lax)
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     (2 (python-quote-syntax 2))
     (3 (python-quote-syntax 3)))
    ;; This doesn't really help.
;;;     (,(rx (and ?\\ (group ?\n))) (1 " "))
    ))

(defun python-quote-syntax (n)
  "Put `syntax-table' property correctly on triple quote.
Used for syntactic keywords.  N is the match number (1, 2 or 3)."
  ;; Given a triple quote, we have to check the context to know
  ;; whether this is an opening or closing triple or whether it's
  ;; quoted anyhow, and should be ignored.  (For that we need to do
  ;; the same job as `syntax-ppss' to be correct and it seems to be OK
  ;; to use it here despite initial worries.)  We also have to sort
  ;; out a possible prefix -- well, we don't _have_ to, but I think it
  ;; should be treated as part of the string.

  ;; Test cases:
  ;;  ur"""ar""" x='"' # """
  ;; x = ''' """ ' a
  ;; '''
  ;; x '"""' x """ \"""" x
  (save-excursion
    (goto-char (match-beginning 0))
    (cond
     ;; Consider property for the last char if in a fenced string.
     ((= n 3)
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      (let* ((font-lock-syntactic-keywords nil)
	     (syntax (syntax-ppss)))
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	(when (eq t (nth 3 syntax))	; after unclosed fence
	  (goto-char (nth 8 syntax))	; fence position
	  (skip-chars-forward "uUrR")	; skip any prefix
	  ;; Is it a matching sequence?
	  (if (eq (char-after) (char-after (match-beginning 2)))
	      (eval-when-compile (string-to-syntax "|"))))))
     ;; Consider property for initial char, accounting for prefixes.
     ((or (and (= n 2)			; leading quote (not prefix)
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	       (not (match-end 1)))     ; prefix is null
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	  (and (= n 1)			; prefix
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	       (match-end 1)))          ; non-empty
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      (let ((font-lock-syntactic-keywords nil))
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	(unless (eq 'string (syntax-ppss-context (syntax-ppss)))
	  (eval-when-compile (string-to-syntax "|")))))
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     ;; Otherwise (we're in a non-matching string) the property is
     ;; nil, which is OK.
     )))

;; This isn't currently in `font-lock-defaults' as probably not worth
;; it -- we basically only mess with a few normally-symbol characters.

;; (defun python-font-lock-syntactic-face-function (state)
;;   "`font-lock-syntactic-face-function' for Python mode.
;; Returns the string or comment face as usual, with side effect of putting
;; a `syntax-table' property on the inside of the string or comment which is
;; the standard syntax table."
;;   (if (nth 3 state)
;;       (save-excursion
;; 	(goto-char (nth 8 state))
;; 	(condition-case nil
;; 	    (forward-sexp)
;; 	  (error nil))
;; 	(put-text-property (1+ (nth 8 state)) (1- (point))
;; 			   'syntax-table (standard-syntax-table))
;; 	'font-lock-string-face)
;;     (put-text-property (1+ (nth 8 state)) (line-end-position)
;; 			   'syntax-table (standard-syntax-table))
;;     'font-lock-comment-face))

;;;; Keymap and syntax

(defvar python-mode-map
  (let ((map (make-sparse-keymap)))
    ;; Mostly taken from python-mode.el.
    (define-key map ":" 'python-electric-colon)
    (define-key map "\177" 'python-backspace)
    (define-key map "\C-c<" 'python-shift-left)
    (define-key map "\C-c>" 'python-shift-right)
    (define-key map "\C-c\C-k" 'python-mark-block)
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    (define-key map "\C-c\C-d" 'python-pdbtrack-toggle-stack-tracking)
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    (define-key map "\C-c\C-n" 'python-next-statement)
    (define-key map "\C-c\C-p" 'python-previous-statement)
    (define-key map "\C-c\C-u" 'python-beginning-of-block)
    (define-key map "\C-c\C-f" 'python-describe-symbol)
    (define-key map "\C-c\C-w" 'python-check)
    (define-key map "\C-c\C-v" 'python-check) ; a la sgml-mode
    (define-key map "\C-c\C-s" 'python-send-string)
    (define-key map [?\C-\M-x] 'python-send-defun)
    (define-key map "\C-c\C-r" 'python-send-region)
    (define-key map "\C-c\M-r" 'python-send-region-and-go)
    (define-key map "\C-c\C-c" 'python-send-buffer)
    (define-key map "\C-c\C-z" 'python-switch-to-python)
    (define-key map "\C-c\C-m" 'python-load-file)
    (define-key map "\C-c\C-l" 'python-load-file) ; a la cmuscheme
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    (substitute-key-definition 'complete-symbol 'completion-at-point
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			       map global-map)
    (define-key map "\C-c\C-i" 'python-find-imports)
    (define-key map "\C-c\C-t" 'python-expand-template)
    (easy-menu-define python-menu map "Python Mode menu"
      `("Python"
	:help "Python-specific Features"
	["Shift region left" python-shift-left :active mark-active
	 :help "Shift by a single indentation step"]
	["Shift region right" python-shift-right :active mark-active
	 :help "Shift by a single indentation step"]
	"-"
	["Mark block" python-mark-block
	 :help "Mark innermost block around point"]
	["Mark def/class" mark-defun
	 :help "Mark innermost definition around point"]
	"-"
	["Start of block" python-beginning-of-block
	 :help "Go to start of innermost definition around point"]
	["End of block" python-end-of-block
	 :help "Go to end of innermost definition around point"]
	["Start of def/class" beginning-of-defun
	 :help "Go to start of innermost definition around point"]
	["End of def/class" end-of-defun
	 :help "Go to end of innermost definition around point"]
	"-"
	("Templates..."
	 :help "Expand templates for compound statements"
	 :filter (lambda (&rest junk)
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                   (abbrev-table-menu python-mode-abbrev-table)))
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	"-"
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	["Start interpreter" python-shell
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	 :help "Run `inferior' Python in separate buffer"]
	["Import/reload file" python-load-file
	 :help "Load into inferior Python session"]
	["Eval buffer" python-send-buffer
	 :help "Evaluate buffer en bloc in inferior Python session"]
	["Eval region" python-send-region :active mark-active
	 :help "Evaluate region en bloc in inferior Python session"]
	["Eval def/class" python-send-defun
	 :help "Evaluate current definition in inferior Python session"]
	["Switch to interpreter" python-switch-to-python
	 :help "Switch to inferior Python buffer"]
	["Set default process" python-set-proc
	 :help "Make buffer's inferior process the default"
	 :active (buffer-live-p python-buffer)]
	["Check file" python-check :help "Run pychecker"]
	["Debugger" pdb :help "Run pdb under GUD"]
	"-"
	["Help on symbol" python-describe-symbol
	 :help "Use pydoc on symbol at point"]
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	["Complete symbol" completion-at-point
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	 :help "Complete (qualified) symbol before point"]
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	["Find function" python-find-function
	 :help "Try to find source definition of function at point"]
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	["Update imports" python-find-imports
	 :help "Update list of top-level imports for completion"]))
    map))
;; Fixme: add toolbar stuff for useful things like symbol help, send
;; region, at least.  (Shouldn't be specific to Python, obviously.)
;; eric has items including: (un)indent, (un)comment, restart script,
;; run script, debug script; also things for profiling, unit testing.

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

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(defvar python-mode-syntax-table
  (let ((table (make-syntax-table)))
    ;; Give punctuation syntax to ASCII that normally has symbol
    ;; syntax or has word syntax and isn't a letter.
    (let ((symbol (string-to-syntax "_"))
	  (sst (standard-syntax-table)))
      (dotimes (i 128)
	(unless (= i ?_)
	  (if (equal symbol (aref sst i))
	      (modify-syntax-entry i "." table)))))
    (modify-syntax-entry ?$ "." table)
    (modify-syntax-entry ?% "." table)
    ;; exceptions
    (modify-syntax-entry ?# "<" table)
    (modify-syntax-entry ?\n ">" table)
    (modify-syntax-entry ?' "\"" table)
    (modify-syntax-entry ?` "$" table)
    table))

;;;; Utility stuff

(defsubst python-in-string/comment ()
  "Return non-nil if point is in a Python literal (a comment or string)."
  ;; We don't need to save the match data.
  (nth 8 (syntax-ppss)))

(defconst python-space-backslash-table
  (let ((table (copy-syntax-table python-mode-syntax-table)))
    (modify-syntax-entry ?\\ " " table)
    table)
  "`python-mode-syntax-table' with backslash given whitespace syntax.")

(defun python-skip-comments/blanks (&optional backward)
  "Skip comments and blank lines.
BACKWARD non-nil means go backwards, otherwise go forwards.
Backslash is treated as whitespace so that continued blank lines
are skipped.  Doesn't move out of comments -- should be outside
or at end of line."
  (let ((arg (if backward
		 ;; If we're in a comment (including on the trailing
		 ;; newline), forward-comment doesn't move backwards out
		 ;; of it.  Don't set the syntax table round this bit!
		 (let ((syntax (syntax-ppss)))
		   (if (nth 4 syntax)
		       (goto-char (nth 8 syntax)))
		   (- (point-max)))
	       (point-max))))
    (with-syntax-table python-space-backslash-table
      (forward-comment arg))))

(defun python-backslash-continuation-line-p ()
  "Non-nil if preceding line ends with backslash that is not in a comment."
  (and (eq ?\\ (char-before (line-end-position 0)))
       (not (syntax-ppss-context (syntax-ppss)))))

(defun python-continuation-line-p ()
  "Return non-nil if current line continues a previous one.
The criteria are that the previous line ends in a backslash outside
comments and strings, or that point is within brackets/parens."
  (or (python-backslash-continuation-line-p)
      (let ((depth (syntax-ppss-depth
		    (save-excursion ; syntax-ppss with arg changes point
		      (syntax-ppss (line-beginning-position))))))
	(or (> depth 0)
	    (if (< depth 0)	  ; Unbalanced brackets -- act locally
		(save-excursion
		  (condition-case ()
		      (progn (backward-up-list) t) ; actually within brackets
		    (error nil))))))))

(defun python-comment-line-p ()
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  "Return non-nil if and only if current line has only a comment."
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  (save-excursion
    (end-of-line)
    (when (eq 'comment (syntax-ppss-context (syntax-ppss)))
      (back-to-indentation)
      (looking-at (rx (or (syntax comment-start) line-end))))))

(defun python-blank-line-p ()
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  "Return non-nil if and only if current line is blank."
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  (save-excursion
    (beginning-of-line)
    (looking-at "\\s-*$")))

(defun python-beginning-of-string ()
  "Go to beginning of string around point.
Do nothing if not in string."
  (let ((state (syntax-ppss)))
    (when (eq 'string (syntax-ppss-context state))
      (goto-char (nth 8 state)))))

(defun python-open-block-statement-p (&optional bos)
  "Return non-nil if statement at point opens a block.
BOS non-nil means point is known to be at beginning of statement."
  (save-excursion
    (unless bos (python-beginning-of-statement))
    (looking-at (rx (and (or "if" "else" "elif" "while" "for" "def"
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			     "class" "try" "except" "finally" "with")
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			 symbol-end)))))

(defun python-close-block-statement-p (&optional bos)
  "Return non-nil if current line is a statement closing a block.
BOS non-nil means point is at beginning of statement.
The criteria are that the line isn't a comment or in string and
 starts with keyword `raise', `break', `continue' or `pass'."
  (save-excursion
    (unless bos (python-beginning-of-statement))
    (back-to-indentation)
    (looking-at (rx (or "return" "raise" "break" "continue" "pass")
		    symbol-end))))

(defun python-outdent-p ()
  "Return non-nil if current line should outdent a level."
  (save-excursion
    (back-to-indentation)
    (and (looking-at (rx (and (or "else" "finally" "except" "elif")
			      symbol-end)))
	 (not (python-in-string/comment))
	 ;; Ensure there's a previous statement and move to it.
	 (zerop (python-previous-statement))
	 (not (python-close-block-statement-p t))
	 ;; Fixme: check this
	 (not (python-open-block-statement-p)))))

;;;; Indentation.

(defcustom python-indent 4
  "Number of columns for a unit of indentation in Python mode.
See also `\\[python-guess-indent]'"
  :group 'python
  :type 'integer)
(put 'python-indent 'safe-local-variable 'integerp)

(defcustom python-guess-indent t
  "Non-nil means Python mode guesses `python-indent' for the buffer."
  :type 'boolean
  :group 'python)

(defcustom python-indent-string-contents t
  "Non-nil means indent contents of multi-line strings together.
This means indent them the same as the preceding non-blank line.
Otherwise preserve their indentation.

This only applies to `doc' strings, i.e. those that form statements;
the indentation is preserved in others."
  :type '(choice (const :tag "Align with preceding" t)
		 (const :tag "Preserve indentation" nil))
  :group 'python)

(defcustom python-honour-comment-indentation nil
  "Non-nil means indent relative to preceding comment line.
Only do this for comments where the leading comment character is
followed by space.  This doesn't apply to comment lines, which
are always indented in lines with preceding comments."
  :type 'boolean
  :group 'python)

(defcustom python-continuation-offset 4
  "Number of columns of additional indentation for continuation lines.
Continuation lines follow a backslash-terminated line starting a
statement."
  :group 'python
  :type 'integer)

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(defcustom python-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 `python-python-command' and
`python-python-command-args' are consulted to determine the interpreter
and arguments to use.

When the value is `jpython', the variables `python-jpython-command' and
`python-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
\\[python-toggle-shells] to change the interpreter shell."
  :type '(choice (const :tag "Python (a.k.a. CPython)" cpython)
		 (const :tag "JPython" jpython))
  :group 'python)

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

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

;; for toggling between CPython and JPython
(defvar python-which-shell nil)
(defvar python-which-args  python-python-command-args)
(defvar python-which-bufname "Python")
(make-variable-buffer-local 'python-which-shell)
(make-variable-buffer-local 'python-which-args)
(make-variable-buffer-local 'python-which-bufname)

(defcustom python-pdbtrack-do-tracking-p t
  "*Controls whether the pdbtrack feature is enabled or not.
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When non-nil, pdbtrack is enabled in all comint-based buffers,
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e.g. shell interaction buffers and the *Python* buffer.

When using pdb to debug a Python program, pdbtrack notices the
pdb prompt and presents the line in the source file where the
program is stopped in a pop-up buffer.  It's similar to what
gud-mode does for debugging C programs with gdb, but without
having to restart the program."
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  :type 'boolean
  :group 'python)
(make-variable-buffer-local 'python-pdbtrack-do-tracking-p)

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(defcustom python-pdbtrack-minor-mode-string " PDB"
  "*Minor-mode sign to be displayed when pdbtrack is active."
  :type 'string
  :group 'python)

;; Add a designator to the minor mode strings
(or (assq 'python-pdbtrack-is-tracking-p minor-mode-alist)
    (push '(python-pdbtrack-is-tracking-p python-pdbtrack-minor-mode-string)
	  minor-mode-alist))

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

(defvar python-pdbtrack-is-tracking-p nil)

(defconst python-pdbtrack-stack-entry-regexp
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  "^> \\(.*\\)(\\([0-9]+\\))\\([?a-zA-Z0-9_<>]+\\)()"
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  "Regular expression pdbtrack uses to find a stack trace entry.")

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(defconst python-pdbtrack-input-prompt "\n[(<]*[Pp]db[>)]+ "
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  "Regular expression pdbtrack uses to recognize a pdb prompt.")

(defconst python-pdbtrack-track-range 10000
  "Max number of characters from end of buffer to search for stack entry.")

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(defun python-guess-indent ()
  "Guess step for indentation of current buffer.
Set `python-indent' locally to the value guessed."
  (interactive)
  (save-excursion
    (save-restriction
      (widen)
      (goto-char (point-min))
      (let (done indent)
	(while (and (not done) (not (eobp)))
	  (when (and (re-search-forward (rx ?: (0+ space)
					    (or (syntax comment-start)
						line-end))
					nil 'move)
		     (python-open-block-statement-p))
	    (save-excursion
	      (python-beginning-of-statement)
	      (let ((initial (current-indentation)))
		(if (zerop (python-next-statement))
		    (setq indent (- (current-indentation) initial)))
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		(if (and indent (>= indent 2) (<= indent 8)) ; sanity check
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		    (setq done t))))))
	(when done
	  (when (/= indent (default-value 'python-indent))
	    (set (make-local-variable 'python-indent) indent)
	    (unless (= tab-width python-indent)
	      (setq indent-tabs-mode nil)))
	  indent)))))

;; Alist of possible indentations and start of statement they would
;; close.  Used in indentation cycling (below).
(defvar python-indent-list nil
  "Internal use.")
;; Length of the above
(defvar python-indent-list-length nil
  "Internal use.")
;; Current index into the alist.
(defvar python-indent-index nil
  "Internal use.")

(defun python-calculate-indentation ()
  "Calculate Python indentation for line at point."
  (setq python-indent-list nil
	python-indent-list-length 1)
  (save-excursion
    (beginning-of-line)
    (let ((syntax (syntax-ppss))
	  start)
      (cond
       ((eq 'string (syntax-ppss-context syntax)) ; multi-line string
	(if (not python-indent-string-contents)
	    (current-indentation)
	  ;; Only respect `python-indent-string-contents' in doc
	  ;; strings (defined as those which form statements).
	  (if (not (save-excursion
		     (python-beginning-of-statement)
		     (looking-at (rx (or (syntax string-delimiter)
					 (syntax string-quote))))))
	      (current-indentation)
	    ;; Find indentation of preceding non-blank line within string.
	    (setq start (nth 8 syntax))
	    (forward-line -1)
	    (while (and (< start (point)) (looking-at "\\s-*$"))
	      (forward-line -1))
	    (current-indentation))))
       ((python-continuation-line-p)   ; after backslash, or bracketed
	(let ((point (point))
	      (open-start (cadr syntax))
	      (backslash (python-backslash-continuation-line-p))
	      (colon (eq ?: (char-before (1- (line-beginning-position))))))
	  (if open-start
	      ;; Inside bracketed expression.
	      (progn
		(goto-char (1+ open-start))
		;; Look for first item in list (preceding point) and
		;; align with it, if found.
		(if (with-syntax-table python-space-backslash-table
		      (let ((parse-sexp-ignore-comments t))
			(condition-case ()
			    (progn (forward-sexp)
				   (backward-sexp)
				   (< (point) point))
			  (error nil))))
		    ;; Extra level if we're backslash-continued or
		    ;; following a key.
		    (if (or backslash colon)
			(+ python-indent (current-column))
			(current-column))
		  ;; Otherwise indent relative to statement start, one
		  ;; level per bracketing level.
		  (goto-char (1+ open-start))
		  (python-beginning-of-statement)
		  (+ (current-indentation) (* (car syntax) python-indent))))
	    ;; Otherwise backslash-continued.
	    (forward-line -1)
	    (if (python-continuation-line-p)
		;; We're past first continuation line.  Align with
		;; previous line.
		(current-indentation)
	      ;; First continuation line.  Indent one step, with an
	      ;; extra one if statement opens a block.
	      (python-beginning-of-statement)
	      (+ (current-indentation) python-continuation-offset
		 (if (python-open-block-statement-p t)
		     python-indent
		   0))))))
       ((bobp) 0)
       ;; Fixme: Like python-mode.el; not convinced by this.
       ((looking-at (rx (0+ space) (syntax comment-start)
			(not (any " \t\n")))) ; non-indentable comment
	(current-indentation))
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       ((and python-honour-comment-indentation
	     ;; Back over whitespace, newlines, non-indentable comments.
	     (catch 'done
	       (while (cond ((bobp) nil)
			    ((not (forward-comment -1))
			     nil)	; not at comment start
			    ;; Now at start of comment -- trailing one?
			    ((/= (current-column) (current-indentation))
			     nil)
			    ;; Indentable comment, like python-mode.el?
			    ((and (looking-at (rx (syntax comment-start)
						  (or space line-end)))
				  (/= 0 (current-column)))
			     (throw 'done (current-column)))
			    ;; Else skip it (loop).
			    (t))))))
       (t
	(python-indentation-levels)
	;; Prefer to indent comments with an immediately-following
	;; statement, e.g.
	;;       ...
	;;   # ...
	;;   def ...
	(when (and (> python-indent-list-length 1)
		   (python-comment-line-p))
	  (forward-line)
	  (unless (python-comment-line-p)
	    (let ((elt (assq (current-indentation) python-indent-list)))
	      (setq python-indent-list
		    (nconc (delete elt python-indent-list)
			   (list elt))))))
	(caar (last python-indent-list)))))))
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;;;; Cycling through the possible indentations with successive TABs.

;; These don't need to be buffer-local since they're only relevant
;; during a cycle.

(defun python-initial-text ()
  "Text of line following indentation and ignoring any trailing comment."
  (save-excursion
    (buffer-substring (progn
			(back-to-indentation)
			(point))
		      (progn
			(end-of-line)
			(forward-comment -1)
			(point)))))

(defconst python-block-pairs
  '(("else" "if" "elif" "while" "for" "try" "except")
    ("elif" "if" "elif")
    ("except" "try" "except")
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    ("finally" "else" "try" "except"))
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  "Alist of keyword matches.
The car of an element is a keyword introducing a statement which
can close a block opened by a keyword in the cdr.")

(defun python-first-word ()
  "Return first word (actually symbol) on the line."
  (save-excursion
    (back-to-indentation)
    (current-word t)))

(defun python-indentation-levels ()
  "Return a list of possible indentations for this line.
It is assumed not to be a continuation line or in a multi-line string.
Includes the default indentation and those which would close all
enclosing blocks.  Elements of the list are actually pairs:
\(INDENTATION . TEXT), where TEXT is the initial text of the
corresponding block opening (or nil)."
  (save-excursion
    (let ((initial "")
	  levels indent)
      ;; Only one possibility immediately following a block open
      ;; statement, assuming it doesn't have a `suite' on the same line.
      (cond
       ((save-excursion (and (python-previous-statement)
			     (python-open-block-statement-p t)
			     (setq indent (current-indentation))
			     ;; Check we don't have something like:
			     ;;   if ...: ...
			     (if (progn (python-end-of-statement)
					(python-skip-comments/blanks t)
					(eq ?: (char-before)))
				 (setq indent (+ python-indent indent)))))
	(push (cons indent initial) levels))
       ;; Only one possibility for comment line immediately following
       ;; another.
       ((save-excursion
	  (when (python-comment-line-p)
	    (forward-line -1)
	    (if (python-comment-line-p)
		(push (cons (current-indentation) initial) levels)))))
       ;; Fixme: Maybe have a case here which indents (only) first
       ;; line after a lambda.
       (t
	(let ((start (car (assoc (python-first-word) python-block-pairs))))
	  (python-previous-statement)
	  ;; Is this a valid indentation for the line of interest?
	  (unless (or (if start		; potentially only outdentable
			  ;; Check for things like:
			  ;;   if ...: ...
			  ;;   else ...:
			  ;; where the second line need not be outdented.
			  (not (member (python-first-word)
				       (cdr (assoc start
						   python-block-pairs)))))
		      ;; Not sensible to indent to the same level as
		      ;; previous `return' &c.
		      (python-close-block-statement-p))
	    (push (cons (current-indentation) (python-initial-text))
		  levels))
	  (while (python-beginning-of-block)
	    (when (or (not start)
		      (member (python-first-word)
			      (cdr (assoc start python-block-pairs))))
	      (push (cons (current-indentation) (python-initial-text))
		    levels))))))
      (prog1 (or levels (setq levels '((0 . ""))))
	(setq python-indent-list levels
	      python-indent-list-length (length python-indent-list))))))

;; This is basically what `python-indent-line' would be if we didn't
;; do the cycling.
(defun python-indent-line-1 (&optional leave)
  "Subroutine of `python-indent-line'.
Does non-repeated indentation.  LEAVE non-nil means leave
indentation if it is valid, i.e. one of the positions returned by
`python-calculate-indentation'."
  (let ((target (python-calculate-indentation))
	(pos (- (point-max) (point))))
    (if (or (= target (current-indentation))
	    ;; Maybe keep a valid indentation.
	    (and leave python-indent-list
		 (assq (current-indentation) python-indent-list)))
	(if (< (current-column) (current-indentation))
	    (back-to-indentation))
      (beginning-of-line)
      (delete-horizontal-space)
      (indent-to target)
      (if (> (- (point-max) pos) (point))
	  (goto-char (- (point-max) pos))))))

(defun python-indent-line ()
  "Indent current line as Python code.
When invoked via `indent-for-tab-command', cycle through possible
indentations for current line.  The cycle is broken by a command
different from `indent-for-tab-command', i.e. successive TABs do
the cycling."
  (interactive)
  (if (and (eq this-command 'indent-for-tab-command)
	   (eq last-command this-command))
      (if (= 1 python-indent-list-length)
	  (message "Sole indentation")
	(progn (setq python-indent-index
		     (% (1+ python-indent-index) python-indent-list-length))
	       (beginning-of-line)
	       (delete-horizontal-space)
	       (indent-to (car (nth python-indent-index python-indent-list)))
	       (if (python-block-end-p)
		   (let ((text (cdr (nth python-indent-index
					 python-indent-list))))
		     (if text
			 (message "Closes: %s" text))))))
    (python-indent-line-1)
    (setq python-indent-index (1- python-indent-list-length))))

(defun python-indent-region (start end)
  "`indent-region-function' for Python.
Leaves validly-indented lines alone, i.e. doesn't indent to
another valid position."
  (save-excursion
    (goto-char end)
    (setq end (point-marker))
    (goto-char start)
    (or (bolp) (forward-line 1))
    (while (< (point) end)
      (or (and (bolp) (eolp))
	  (python-indent-line-1 t))
      (forward-line 1))
    (move-marker end nil)))

(defun python-block-end-p ()
  "Non-nil if this is a line in a statement closing a block,
or a blank line indented to where it would close a block."
  (and (not (python-comment-line-p))
       (or (python-close-block-statement-p t)
	   (< (current-indentation)
	      (save-excursion
		(python-previous-statement)
		(current-indentation))))))

;;;; Movement.

;; Fixme:  Define {for,back}ward-sexp-function?  Maybe skip units like
;; block, statement, depending on context.

(defun python-beginning-of-defun ()
  "`beginning-of-defun-function' for Python.
Finds beginning of innermost nested class or method definition.
Returns the name of the definition found at the end, or nil if
reached start of buffer."
  (let ((ci (current-indentation))
	(def-re (rx line-start (0+ space) (or "def" "class") (1+ space)
		    (group (1+ (or word (syntax symbol))))))
	found lep) ;; def-line
    (if (python-comment-line-p)
	(setq ci most-positive-fixnum))
    (while (and (not (bobp)) (not found))
      ;; Treat bol at beginning of function as outside function so
      ;; that successive C-M-a makes progress backwards.
      ;;(setq def-line (looking-at def-re))
      (unless (bolp) (end-of-line))
      (setq lep (line-end-position))
      (if (and (re-search-backward def-re nil 'move)
	       ;; Must be less indented or matching top level, or
	       ;; equally indented if we started on a definition line.
	       (let ((in (current-indentation)))
		 (or (and (zerop ci) (zerop in))
		     (= lep (line-end-position)) ; on initial line
		     ;; Not sure why it was like this -- fails in case of
		     ;; last internal function followed by first
		     ;; non-def statement of the main body.
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;; 		     (and def-line (= in ci))
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		     (= in ci)
		     (< in ci)))
	       (not (python-in-string/comment)))
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	  (setq found t)))
    found))
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(defun python-end-of-defun ()
  "`end-of-defun-function' for Python.
Finds end of innermost nested class or method definition."
  (let ((orig (point))
	(pattern (rx line-start (0+ space) (or "def" "class") space)))
    ;; Go to start of current block and check whether it's at top
    ;; level.  If it is, and not a block start, look forward for
    ;; definition statement.
    (when (python-comment-line-p)
      (end-of-line)
      (forward-comment most-positive-fixnum))
    (if (not (python-open-block-statement-p))
	(python-beginning-of-block))
    (if (zerop (current-indentation))
	(unless (python-open-block-statement-p)
	  (while (and (re-search-forward pattern nil 'move)
		      (python-in-string/comment))) ; just loop
	  (unless (eobp)
	    (beginning-of-line)))
      ;; Don't move before top-level statement that would end defun.
      (end-of-line)
      (python-beginning-of-defun))
    ;; If we got to the start of buffer, look forward for
    ;; definition statement.
    (if (and (bobp) (not (looking-at "def\\|class")))
	(while (and (not (eobp))
		    (re-search-forward pattern nil 'move)
		    (python-in-string/comment)))) ; just loop
    ;; We're at a definition statement (or end-of-buffer).
    (unless (eobp)
      (python-end-of-block)
      ;; Count trailing space in defun (but not trailing comments).
      (skip-syntax-forward " >")
      (unless (eobp)			; e.g. missing final newline
	(beginning-of-line)))
    ;; Catch pathological cases like this, where the beginning-of-defun
    ;; skips to a definition we're not in:
    ;; if ...:
    ;;     ...
    ;; else:
    ;;     ...  # point here
    ;;     ...
    ;;     def ...
    (if (< (point) orig)
	(goto-char (point-max)))))

(defun python-beginning-of-statement ()
  "Go to start of current statement.
Accounts for continuation lines, multi-line strings, and
multi-line bracketed expressions."
  (beginning-of-line)
  (python-beginning-of-string)
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  (let (point)
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    (while (and (python-continuation-line-p)
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		(if point
		    (< (point) point)
		  t))
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      (beginning-of-line)
      (if (python-backslash-continuation-line-p)
	  (progn
	    (forward-line -1)
	    (while (python-backslash-continuation-line-p)
	      (forward-line -1)))
	(python-beginning-of-string)
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	(python-skip-out))
      (setq point (point))))
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  (back-to-indentation))

(defun python-skip-out (&optional forward syntax)
  "Skip out of any nested brackets.
Skip forward if FORWARD is non-nil, else backward.
If SYNTAX is non-nil it is the state returned by `syntax-ppss' at point.
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Return non-nil if and only if skipping was done."
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  (let ((depth (syntax-ppss-depth (or syntax (syntax-ppss))))
	(forward (if forward -1 1)))
    (unless (zerop depth)
      (if (> depth 0)
	  ;; Skip forward out of nested brackets.
	  (condition-case ()		; beware invalid syntax
	      (progn (backward-up-list (* forward depth)) t)
	    (error nil))
	;; Invalid syntax (too many closed brackets).
	;; Skip out of as many as possible.
	(let (done)
	  (while (condition-case ()
		     (progn (backward-up-list forward)
			    (setq done t))
		   (error nil)))
	  done)))))

(defun python-end-of-statement ()
  "Go to the end of the current statement and return point.
Usually this is the start of the next line, but if this is a
multi-line statement we need to skip over the continuation lines.
On a comment line, go to end of line."
  (end-of-line)
  (while (let (comment)
	   ;; Move past any enclosing strings and sexps, or stop if
	   ;; we're in a comment.
	   (while (let ((s (syntax-ppss)))
		    (cond ((eq 'comment (syntax-ppss-context s))
			   (setq comment t)
			   nil)
			  ((eq 'string (syntax-ppss-context s))
			   ;; Go to start of string and skip it.
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                           (let ((pos (point)))
                             (goto-char (nth 8 s))
                             (condition-case () ; beware invalid syntax
                                 (progn (forward-sexp) t)
                               ;; If there's a mismatched string, make sure
                               ;; we still overall move *forward*.
                               (error (goto-char pos) (end-of-line)))))
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			  ((python-skip-out t s))))
	     (end-of-line))
	   (unless comment
	     (eq ?\\ (char-before))))	; Line continued?
    (end-of-line 2))			; Try next line.
  (point))

(defun python-previous-statement (&optional count)
  "Go to start of previous statement.
With argument COUNT, do it COUNT times.  Stop at beginning of buffer.
Return count of statements left to move."
  (interactive "p")
  (unless count (setq count 1))
  (if (< count 0)
      (python-next-statement (- count))
    (python-beginning-of-statement)
    (while (and (> count 0) (not (bobp)))
      (python-skip-comments/blanks t)
      (python-beginning-of-statement)
      (unless (bobp) (setq count (1- count))))
    count))

(defun python-next-statement (&optional count)
  "Go to start of next statement.
With argument COUNT, do it COUNT times.  Stop at end of buffer.
Return count of statements left to move."
  (interactive "p")
  (unless count (setq count 1))
  (if (< count 0)
      (python-previous-statement (- count))
    (beginning-of-line)
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    (let (bogus)
      (while (and (> count 0) (not (eobp)) (not bogus))
	(python-end-of-statement)
	(python-skip-comments/blanks)
	(if (eq 'string (syntax-ppss-context (syntax-ppss)))
	    (setq bogus t)
	  (unless (eobp)
	    (setq count (1- count))))))
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    count))

(defun python-beginning-of-block (&optional arg)
  "Go to start of current block.
With numeric arg, do it that many times.  If ARG is negative, call
`python-end-of-block' instead.
If point is on the first line of a block, use its outer block.
If current statement is in column zero, don't move and return nil.
Otherwise return non-nil."
  (interactive "p")
  (unless arg (setq arg 1))
  (cond
   ((zerop arg))
   ((< arg 0) (python-end-of-block (- arg)))
   (t
    (let ((point (point)))
      (if (or (python-comment-line-p)
	      (python-blank-line-p))
	  (python-skip-comments/blanks t))
      (python-beginning-of-statement)
      (let ((ci (current-indentation)))
	(if (zerop ci)
	    (not (goto-char point))	; return nil
	  ;; Look upwards for less indented statement.
	  (if (catch 'done
;;; This is slower than the below.
;;; 	  (while (zerop (python-previous-statement))
;;; 	    (when (and (< (current-indentation) ci)
;;; 		       (python-open-block-statement-p t))
;;; 	      (beginning-of-line)
;;; 	      (throw 'done t)))
		(while (and (zerop (forward-line -1)))
		  (when (and (< (current-indentation) ci)
			     (not (python-comment-line-p))
			     ;; Move to beginning to save effort in case
			     ;; this is in string.
			     (progn (python-beginning-of-statement) t)
			     (python-open-block-statement-p t))
		    (beginning-of-line)
		    (throw 'done t)))
		(not (goto-char point))) ; Failed -- return nil
	      (python-beginning-of-block (1- arg)))))))))

(defun python-end-of-block (&optional arg)
  "Go to end of current block.
With numeric arg, do it that many times.  If ARG is negative,
call `python-beginning-of-block' instead.
If current statement is in column zero and doesn't open a block,
don't move and return nil.  Otherwise return t."
  (interactive "p")
  (unless arg (setq arg 1))
  (if (< arg 0)
      (python-beginning-of-block (- arg))
    (while (and (> arg 0)
		(let* ((point (point))
		       (_ (if (python-comment-line-p)
			      (python-skip-comments/blanks t)))
		       (ci (current-indentation))
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		       (open (python-open-block-statement-p)))
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		  (if (and (zerop ci) (not open))
		      (not (goto-char point))
		    (catch 'done
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		      (while (zerop (python-next-statement))
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			(when (or (and open (<= (current-indentation) ci))
				  (< (current-indentation) ci))
			  (python-skip-comments/blanks t)
			  (beginning-of-line 2)
			  (throw 'done t)))))))
      (setq arg (1- arg)))
    (zerop arg)))
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(defvar python-which-func-length-limit 40
  "Non-strict length limit for `python-which-func' output.")

(defun python-which-func ()
  (let ((function-name (python-current-defun python-which-func-length-limit)))
    (set-text-properties 0 (length function-name) nil function-name)
    function-name))

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;;;; Imenu.

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;; For possibily speeding this up, here's the top of the ELP profile
;; for rescanning pydoc.py (2.2k lines, 90kb):
;; Function Name                         Call Count  Elapsed Time  Average Time
;; ====================================  ==========  =============  ============
;; python-imenu-create-index             156         2.430906      0.0155827307
;; python-end-of-defun                   155         1.2718260000  0.0082053290
;; python-end-of-block                   155         1.1898689999  0.0076765741
;; python-next-statement                 2970        1.024717      0.0003450225
;; python-end-of-statement               2970        0.4332190000  0.0001458649
;; python-beginning-of-defun             265         0.0918479999  0.0003465962
;; python-skip-comments/blanks           3125        0.0753319999  2.410...e-05

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(defvar python-recursing)
(defun python-imenu-create-index ()
  "`imenu-create-index-function' for Python.

Makes nested Imenu menus from nested `class' and `def' statements.
The nested menus are headed by an item referencing the outer
definition; it has a space prepended to the name so that it sorts
first with `imenu--sort-by-name' (though, unfortunately, sub-menus
precede it)."
  (unless (boundp 'python-recursing)	; dynamically bound below
    ;; Normal call from Imenu.
    (goto-char (point-min))
    ;; Without this, we can get an infloop if the buffer isn't all
    ;; fontified.  I guess this is really a bug in syntax.el.  OTOH,
    ;; _with_ this, imenu doesn't immediately work; I can't figure out
    ;; what's going on, but it must be something to do with timers in
    ;; font-lock.
    ;; This can't be right, especially not when jit-lock is not used.  --Stef
    ;; (unless (get-text-property (1- (point-max)) 'fontified)
    ;;   (font-lock-fontify-region (point-min) (point-max)))
    )
  (let (index-alist)			; accumulated value to return
    (while (re-search-forward
	    (rx line-start (0+ space)	; leading space
		(or (group "def") (group "class"))	   ; type
		(1+ space) (group (1+ (or word ?_))))	   ; name
	    nil t)
      (unless (python-in-string/comment)
	(let ((pos (match-beginning 0))
	      (name (match-string-no-properties 3)))
	  (if (match-beginning 2)	; def or class?
	      (setq name (concat "class " name)))
	  (save-restriction
	    (narrow-to-defun)
	    (let* ((python-recursing t)
		   (sublist (python-imenu-create-index)))
	      (if sublist
		  (progn (push (cons (concat " " name) pos) sublist)
			 (push (cons name sublist) index-alist))
		(push (cons name pos) index-alist)))))))
    (unless (boundp 'python-recursing)
      ;; Look for module variables.
      (let (vars)
	(goto-char (point-min))
	(while (re-search-forward
		(rx line-start (group (1+ (or word ?_))) (0+ space) "=")
		nil t)
	  (unless (python-in-string/comment)
	    (push (cons (match-string 1) (match-beginning 1))
		  vars)))
	(setq index-alist (nreverse index-alist))
	(if vars
	    (push (cons "Module variables"
			(nreverse vars))
		  index-alist))))
    index-alist))

;;;; `Electric' commands.

(defun python-electric-colon (arg)
  "Insert a colon and maybe outdent the line if it is a statement like `else'.
With numeric ARG, just insert that many colons.  With \\[universal-argument],
just insert a single colon."
  (interactive "*P")
  (self-insert-command (if (not (integerp arg)) 1 arg))
  (and (not arg)
       (eolp)
       (python-outdent-p)
       (not (python-in-string/comment))
       (> (current-indentation) (python-calculate-indentation))
       (python-indent-line)))		; OK, do it
(put 'python-electric-colon 'delete-selection t)

(defun python-backspace (arg)
  "Maybe delete a level of indentation on the current line.
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Do so if point is at the end of the line's indentation outside
strings and comments.
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Otherwise just call `backward-delete-char-untabify'.
Repeat ARG times."
  (interactive "*p")
  (if (or (/= (current-indentation) (current-column))
	  (bolp)
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	  (python-continuation-line-p)
	  (python-in-string/comment))
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      (backward-delete-char-untabify arg)
    ;; Look for the largest valid indentation which is smaller than
    ;; the current indentation.
    (let ((indent 0)
	  (ci (current-indentation))
	  (indents (python-indentation-levels))
	  initial)
      (dolist (x indents)
	(if (< (car x) ci)
	    (setq indent (max indent (car x)))))
      (setq initial (cdr (assq indent indents)))
      (if (> (length initial) 0)
	  (message "Closes %s" initial))
      (delete-horizontal-space)
      (indent-to indent))))
(put 'python-backspace 'delete-selection 'supersede)

;;;; pychecker

(defcustom python-check-command "pychecker --stdlib"
  "Command used to check a Python file."
  :type 'string
  :group 'python)

(defvar python-saved-check-command nil
  "Internal use.")

;; After `sgml-validate-command'.
(defun python-check (command)
  "Check a Python file (default current buffer's file).
Runs COMMAND, a shell command, as if by `compile'.
See `python-check-command' for the default."
  (interactive
   (list (read-string "Checker command: "
		      (or python-saved-check-command
			  (concat python-check-command " "
				  (let ((name (buffer-file-name)))
				    (if name
					(file-name-nondirectory name))))))))
  (setq python-saved-check-command command)
  (require 'compile)                    ;To define compilation-* variables.
  (save-some-buffers (not compilation-ask-about-save) nil)
  (let ((compilation-error-regexp-alist
	 (cons '("(\\([^,]+\\), line \\([0-9]+\\))" 1 2)
	       compilation-error-regexp-alist)))
    (compilation-start command)))

;;;; Inferior mode stuff (following cmuscheme).

;; Fixme: Make sure we can work with IPython.

(defcustom python-python-command "python"
  "Shell command to run Python interpreter.
Any arguments can't contain whitespace.
Note that IPython may not work properly; it must at least be used
with the `-cl' flag, i.e. use `ipython -cl'."
  :group 'python
  :type 'string)

(defcustom python-jython-command "jython"
  "Shell command to run Jython interpreter.
Any arguments can't contain whitespace."
  :group 'python
  :type 'string)

(defvar python-command python-python-command
  "Actual command used to run Python.
May be `python-python-command' or `python-jython-command', possibly
modified by the user.  Additional arguments are added when the command
is used by `run-python' et al.")

(defvar python-buffer nil
  "*The current Python process buffer.

Commands that send text from source buffers to Python processes have
to choose a process to send to.  This is determined by buffer-local
value of `python-buffer'.  If its value in the current buffer,
i.e. both any local value and the default one, is nil, `run-python'
and commands that send to the Python process will start a new process.

Whenever \\[run-python] starts a new process, it resets the default
value of `python-buffer' to be the new process's buffer and sets the
buffer-local value similarly if the current buffer is in Python mode
or Inferior Python mode, so that source buffer stays associated with a
specific sub-process.

Use \\[python-set-proc] to set the default value from a buffer with a
local value.")
(make-variable-buffer-local 'python-buffer)

(defconst python-compilation-regexp-alist
  ;; FIXME: maybe these should move to compilation-error-regexp-alist-alist.
  ;;   The first already is (for CAML), but the second isn't.  Anyhow,
  ;;   these are specific to the inferior buffer.  -- fx
  `((,(rx line-start (1+ (any " \t")) "File \""
	  (group (1+ (not (any "\"<")))) ; avoid `<stdin>' &c
	  "\", line " (group (1+ digit)))
     1 2)
    (,(rx " in file " (group (1+ not-newline)) " on line "
	  (group (1+ digit)))
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     1 2)
    ;; pdb stack trace
    (,(rx line-start "> " (group (1+ (not (any "(\"<"))))
	  "(" (group (1+ digit)) ")" (1+ (not (any "("))) "()")
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     1 2))
  "`compilation-error-regexp-alist' for inferior Python.")

(defvar inferior-python-mode-map
  (let ((map (make-sparse-keymap)))
    ;; This will inherit from comint-mode-map.
    (define-key map "\C-c\C-l" 'python-load-file)
    (define-key map "\C-c\C-v" 'python-check)
    ;; Note that we _can_ still use these commands which send to the
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    ;; Python process even at the prompt iff we have a normal prompt,
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    ;; i.e. '>>> ' and not '... '.  See the comment before
    ;; python-send-region.  Fixme: uncomment these if we address that.

    ;; (define-key map [(meta ?\t)] 'python-complete-symbol)
    ;; (define-key map "\C-c\C-f" 'python-describe-symbol)
    map))

(defvar inferior-python-mode-syntax-table
  (let ((st (make-syntax-table python-mode-syntax-table)))
    ;; Don't get confused by apostrophes in the process's output (e.g. if
    ;; you execute "help(os)").
    (modify-syntax-entry ?\' "." st)
    ;; Maybe we should do the same for double quotes?
    ;; (modify-syntax-entry ?\" "." st)
    st))

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;; Autoloaded.
(declare-function compilation-shell-minor-mode "compile" (&optional arg))

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;; Fixme: This should inherit some stuff from `python-mode', but I'm
;; not sure how much: at least some keybindings, like C-c C-f;
;; syntax?; font-locking, e.g. for triple-quoted strings?
(define-derived-mode inferior-python-mode comint-mode "Inferior Python"
  "Major mode for interacting with an inferior Python process.
A Python process can be started with \\[run-python].

Hooks `comint-mode-hook' and `inferior-python-mode-hook' are run in
that order.

You can send text to the inferior Python process from other buffers
containing Python source.
 * \\[python-switch-to-python] switches the current buffer to the Python
    process buffer.
 * \\[python-send-region] sends the current region to the Python process.
 * \\[python-send-region-and-go] switches to the Python process buffer
    after sending the text.
For running multiple processes in multiple buffers, see `run-python' and
`python-buffer'.

\\{inferior-python-mode-map}"
  :group 'python
  (setq mode-line-process '(":%s"))
  (set (make-local-variable 'comint-input-filter) 'python-input-filter)
  (add-hook 'comint-preoutput-filter-functions #'python-preoutput-filter
	    nil t)
  ;; Still required by `comint-redirect-send-command', for instance
  ;; (and we need to match things like `>>> ... >>> '):
  (set (make-local-variable 'comint-prompt-regexp)
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       (rx line-start (1+ (and (or (repeat 3 (any ">.")) "(Pdb)") " "))))
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  (set (make-local-variable 'compilation-error-regexp-alist)
       python-compilation-regexp-alist)
  (compilation-shell-minor-mode 1))

(defcustom inferior-python-filter-regexp "\\`\\s-*\\S-?\\S-?\\s-*\\'"
  "Input matching this regexp is not saved on the history list.
Default ignores all inputs of 0, 1, or 2 non-blank characters."
  :type 'regexp
  :group 'python)

(defun python-input-filter (str)
  "`comint-input-filter' function for inferior Python.
Don't save anything for STR matching `inferior-python-filter-regexp'."
  (not (string-match inferior-python-filter-regexp str)))

;; Fixme: Loses with quoted whitespace.
(defun python-args-to-list (string)
  (let ((where (string-match "[ \t]" string)))
    (cond ((null where) (list string))
	  ((not (= where 0))
	   (cons (substring string 0 where)
		 (python-args-to-list (substring string (+ 1 where)))))
	  (t (let ((pos (string-match "[^ \t]" string)))
	       (if pos (python-args-to-list (substring string pos))))))))

(defvar python-preoutput-result nil
  "Data from last `_emacs_out' line seen by the preoutput filter.")

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(defvar python-preoutput-continuation nil
  "If non-nil, funcall this when `python-preoutput-filter' sees `_emacs_ok'.")

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(defvar python-preoutput-leftover nil)
(defvar python-preoutput-skip-next-prompt nil)

;; Using this stops us getting lines in the buffer like
;; >>> ... ... >>>
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;; Also look for (and delete) an `_emacs_ok' string and call
;; `python-preoutput-continuation' if we get it.
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(defun python-preoutput-filter (s)
  "`comint-preoutput-filter-functions' function: ignore prompts not at bol."
  (when python-preoutput-leftover
    (setq s (concat python-preoutput-leftover s))
    (setq python-preoutput-leftover nil))
  (let ((start 0)
        (res ""))
    ;; First process whole lines.
    (while (string-match "\n" s start)
      (let ((line (substring s start (setq start (match-end 0)))))
        ;; Skip prompt if needed.
        (when (and python-preoutput-skip-next-prompt
                   (string-match comint-prompt-regexp line))
          (setq python-preoutput-skip-next-prompt nil)
          (setq line (substring line (match-end 0))))
        ;; Recognize special _emacs_out lines.
        (if (and (string-match "\\`_emacs_out \\(.*\\)\n\\'" line)
                 (local-variable-p 'python-preoutput-result))
            (progn
              (setq python-preoutput-result (match-string 1 line))
              (set (make-local-variable 'python-preoutput-skip-next-prompt) t))
          (setq res (concat res line)))))
    ;; Then process the remaining partial line.
    (unless (zerop start) (setq s (substring s start)))
    (cond ((and (string-match comint-prompt-regexp s)
                ;; Drop this prompt if it follows an _emacs_out...
                (or python-preoutput-skip-next-prompt
                    ;; ... or if it's not gonna be inserted at BOL.
                    ;; Maybe we could be more selective here.
                    (if (zerop (length res))
                        (not (bolp))
                      (string-match ".\\'" res))))
           ;; The need for this seems to be system-dependent:
           ;; What is this all about, exactly?  --Stef
           ;; (if (and (eq ?. (aref s 0)))
           ;;     (accept-process-output (get-buffer-process (current-buffer)) 1))
           (setq python-preoutput-skip-next-prompt nil)
           res)
          ((let ((end (min (length "_emacs_out ") (length s))))
             (eq t (compare-strings s nil end "_emacs_out " nil end)))
           ;; The leftover string is a prefix of _emacs_out so we don't know
           ;; yet whether it's an _emacs_out or something else: wait until we
           ;; get more output so we can resolve this ambiguity.
           (set (make-local-variable 'python-preoutput-leftover) s)
           res)
          (t (concat res s)))))

(autoload 'comint-check-proc "comint")

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(defvar python-version-checked nil)
(defun python-check-version (cmd)
  "Check that CMD runs a suitable version of Python."
  ;; Fixme:  Check on Jython.
  (unless (or python-version-checked
	      (equal 0 (string-match (regexp-quote python-python-command)
				     cmd)))
    (unless (shell-command-to-string cmd)
      (error "Can't run Python command `%s'" cmd))
    (let* ((res (shell-command-to-string (concat cmd " --version"))))
      (string-match "Python \\([0-9]\\)\\.\\([0-9]\\)" res)
      (unless (and (equal "2" (match-string 1 res))
		   (match-beginning 2)
		   (>= (string-to-number (match-string 2 res)) 2))
	(error "Only Python versions >= 2.2 and < 3.0 supported")))
    (setq python-version-checked t)))

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;;;###autoload
(defun run-python (&optional cmd noshow new)
  "Run an inferior Python process, input and output via buffer *Python*.
CMD is the Python command to run.  NOSHOW non-nil means don't show the
buffer automatically.

Normally, if there is a process already running in `python-buffer',
switch to that buffer.  Interactively, a prefix arg allows you to edit
the initial command line (default is `python-command'); `-i' etc. args
will be added to this as appropriate.  A new process is started if:
one isn't running attached to `python-buffer', or interactively the
default `python-command', or argument NEW is non-nil.  See also the
documentation for `python-buffer'.

Runs the hook `inferior-python-mode-hook' \(after the
`comint-mode-hook' is run).  \(Type \\[describe-mode] in the process
buffer for a list of commands.)"
  (interactive (if current-prefix-arg
		   (list (read-string "Run Python: " python-command) nil t)
		 (list python-command)))
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  (unless cmd (setq cmd python-command))
  (python-check-version cmd)
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  (setq python-command cmd)
  ;; Fixme: Consider making `python-buffer' buffer-local as a buffer
  ;; (not a name) in Python buffers from which `run-python' &c is
  ;; invoked.  Would support multiple processes better.
  (when (or new (not (comint-check-proc python-buffer)))
    (with-current-buffer
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	(let* ((cmdlist
		(append (python-args-to-list cmd)
Glenn Morris's avatar
Glenn Morris committed
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                        ;; See http://lists.gnu.org/archive/html/emacs-devel/2008-09/msg00215.html
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			'("-i" "-c" "import sys; sys.path.remove('')")))
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	       (path (getenv "PYTHONPATH"))
	       (process-environment	; to import emacs.py
		(cons (concat "PYTHONPATH="
			      (if path (concat path path-separator))
			      data-directory)
		      process-environment))
	       ;; Suppress use of pager for help output:
	       (process-connection-type nil))
	  (apply 'make-comint-in-buffer "Python"
		 (generate-new-buffer "*Python*")
		 (car cmdlist) nil (cdr cmdlist)))
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      (setq-default python-buffer (current-buffer))
      (setq python-buffer (current-buffer))
      (accept-process-output (get-buffer-process python-buffer) 5)
      (inferior-python-mode)
      ;; Load function definitions we need.
      ;; Before the preoutput function was used, this was done via -c in
      ;; cmdlist, but that loses the banner and doesn't run the startup
      ;; file.  The code might be inline here, but there's enough that it
      ;; seems worth putting in a separate file, and it's probably cleaner
      ;; to put it in a module.
      ;; Ensure we're at a prompt before doing anything else.
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      (python-send-string "import emacs")
      ;; The following line was meant to ensure that we're at a prompt
      ;; before doing anything else.  However, this can cause Emacs to
      ;; hang waiting for a response, if that Python function fails
      ;; (i.e. raises an exception).
      ;; (python-send-receive "print '_emacs_out ()'")
      ))
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  (if (derived-mode-p 'python-mode)
      (setq python-buffer (default-value 'python-buffer))) ; buffer-local
  ;; Without this, help output goes into the inferior python buffer if
  ;; the process isn't already running.
  (sit-for 1 t)        ;Should we use accept-process-output instead?  --Stef
  (unless noshow (pop-to-buffer python-buffer t)))

(defun python-send-command (command)
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  "Like `python-send-string' but resets `compilation-shell-minor-mode'."
  (when (python-check-comint-prompt)
    (with-current-buffer (process-buffer (python-proc))
      (goto-char (point-max))
      (compilation-forget-errors)
      (python-send-string command)
      (setq compilation-last-buffer (current-buffer)))))
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