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;;; subr.el --- basic lisp subroutines for Emacs  -*- coding: utf-8 -*-
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;; Copyright (C) 1985-1986, 1992, 1994-1995, 1999-2012
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;;   Free Software Foundation, Inc.
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;; Maintainer: FSF
;; Keywords: internal
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;; Package: emacs
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;; 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:

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;;; Code:
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;; Beware: while this file has tag `utf-8', before it's compiled, it gets
;; loaded as "raw-text", so non-ASCII chars won't work right during bootstrap.

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(defvar custom-declare-variable-list nil
  "Record `defcustom' calls made before `custom.el' is loaded to handle them.
Each element of this list holds the arguments to one call to `defcustom'.")

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;; Use this, rather than defcustom, in subr.el and other files loaded
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;; before custom.el.
(defun custom-declare-variable-early (&rest arguments)
  (setq custom-declare-variable-list
	(cons arguments custom-declare-variable-list)))
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(defmacro declare-function (fn file &optional arglist fileonly)
  "Tell the byte-compiler that function FN is defined, in FILE.
Optional ARGLIST is the argument list used by the function.  The
FILE argument is not used by the byte-compiler, but by the
`check-declare' package, which checks that FILE contains a
definition for FN.  ARGLIST is used by both the byte-compiler and
`check-declare' to check for consistency.

FILE can be either a Lisp file (in which case the \".el\"
extension is optional), or a C file.  C files are expanded
relative to the Emacs \"src/\" directory.  Lisp files are
searched for using `locate-library', and if that fails they are
expanded relative to the location of the file containing the
declaration.  A FILE with an \"ext:\" prefix is an external file.
`check-declare' will check such files if they are found, and skip
them without error if they are not.

FILEONLY non-nil means that `check-declare' will only check that
FILE exists, not that it defines FN.  This is intended for
function-definitions that `check-declare' does not recognize, e.g.
`defstruct'.

To specify a value for FILEONLY without passing an argument list,
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set ARGLIST to t.  This is necessary because nil means an
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empty argument list, rather than an unspecified one.

Note that for the purposes of `check-declare', this statement
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must be the first non-whitespace on a line.
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For more information, see Info node `(elisp)Declaring Functions'."
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  ;; Does nothing - byte-compile-declare-function does the work.
  nil)
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75

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;;;; Basic Lisp macros.
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(defalias 'not 'null)

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(defmacro noreturn (form)
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  "Evaluate FORM, expecting it not to return.
If FORM does return, signal an error."
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  (declare (debug t))
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  `(prog1 ,form
     (error "Form marked with `noreturn' did return")))

(defmacro 1value (form)
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  "Evaluate FORM, expecting a constant return value.
This is the global do-nothing version.  There is also `testcover-1value'
that complains if FORM ever does return differing values."
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  (declare (debug t))
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  form)

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(defmacro def-edebug-spec (symbol spec)
  "Set the `edebug-form-spec' property of SYMBOL according to SPEC.
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Both SYMBOL and SPEC are unevaluated.  The SPEC can be:
0 (instrument no arguments); t (instrument all arguments);
a symbol (naming a function with an Edebug specification); or a list.
The elements of the list describe the argument types; see
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Info node `(elisp)Specification List' for details."
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  `(put (quote ,symbol) 'edebug-form-spec (quote ,spec)))

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(defmacro lambda (&rest cdr)
  "Return a lambda expression.
A call of the form (lambda ARGS DOCSTRING INTERACTIVE BODY) is
self-quoting; the result of evaluating the lambda expression is the
expression itself.  The lambda expression may then be treated as a
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function, i.e., stored as the function value of a symbol, passed to
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`funcall' or `mapcar', etc.
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ARGS should take the same form as an argument list for a `defun'.
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DOCSTRING is an optional documentation string.
 If present, it should describe how to call the function.
 But documentation strings are usually not useful in nameless functions.
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INTERACTIVE should be a call to the function `interactive', which see.
It may also be omitted.
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BODY should be a list of Lisp expressions.

\(fn ARGS [DOCSTRING] [INTERACTIVE] BODY)"
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  (declare (doc-string 2) (indent defun)
           (debug (&define lambda-list
                           [&optional stringp]
                           [&optional ("interactive" interactive)]
                           def-body)))
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  ;; Note that this definition should not use backquotes; subr.el should not
  ;; depend on backquote.el.
  (list 'function (cons 'lambda cdr)))

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(defmacro setq-local (var val)
  "Set variable VAR to value VAL in current buffer."
  ;; Can't use backquote here, it's too early in the bootstrap.
  (list 'set (list 'make-local-variable (list 'quote var)) val))

(defmacro defvar-local (var val &optional docstring)
  "Define VAR as a buffer-local variable with default value VAL.
Like `defvar' but additionally marks the variable as being automatically
buffer-local wherever it is set."
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  (declare (debug defvar) (doc-string 3))
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  ;; Can't use backquote here, it's too early in the bootstrap.
  (list 'progn (list 'defvar var val docstring)
        (list 'make-variable-buffer-local (list 'quote var))))

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(defun apply-partially (fun &rest args)
  "Return a function that is a partial application of FUN to ARGS.
ARGS is a list of the first N arguments to pass to FUN.
The result is a new function which does the same as FUN, except that
the first N arguments are fixed at the values with which this function
was called."
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  `(closure (t) (&rest args)
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            (apply ',fun ,@(mapcar (lambda (arg) `',arg) args) args)))

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(defmacro push (newelt place)
  "Add NEWELT to the list stored in the generalized variable PLACE.
This is morally equivalent to (setf PLACE (cons NEWELT PLACE)),
except that PLACE is only evaluated once (after NEWELT)."
  (declare (debug (form gv-place)))
  (if (symbolp place)
      ;; Important special case, to avoid triggering GV too early in
      ;; the bootstrap.
      (list 'setq place
            (list 'cons newelt place))
    (require 'macroexp)
    (macroexp-let2 macroexp-copyable-p v newelt
      (gv-letplace (getter setter) place
        (funcall setter `(cons ,v ,getter))))))

(defmacro pop (place)
  "Return the first element of PLACE's value, and remove it from the list.
PLACE must be a generalized variable whose value is a list.
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If the value is nil, `pop' returns nil but does not actually
change the list."
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  (declare (debug (gv-place)))
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  (list 'car
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        (if (symbolp place)
            ;; So we can use `pop' in the bootstrap before `gv' can be used.
            (list 'prog1 place (list 'setq place (list 'cdr place)))
          (gv-letplace (getter setter) place
            `(prog1 ,getter ,(funcall setter `(cdr ,getter)))))))
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(defmacro when (cond &rest body)
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  "If COND yields non-nil, do BODY, else return nil.
When COND yields non-nil, eval BODY forms sequentially and return
value of last one, or nil if there are none.

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\(fn COND BODY...)"
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  (declare (indent 1) (debug t))
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  (list 'if cond (cons 'progn body)))
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(defmacro unless (cond &rest body)
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  "If COND yields nil, do BODY, else return nil.
When COND yields nil, eval BODY forms sequentially and return
value of last one, or nil if there are none.

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\(fn COND BODY...)"
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  (declare (indent 1) (debug t))
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  (cons 'if (cons cond (cons nil body))))
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(if (null (featurep 'cl))
    (progn
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  ;; If we reload subr.el after having loaded CL, be careful not to
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  ;; overwrite CL's extended definition of `dolist', `dotimes', `declare'.
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(defmacro dolist (spec &rest body)
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  "Loop over a list.
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Evaluate BODY with VAR bound to each car from LIST, in turn.
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Then evaluate RESULT to get return value, default nil.

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\(fn (VAR LIST [RESULT]) BODY...)"
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  (declare (indent 1) (debug ((symbolp form &optional form) body)))
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  ;; It would be cleaner to create an uninterned symbol,
  ;; but that uses a lot more space when many functions in many files
  ;; use dolist.
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  ;; FIXME: This cost disappears in byte-compiled lexical-binding files.
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  (let ((temp '--dolist-tail--))
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    ;; This is not a reliable test, but it does not matter because both
    ;; semantics are acceptable, tho one is slightly faster with dynamic
    ;; scoping and the other is slightly faster (and has cleaner semantics)
    ;; with lexical scoping.
    (if lexical-binding
        `(let ((,temp ,(nth 1 spec)))
           (while ,temp
             (let ((,(car spec) (car ,temp)))
               ,@body
               (setq ,temp (cdr ,temp))))
           ,@(if (cdr (cdr spec))
                 ;; FIXME: This let often leads to "unused var" warnings.
                 `((let ((,(car spec) nil)) ,@(cdr (cdr spec))))))
      `(let ((,temp ,(nth 1 spec))
             ,(car spec))
         (while ,temp
           (setq ,(car spec) (car ,temp))
           ,@body
           (setq ,temp (cdr ,temp)))
         ,@(if (cdr (cdr spec))
               `((setq ,(car spec) nil) ,@(cdr (cdr spec))))))))
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(defmacro dotimes (spec &rest body)
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  "Loop a certain number of times.
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Evaluate BODY with VAR bound to successive integers running from 0,
inclusive, to COUNT, exclusive.  Then evaluate RESULT to get
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the return value (nil if RESULT is omitted).

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\(fn (VAR COUNT [RESULT]) BODY...)"
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  (declare (indent 1) (debug dolist))
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  ;; It would be cleaner to create an uninterned symbol,
  ;; but that uses a lot more space when many functions in many files
  ;; use dotimes.
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  ;; FIXME: This cost disappears in byte-compiled lexical-binding files.
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  (let ((temp '--dotimes-limit--)
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	(start 0)
	(end (nth 1 spec)))
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    ;; This is not a reliable test, but it does not matter because both
    ;; semantics are acceptable, tho one is slightly faster with dynamic
    ;; scoping and the other has cleaner semantics.
    (if lexical-binding
        (let ((counter '--dotimes-counter--))
          `(let ((,temp ,end)
                 (,counter ,start))
             (while (< ,counter ,temp)
               (let ((,(car spec) ,counter))
                 ,@body)
               (setq ,counter (1+ ,counter)))
             ,@(if (cddr spec)
                   ;; FIXME: This let often leads to "unused var" warnings.
                   `((let ((,(car spec) ,counter)) ,@(cddr spec))))))
      `(let ((,temp ,end)
             (,(car spec) ,start))
         (while (< ,(car spec) ,temp)
           ,@body
           (setq ,(car spec) (1+ ,(car spec))))
         ,@(cdr (cdr spec))))))
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(defmacro declare (&rest _specs)
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  "Do not evaluate any arguments, and return nil.
If a `declare' form appears as the first form in the body of a
`defun' or `defmacro' form, SPECS specifies various additional
information about the function or macro; these go into effect
during the evaluation of the `defun' or `defmacro' form.

The possible values of SPECS are specified by
`defun-declarations-alist' and `macro-declarations-alist'."
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  ;; FIXME: edebug spec should pay attention to defun-declarations-alist.
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  nil)
))
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(defmacro ignore-errors (&rest body)
  "Execute BODY; if an error occurs, return nil.
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Otherwise, return result of last form in BODY.
See also `with-demoted-errors' that does something similar
without silencing all errors."
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  (declare (debug t) (indent 0))
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  `(condition-case nil (progn ,@body) (error nil)))
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;;;; Basic Lisp functions.

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(defun ignore (&rest _ignore)
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  "Do nothing and return nil.
This function accepts any number of arguments, but ignores them."
  (interactive)
  nil)

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;; Signal a compile-error if the first arg is missing.
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(defun error (&rest args)
  "Signal an error, making error message by passing all args to `format'.
In Emacs, the convention is that error messages start with a capital
letter but *do not* end with a period.  Please follow this convention
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for the sake of consistency."
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  (while t
    (signal 'error (list (apply 'format args)))))
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(set-advertised-calling-convention 'error '(string &rest args) "23.1")
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(defun user-error (format &rest args)
  "Signal a pilot error, making error message by passing all args to `format'.
In Emacs, the convention is that error messages start with a capital
letter but *do not* end with a period.  Please follow this convention
for the sake of consistency.
This is just like `error' except that `user-error's are expected to be the
result of an incorrect manipulation on the part of the user, rather than the
result of an actual problem."
  (while t
    (signal 'user-error (list (apply #'format format args)))))

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;; We put this here instead of in frame.el so that it's defined even on
;; systems where frame.el isn't loaded.
(defun frame-configuration-p (object)
  "Return non-nil if OBJECT seems to be a frame configuration.
Any list whose car is `frame-configuration' is assumed to be a frame
configuration."
  (and (consp object)
       (eq (car object) 'frame-configuration)))

;;;; List functions.
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(defsubst caar (x)
  "Return the car of the car of X."
  (car (car x)))

(defsubst cadr (x)
  "Return the car of the cdr of X."
  (car (cdr x)))

(defsubst cdar (x)
  "Return the cdr of the car of X."
  (cdr (car x)))

(defsubst cddr (x)
  "Return the cdr of the cdr of X."
  (cdr (cdr x)))
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(defun last (list &optional n)
  "Return the last link of LIST.  Its car is the last element.
If LIST is nil, return nil.
If N is non-nil, return the Nth-to-last link of LIST.
If N is bigger than the length of LIST, return LIST."
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  (if n
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      (and (>= n 0)
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           (let ((m (safe-length list)))
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             (if (< n m) (nthcdr (- m n) list) list)))
    (and list
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         (nthcdr (1- (safe-length list)) list))))
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(defun butlast (list &optional n)
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  "Return a copy of LIST with the last N elements removed."
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  (if (and n (<= n 0)) list
    (nbutlast (copy-sequence list) n)))
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(defun nbutlast (list &optional n)
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  "Modifies LIST to remove the last N elements."
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  (let ((m (length list)))
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    (or n (setq n 1))
    (and (< n m)
	 (progn
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	   (if (> n 0) (setcdr (nthcdr (- (1- m) n) list) nil))
	   list))))
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(defun delete-dups (list)
  "Destructively remove `equal' duplicates from LIST.
Store the result in LIST and return it.  LIST must be a proper list.
Of several `equal' occurrences of an element in LIST, the first
one is kept."
  (let ((tail list))
    (while tail
      (setcdr tail (delete (car tail) (cdr tail)))
      (setq tail (cdr tail))))
  list)

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(defun number-sequence (from &optional to inc)
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  "Return a sequence of numbers from FROM to TO (both inclusive) as a list.
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INC is the increment used between numbers in the sequence and defaults to 1.
So, the Nth element of the list is \(+ FROM \(* N INC)) where N counts from
zero.  TO is only included if there is an N for which TO = FROM + N * INC.
If TO is nil or numerically equal to FROM, return \(FROM).
If INC is positive and TO is less than FROM, or INC is negative
and TO is larger than FROM, return nil.
If INC is zero and TO is neither nil nor numerically equal to
FROM, signal an error.

This function is primarily designed for integer arguments.
Nevertheless, FROM, TO and INC can be integer or float.  However,
floating point arithmetic is inexact.  For instance, depending on
the machine, it may quite well happen that
\(number-sequence 0.4 0.6 0.2) returns the one element list \(0.4),
whereas \(number-sequence 0.4 0.8 0.2) returns a list with three
elements.  Thus, if some of the arguments are floats and one wants
to make sure that TO is included, one may have to explicitly write
TO as \(+ FROM \(* N INC)) or use a variable whose value was
computed with this exact expression.  Alternatively, you can,
of course, also replace TO with a slightly larger value
\(or a slightly more negative value if INC is negative)."
  (if (or (not to) (= from to))
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      (list from)
    (or inc (setq inc 1))
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    (when (zerop inc) (error "The increment can not be zero"))
    (let (seq (n 0) (next from))
      (if (> inc 0)
          (while (<= next to)
            (setq seq (cons next seq)
                  n (1+ n)
                  next (+ from (* n inc))))
        (while (>= next to)
          (setq seq (cons next seq)
                n (1+ n)
                next (+ from (* n inc)))))
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      (nreverse seq))))
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(defun copy-tree (tree &optional vecp)
  "Make a copy of TREE.
If TREE is a cons cell, this recursively copies both its car and its cdr.
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Contrast to `copy-sequence', which copies only along the cdrs.  With second
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argument VECP, this copies vectors as well as conses."
  (if (consp tree)
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      (let (result)
	(while (consp tree)
	  (let ((newcar (car tree)))
	    (if (or (consp (car tree)) (and vecp (vectorp (car tree))))
		(setq newcar (copy-tree (car tree) vecp)))
	    (push newcar result))
	  (setq tree (cdr tree)))
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	(nconc (nreverse result) tree))
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    (if (and vecp (vectorp tree))
	(let ((i (length (setq tree (copy-sequence tree)))))
	  (while (>= (setq i (1- i)) 0)
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	    (aset tree i (copy-tree (aref tree i) vecp)))
	  tree)
      tree)))
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;;;; Various list-search functions.
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(defun assoc-default (key alist &optional test default)
  "Find object KEY in a pseudo-alist ALIST.
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ALIST is a list of conses or objects.  Each element
 (or the element's car, if it is a cons) is compared with KEY by
 calling TEST, with two arguments: (i) the element or its car,
 and (ii) KEY.
If that is non-nil, the element matches; then `assoc-default'
 returns the element's cdr, if it is a cons, or DEFAULT if the
 element is not a cons.
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If no element matches, the value is nil.
If TEST is omitted or nil, `equal' is used."
  (let (found (tail alist) value)
    (while (and tail (not found))
      (let ((elt (car tail)))
	(when (funcall (or test 'equal) (if (consp elt) (car elt) elt) key)
	  (setq found t value (if (consp elt) (cdr elt) default))))
      (setq tail (cdr tail)))
    value))
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(defun assoc-ignore-case (key alist)
  "Like `assoc', but ignores differences in case and text representation.
KEY must be a string.  Upper-case and lower-case letters are treated as equal.
Unibyte strings are converted to multibyte for comparison."
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  (declare (obsolete assoc-string "22.1"))
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  (assoc-string key alist t))
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(defun assoc-ignore-representation (key alist)
  "Like `assoc', but ignores differences in text representation.
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KEY must be a string.
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Unibyte strings are converted to multibyte for comparison."
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  (declare (obsolete assoc-string "22.1"))
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  (assoc-string key alist nil))
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(defun member-ignore-case (elt list)
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  "Like `member', but ignore differences in case and text representation.
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ELT must be a string.  Upper-case and lower-case letters are treated as equal.
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Unibyte strings are converted to multibyte for comparison.
Non-strings in LIST are ignored."
  (while (and list
	      (not (and (stringp (car list))
			(eq t (compare-strings elt 0 nil (car list) 0 nil t)))))
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    (setq list (cdr list)))
  list)
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(defun assq-delete-all (key alist)
  "Delete from ALIST all elements whose car is `eq' to KEY.
Return the modified alist.
Elements of ALIST that are not conses are ignored."
  (while (and (consp (car alist))
	      (eq (car (car alist)) key))
    (setq alist (cdr alist)))
  (let ((tail alist) tail-cdr)
    (while (setq tail-cdr (cdr tail))
      (if (and (consp (car tail-cdr))
	       (eq (car (car tail-cdr)) key))
	  (setcdr tail (cdr tail-cdr))
	(setq tail tail-cdr))))
  alist)

(defun rassq-delete-all (value alist)
  "Delete from ALIST all elements whose cdr is `eq' to VALUE.
Return the modified alist.
Elements of ALIST that are not conses are ignored."
  (while (and (consp (car alist))
	      (eq (cdr (car alist)) value))
    (setq alist (cdr alist)))
  (let ((tail alist) tail-cdr)
    (while (setq tail-cdr (cdr tail))
      (if (and (consp (car tail-cdr))
	       (eq (cdr (car tail-cdr)) value))
	  (setcdr tail (cdr tail-cdr))
	(setq tail tail-cdr))))
  alist)

(defun remove (elt seq)
  "Return a copy of SEQ with all occurrences of ELT removed.
SEQ must be a list, vector, or string.  The comparison is done with `equal'."
  (if (nlistp seq)
      ;; If SEQ isn't a list, there's no need to copy SEQ because
      ;; `delete' will return a new object.
      (delete elt seq)
    (delete elt (copy-sequence seq))))

(defun remq (elt list)
  "Return LIST with all occurrences of ELT removed.
The comparison is done with `eq'.  Contrary to `delq', this does not use
side-effects, and the argument LIST is not modified."
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  (while (and (eq elt (car list)) (setq list (cdr list))))
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  (if (memq elt list)
      (delq elt (copy-sequence list))
    list))
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;;;; Keymap support.
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(defun kbd (keys)
  "Convert KEYS to the internal Emacs key representation.
KEYS should be a string constant in the format used for
saving keyboard macros (see `edmacro-mode')."
  ;; Don't use a defalias, since the `pure' property is only true for
  ;; the calling convention of `kbd'.
  (read-kbd-macro keys))
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(put 'kbd 'pure t)
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(defun undefined ()
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  "Beep to tell the user this binding is undefined."
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  (interactive)
  (ding))

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;; Prevent the \{...} documentation construct
;; from mentioning keys that run this command.
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(put 'undefined 'suppress-keymap t)

(defun suppress-keymap (map &optional nodigits)
  "Make MAP override all normally self-inserting keys to be undefined.
Normally, as an exception, digits and minus-sign are set to make prefix args,
but optional second arg NODIGITS non-nil treats them like other chars."
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  (define-key map [remap self-insert-command] 'undefined)
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  (or nodigits
      (let (loop)
	(define-key map "-" 'negative-argument)
	;; Make plain numbers do numeric args.
	(setq loop ?0)
	(while (<= loop ?9)
	  (define-key map (char-to-string loop) 'digit-argument)
	  (setq loop (1+ loop))))))

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(defun make-composed-keymap (maps &optional parent)
  "Construct a new keymap composed of MAPS and inheriting from PARENT.
When looking up a key in the returned map, the key is looked in each
keymap of MAPS in turn until a binding is found.
If no binding is found in MAPS, the lookup continues in PARENT, if non-nil.
As always with keymap inheritance, a nil binding in MAPS overrides
any corresponding binding in PARENT, but it does not override corresponding
bindings in other keymaps of MAPS.
MAPS can be a list of keymaps or a single keymap.
PARENT if non-nil should be a keymap."
  `(keymap
    ,@(if (keymapp maps) (list maps) maps)
    ,@parent))

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(defun define-key-after (keymap key definition &optional after)
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  "Add binding in KEYMAP for KEY => DEFINITION, right after AFTER's binding.
This is like `define-key' except that the binding for KEY is placed
just after the binding for the event AFTER, instead of at the beginning
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of the map.  Note that AFTER must be an event type (like KEY), NOT a command
\(like DEFINITION).

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If AFTER is t or omitted, the new binding goes at the end of the keymap.
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AFTER should be a single event type--a symbol or a character, not a sequence.
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Bindings are always added before any inherited map.
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The order of bindings in a keymap only matters when it is used as
a menu, so this function is not useful for non-menu keymaps."
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  (unless after (setq after t))
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  (or (keymapp keymap)
      (signal 'wrong-type-argument (list 'keymapp keymap)))
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  (setq key
	(if (<= (length key) 1) (aref key 0)
	  (setq keymap (lookup-key keymap
				   (apply 'vector
					  (butlast (mapcar 'identity key)))))
	  (aref key (1- (length key)))))
  (let ((tail keymap) done inserted)
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    (while (and (not done) tail)
      ;; Delete any earlier bindings for the same key.
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      (if (eq (car-safe (car (cdr tail))) key)
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	  (setcdr tail (cdr (cdr tail))))
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      ;; If we hit an included map, go down that one.
      (if (keymapp (car tail)) (setq tail (car tail)))
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      ;; When we reach AFTER's binding, insert the new binding after.
      ;; If we reach an inherited keymap, insert just before that.
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      ;; If we reach the end of this keymap, insert at the end.
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      (if (or (and (eq (car-safe (car tail)) after)
		   (not (eq after t)))
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	      (eq (car (cdr tail)) 'keymap)
	      (null (cdr tail)))
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	  (progn
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	    ;; Stop the scan only if we find a parent keymap.
	    ;; Keep going past the inserted element
	    ;; so we can delete any duplications that come later.
	    (if (eq (car (cdr tail)) 'keymap)
		(setq done t))
	    ;; Don't insert more than once.
	    (or inserted
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		(setcdr tail (cons (cons key definition) (cdr tail))))
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	    (setq inserted t)))
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      (setq tail (cdr tail)))))

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(defun map-keymap-sorted (function keymap)
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  "Implement `map-keymap' with sorting.
Don't call this function; it is for internal use only."
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  (let (list)
    (map-keymap (lambda (a b) (push (cons a b) list))
                keymap)
    (setq list (sort list
                     (lambda (a b)
                       (setq a (car a) b (car b))
                       (if (integerp a)
                           (if (integerp b) (< a b)
                             t)
                         (if (integerp b) t
                           ;; string< also accepts symbols.
                           (string< a b))))))
    (dolist (p list)
      (funcall function (car p) (cdr p)))))
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(defun keymap--menu-item-binding (val)
  "Return the binding part of a menu-item."
  (cond
   ((not (consp val)) val)              ;Not a menu-item.
   ((eq 'menu-item (car val))
    (let* ((binding (nth 2 val))
           (plist (nthcdr 3 val))
           (filter (plist-get plist :filter)))
      (if filter (funcall filter binding)
        binding)))
   ((and (consp (cdr val)) (stringp (cadr val)))
    (cddr val))
   ((stringp (car val))
    (cdr val))
   (t val)))                            ;Not a menu-item either.

(defun keymap--menu-item-with-binding (item binding)
  "Build a menu-item like ITEM but with its binding changed to BINDING."
  (cond
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   ((not (consp item)) binding)		;Not a menu-item.
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   ((eq 'menu-item (car item))
    (setq item (copy-sequence item))
    (let ((tail (nthcdr 2 item)))
      (setcar tail binding)
      ;; Remove any potential filter.
      (if (plist-get (cdr tail) :filter)
          (setcdr tail (plist-put (cdr tail) :filter nil))))
    item)
   ((and (consp (cdr item)) (stringp (cadr item)))
    (cons (car item) (cons (cadr item) binding)))
   (t (cons (car item) binding))))

(defun keymap--merge-bindings (val1 val2)
  "Merge bindings VAL1 and VAL2."
  (let ((map1 (keymap--menu-item-binding val1))
        (map2 (keymap--menu-item-binding val2)))
    (if (not (and (keymapp map1) (keymapp map2)))
        ;; There's nothing to merge: val1 takes precedence.
        val1
      (let ((map (list 'keymap map1 map2))
            (item (if (keymapp val1) (if (keymapp val2) nil val2) val1)))
        (keymap--menu-item-with-binding item map)))))

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(defun keymap-canonicalize (map)
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  "Return a simpler equivalent keymap.
This resolves inheritance and redefinitions.  The returned keymap
should behave identically to a copy of KEYMAP w.r.t `lookup-key'
and use in active keymaps and menus.
Subkeymaps may be modified but are not canonicalized."
  ;; FIXME: Problem with the difference between a nil binding
  ;; that hides a binding in an inherited map and a nil binding that's ignored
  ;; to let some further binding visible.  Currently a nil binding hides all.
  ;; FIXME: we may want to carefully (re)order elements in case they're
  ;; menu-entries.
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  (let ((bindings ())
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        (ranges ())
	(prompt (keymap-prompt map)))
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    (while (keymapp map)
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      (setq map (map-keymap ;; -internal
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                 (lambda (key item)
                   (if (consp key)
                       ;; Treat char-ranges specially.
                       (push (cons key item) ranges)
                     (push (cons key item) bindings)))
                 map)))
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    ;; Create the new map.
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    (setq map (funcall (if ranges 'make-keymap 'make-sparse-keymap) prompt))
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    (dolist (binding ranges)
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      ;; Treat char-ranges specially.  FIXME: need to merge as well.
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      (define-key map (vector (car binding)) (cdr binding)))
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    ;; Process the bindings starting from the end.
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    (dolist (binding (prog1 bindings (setq bindings ())))
      (let* ((key (car binding))
             (oldbind (assq key bindings)))
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        (push (if (not oldbind)
                  ;; The normal case: no duplicate bindings.
                  binding
                ;; This is the second binding for this key.
                (setq bindings (delq oldbind bindings))
                (cons key (keymap--merge-bindings (cdr binding)
                                                  (cdr oldbind))))
              bindings)))
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    (nconc map bindings)))

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(put 'keyboard-translate-table 'char-table-extra-slots 0)

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(defun keyboard-translate (from to)
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  "Translate character FROM to TO on the current terminal.
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This function creates a `keyboard-translate-table' if necessary
and then modifies one entry in it."
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  (or (char-table-p keyboard-translate-table)
      (setq keyboard-translate-table
	    (make-char-table 'keyboard-translate-table nil)))
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  (aset keyboard-translate-table from to))

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;;;; Key binding commands.
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(defun global-set-key (key command)
  "Give KEY a global binding as COMMAND.
COMMAND is the command definition to use; usually it is
a symbol naming an interactively-callable function.
KEY is a key sequence; noninteractively, it is a string or vector
of characters or event types, and non-ASCII characters with codes
above 127 (such as ISO Latin-1) can be included if you use a vector.
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Note that if KEY has a local binding in the current buffer,
that local binding will continue to shadow any global binding
that you make with this function."
  (interactive "KSet key globally: \nCSet key %s to command: ")
  (or (vectorp key) (stringp key)
      (signal 'wrong-type-argument (list 'arrayp key)))
  (define-key (current-global-map) key command))
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(defun local-set-key (key command)
  "Give KEY a local binding as COMMAND.
COMMAND is the command definition to use; usually it is
a symbol naming an interactively-callable function.
KEY is a key sequence; noninteractively, it is a string or vector
of characters or event types, and non-ASCII characters with codes
above 127 (such as ISO Latin-1) can be included if you use a vector.
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The binding goes in the current buffer's local map,
which in most cases is shared with all other buffers in the same major mode."
  (interactive "KSet key locally: \nCSet key %s locally to command: ")
  (let ((map (current-local-map)))
    (or map
	(use-local-map (setq map (make-sparse-keymap))))
    (or (vectorp key) (stringp key)
	(signal 'wrong-type-argument (list 'arrayp key)))
    (define-key map key command)))
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(defun global-unset-key (key)
  "Remove global binding of KEY.
KEY is a string or vector representing a sequence of keystrokes."
  (interactive "kUnset key globally: ")
  (global-set-key key nil))
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(defun local-unset-key (key)
  "Remove local binding of KEY.
KEY is a string or vector representing a sequence of keystrokes."
  (interactive "kUnset key locally: ")
  (if (current-local-map)
      (local-set-key key nil))
  nil)

;;;; substitute-key-definition and its subroutines.

(defvar key-substitution-in-progress nil
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  "Used internally by `substitute-key-definition'.")
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(defun substitute-key-definition (olddef newdef keymap &optional oldmap prefix)
  "Replace OLDDEF with NEWDEF for any keys in KEYMAP now defined as OLDDEF.
In other words, OLDDEF is replaced with NEWDEF where ever it appears.
Alternatively, if optional fourth argument OLDMAP is specified, we redefine
in KEYMAP as NEWDEF those keys which are defined as OLDDEF in OLDMAP.

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If you don't specify OLDMAP, you can usually get the same results
in a cleaner way with command remapping, like this:
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  \(define-key KEYMAP [remap OLDDEF] NEWDEF)
\n(fn OLDDEF NEWDEF KEYMAP &optional OLDMAP)"
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  ;; Don't document PREFIX in the doc string because we don't want to
  ;; advertise it.  It's meant for recursive calls only.  Here's its
  ;; meaning

  ;; If optional argument PREFIX is specified, it should be a key
  ;; prefix, a string.  Redefined bindings will then be bound to the
  ;; original key, with PREFIX added at the front.
  (or prefix (setq prefix ""))
  (let* ((scan (or oldmap keymap))
	 (prefix1 (vconcat prefix [nil]))
	 (key-substitution-in-progress
	  (cons scan key-substitution-in-progress)))
    ;; Scan OLDMAP, finding each char or event-symbol that
    ;; has any definition, and act on it with hack-key.
    (map-keymap
     (lambda (char defn)
       (aset prefix1 (length prefix) char)
       (substitute-key-definition-key defn olddef newdef prefix1 keymap))
     scan)))

(defun substitute-key-definition-key (defn olddef newdef prefix keymap)
  (let (inner-def skipped menu-item)
    ;; Find the actual command name within the binding.
    (if (eq (car-safe defn) 'menu-item)
	(setq menu-item defn defn (nth 2 defn))
      ;; Skip past menu-prompt.
      (while (stringp (car-safe defn))
	(push (pop defn) skipped))
      ;; Skip past cached key-equivalence data for menu items.
      (if (consp (car-safe defn))
	  (setq defn (cdr defn))))
    (if (or (eq defn olddef)
	    ;; Compare with equal if definition is a key sequence.
	    ;; That is useful for operating on function-key-map.
	    (and (or (stringp defn) (vectorp defn))
		 (equal defn olddef)))
	(define-key keymap prefix
	  (if menu-item
	      (let ((copy (copy-sequence menu-item)))
		(setcar (nthcdr 2 copy) newdef)
		copy)
	    (nconc (nreverse skipped) newdef)))
      ;; Look past a symbol that names a keymap.
      (setq inner-def
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	    (or (indirect-function defn t) defn))
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      ;; For nested keymaps, we use `inner-def' rather than `defn' so as to
      ;; avoid autoloading a keymap.  This is mostly done to preserve the
      ;; original non-autoloading behavior of pre-map-keymap times.
      (if (and (keymapp inner-def)
	       ;; Avoid recursively scanning
	       ;; where KEYMAP does not have a submap.
	       (let ((elt (lookup-key keymap prefix)))
		 (or (null elt) (natnump elt) (keymapp elt)))
	       ;; Avoid recursively rescanning keymap being scanned.
	       (not (memq inner-def key-substitution-in-progress)))
	  ;; If this one isn't being scanned already, scan it now.
	  (substitute-key-definition olddef newdef keymap inner-def prefix)))))
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;;;; The global keymap tree.
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;; global-map, esc-map, and ctl-x-map have their values set up in
;; keymap.c; we just give them docstrings here.
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(defvar global-map nil
  "Default global keymap mapping Emacs keyboard input into commands.
The value is a keymap which is usually (but not necessarily) Emacs's
global map.")

(defvar esc-map nil
  "Default keymap for ESC (meta) commands.
The normal global definition of the character ESC indirects to this keymap.")

(defvar ctl-x-map nil
  "Default keymap for C-x commands.
The normal global definition of the character C-x indirects to this keymap.")

(defvar ctl-x-4-map (make-sparse-keymap)
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  "Keymap for subcommands of C-x 4.")
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(defalias 'ctl-x-4-prefix ctl-x-4-map)
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(define-key ctl-x-map "4" 'ctl-x-4-prefix)

(defvar ctl-x-5-map (make-sparse-keymap)
  "Keymap for frame commands.")
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(defalias 'ctl-x-5-prefix ctl-x-5-map)
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(define-key ctl-x-map "5" 'ctl-x-5-prefix)

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;;;; Event manipulation functions.

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(defconst listify-key-sequence-1 (logior 128 ?\M-\C-@))
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(defun listify-key-sequence (key)
  "Convert a key sequence to a list of events."
  (if (vectorp key)
      (append key nil)
    (mapcar (function (lambda (c)
			(if (> c 127)
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			    (logxor c listify-key-sequence-1)
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			  c)))
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	    key)))
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(defun eventp (obj)
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  "True if the argument is an event object."
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  (when obj
    (or (integerp obj)
        (and (symbolp obj) obj (not (keywordp obj)))
        (and (consp obj) (symbolp (car obj))))))
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(defun event-modifiers (event)
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  "Return a list of symbols representing the modifier keys in event EVENT.
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The elements of the list may include `meta', `control',
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`shift', `hyper', `super', `alt', `click', `double', `triple', `drag',
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and `down'.
EVENT may be an event or an event type.  If EVENT is a symbol
that has never been used in an event that has been read as input
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in the current Emacs session, then this function may fail to include
the `click' modifier."
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  (let ((type event))
    (if (listp type)
	(setq type (car type)))
    (if (symbolp type)
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        ;; Don't read event-symbol-elements directly since we're not
        ;; sure the symbol has already been parsed.
	(cdr (internal-event-symbol-parse-modifiers type))
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      (let ((list nil)
	    (char (logand type (lognot (logior ?\M-\^@ ?\C-\^@ ?\S-\^@
					       ?\H-\^@ ?\s-\^@ ?\A-\^@)))))
	(if (not (zerop (logand type ?\M-\^@)))
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	    (push 'meta list))
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	(if (or (not (zerop (logand type ?\C-\^@)))
		(< char 32))
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	    (push 'control list))
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	(if (or (not (zerop (logand type ?\S-\^@)))
		(/= char (downcase char)))
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	    (push 'shift list))
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	(or (zerop (logand type ?\H-\^@))
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	    (push 'hyper list))
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	(or (zerop (logand type ?\s-\^@))
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	    (push 'super list))
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	(or (zerop (logand type ?\A-\^@))
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	    (push 'alt list))
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	list))))

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(defun event-basic-type (event)
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  "Return the basic type of the given event (all modifiers removed).
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The value is a printing character (not upper case) or a symbol.
EVENT may be an event or an event type.  If EVENT is a symbol
that has never been used in an event that has been read as input
in the current Emacs session, then this function may return nil."
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  (if (consp event)
      (setq event (car event)))
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  (if (symbolp event)
      (car (get event 'event-symbol-elements))
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    (let* ((base (logand event (1- ?\A-\^@)))
	   (uncontrolled (if (< base 32) (logior base 64) base)))
      ;; There are some numbers that are invalid characters and
      ;; cause `downcase' to get an error.
      (condition-case ()
	  (downcase uncontrolled)
	(error uncontrolled)))))
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(defsubst mouse-movement-p (object)
  "Return non-nil if OBJECT is a mouse movement event."
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  (eq (car-safe object) 'mouse-movement))
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(defun mouse-event-p (object)
  "Return non-nil if OBJECT is a mouse click event."
  ;; is this really correct? maybe remove mouse-movement?
  (memq (event-basic-type object) '(mouse-1 mouse-2 mouse-3 mouse-movement)))

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(defun event-start (event)
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  "Return the starting position of EVENT.
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EVENT should be a click, drag, or key press event.
If it is a key press event, the return value has the form
    (WINDOW POS (0 . 0) 0)
If it is a click or drag event, it has the form
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   (WINDOW AREA-OR-POS (X . Y) TIMESTAMP OBJECT POS (COL . ROW)
    IMAGE (DX . DY) (WIDTH . HEIGHT))
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The `posn-' functions access elements of such lists.
For more information, see Info node `(elisp)Click Events'.

If EVENT is a mouse or key press or a mouse click, this is the
position of the event.  If EVENT is a drag, this is the starting
position of the drag."
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  (if (consp event) (nth 1 event)
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    (or (posn-at-point)
        (list (selected-window) (point) '(0 . 0) 0))))
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(defun event-end (event)
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  "Return the ending location of EVENT.
EVENT should be a click, drag, or key press event.
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If EVENT is a key press event, the return value has the form
    (WINDOW POS (0 . 0) 0)
If EVENT is a click event, this function is the same as
`event-start'.  For click and drag events, the return value has
the form
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   (WINDOW AREA-OR-POS (X . Y) TIMESTAMP OBJECT POS (COL . ROW)
    IMAGE (DX . DY) (WIDTH . HEIGHT))
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The `posn-' functions access elements of such lists.
For more information, see Info node `(elisp)Click Events'.

If EVENT is a mouse or key press or a mouse click, this is the
position of the event.  If EVENT is a drag, this is the starting
position of the drag."
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