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;;; minibuffer.el --- Minibuffer completion functions -*- lexical-binding: t -*-
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;; Copyright (C) 2008-2012  Free Software Foundation, Inc.
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;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
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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
;; 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,
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;; 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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;; Names with "--" are for functions and variables that are meant to be for
;; internal use only.

;; Functional completion tables have an extended calling conventions:
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;; The `action' can be (additionally to nil, t, and lambda) of the form
;; - (boundaries . SUFFIX) in which case it should return
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;;   (boundaries START . END).  See `completion-boundaries'.
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;;   Any other return value should be ignored (so we ignore values returned
;;   from completion tables that don't know about this new `action' form).
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;; - `metadata' in which case it should return (metadata . ALIST) where
;;   ALIST is the metadata of this table.  See `completion-metadata'.
;;   Any other return value should be ignored (so we ignore values returned
;;   from completion tables that don't know about this new `action' form).
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;;; Bugs:

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;; - completion-all-sorted-completions list all the completions, whereas
;;   it should only lists the ones that `try-completion' would consider.
;;   E.g.  it should honor completion-ignored-extensions.
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;; - choose-completion can't automatically figure out the boundaries
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;;   corresponding to the displayed completions because we only
;;   provide the start info but not the end info in
;;   completion-base-position.
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;; - quoting is problematic.  E.g. the double-dollar quoting used in
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;;   substitute-in-file-name (and hence read-file-name-internal) bumps
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;;   into various bugs:
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;; - choose-completion doesn't know how to quote the text it inserts.
;;   E.g. it fails to double the dollars in file-name completion, or
;;   to backslash-escape spaces and other chars in comint completion.
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Paul Eggert committed
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;;   - when completing ~/tmp/fo$$o, the highlighting in *Completions*
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;;     is off by one position.
;;   - all code like PCM which relies on all-completions to match
;;     its argument gets confused because all-completions returns unquoted
;;     texts (as desired for *Completions* output).
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;; - C-x C-f ~/*/sr ? should not list "~/./src".
;; - minibuffer-force-complete completes ~/src/emacs/t<!>/lisp/minibuffer.el
;;   to ~/src/emacs/trunk/ and throws away lisp/minibuffer.el.
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;;; Todo:

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;; - for M-x, cycle-sort commands that have no key binding first.
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;; - Make things like icomplete-mode or lightning-completion work with
;;   completion-in-region-mode.
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;; - extend `metadata':
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;;   - quoting/unquoting (so we can complete files names with envvars
;;     and backslashes, and all-completion can list names without
;;     quoting backslashes and dollars).
;;   - indicate how to turn all-completion's output into
;;     try-completion's output: e.g. completion-ignored-extensions.
;;     maybe that could be merged with the "quote" operation above.
;;   - indicate that `all-completions' doesn't do prefix-completion
;;     but just returns some list that relates in some other way to
;;     the provided string (as is the case in filecache.el), in which
;;     case partial-completion (for example) doesn't make any sense
;;     and neither does the completions-first-difference highlight.
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;;   - indicate how to display the completions in *Completions* (turn
;;     \n into something else, add special boundaries between
;;     completions).  E.g. when completing from the kill-ring.
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;; - case-sensitivity currently confuses two issues:
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;;   - whether or not a particular completion table should be case-sensitive
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;;     (i.e. whether strings that differ only by case are semantically
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;;     equivalent)
;;   - whether the user wants completion to pay attention to case.
;;   e.g. we may want to make it possible for the user to say "first try
;;   completion case-sensitively, and if that fails, try to ignore case".

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;; - add support for ** to pcm.
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;; - Add vc-file-name-completion-table to read-file-name-internal.
;; - A feature like completing-help.el.
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;;; Code:

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

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;;; Completion table manipulation

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;; New completion-table operation.
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(defun completion-boundaries (string table pred suffix)
  "Return the boundaries of the completions returned by TABLE for STRING.
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STRING is the string on which completion will be performed.
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SUFFIX is the string after point.
The result is of the form (START . END) where START is the position
in STRING of the beginning of the completion field and END is the position
in SUFFIX of the end of the completion field.
E.g. for simple completion tables, the result is always (0 . (length SUFFIX))
and for file names the result is the positions delimited by
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the closest directory separators."
  (let ((boundaries (if (functionp table)
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                        (funcall table string pred
                                 (cons 'boundaries suffix)))))
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    (if (not (eq (car-safe boundaries) 'boundaries))
        (setq boundaries nil))
    (cons (or (cadr boundaries) 0)
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          (or (cddr boundaries) (length suffix)))))
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(defun completion-metadata (string table pred)
  "Return the metadata of elements to complete at the end of STRING.
This metadata is an alist.  Currently understood keys are:
- `category': the kind of objects returned by `all-completions'.
   Used by `completion-category-overrides'.
- `annotation-function': function to add annotations in *Completions*.
   Takes one argument (STRING), which is a possible completion and
   returns a string to append to STRING.
- `display-sort-function': function to sort entries in *Completions*.
   Takes one argument (COMPLETIONS) and should return a new list
   of completions.  Can operate destructively.
- `cycle-sort-function': function to sort entries when cycling.
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   Works like `display-sort-function'.
The metadata of a completion table should be constant between two boundaries."
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  (let ((metadata (if (functionp table)
                      (funcall table string pred 'metadata))))
    (if (eq (car-safe metadata) 'metadata)
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        metadata
      '(metadata))))
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(defun completion--field-metadata (field-start)
  (completion-metadata (buffer-substring-no-properties field-start (point))
                       minibuffer-completion-table
                       minibuffer-completion-predicate))

(defun completion-metadata-get (metadata prop)
  (cdr (assq prop metadata)))

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(defun completion--some (fun xs)
  "Apply FUN to each element of XS in turn.
Return the first non-nil returned value.
Like CL's `some'."
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  (let ((firsterror nil)
        res)
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    (while (and (not res) xs)
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      (condition-case err
          (setq res (funcall fun (pop xs)))
        (error (unless firsterror (setq firsterror err)) nil)))
    (or res
        (if firsterror (signal (car firsterror) (cdr firsterror))))))
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(defun complete-with-action (action table string pred)
  "Perform completion ACTION.
STRING is the string to complete.
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TABLE is the completion table.
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PRED is a completion predicate.
ACTION can be one of nil, t or `lambda'."
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  (cond
   ((functionp table) (funcall table string pred action))
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   ((eq (car-safe action) 'boundaries) nil)
   ((eq action 'metadata) nil)
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   (t
    (funcall
     (cond
      ((null action) 'try-completion)
      ((eq action t) 'all-completions)
      (t 'test-completion))
     string table pred))))
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(defun completion-table-dynamic (fun)
  "Use function FUN as a dynamic completion table.
FUN is called with one argument, the string for which completion is required,
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and it should return an alist containing all the intended possible completions.
This alist may be a full list of possible completions so that FUN can ignore
the value of its argument.  If completion is performed in the minibuffer,
FUN will be called in the buffer from which the minibuffer was entered.
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The result of the `completion-table-dynamic' form is a function
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that can be used as the COLLECTION argument to `try-completion' and
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`all-completions'.  See Info node `(elisp)Programmed Completion'."
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  (lambda (string pred action)
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    (if (or (eq (car-safe action) 'boundaries) (eq action 'metadata))
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        ;; `fun' is not supposed to return another function but a plain old
        ;; completion table, whose boundaries are always trivial.
        nil
      (with-current-buffer (let ((win (minibuffer-selected-window)))
                             (if (window-live-p win) (window-buffer win)
                               (current-buffer)))
        (complete-with-action action (funcall fun string) string pred)))))
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(defmacro lazy-completion-table (var fun)
  "Initialize variable VAR as a lazy completion table.
If the completion table VAR is used for the first time (e.g., by passing VAR
as an argument to `try-completion'), the function FUN is called with no
arguments.  FUN must return the completion table that will be stored in VAR.
If completion is requested in the minibuffer, FUN will be called in the buffer
from which the minibuffer was entered.  The return value of
`lazy-completion-table' must be used to initialize the value of VAR.

You should give VAR a non-nil `risky-local-variable' property."
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  (declare (debug (symbolp lambda-expr)))
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  (let ((str (make-symbol "string")))
    `(completion-table-dynamic
      (lambda (,str)
        (when (functionp ,var)
          (setq ,var (,fun)))
        ,var))))

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(defun completion-table-case-fold (table &optional dont-fold)
  "Return new completion TABLE that is case insensitive.
If DONT-FOLD is non-nil, return a completion table that is
case sensitive instead."
  (lambda (string pred action)
    (let ((completion-ignore-case (not dont-fold)))
      (complete-with-action action table string pred))))
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(defun completion-table-with-context (prefix table string pred action)
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  ;; TODO: add `suffix' maybe?
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  (let ((pred
         (if (not (functionp pred))
             ;; Notice that `pred' may not be a function in some abusive cases.
             pred
           ;; Predicates are called differently depending on the nature of
           ;; the completion table :-(
           (cond
            ((vectorp table)            ;Obarray.
             (lambda (sym) (funcall pred (concat prefix (symbol-name sym)))))
            ((hash-table-p table)
             (lambda (s _v) (funcall pred (concat prefix s))))
            ((functionp table)
             (lambda (s) (funcall pred (concat prefix s))))
            (t                          ;Lists and alists.
             (lambda (s)
               (funcall pred (concat prefix (if (consp s) (car s) s)))))))))
    (if (eq (car-safe action) 'boundaries)
        (let* ((len (length prefix))
               (bound (completion-boundaries string table pred (cdr action))))
          (list* 'boundaries (+ (car bound) len) (cdr bound)))
      (let ((comp (complete-with-action action table string pred)))
        (cond
         ;; In case of try-completion, add the prefix.
         ((stringp comp) (concat prefix comp))
         (t comp))))))
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(defun completion-table-with-terminator (terminator table string pred action)
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  "Construct a completion table like TABLE but with an extra TERMINATOR.
This is meant to be called in a curried way by first passing TERMINATOR
and TABLE only (via `apply-partially').
TABLE is a completion table, and TERMINATOR is a string appended to TABLE's
completion if it is complete.  TERMINATOR is also used to determine the
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completion suffix's boundary.
TERMINATOR can also be a cons cell (TERMINATOR . TERMINATOR-REGEXP)
in which case TERMINATOR-REGEXP is a regular expression whose submatch
number 1 should match TERMINATOR.  This is used when there is a need to
distinguish occurrences of the TERMINATOR strings which are really terminators
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from others (e.g. escaped).  In this form, the car of TERMINATOR can also be,
instead of a string, a function that takes the completion and returns the
\"terminated\" string."
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  ;; FIXME: This implementation is not right since it only adds the terminator
  ;; in try-completion, so any completion-style that builds the completion via
  ;; all-completions won't get the terminator, and selecting an entry in
  ;; *Completions* won't get the terminator added either.
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  (cond
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   ((eq (car-safe action) 'boundaries)
    (let* ((suffix (cdr action))
           (bounds (completion-boundaries string table pred suffix))
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           (terminator-regexp (if (consp terminator)
                                  (cdr terminator) (regexp-quote terminator)))
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           (max (and terminator-regexp
                     (string-match terminator-regexp suffix))))
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      (list* 'boundaries (car bounds)
             (min (cdr bounds) (or max (length suffix))))))
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   ((eq action nil)
    (let ((comp (try-completion string table pred)))
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      (if (consp terminator) (setq terminator (car terminator)))
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      (if (eq comp t)
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          (if (functionp terminator)
              (funcall terminator string)
            (concat string terminator))
        (if (and (stringp comp) (not (zerop (length comp)))
                 ;; Try to avoid the second call to try-completion, since
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                 ;; it may be very inefficient (because `comp' made us
                 ;; jump to a new boundary, so we complete in that
                 ;; boundary with an empty start string).
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                 (let ((newbounds (completion-boundaries comp table pred "")))
                   (< (car newbounds) (length comp)))
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                 (eq (try-completion comp table pred) t))
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            (if (functionp terminator)
                (funcall terminator comp)
              (concat comp terminator))
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          comp))))
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   ;; completion-table-with-terminator is always used for
   ;; "sub-completions" so it's only called if the terminator is missing,
   ;; in which case `test-completion' should return nil.
   ((eq action 'lambda) nil)
   (t
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    ;; FIXME: We generally want the `try' and `all' behaviors to be
    ;; consistent so pcm can merge the `all' output to get the `try' output,
    ;; but that sometimes clashes with the need for `all' output to look
    ;; good in *Completions*.
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    ;; (mapcar (lambda (s) (concat s terminator))
    ;;         (all-completions string table pred))))
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    (complete-with-action action table string pred))))
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(defun completion-table-with-predicate (table pred1 strict string pred2 action)
  "Make a completion table equivalent to TABLE but filtered through PRED1.
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PRED1 is a function of one argument which returns non-nil if and only if the
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argument is an element of TABLE which should be considered for completion.
STRING, PRED2, and ACTION are the usual arguments to completion tables,
as described in `try-completion', `all-completions', and `test-completion'.
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If STRICT is t, the predicate always applies; if nil it only applies if
it does not reduce the set of possible completions to nothing.
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Note: TABLE needs to be a proper completion table which obeys predicates."
  (cond
   ((and (not strict) (eq action 'lambda))
    ;; Ignore pred1 since it doesn't really have to apply anyway.
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    (test-completion string table pred2))
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   (t
    (or (complete-with-action action table string
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                              (if (not (and pred1 pred2))
                                  (or pred1 pred2)
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                                (lambda (x)
                                  ;; Call `pred1' first, so that `pred2'
                                  ;; really can't tell that `x' is in table.
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                                  (and (funcall pred1 x) (funcall pred2 x)))))
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        ;; If completion failed and we're not applying pred1 strictly, try
        ;; again without pred1.
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        (and (not strict) pred1 pred2
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             (complete-with-action action table string pred2))))))
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(defun completion-table-in-turn (&rest tables)
  "Create a completion table that tries each table in TABLES in turn."
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  ;; FIXME: the boundaries may come from TABLE1 even when the completion list
  ;; is returned by TABLE2 (because TABLE1 returned an empty list).
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  (lambda (string pred action)
    (completion--some (lambda (table)
                        (complete-with-action action table string pred))
                      tables)))
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;; (defmacro complete-in-turn (a b) `(completion-table-in-turn ,a ,b))
;; (defmacro dynamic-completion-table (fun) `(completion-table-dynamic ,fun))
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(define-obsolete-function-alias
  'complete-in-turn 'completion-table-in-turn "23.1")
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(define-obsolete-function-alias
  'dynamic-completion-table 'completion-table-dynamic "23.1")
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;;; Minibuffer completion

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(defgroup minibuffer nil
  "Controlling the behavior of the minibuffer."
  :link '(custom-manual "(emacs)Minibuffer")
  :group 'environment)

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(defun minibuffer-message (message &rest args)
  "Temporarily display MESSAGE at the end of the minibuffer.
The text is displayed for `minibuffer-message-timeout' seconds,
or until the next input event arrives, whichever comes first.
Enclose MESSAGE in [...] if this is not yet the case.
If ARGS are provided, then pass MESSAGE through `format'."
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  (if (not (minibufferp (current-buffer)))
      (progn
        (if args
            (apply 'message message args)
          (message "%s" message))
        (prog1 (sit-for (or minibuffer-message-timeout 1000000))
          (message nil)))
    ;; Clear out any old echo-area message to make way for our new thing.
    (message nil)
    (setq message (if (and (null args) (string-match-p "\\` *\\[.+\\]\\'" message))
                      ;; Make sure we can put-text-property.
                      (copy-sequence message)
                    (concat " [" message "]")))
    (when args (setq message (apply 'format message args)))
    (let ((ol (make-overlay (point-max) (point-max) nil t t))
          ;; A quit during sit-for normally only interrupts the sit-for,
          ;; but since minibuffer-message is used at the end of a command,
          ;; at a time when the command has virtually finished already, a C-g
          ;; should really cause an abort-recursive-edit instead (i.e. as if
          ;; the C-g had been typed at top-level).  Binding inhibit-quit here
          ;; is an attempt to get that behavior.
          (inhibit-quit t))
      (unwind-protect
          (progn
            (unless (zerop (length message))
              ;; The current C cursor code doesn't know to use the overlay's
              ;; marker's stickiness to figure out whether to place the cursor
              ;; before or after the string, so let's spoon-feed it the pos.
              (put-text-property 0 1 'cursor t message))
            (overlay-put ol 'after-string message)
            (sit-for (or minibuffer-message-timeout 1000000)))
        (delete-overlay ol)))))
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(defun minibuffer-completion-contents ()
  "Return the user input in a minibuffer before point as a string.
That is what completion commands operate on."
  (buffer-substring (field-beginning) (point)))

(defun delete-minibuffer-contents ()
  "Delete all user input in a minibuffer.
If the current buffer is not a minibuffer, erase its entire contents."
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  ;; We used to do `delete-field' here, but when file name shadowing
  ;; is on, the field doesn't cover the entire minibuffer contents.
  (delete-region (minibuffer-prompt-end) (point-max)))
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(defvar completion-show-inline-help t
  "If non-nil, print helpful inline messages during completion.")

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(defcustom completion-auto-help t
  "Non-nil means automatically provide help for invalid completion input.
If the value is t the *Completion* buffer is displayed whenever completion
is requested but cannot be done.
If the value is `lazy', the *Completions* buffer is only displayed after
the second failed attempt to complete."
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  :type '(choice (const nil) (const t) (const lazy))
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  :group 'minibuffer)

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(defconst completion-styles-alist
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  '((emacs21
     completion-emacs21-try-completion completion-emacs21-all-completions
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     "Simple prefix-based completion.
I.e. when completing \"foo_bar\" (where _ is the position of point),
it will consider all completions candidates matching the glob
pattern \"foobar*\".")
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    (emacs22
     completion-emacs22-try-completion completion-emacs22-all-completions
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     "Prefix completion that only operates on the text before point.
I.e. when completing \"foo_bar\" (where _ is the position of point),
it will consider all completions candidates matching the glob
pattern \"foo*\" and will add back \"bar\" to the end of it.")
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    (basic
     completion-basic-try-completion completion-basic-all-completions
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     "Completion of the prefix before point and the suffix after point.
I.e. when completing \"foo_bar\" (where _ is the position of point),
it will consider all completions candidates matching the glob
pattern \"foo*bar*\".")
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    (partial-completion
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     completion-pcm-try-completion completion-pcm-all-completions
     "Completion of multiple words, each one taken as a prefix.
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I.e. when completing \"l-co_h\" (where _ is the position of point),
it will consider all completions candidates matching the glob
pattern \"l*-co*h*\".
Furthermore, for completions that are done step by step in subfields,
the method is applied to all the preceding fields that do not yet match.
E.g. C-x C-f /u/mo/s TAB could complete to /usr/monnier/src.
Additionally the user can use the char \"*\" as a glob pattern.")
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    (substring
     completion-substring-try-completion completion-substring-all-completions
     "Completion of the string taken as a substring.
I.e. when completing \"foo_bar\" (where _ is the position of point),
it will consider all completions candidates matching the glob
pattern \"*foo*bar*\".")
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    (initials
     completion-initials-try-completion completion-initials-all-completions
     "Completion of acronyms and initialisms.
E.g. can complete M-x lch to list-command-history
and C-x C-f ~/sew to ~/src/emacs/work."))
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  "List of available completion styles.
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Each element has the form (NAME TRY-COMPLETION ALL-COMPLETIONS DOC):
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where NAME is the name that should be used in `completion-styles',
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TRY-COMPLETION is the function that does the completion (it should
follow the same calling convention as `completion-try-completion'),
ALL-COMPLETIONS is the function that lists the completions (it should
follow the calling convention of `completion-all-completions'),
and DOC describes the way this style of completion works.")
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(defconst completion--styles-type
  `(repeat :tag "insert a new menu to add more styles"
           (choice ,@(mapcar (lambda (x) (list 'const (car x)))
                             completion-styles-alist))))
(defconst completion--cycling-threshold-type
  '(choice (const :tag "No cycling" nil)
           (const :tag "Always cycle" t)
           (integer :tag "Threshold")))

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(defcustom completion-styles
  ;; First, use `basic' because prefix completion has been the standard
  ;; for "ever" and works well in most cases, so using it first
  ;; ensures that we obey previous behavior in most cases.
  '(basic
    ;; Then use `partial-completion' because it has proven to
    ;; be a very convenient extension.
    partial-completion
    ;; Finally use `emacs22' so as to maintain (in many/most cases)
    ;; the previous behavior that when completing "foobar" with point
    ;; between "foo" and "bar" the completion try to complete "foo"
    ;; and simply add "bar" to the end of the result.
    emacs22)
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  "List of completion styles to use.
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The available styles are listed in `completion-styles-alist'.

Note that `completion-category-overrides' may override these
styles for specific categories, such as files, buffers, etc."
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  :type completion--styles-type
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  :group 'minibuffer
  :version "23.1")

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(defcustom completion-category-overrides
  '((buffer (styles . (basic substring))))
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  "List of `completion-styles' overrides for specific categories.
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Each override has the shape (CATEGORY . ALIST) where ALIST is
an association list that can specify properties such as:
- `styles': the list of `completion-styles' to use for that category.
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- `cycle': the `completion-cycle-threshold' to use for that category.
Categories are symbols such as `buffer' and `file', used when
completing buffer and file names, respectively."
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  :version "24.1"
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  :type `(alist :key-type (choice :tag "Category"
				  (const buffer)
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                                  (const file)
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                                  (const unicode-name)
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                                  symbol)
          :value-type
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          (set :tag "Properties to override"
	   (cons :tag "Completion Styles"
		 (const :tag "Select a style from the menu;" styles)
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		 ,completion--styles-type)
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           (cons :tag "Completion Cycling"
		 (const :tag "Select one value from the menu." cycle)
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                 ,completion--cycling-threshold-type))))
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(defun completion--styles (metadata)
  (let* ((cat (completion-metadata-get metadata 'category))
         (over (assq 'styles (cdr (assq cat completion-category-overrides)))))
    (if over
        (delete-dups (append (cdr over) (copy-sequence completion-styles)))
       completion-styles)))

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(defun completion-try-completion (string table pred point &optional metadata)
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  "Try to complete STRING using completion table TABLE.
Only the elements of table that satisfy predicate PRED are considered.
POINT is the position of point within STRING.
The return value can be either nil to indicate that there is no completion,
t to indicate that STRING is the only possible completion,
or a pair (STRING . NEWPOINT) of the completed result string together with
a new position for point."
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  (completion--some (lambda (style)
                      (funcall (nth 1 (assq style completion-styles-alist))
                               string table pred point))
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                    (completion--styles (or metadata
                                            (completion-metadata
                                             (substring string 0 point)
                                             table pred)))))
553

554
(defun completion-all-completions (string table pred point &optional metadata)
555 556 557
  "List the possible completions of STRING in completion table TABLE.
Only the elements of table that satisfy predicate PRED are considered.
POINT is the position of point within STRING.
558
The return value is a list of completions and may contain the base-size
559
in the last `cdr'."
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  ;; FIXME: We need to additionally return the info needed for the
  ;; second part of completion-base-position.
562 563 564
  (completion--some (lambda (style)
                      (funcall (nth 2 (assq style completion-styles-alist))
                               string table pred point))
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                    (completion--styles (or metadata
                                            (completion-metadata
                                             (substring string 0 point)
                                             table pred)))))
569

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(defun minibuffer--bitset (modified completions exact)
  (logior (if modified    4 0)
          (if completions 2 0)
          (if exact       1 0)))

575 576 577
(defun completion--replace (beg end newtext)
  "Replace the buffer text between BEG and END with NEWTEXT.
Moves point to the end of the new text."
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  ;; The properties on `newtext' include things like
  ;; completions-first-difference, which we don't want to include
  ;; upon insertion.
  (set-text-properties 0 (length newtext) nil newtext)
582
  ;; Maybe this should be in subr.el.
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  ;; You'd think this is trivial to do, but details matter if you want
  ;; to keep markers "at the right place" and be robust in the face of
  ;; after-change-functions that may themselves modify the buffer.
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  (let ((prefix-len 0))
    ;; Don't touch markers in the shared prefix (if any).
    (while (and (< prefix-len (length newtext))
                (< (+ beg prefix-len) end)
                (eq (char-after (+ beg prefix-len))
                    (aref newtext prefix-len)))
      (setq prefix-len (1+ prefix-len)))
    (unless (zerop prefix-len)
      (setq beg (+ beg prefix-len))
      (setq newtext (substring newtext prefix-len))))
  (let ((suffix-len 0))
    ;; Don't touch markers in the shared suffix (if any).
    (while (and (< suffix-len (length newtext))
                (< beg (- end suffix-len))
                (eq (char-before (- end suffix-len))
                    (aref newtext (- (length newtext) suffix-len 1))))
      (setq suffix-len (1+ suffix-len)))
    (unless (zerop suffix-len)
      (setq end (- end suffix-len))
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      (setq newtext (substring newtext 0 (- suffix-len))))
    (goto-char beg)
607
    (insert-and-inherit newtext)
608 609
    (delete-region (point) (+ (point) (- end beg)))
    (forward-char suffix-len)))
610

611 612 613 614 615 616 617 618
(defcustom completion-cycle-threshold nil
  "Number of completion candidates below which cycling is used.
Depending on this setting `minibuffer-complete' may use cycling,
like `minibuffer-force-complete'.
If nil, cycling is never used.
If t, cycling is always used.
If an integer, cycling is used as soon as there are fewer completion
candidates than this number."
619
  :version "24.1"
620
  :type completion--cycling-threshold-type)
621

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(defun completion--cycle-threshold (metadata)
  (let* ((cat (completion-metadata-get metadata 'category))
         (over (assq 'cycle (cdr (assq cat completion-category-overrides)))))
    (if over (cdr over) completion-cycle-threshold)))

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(defvar completion-all-sorted-completions nil)
(make-variable-buffer-local 'completion-all-sorted-completions)
(defvar completion-cycling nil)

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(defvar completion-fail-discreetly nil
  "If non-nil, stay quiet when there  is no match.")

634 635 636 637
(defun completion--message (msg)
  (if completion-show-inline-help
      (minibuffer-message msg)))

638 639
(defun completion--do-completion (&optional try-completion-function
                                            expect-exact)
640
  "Do the completion and return a summary of what happened.
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M = completion was performed, the text was Modified.
C = there were available Completions.
E = after completion we now have an Exact match.

 MCE
 000  0 no possible completion
 001  1 was already an exact and unique completion
 010  2 no completion happened
 011  3 was already an exact completion
 100  4 ??? impossible
 101  5 ??? impossible
 110  6 some completion happened
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 111  7 completed to an exact completion

TRY-COMPLETION-FUNCTION is a function to use in place of `try-completion'.
EXPECT-EXACT, if non-nil, means that there is no need to tell the user
when the buffer's text is already an exact match."
658 659 660
  (let* ((beg (field-beginning))
         (end (field-end))
         (string (buffer-substring beg end))
661
         (md (completion--field-metadata beg))
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         (comp (funcall (or try-completion-function
                            'completion-try-completion)
                        string
                        minibuffer-completion-table
                        minibuffer-completion-predicate
667 668
                        (- (point) beg)
                        md)))
669
    (cond
670
     ((null comp)
671
      (minibuffer-hide-completions)
672
      (unless completion-fail-discreetly
673
	(ding)
674
	(completion--message "No match"))
675
      (minibuffer--bitset nil nil nil))
676
     ((eq t comp)
677
      (minibuffer-hide-completions)
678 679 680
      (goto-char end)
      (completion--done string 'finished
                        (unless expect-exact "Sole completion"))
681
      (minibuffer--bitset nil nil t))   ;Exact and unique match.
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     (t
      ;; `completed' should be t if some completion was done, which doesn't
      ;; include simply changing the case of the entered string.  However,
      ;; for appearance, the string is rewritten if the case changes.
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      (let* ((comp-pos (cdr comp))
             (completion (car comp))
             (completed (not (eq t (compare-strings completion nil nil
                                                    string nil nil t))))
             (unchanged (eq t (compare-strings completion nil nil
                                               string nil nil nil))))
692
        (if unchanged
693
	    (goto-char end)
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          ;; Insert in minibuffer the chars we got.
          (completion--replace beg end completion))
	;; Move point to its completion-mandated destination.
	(forward-char (- comp-pos (length completion)))
698

699
        (if (not (or unchanged completed))
700 701 702 703
            ;; The case of the string changed, but that's all.  We're not sure
            ;; whether this is a unique completion or not, so try again using
            ;; the real case (this shouldn't recurse again, because the next
            ;; time try-completion will return either t or the exact string).
704
            (completion--do-completion try-completion-function expect-exact)
705 706

          ;; It did find a match.  Do we match some possibility exactly now?
707
          (let* ((exact (test-completion completion
708 709
                                         minibuffer-completion-table
                                         minibuffer-completion-predicate))
710
                 (threshold (completion--cycle-threshold md))
711 712 713 714 715 716
                 (comps
                  ;; Check to see if we want to do cycling.  We do it
                  ;; here, after having performed the normal completion,
                  ;; so as to take advantage of the difference between
                  ;; try-completion and all-completions, for things
                  ;; like completion-ignored-extensions.
717
                  (when (and threshold
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                             ;; Check that the completion didn't make
                             ;; us jump to a different boundary.
                             (or (not completed)
                                 (< (car (completion-boundaries
                                          (substring completion 0 comp-pos)
                                          minibuffer-completion-table
                                          minibuffer-completion-predicate
725 726 727
                                         ""))
                                   comp-pos)))
                   (completion-all-sorted-completions))))
728
            (completion--flush-all-sorted-completions)
729
            (cond
730 731
             ((and (consp (cdr comps)) ;; There's something to cycle.
                   (not (ignore-errors
732 733
                          ;; This signal an (intended) error if comps is too
                          ;; short or if completion-cycle-threshold is t.
734
                          (consp (nthcdr threshold comps)))))
735 736 737
              ;; Fewer than completion-cycle-threshold remaining
              ;; completions: let's cycle.
              (setq completed t exact t)
738
              (completion--cache-all-sorted-completions comps)
739 740
              (minibuffer-force-complete))
             (completed
741 742 743
              ;; We could also decide to refresh the completions,
              ;; if they're displayed (and assuming there are
              ;; completions left).
744 745 746 747 748 749 750
              (minibuffer-hide-completions)
              (if exact
                  ;; If completion did not put point at end of field,
                  ;; it's a sign that completion is not finished.
                  (completion--done completion
                                    (if (< comp-pos (length completion))
                                        'exact 'unknown))))
751 752
             ;; Show the completion table, if requested.
             ((not exact)
753 754 755
	      (if (case completion-auto-help
                    (lazy (eq this-command last-command))
                    (t completion-auto-help))
756
                  (minibuffer-completion-help)
757
                (completion--message "Next char not unique")))
758
             ;; If the last exact completion and this one were the same, it
759
             ;; means we've already given a "Complete, but not unique" message
760
             ;; and the user's hit TAB again, so now we give him help.
761 762 763 764 765 766
             (t
              (if (and (eq this-command last-command) completion-auto-help)
                  (minibuffer-completion-help))
              (completion--done completion 'exact
                                (unless expect-exact
                                  "Complete, but not unique"))))
767 768

            (minibuffer--bitset completed t exact))))))))
769 770 771 772 773 774 775 776 777 778

(defun minibuffer-complete ()
  "Complete the minibuffer contents as far as possible.
Return nil if there is no valid completion, else t.
If no characters can be completed, display a list of possible completions.
If you repeat this command after it displayed such a list,
scroll the window of possible completions."
  (interactive)
  ;; If the previous command was not this,
  ;; mark the completion buffer obsolete.
779 780
  (setq this-command 'completion-at-point)
  (unless (eq 'completion-at-point last-command)
781
    (completion--flush-all-sorted-completions)
782 783
    (setq minibuffer-scroll-window nil))

784
  (cond
785 786
   ;; If there's a fresh completion window with a live buffer,
   ;; and this command is repeated, scroll that window.
787 788
   ((window-live-p minibuffer-scroll-window)
    (let ((window minibuffer-scroll-window))
789 790 791 792 793 794
      (with-current-buffer (window-buffer window)
        (if (pos-visible-in-window-p (point-max) window)
            ;; If end is in view, scroll up to the beginning.
            (set-window-start window (point-min) nil)
          ;; Else scroll down one screen.
          (scroll-other-window))
795 796
        nil)))
   ;; If we're cycling, keep on cycling.
797
   ((and completion-cycling completion-all-sorted-completions)
798 799 800
    (minibuffer-force-complete)
    t)
   (t (case (completion--do-completion)
801 802
        (#b000 nil)
        (t     t)))))
803

804 805 806 807 808
(defun completion--cache-all-sorted-completions (comps)
  (add-hook 'after-change-functions
               'completion--flush-all-sorted-completions nil t)
  (setq completion-all-sorted-completions comps))

809
(defun completion--flush-all-sorted-completions (&rest _ignore)
810 811
  (remove-hook 'after-change-functions
               'completion--flush-all-sorted-completions t)
812
  (setq completion-cycling nil)
813 814
  (setq completion-all-sorted-completions nil))

815 816 817 818 819 820 821 822
(defun completion--metadata (string base md-at-point table pred)
  ;; Like completion-metadata, but for the specific case of getting the
  ;; metadata at `base', which tends to trigger pathological behavior for old
  ;; completion tables which don't understand `metadata'.
  (let ((bounds (completion-boundaries string table pred "")))
    (if (eq (car bounds) base) md-at-point
      (completion-metadata (substring string 0 base) table pred))))

823 824 825 826
(defun completion-all-sorted-completions ()
  (or completion-all-sorted-completions
      (let* ((start (field-beginning))
             (end (field-end))
827
             (string (buffer-substring start end))
828
             (md (completion--field-metadata start))
829 830 831 832 833
             (all (completion-all-completions
                   string
                   minibuffer-completion-table
                   minibuffer-completion-predicate
                   (- (point) start)
834
                   md))
835
             (last (last all))
836
             (base-size (or (cdr last) 0))
837 838 839 840 841
             (all-md (completion--metadata (buffer-substring-no-properties
                                            start (point))
                                           base-size md
                                           minibuffer-completion-table
                                           minibuffer-completion-predicate))
842
             (sort-fun (completion-metadata-get all-md 'cycle-sort-function)))
843 844
        (when last
          (setcdr last nil)
845 846 847
          (setq all (if sort-fun (funcall sort-fun all)
                      ;; Prefer shorter completions, by default.
                      (sort all (lambda (c1 c2) (< (length c1) (length c2))))))
848
          ;; Prefer recently used completions.
849 850 851 852 853
          (when (minibufferp)
            (let ((hist (symbol-value minibuffer-history-variable)))
              (setq all (sort all (lambda (c1 c2)
                                    (> (length (member c1 hist))
                                       (length (member c2 hist))))))))
854 855 856
          ;; Cache the result.  This is not just for speed, but also so that
          ;; repeated calls to minibuffer-force-complete can cycle through
          ;; all possibilities.
857
          (completion--cache-all-sorted-completions (nconc all base-size))))))
858 859 860 861 862 863

(defun minibuffer-force-complete ()
  "Complete the minibuffer to an exact match.
Repeated uses step through the possible completions."
  (interactive)
  ;; FIXME: Need to deal with the extra-size issue here as well.
864 865
  ;; FIXME: ~/src/emacs/t<M-TAB>/lisp/minibuffer.el completes to
  ;; ~/src/emacs/trunk/ and throws away lisp/minibuffer.el.
866 867
  (let* ((start (field-beginning))
         (end (field-end))
868
         ;; (md (completion--field-metadata start))
869 870 871 872
         (all (completion-all-sorted-completions))
         (base (+ start (or (cdr (last all)) 0))))
    (cond
     ((not (consp all))
873
        (completion--message
874 875 876 877 878 879 880 881 882
       (if all "No more completions" "No completions")))
     ((not (consp (cdr all)))
      (let ((mod (equal (car all) (buffer-substring-no-properties base end))))
        (if mod (completion--replace base end (car all)))
        (completion--done (buffer-substring-no-properties start (point))
                          'finished (unless mod "Sole completion"))))
     (t
      (completion--replace base end (car all))
      (completion--done (buffer-substring-no-properties start (point)) 'sole)
883 884
      ;; Set cycling after modifying the buffer since the flush hook resets it.
      (setq completion-cycling t)
885 886 887 888 889
      ;; If completing file names, (car all) may be a directory, so we'd now
      ;; have a new set of possible completions and might want to reset
      ;; completion-all-sorted-completions to nil, but we prefer not to,
      ;; so that repeated calls minibuffer-force-complete still cycle
      ;; through the previous possible completions.
890 891
      (let ((last (last all)))
        (setcdr last (cons (car all) (cdr last)))
892
        (completion--cache-all-sorted-completions (cdr all)))))))
893

894
(defvar minibuffer-confirm-exit-commands
895
  '(minibuffer-complete minibuffer-complete-word PC-complete PC-complete-word)
896 897 898
  "A list of commands which cause an immediately following
`minibuffer-complete-and-exit' to ask for extra confirmation.")

899
(defun minibuffer-complete-and-exit ()
900 901 902 903 904 905 906 907 908 909
  "Exit if the minibuffer contains a valid completion.
Otherwise, try to complete the minibuffer contents.  If
completion leads to a valid completion, a repetition of this
command will exit.

If `minibuffer-completion-confirm' is `confirm', do not try to
 complete; instead, ask for confirmation and accept any input if
 confirmed.
If `minibuffer-completion-confirm' is `confirm-after-completion',
 do not try to complete; instead, ask for confirmation if the
910 911 912
 preceding minibuffer command was a member of
 `minibuffer-confirm-exit-commands', and accept the input
 otherwise."
913
  (interactive)
914 915
  (let ((beg (field-beginning))
        (end (field-end)))
916 917 918 919 920 921
    (cond
     ;; Allow user to specify null string
     ((= beg end) (exit-minibuffer))
     ((test-completion (buffer-substring beg end)
                       minibuffer-completion-table
                       minibuffer-completion-predicate)
922 923 924 925 926 927
      ;; FIXME: completion-ignore-case has various slightly
      ;; incompatible meanings.  E.g. it can reflect whether the user
      ;; wants completion to pay attention to case, or whether the
      ;; string will be used in a context where case is significant.
      ;; E.g. usually try-completion should obey the first, whereas
      ;; test-completion should obey the second.
928 929
      (when completion-ignore-case
        ;; Fixup case of the field, if necessary.
930
        (let* ((string (buffer-substring beg end))
931 932 933 934
               (compl (try-completion
                       string
                       minibuffer-completion-table
                       minibuffer-completion-predicate)))
935
          (when (and (stringp compl) (not (equal string compl))
936 937
                     ;; If it weren't for this piece of paranoia, I'd replace
                     ;; the whole thing with a call to do-completion.
938 939 940 941
                     ;; This is important, e.g. when the current minibuffer's
                     ;; content is a directory which only contains a single
                     ;; file, so `try-completion' actually completes to
                     ;; that file.
942
                     (= (length string) (length compl)))
943
            (completion--replace beg end compl))))
944
      (exit-minibuffer))
945

946
     ((memq minibuffer-completion-confirm '(confirm confirm-after-completion))
947
      ;; The user is permitted to exit with an input that's rejected
948
      ;; by test-completion, after confirming her choice.
949 950 951 952 953 954
      (if (or (eq last-command this-command)
              ;; For `confirm-after-completion' we only ask for confirmation
              ;; if trying to exit immediately after typing TAB (this
              ;; catches most minibuffer typos).
              (and (eq minibuffer-completion-confirm 'confirm-after-completion)
                   (not (memq last-command minibuffer-confirm-exit-commands))))
955 956 957
          (exit-minibuffer)
        (minibuffer-message "Confirm")
        nil))
958

959 960 961
     (t
      ;; Call do-completion, but ignore errors.
      (case (condition-case nil
962
                (completion--do-completion nil 'expect-exact)
963
              (error 1))
964 965 966 967 968
        ((#b001 #b011) (exit-minibuffer))
        (#b111 (if (not minibuffer-completion-confirm)
                   (exit-minibuffer)
                 (minibuffer-message "Confirm")
                 nil))
969 970
        (t nil))))))

971 972
(defun completion--try-word-completion (string table predicate point md)
  (let ((comp (completion-try-completion string table predicate point md)))
973 974
    (if (not (consp comp))
        comp
975

976 977
      ;; If completion finds next char not unique,
      ;; consider adding a space or a hyphen.