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;;; minibuffer.el --- Minibuffer completion functions -*- lexical-binding: t -*-
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;; Copyright (C) 2008-2019 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 <https://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 lists all the completions, whereas
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;;   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.
;; - 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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;; - Make *Completions* readable even if some of the completion
;;   entries have LF chars or spaces in them (including at
;;   beginning/end) or are very long.
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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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;;   - indicate how to turn all-completion's output into
;;     try-completion's output: e.g. completion-ignored-extensions.
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;;     maybe that could be merged with the "quote" operation.
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;;   - 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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;;   Maybe the trick is that we should distinguish completion-ignore-case in
;;   try/all-completions (obey user's preference) from its use in
;;   test-completion (obey the underlying object's semantics).
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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:

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(eval-when-compile (require 'cl-lib))
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;;; Completion table manipulation

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;; New completion-table operation.
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(defun completion-boundaries (string collection pred suffix)
  "Return the boundaries of text on which COLLECTION will operate.
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STRING is the string on which completion will be performed.
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SUFFIX is the string after point.
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If COLLECTION is a function, it is called with 3 arguments: STRING,
PRED, and a cons cell of the form (boundaries . SUFFIX).

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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."
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  (let ((boundaries (if (functionp collection)
                        (funcall collection string pred
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                                 (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-unless-debug err
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          (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 &optional switch-buffer)
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  "Use function FUN as a dynamic completion table.
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FUN is called with one argument, the string for which completion is requested,
and it should return a completion table containing all the intended possible
completions.
This table is allowed to include elements that do not actually match the
string: they will be automatically filtered out.
The completion table returned by FUN can use any of the usual formats of
completion tables such as lists, alists, and hash-tables.

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If SWITCH-BUFFER is non-nil and 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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The completion table returned by `completion-table-dynamic' has empty
metadata and trivial boundaries.
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See also the related function `completion-table-with-cache'."
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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
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      (with-current-buffer (if (not switch-buffer) (current-buffer)
                             (let ((win (minibuffer-selected-window)))
                               (if (window-live-p win) (window-buffer win)
                                 (current-buffer))))
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        (complete-with-action action (funcall fun string) string pred)))))
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(defun completion-table-with-cache (fun &optional ignore-case)
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  "Create dynamic completion table from function FUN, with cache.
This is a wrapper for `completion-table-dynamic' that saves the last
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argument-result pair from FUN, so that several lookups with the
same argument (or with an argument that starts with the first one)
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only need to call FUN once.  This can be useful when FUN performs a
relatively slow operation, such as calling an external process.

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When IGNORE-CASE is non-nil, FUN is expected to be case-insensitive."
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  ;; See eg bug#11906.
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  (let* (last-arg last-result
         (new-fun
          (lambda (arg)
            (if (and last-arg (string-prefix-p last-arg arg ignore-case))
                last-result
              (prog1
                  (setq last-result (funcall fun arg))
                (setq last-arg arg))))))
    (completion-table-dynamic new-fun)))

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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)
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          (setq ,var (funcall #',fun)))
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        ,var)
      'do-switch-buffer)))
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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-subvert (table s1 s2)
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  "Return a completion table from TABLE with S1 replaced by S2.
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The result is a completion table which completes strings of the
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form (concat S1 S) in the same way as TABLE completes strings of
the form (concat S2 S)."
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  (lambda (string pred action)
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    (let* ((str (if (string-prefix-p s1 string completion-ignore-case)
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                    (concat s2 (substring string (length s1)))))
           (res (if str (complete-with-action action table str pred))))
      (when res
        (cond
         ((eq (car-safe action) 'boundaries)
          (let ((beg (or (and (eq (car-safe res) 'boundaries) (cadr res)) 0)))
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            `(boundaries
              ,(max (length s1)
                    (+ beg (- (length s1) (length s2))))
              . ,(and (eq (car-safe res) 'boundaries) (cddr res)))))
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         ((stringp res)
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          (if (string-prefix-p s2 res completion-ignore-case)
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              (concat s1 (substring res (length s2)))))
         ((eq action t)
          (let ((bounds (completion-boundaries str table pred "")))
            (if (>= (car bounds) (length s2))
                res
              (let ((re (concat "\\`"
                                (regexp-quote (substring s2 (car bounds))))))
                (delq nil
                      (mapcar (lambda (c)
                                (if (string-match re c)
                                    (substring c (match-end 0))))
                              res))))))
         ;; E.g. action=nil and it's the only completion.
         (res))))))

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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))))
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          `(boundaries ,(+ (car bound) len) . ,(cdr bound)))
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      (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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      `(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 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'.  If
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STRICT is non-nil, the predicate always applies; if nil it only
applies if it does not reduce the set of possible completions to
nothing.  Note: TABLE needs to be a proper completion table which
obeys predicates."
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  (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
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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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  ;; Same potential problem if any of the tables use quoting.
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  (lambda (string pred action)
    (completion--some (lambda (table)
                        (complete-with-action action table string pred))
                      tables)))
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(defun completion-table-merge (&rest tables)
  "Create a completion table that collects completions from all TABLES."
  ;; FIXME: same caveats as in `completion-table-in-turn'.
  (lambda (string pred action)
    (cond
     ((null action)
      (let ((retvals (mapcar (lambda (table)
                               (try-completion string table pred))
                             tables)))
        (if (member string retvals)
            string
          (try-completion string
                          (mapcar (lambda (value)
                                    (if (eq value t) string value))
                                  (delq nil retvals))
                          pred))))
     ((eq action t)
      (apply #'append (mapcar (lambda (table)
                                (all-completions string table pred))
                              tables)))
     (t
      (completion--some (lambda (table)
                          (complete-with-action action table string pred))
                        tables)))))

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(defun completion-table-with-quoting (table unquote requote)
  ;; A difficult part of completion-with-quoting is to map positions in the
  ;; quoted string to equivalent positions in the unquoted string and
  ;; vice-versa.  There is no efficient and reliable algorithm that works for
  ;; arbitrary quote and unquote functions.
  ;; So to map from quoted positions to unquoted positions, we simply assume
  ;; that `concat' and `unquote' commute (which tends to be the case).
  ;; And we ask `requote' to do the work of mapping from unquoted positions
  ;; back to quoted positions.
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  ;; FIXME: For some forms of "quoting" such as the truncation behavior of
  ;; substitute-in-file-name, it would be desirable not to requote completely.
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  "Return a new completion table operating on quoted text.
TABLE operates on the unquoted text.
UNQUOTE is a function that takes a string and returns a new unquoted string.
REQUOTE is a function of 2 args (UPOS QSTR) where
  QSTR is a string entered by the user (and hence indicating
  the user's preferred form of quoting); and
  UPOS is a position within the unquoted form of QSTR.
REQUOTE should return a pair (QPOS . QFUN) such that QPOS is the
position corresponding to UPOS but in QSTR, and QFUN is a function
of one argument (a string) which returns that argument appropriately quoted
for use at QPOS."
  ;; FIXME: One problem with the current setup is that `qfun' doesn't know if
  ;; its argument is "the end of the completion", so if the quoting used double
  ;; quotes (for example), we end up completing "fo" to "foobar and throwing
  ;; away the closing double quote.
  (lambda (string pred action)
    (cond
     ((eq action 'metadata)
      (append (completion-metadata string table pred)
              '((completion--unquote-requote . t))))

     ((eq action 'lambda) ;;test-completion
      (let ((ustring (funcall unquote string)))
        (test-completion ustring table pred)))

     ((eq (car-safe action) 'boundaries)
      (let* ((ustring (funcall unquote string))
             (qsuffix (cdr action))
             (ufull (if (zerop (length qsuffix)) ustring
                      (funcall unquote (concat string qsuffix))))
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             (_ (cl-assert (string-prefix-p ustring ufull)))
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             (usuffix (substring ufull (length ustring)))
             (boundaries (completion-boundaries ustring table pred usuffix))
             (qlboundary (car (funcall requote (car boundaries) string)))
             (qrboundary (if (zerop (cdr boundaries)) 0 ;Common case.
                           (let* ((urfullboundary
                                   (+ (cdr boundaries) (length ustring))))
                             (- (car (funcall requote urfullboundary
                                              (concat string qsuffix)))
                                (length string))))))
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        `(boundaries ,qlboundary . ,qrboundary)))
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     ;; In "normal" use a c-t-with-quoting completion table should never be
     ;; called with action in (t nil) because `completion--unquote' should have
     ;; been called before and would have returned a different completion table
     ;; to apply to the unquoted text.  But there's still a lot of code around
     ;; that likes to use all/try-completions directly, so we do our best to
     ;; handle those calls as well as we can.

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     ((eq action nil) ;;try-completion
      (let* ((ustring (funcall unquote string))
             (completion (try-completion ustring table pred)))
        ;; Most forms of quoting allow several ways to quote the same string.
        ;; So here we could simply requote `completion' in a kind of
        ;; "canonical" quoted form without paying attention to the way
        ;; `string' was quoted.  But since we have to solve the more complex
        ;; problems of "pay attention to the original quoting" for
        ;; all-completions, we may as well use it here, since it provides
        ;; a nicer behavior.
        (if (not (stringp completion)) completion
          (car (completion--twq-try
                string ustring completion 0 unquote requote)))))

     ((eq action t) ;;all-completions
      ;; When all-completions is used for completion-try/all-completions
      ;; (e.g. for `pcm' style), we can't do the job properly here because
      ;; the caller will match our output against some pattern derived from
      ;; the user's (quoted) input, and we don't have access to that
      ;; pattern, so we can't know how to requote our output so that it
      ;; matches the quoting used in the pattern.  It is to fix this
      ;; fundamental problem that we have to introduce the new
      ;; unquote-requote method so that completion-try/all-completions can
      ;; pass the unquoted string to the style functions.
      (pcase-let*
          ((ustring (funcall unquote string))
           (completions (all-completions ustring table pred))
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           (boundary (car (completion-boundaries ustring table pred "")))
           (completions
            (completion--twq-all
             string ustring completions boundary unquote requote))
           (last (last completions)))
        (when (consp last) (setcdr last nil))
        completions))
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     ((eq action 'completion--unquote)
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      ;; PRED is really a POINT in STRING.
      ;; We should return a new set (STRING TABLE POINT REQUOTE)
      ;; where STRING is a new (unquoted) STRING to match against the new TABLE
      ;; using a new POINT inside it, and REQUOTE is a requoting function which
      ;; should reverse the unquoting, (i.e. it receives the completion result
      ;; of using the new TABLE and should turn it into the corresponding
      ;; quoted result).
      (let* ((qpos pred)
	     (ustring (funcall unquote string))
	     (uprefix (funcall unquote (substring string 0 qpos)))
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	     ;; FIXME: we really should pass `qpos' to `unquote' and have that
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	     ;; function give us the corresponding `uqpos'.  But for now we
	     ;; presume (more or less) that `concat' and `unquote' commute.
	     (uqpos (if (string-prefix-p uprefix ustring)
			;; Yay!!  They do seem to commute!
			(length uprefix)
		      ;; They don't commute this time!  :-(
		      ;; Maybe qpos is in some text that disappears in the
		      ;; ustring (bug#17239).  Let's try a second chance guess.
		      (let ((usuffix (funcall unquote (substring string qpos))))
			(if (string-suffix-p usuffix ustring)
			    ;; Yay!!  They still "commute" in a sense!
			    (- (length ustring) (length usuffix))
			  ;; Still no luck!  Let's just choose *some* position
			  ;; within ustring.
			  (/ (+ (min (length uprefix) (length ustring))
				(max (- (length ustring) (length usuffix)) 0))
			     2))))))
        (list ustring table uqpos
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              (lambda (unquoted-result op)
                (pcase op
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                  (1 ;;try
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                   (if (not (stringp (car-safe unquoted-result)))
                       unquoted-result
                     (completion--twq-try
                      string ustring
                      (car unquoted-result) (cdr unquoted-result)
                      unquote requote)))
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                  (2 ;;all
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                   (let* ((last (last unquoted-result))
                          (base (or (cdr last) 0)))
                     (when last
                       (setcdr last nil)
                       (completion--twq-all string ustring
                                            unquoted-result base
                                            unquote requote))))))))))))

(defun completion--twq-try (string ustring completion point
                                   unquote requote)
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  ;; Basically two cases: either the new result is
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  ;; - commonprefix1 <point> morecommonprefix <qpos> suffix
  ;; - commonprefix <qpos> newprefix <point> suffix
  (pcase-let*
      ((prefix (fill-common-string-prefix ustring completion))
       (suffix (substring completion (max point (length prefix))))
       (`(,qpos . ,qfun) (funcall requote (length prefix) string))
       (qstr1 (if (> point (length prefix))
                  (funcall qfun (substring completion (length prefix) point))))
       (qsuffix (funcall qfun suffix))
       (qstring (concat (substring string 0 qpos) qstr1 qsuffix))
       (qpoint
        (cond
         ((zerop point) 0)
         ((> point (length prefix)) (+ qpos (length qstr1)))
         (t (car (funcall requote point string))))))
    ;; Make sure `requote' worked.
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    (if (equal (funcall unquote qstring) completion)
	(cons qstring qpoint)
      ;; If requote failed (e.g. because sifn-requote did not handle
      ;; Tramp's "/foo:/bar//baz -> /foo:/baz" truncation), then at least
      ;; try requote properly.
      (let ((qstr (funcall qfun completion)))
	(cons qstr (length qstr))))))
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(defun completion--string-equal-p (s1 s2)
  (eq t (compare-strings s1 nil nil s2 nil nil 'ignore-case)))

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(defun completion--twq-all (string ustring completions boundary
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                                   _unquote requote)
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  (when completions
    (pcase-let*
        ((prefix
          (let ((completion-regexp-list nil))
            (try-completion "" (cons (substring ustring boundary)
                                     completions))))
         (`(,qfullpos . ,qfun)
          (funcall requote (+ boundary (length prefix)) string))
         (qfullprefix (substring string 0 qfullpos))
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	 ;; FIXME: This assertion can be wrong, e.g. in Cygwin, where
	 ;; (unquote "c:\bin") => "/usr/bin" but (unquote "c:\") => "/".
         ;;(cl-assert (completion--string-equal-p
         ;;            (funcall unquote qfullprefix)
         ;;            (concat (substring ustring 0 boundary) prefix))
         ;;           t))
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         (qboundary (car (funcall requote boundary string)))
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         (_ (cl-assert (<= qboundary qfullpos)))
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         ;; FIXME: this split/quote/concat business messes up the carefully
         ;; placed completions-common-part and completions-first-difference
         ;; faces.  We could try within the mapcar loop to search for the
         ;; boundaries of those faces, pass them to `requote' to find their
         ;; equivalent positions in the quoted output and re-add the faces:
         ;; this might actually lead to correct results but would be
         ;; pretty expensive.
         ;; The better solution is to not quote the *Completions* display,
         ;; which nicely circumvents the problem.  The solution I used here
         ;; instead is to hope that `qfun' preserves the text-properties and
         ;; presume that the `first-difference' is not within the `prefix';
         ;; this presumption is not always true, but at least in practice it is
         ;; true in most cases.
         (qprefix (propertize (substring qfullprefix qboundary)
                              'face 'completions-common-part)))

      ;; Here we choose to quote all elements returned, but a better option
      ;; would be to return unquoted elements together with a function to
      ;; requote them, so that *Completions* can show nicer unquoted values
      ;; which only get quoted when needed by choose-completion.
      (nconc
       (mapcar (lambda (completion)
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                 (cl-assert (string-prefix-p prefix completion 'ignore-case) t)
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                 (let* ((new (substring completion (length prefix)))
                        (qnew (funcall qfun new))
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 			(qprefix
                         (if (not completion-ignore-case)
                             qprefix
                           ;; Make qprefix inherit the case from `completion'.
                           (let* ((rest (substring completion
                                                   0 (length prefix)))
                                  (qrest (funcall qfun rest)))
                             (if (completion--string-equal-p qprefix qrest)
                                 (propertize qrest 'face
                                             'completions-common-part)
                               qprefix))))
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                        (qcompletion (concat qprefix qnew)))
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		   ;; FIXME: Similarly here, Cygwin's mapping trips this
		   ;; assertion.
                   ;;(cl-assert
                   ;; (completion--string-equal-p
		   ;;  (funcall unquote
		   ;;           (concat (substring string 0 qboundary)
		   ;;                   qcompletion))
		   ;;  (concat (substring ustring 0 boundary)
		   ;;          completion))
		   ;; t)
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                   qcompletion))
               completions)
       qboundary))))

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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
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  'complete-in-turn #'completion-table-in-turn "23.1")
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(define-obsolete-function-alias
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  '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.
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If ARGS are provided, then pass MESSAGE through `format-message'."
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  (if (not (minibufferp (current-buffer)))
      (progn
        (if args
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            (apply #'message message args)
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          (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)
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    (setq message (if (and (null args)
                           (string-match-p "\\` *\\[.+\\]\\'" message))
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                      ;; Make sure we can put-text-property.
                      (copy-sequence message)
                    (concat " [" message "]")))
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    (when args (setq message (apply #'format-message message args)))
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    (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.
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In Emacs 22, that was what completion commands operated on.
If the current buffer is not a minibuffer, return everything before point."
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  (declare (obsolete nil "24.4"))
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  (buffer-substring (minibuffer-prompt-end) (point)))
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(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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  (interactive)
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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.
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If the value is t the *Completions* buffer is displayed whenever completion
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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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(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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    (flex
     completion-flex-try-completion completion-flex-all-completions
     "Completion of an in-order subset of characters.
When completing \"foo\" the glob \"*f*o*o*\" is used, so that
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\"foo\" can complete to \"frodo\".")
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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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  :version "23.1")

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(defvar completion-category-defaults
  '((buffer (styles . (basic substring)))
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    (unicode-name (styles . (basic substring)))
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    (uniquify-file (styles . (uniquify-file)))
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    (project-file (styles . (substring)))
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    (info-menu (styles . (basic substring))))
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  "Default settings for specific completion categories.
Each entry 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.
- `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.")

(defcustom completion-category-overrides nil
  "List of category-specific user overrides for completion styles.
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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
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completing buffer and file names, respectively.
This overrides the defaults specified in `completion-category-defaults'."
  :version "25.1"
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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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				  (const bookmark)
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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--category-override (category tag)
  (or (assq tag (cdr (assq category completion-category-overrides)))
      (assq tag (cdr (assq category completion-category-defaults)))))

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(defun completion--styles (metadata)
  (let* ((cat (completion-metadata-get metadata 'category))
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         (over (completion--category-override cat 'styles)))
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    (if over
        (delete-dups (append (cdr over) (copy-sequence completion-styles)))
       completion-styles)))

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(defun completion--nth-completion (n string table pred point metadata)
  "Call the Nth method of completion styles."
  (unless metadata
    (setq metadata
          (completion-metadata (substring string 0 point) table pred)))
  ;; We provide special support for quoting/unquoting here because it cannot
  ;; reliably be done within the normal completion-table routines: Completion
  ;; styles such as `substring' or `partial-completion' need to match the
  ;; output of all-completions with the user's input, and since most/all
  ;; quoting mechanisms allow several equivalent quoted forms, the
  ;; completion-style can't do this matching (e.g. `substring' doesn't know
  ;; that "\a\b\e" is a valid (quoted) substring of "label").
  ;; The quote/unquote function needs to come from the completion table (rather
  ;; than from completion-extra-properties) because it may apply only to some
  ;; part of the string (e.g. substitute-in-file-name).
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  (let ((requote
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         (when (and
                (completion-metadata-get metadata 'completion--unquote-requote)
                ;; Sometimes a table's metadata is used on another
                ;; table (typically that other table is just a list taken
                ;; from the output of `all-completions' or something equivalent,
                ;; for progressive refinement).  See bug#28898 and bug#16274.
                ;; FIXME: Rather than do nothing, we should somehow call
                ;; the original table, in that case!
                (functionp table))
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           (let ((new (funcall table string point 'completion--unquote)))
             (setq string (pop new))
             (setq table (pop new))
             (setq point (pop new))
	     (cl-assert (<= point (length string)))
             (pop new))))
        (result
         (completion--some (lambda (style)
                             (funcall (nth n (assq style
                                                   completion-styles-alist))
                                      string table pred point))
                           (completion--styles metadata))))
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    (if requote
        (funcall requote result n)
      result)))

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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,
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or a pair (NEWSTRING . NEWPOINT) of the completed result string together with
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a new position for point."
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  (completion--nth-completion 1 string table pred point metadata))
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(defun completion-all-completions (string table pred point &optional metadata)
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  "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.
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The return value is a list of completions and may contain the base-size
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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.
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  (completion--nth-completion 2 string table pred point metadata))
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(defun minibuffer--bitset (modified completions exact)
  (logior (if modified    4 0)
          (if completions 2 0)
          (if exact       1 0)))

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(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)
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  ;; 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)
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    (let ((length (- end beg)))         ;Read `end' before we insert the text.
      (insert-and-inherit newtext)
      (delete-region (point) (+ (point) length)))
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    (forward-char suffix-len)))
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(defcustom completion-cycle-threshold nil
  "Number of completion candidates below which cycling is used.
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Depending on this setting `completion-in-region' may use cycling,
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whereby invoking a completion command several times in a row
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completes to each of the candidates in turn, in a cyclic manner.
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If nil, cycling is never used.
If t, cycling is always used.
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If an integer, cycling is used so long as there are not more
completion candidates than this number."
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  :version "24.1"
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  :type completion--cycling-threshold-type)
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(defun completion--cycle-threshold (metadata)
  (let* ((cat (completion-metadata-get metadata 'category))
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         (over (completion--category-override cat 'cycle)))
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    (if over (cdr over) completion-cycle-threshold)))

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(defvar-local completion-all-sorted-completions nil)
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(defvar-local completion--all-sorted-completions-location nil)
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(defvar completion-cycling nil)      ;Function that takes down the cycling map.
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(defvar completion-fail-discreetly nil
  "If non-nil, stay quiet when there  is no match.")

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(defun completion--message (msg)
  (if completion-show-inline-help
      (minibuffer-message msg)))

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(defun completion--do-completion (beg end &optional
                                      try-completion-function expect-exact)
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  "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."
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  (let* ((string (buffer-substring beg end))
1048
         (md (completion--field-metadata beg))
1049
         (comp (funcall (or try-completion-function
1050
                            #'completion-try-completion)
1051 1052 1053
                        string
                        minibuffer-completion-table
                        minibuffer-completion-predicate
1054 1055
                        (- (point) beg)
                        md)))
1056
    (cond
1057
     ((null comp)
1058
      (minibuffer-hide-completions)
1059
      (unless completion-fail-discreetly
1060
	(ding)
1061
	(completion--message "No match"))
1062
      (minibuffer--bitset nil nil nil))
1063
     ((eq t comp)
1064
      (minibuffer-hide-completions)
1065 1066 1067
      (goto-char end)
      (completion--done string 'finished
                        (unless expect-exact "Sole completion"))
1068
      (minibuffer--bitset nil nil t))   ;Exact and unique match.
1069 1070 1071 1072
     (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.
1073 1074 1075 1076 1077 1078
      (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))))
1079
        (if unchanged
1080
	    (goto-char end)
1081
          ;; Insert in minibuffer the chars we got.
1082 1083
          (completion--replace beg end completion)
          (setq end (+ beg (length completion))))
1084 1085
	;; Move point to its completion-mandated destination.
	(forward-char (- comp-pos (length completion)))
1086

1087
        (if (not (or unchanged completed))
1088 1089 1090 1091
            ;; 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).
1092 1093
            (completion--do-completion beg end
                                       try-completion-function expect-exact)
1094