250 lines
9.3 KiB
EmacsLisp
250 lines
9.3 KiB
EmacsLisp
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;;; Clang Code-Completion minor mode, for use with C/Objective-C/C++.
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;;; Commentary:
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;; This minor mode uses Clang's command line interface for code
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;; completion to provide code completion results for C, Objective-C,
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;; and C++ source files. When enabled, Clang will provide
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;; code-completion results in a secondary buffer based on the code
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;; being typed. For example, after typing "struct " (triggered via the
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;; space), Clang will provide the names of all structs visible from
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;; the current scope. After typing "p->" (triggered via the ">"),
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;; Clang will provide the names of all of the members of whatever
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;; class/struct/union "p" points to. Note that this minor mode isn't
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;; meant for serious use: it is meant to help experiment with code
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;; completion based on Clang. It needs your help to make it better!
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;;
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;; To use the Clang code completion mode, first make sure that the
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;; "clang" variable below refers to the "clang" executable,
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;; which is typically installed in libexec/. Then, place
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;; clang-completion-mode.el somewhere in your Emacs load path. You can
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;; add a new load path to Emacs by adding some like the following to
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;; your .emacs:
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;;
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;; (setq load-path (cons "~/.emacs.d" load-path))
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;;
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;; Then, use
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;;
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;; M-x load-library
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;;
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;; to load the library in your Emacs session or add the following to
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;; your .emacs to always load this mode (not recommended):
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;;
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;; (load-library "clang-completion-mode")
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;;
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;; Once you have done this, you can set various parameters with
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;;
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;; M-x customize-group RET clang-completion-mode RET
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;;
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;; Finally, to try Clang-based code completion in a particular buffer,
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;; use M-x clang-completion-mode. When "Clang" shows up in the mode
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;; line, Clang's code-completion is enabled.
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;;
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;; Clang's code completion is based on parsing the complete source
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;; file up to the point where the cursor is located. Therefore, Clang
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;; needs all of the various compilation flags (include paths, dialect
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;; options, etc.) to provide code-completion results. Currently, these
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;; need to be placed into the clang-flags variable in a format
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;; acceptable to clang. This is a hack: patches are welcome to
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;; improve the interface between this Emacs mode and Clang!
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;;
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;;; Code:
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;;; The clang executable
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(defcustom clang "clang"
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"The location of the Clang compiler executable"
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:type 'file
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:group 'clang-completion-mode)
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;;; Extra compilation flags to pass to clang.
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(defcustom clang-flags nil
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"Extra flags to pass to the Clang executable.
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This variable will typically contain include paths, e.g., -I~/MyProject."
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:type '(repeat (string :tag "Argument" ""))
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:group 'clang-completion-mode)
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;;; The prefix header to use with Clang code completion.
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(setq clang-completion-prefix-header "")
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;;; The substring we will use to filter completion results
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(setq clang-completion-substring "")
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;;; The current completion buffer
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(setq clang-completion-buffer nil)
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(setq clang-result-string "")
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;;; Compute the current line in the buffer
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(defun current-line ()
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"Return the vertical position of point..."
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(+ (count-lines (point-min) (point))
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(if (= (current-column) 0) 1 0)
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-1))
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;;; Set the Clang prefix header
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(defun clang-prefix-header ()
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(interactive)
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(setq clang-completion-prefix-header
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(read-string "Clang prefix header> " "" clang-completion-prefix-header
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"")))
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;; Process "filter" that keeps track of the code-completion results
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;; produced. We store all of the results in a string, then the
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;; sentinel processes the entire string at once.
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(defun clang-completion-stash-filter (proc string)
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(setq clang-result-string (concat clang-result-string string)))
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;; Filter the given list based on a predicate.
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(defun filter (condp lst)
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(delq nil
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(mapcar (lambda (x) (and (funcall condp x) x)) lst)))
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;; Determine whether FIXME: explain better
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(defun is-completion-line (line)
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(or (string-match "OVERLOAD:" line)
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(string-match (concat "COMPLETION: " clang-completion-substring) line)))
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;; re-process the completions when further input narrows the field
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(defun clang-completion-display (buffer)
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(fill-buffer buffer))
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(defun fill-buffer (buffer)
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(let* ((all-lines (split-string clang-result-string "\n"))
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(completion-lines (filter 'is-completion-line all-lines)))
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(if (consp completion-lines)
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(progn
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;; Erase the process buffer.
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(let ((cur (current-buffer)))
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(set-buffer buffer)
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(goto-char (point-min))
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(erase-buffer)
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(set-buffer cur))
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;; Display the process buffer.
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(display-buffer buffer)
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;; Insert the code-completion string into the process buffer.
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(with-current-buffer buffer
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(insert (mapconcat 'identity completion-lines "\n")))
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))))
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;; Process "sentinel" that, on successful code completion, replaces the
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;; contents of the code-completion buffer with the new code-completion results
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;; and ensures that the buffer is visible.
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(defun clang-completion-sentinel (proc event)
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(fill-buffer (process-buffer proc)))
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(defun clang-complete ()
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(let* ((cc-point (concat (buffer-file-name)
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":"
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(number-to-string (+ 1 (current-line)))
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":"
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(number-to-string (+ 1 (current-column)))))
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(cc-pch (if (equal clang-completion-prefix-header "") nil
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(list "-include-pch"
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(concat clang-completion-prefix-header ".pch"))))
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(cc-flags (if (listp clang-flags) clang-flags nil))
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(cc-command (append `(,clang "-cc1" "-fsyntax-only")
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cc-flags
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cc-pch
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`("-code-completion-at" ,cc-point)
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(list (buffer-file-name))))
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(cc-buffer-name (concat "*Clang Completion for " (buffer-name) "*")))
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;; Start the code-completion process.
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(if (buffer-file-name)
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(progn
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;; If there is already a code-completion process, kill it first.
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(let ((cc-proc (get-process "Clang Code-Completion")))
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(if cc-proc
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(delete-process cc-proc)))
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(setq clang-completion-substring "")
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(setq clang-result-string "")
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(setq clang-completion-buffer cc-buffer-name)
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(let ((cc-proc (apply 'start-process
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(append (list "Clang Code-Completion" cc-buffer-name)
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cc-command))))
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(set-process-filter cc-proc 'clang-completion-stash-filter)
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(set-process-sentinel cc-proc 'clang-completion-sentinel)
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)))))
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;; Code-completion when one of the trigger characters is typed into
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;; the buffer, e.g., '(', ',' or '.'.
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(defun clang-complete-self-insert (arg)
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(interactive "p")
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(self-insert-command arg)
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(save-buffer)
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(clang-complete))
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;; When the user has typed a character that requires the filter to be
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;; updated, do so (and update the display of results).
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(defun clang-update-filter ()
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(setq clang-completion-substring (thing-at-point 'symbol))
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(if (get-process "Clang Code-Completion")
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()
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(clang-completion-display clang-completion-buffer)
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))
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;; Invoked when the user types an alphanumeric character or "_" to
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;; update the filter for the currently-active code completion.
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(defun clang-filter-self-insert (arg)
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(interactive "p")
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(self-insert-command arg)
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(clang-update-filter)
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)
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;; Invoked when the user types the backspace key to update the filter
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;; for the currently-active code completion.
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(defun clang-backspace ()
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(interactive)
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(delete-backward-char 1)
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(clang-update-filter))
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;; Invoked when the user types the delete key to update the filter
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;; for the currently-active code completion.
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(defun clang-delete ()
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(interactive)
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(delete-backward-char 1)
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(clang-update-filter))
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;; Set up the keymap for the Clang minor mode.
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(defvar clang-completion-mode-map nil
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"Keymap for Clang Completion Mode.")
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(if (null clang-completion-mode-map)
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(fset 'clang-completion-mode-map
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(setq clang-completion-mode-map (make-sparse-keymap))))
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(if (not (assq 'clang-completion-mode minor-mode-map-alist))
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(setq minor-mode-map-alist
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(cons (cons 'clang-completion-mode clang-completion-mode-map)
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minor-mode-map-alist)))
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;; Punctuation characters trigger code completion.
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(dolist (char '("(" "," "." ">" ":" "=" ")" " "))
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(define-key clang-completion-mode-map char 'clang-complete-self-insert))
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;; Alphanumeric characters (and "_") filter the results of the
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;; currently-active code completion.
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(dolist (char '("A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O"
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"P" "Q" "R" "S" "T" "U" "V" "W" "X" "Y" "Z"
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"a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o"
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"p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z"
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"_" "0" "1" "2" "3" "4" "5" "6" "7" "8" "9"))
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(define-key clang-completion-mode-map char 'clang-filter-self-insert))
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;; Delete and backspace filter the results of the currently-active
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;; code completion.
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(define-key clang-completion-mode-map [(backspace)] 'clang-backspace)
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(define-key clang-completion-mode-map [(delete)] 'clang-delete)
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;; Set up the Clang minor mode.
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(define-minor-mode clang-completion-mode
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"Clang code-completion mode"
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nil
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" Clang"
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clang-completion-mode-map)
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