1;;; Clang Code-Completion minor mode, for use with C/Objective-C/C++. 2 3;;; Commentary: 4 5;; This minor mode uses Clang's command line interface for code 6;; completion to provide code completion results for C, Objective-C, 7;; and C++ source files. When enabled, Clang will provide 8;; code-completion results in a secondary buffer based on the code 9;; being typed. For example, after typing "struct " (triggered via the 10;; space), Clang will provide the names of all structs visible from 11;; the current scope. After typing "p->" (triggered via the ">"), 12;; Clang will provide the names of all of the members of whatever 13;; class/struct/union "p" points to. Note that this minor mode isn't 14;; meant for serious use: it is meant to help experiment with code 15;; completion based on Clang. It needs your help to make it better! 16;; 17;; To use the Clang code completion mode, first make sure that the 18;; "clang" variable below refers to the "clang" executable, 19;; which is typically installed in libexec/. Then, place 20;; clang-completion-mode.el somewhere in your Emacs load path. You can 21;; add a new load path to Emacs by adding some like the following to 22;; your .emacs: 23;; 24;; (setq load-path (cons "~/.emacs.d" load-path)) 25;; 26;; Then, use 27;; 28;; M-x load-library 29;; 30;; to load the library in your Emacs session or add the following to 31;; your .emacs to always load this mode (not recommended): 32;; 33;; (load-library "clang-completion-mode") 34;; 35;; Once you have done this, you can set various parameters with 36;; 37;; M-x customize-group RET clang-completion-mode RET 38;; 39;; Finally, to try Clang-based code completion in a particular buffer, 40;; use M-x clang-completion-mode. When "Clang" shows up in the mode 41;; line, Clang's code-completion is enabled. 42;; 43;; Clang's code completion is based on parsing the complete source 44;; file up to the point where the cursor is located. Therefore, Clang 45;; needs all of the various compilation flags (include paths, dialect 46;; options, etc.) to provide code-completion results. Currently, these 47;; need to be placed into the clang-flags variable in a format 48;; acceptable to clang. This is a hack: patches are welcome to 49;; improve the interface between this Emacs mode and Clang! 50;; 51 52;;; Code: 53;;; The clang executable 54(defcustom clang "clang" 55 "The location of the Clang compiler executable" 56 :type 'file 57 :group 'clang-completion-mode) 58 59;;; Extra compilation flags to pass to clang. 60(defcustom clang-flags nil 61 "Extra flags to pass to the Clang executable. 62This variable will typically contain include paths, e.g., -I~/MyProject." 63 :type '(repeat (string :tag "Argument" "")) 64 :group 'clang-completion-mode) 65 66;;; The prefix header to use with Clang code completion. 67(setq clang-completion-prefix-header "") 68 69;;; The substring we will use to filter completion results 70(setq clang-completion-substring "") 71 72;;; The current completion buffer 73(setq clang-completion-buffer nil) 74 75(setq clang-result-string "") 76 77;;; Compute the current line in the buffer 78(defun current-line () 79 "Return the vertical position of point..." 80 (+ (count-lines (point-min) (point)) 81 (if (= (current-column) 0) 1 0) 82 -1)) 83 84;;; Set the Clang prefix header 85(defun clang-prefix-header () 86 (interactive) 87 (setq clang-completion-prefix-header 88 (read-string "Clang prefix header> " "" clang-completion-prefix-header 89 ""))) 90 91;; Process "filter" that keeps track of the code-completion results 92;; produced. We store all of the results in a string, then the 93;; sentinel processes the entire string at once. 94(defun clang-completion-stash-filter (proc string) 95 (setq clang-result-string (concat clang-result-string string))) 96 97;; Filter the given list based on a predicate. 98(defun filter (condp lst) 99 (delq nil 100 (mapcar (lambda (x) (and (funcall condp x) x)) lst))) 101 102;; Determine whether FIXME: explain better 103(defun is-completion-line (line) 104 (or (string-match "OVERLOAD:" line) 105 (string-match (concat "COMPLETION: " clang-completion-substring) line))) 106 107 108;; re-process the completions when further input narrows the field 109(defun clang-completion-display (buffer) 110 (fill-buffer buffer)) 111 112(defun fill-buffer (buffer) 113 (let* ((all-lines (split-string clang-result-string "\n")) 114 (completion-lines (filter 'is-completion-line all-lines))) 115 (if (consp completion-lines) 116 (progn 117 ;; Erase the process buffer. 118 (let ((cur (current-buffer))) 119 (set-buffer buffer) 120 (goto-char (point-min)) 121 (erase-buffer) 122 (set-buffer cur)) 123 124 ;; Display the process buffer. 125 (display-buffer buffer) 126 127 ;; Insert the code-completion string into the process buffer. 128 (with-current-buffer buffer 129 (insert (mapconcat 'identity completion-lines "\n"))) 130 )))) 131 132;; Process "sentinel" that, on successful code completion, replaces the 133;; contents of the code-completion buffer with the new code-completion results 134;; and ensures that the buffer is visible. 135(defun clang-completion-sentinel (proc event) 136 (fill-buffer (process-buffer proc))) 137 138(defun clang-complete () 139 (let* ((cc-point (concat (buffer-file-name) 140 ":" 141 (number-to-string (+ 1 (current-line))) 142 ":" 143 (number-to-string (+ 1 (current-column))))) 144 (cc-pch (if (equal clang-completion-prefix-header "") nil 145 (list "-include-pch" 146 (concat clang-completion-prefix-header ".pch")))) 147 (cc-flags (if (listp clang-flags) clang-flags nil)) 148 (cc-command (append `(,clang "-cc1" "-fsyntax-only") 149 cc-flags 150 cc-pch 151 `("-code-completion-at" ,cc-point) 152 (list (buffer-file-name)))) 153 (cc-buffer-name (concat "*Clang Completion for " (buffer-name) "*"))) 154 ;; Start the code-completion process. 155 (if (buffer-file-name) 156 (progn 157 ;; If there is already a code-completion process, kill it first. 158 (let ((cc-proc (get-process "Clang Code-Completion"))) 159 (if cc-proc 160 (delete-process cc-proc))) 161 162 (setq clang-completion-substring "") 163 (setq clang-result-string "") 164 (setq clang-completion-buffer cc-buffer-name) 165 166 (let ((cc-proc (apply 'start-process 167 (append (list "Clang Code-Completion" cc-buffer-name) 168 cc-command)))) 169 (set-process-filter cc-proc 'clang-completion-stash-filter) 170 (set-process-sentinel cc-proc 'clang-completion-sentinel) 171 ))))) 172 173;; Code-completion when one of the trigger characters is typed into 174;; the buffer, e.g., '(', ',' or '.'. 175(defun clang-complete-self-insert (arg) 176 (interactive "p") 177 (self-insert-command arg) 178 (save-buffer) 179 (clang-complete)) 180 181;; When the user has typed a character that requires the filter to be 182;; updated, do so (and update the display of results). 183(defun clang-update-filter () 184 (setq clang-completion-substring (thing-at-point 'symbol)) 185 (if (get-process "Clang Code-Completion") 186 () 187 (clang-completion-display clang-completion-buffer) 188 )) 189 190;; Invoked when the user types an alphanumeric character or "_" to 191;; update the filter for the currently-active code completion. 192(defun clang-filter-self-insert (arg) 193 (interactive "p") 194 (self-insert-command arg) 195 (clang-update-filter) 196 ) 197 198;; Invoked when the user types the backspace key to update the filter 199;; for the currently-active code completion. 200(defun clang-backspace () 201 (interactive) 202 (delete-backward-char 1) 203 (clang-update-filter)) 204 205;; Invoked when the user types the delete key to update the filter 206;; for the currently-active code completion. 207(defun clang-delete () 208 (interactive) 209 (delete-backward-char 1) 210 (clang-update-filter)) 211 212;; Set up the keymap for the Clang minor mode. 213(defvar clang-completion-mode-map nil 214 "Keymap for Clang Completion Mode.") 215 216(if (null clang-completion-mode-map) 217 (fset 'clang-completion-mode-map 218 (setq clang-completion-mode-map (make-sparse-keymap)))) 219 220(if (not (assq 'clang-completion-mode minor-mode-map-alist)) 221 (setq minor-mode-map-alist 222 (cons (cons 'clang-completion-mode clang-completion-mode-map) 223 minor-mode-map-alist))) 224 225;; Punctuation characters trigger code completion. 226(dolist (char '("(" "," "." ">" ":" "=" ")" " ")) 227 (define-key clang-completion-mode-map char 'clang-complete-self-insert)) 228 229;; Alphanumeric characters (and "_") filter the results of the 230;; currently-active code completion. 231(dolist (char '("A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" 232 "P" "Q" "R" "S" "T" "U" "V" "W" "X" "Y" "Z" 233 "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" 234 "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" 235 "_" "0" "1" "2" "3" "4" "5" "6" "7" "8" "9")) 236 (define-key clang-completion-mode-map char 'clang-filter-self-insert)) 237 238;; Delete and backspace filter the results of the currently-active 239;; code completion. 240(define-key clang-completion-mode-map [(backspace)] 'clang-backspace) 241(define-key clang-completion-mode-map [(delete)] 'clang-delete) 242 243;; Set up the Clang minor mode. 244(define-minor-mode clang-completion-mode 245 "Clang code-completion mode" 246 nil 247 " Clang" 248 clang-completion-mode-map) 249 250