;;; find-func.el --- find the definition of the Emacs Lisp function near point

;; Copyright (C) 1997, 1999, 2001, 2002, 2003, 2004,
;;   2005, 2006 Free Software Foundation, Inc.

;; Author: Jens Petersen <petersen@kurims.kyoto-u.ac.jp>
;; Maintainer: petersen@kurims.kyoto-u.ac.jp
;; Keywords: emacs-lisp, functions, variables
;; Created: 97/07/25

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:
;;
;; The funniest thing about this is that I can't imagine why a package
;; so obviously useful as this hasn't been written before!!
;; ;;; find-func
;; (find-function-setup-keys)
;;
;; or just:
;;
;; (load "find-func")
;;
;; if you don't like the given keybindings and away you go!  It does
;; pretty much what you would expect, putting the cursor at the
;; definition of the function or variable at point.
;;
;; The code started out from `describe-function', `describe-key'
;; ("help.el") and `fff-find-loaded-emacs-lisp-function' (Noah Friedman's
;; "fff.el").

;;; Code:

(require 'loadhist)

;;; User variables:

(defgroup find-function nil
  "Finds the definition of the Emacs Lisp symbol near point."
;;   :prefix "find-function"
  :group 'lisp)

(defconst find-function-space-re "\\(?:\\s-\\|\n\\|;.*\n\\)+")

(defcustom find-function-regexp
  ;; Match things like (defun foo ...), (defmacro foo ...),
  ;; (define-skeleton foo ...), (define-generic-mode 'foo ...),
  ;;  (define-derived-mode foo ...), (define-minor-mode foo)
  (concat
   "^\\s-*(\\(def\\(ine-skeleton\\|ine-generic-mode\\|ine-derived-mode\\|\
ine\\(?:-global\\)?-minor-mode\\|ine-compilation-mode\\|un-cvs-mode\\|\
foo\\|[^cfgv]\\(\\w\\|\\s_\\)+\\*?\\)\\|easy-mmode-define-[a-z-]+\\|easy-menu-define\\|\
menu-bar-make-toggle\\)"
   find-function-space-re
   "\\('\\|\(quote \\)?%s\\(\\s-\\|$\\|\(\\|\)\\)")
  "The regexp used by `find-function' to search for a function definition.
Note it must contain a `%s' at the place where `format'
should insert the function name.  The default value avoids `defconst',
`defgroup', `defvar', `defface'.

Please send improvements and fixes to the maintainer."
  :type 'regexp
  :group 'find-function
  :version "21.1")

(defcustom find-variable-regexp
  (concat
   "^\\s-*(\\(def[^fumag]\\(\\w\\|\\s_\\)+\\*?\\|\
easy-mmode-def\\(map\\|syntax\\)\\|easy-menu-define\\)"
   find-function-space-re
   "%s\\(\\s-\\|$\\)")
  "The regexp used by `find-variable' to search for a variable definition.
Note it must contain a `%s' at the place where `format'
should insert the variable name.  The default value
avoids `defun', `defmacro', `defalias', `defadvice', `defgroup', `defface'.

Please send improvements and fixes to the maintainer."
  :type 'regexp
  :group 'find-function
  :version "21.1")

(defcustom find-face-regexp
  (concat"^\\s-*(defface" find-function-space-re "%s\\(\\s-\\|$\\)")
  "The regexp used by `find-face' to search for a face definition.
Note it must contain a `%s' at the place where `format'
should insert the face name.

Please send improvements and fixes to the maintainer."
  :type 'regexp
  :group 'find-function
  :version "22.1")

(defvar find-function-regexp-alist
  '((nil . find-function-regexp)
    (defvar . find-variable-regexp)
    (defface . find-face-regexp))
  "Alist mapping definition types into regexp variables.
Each regexp variable's value should actually be a format string
to be used to substitute the desired symbol name into the regexp.")
(put 'find-function-regexp-alist 'risky-local-variable t)

(defcustom find-function-source-path nil
  "The default list of directories where `find-function' searches.

If this variable is nil then `find-function' searches `load-path' by
default."
  :type '(repeat directory)
  :group 'find-function)

(defcustom find-function-recenter-line 1
  "The window line-number from which to start displaying a symbol definition.
A value of nil implies center the beginning of the definition.
See `find-function' and `find-variable'."
  :type '(choice (const :tag "Center" nil)
		 integer)
  :group 'find-function
  :version "20.3")

(defcustom find-function-after-hook nil
  "Hook run after finding symbol definition.

See the functions `find-function' and `find-variable'."
  :group 'find-function
  :version "20.3")

;;; Functions:

(defun find-library-suffixes ()
  (let ((suffixes nil))
    (dolist (suffix (get-load-suffixes) (nreverse suffixes))
      (unless (string-match "elc" suffix) (push suffix suffixes)))))

(defun find-library-name (library)
  "Return the absolute file name of the Lisp source of LIBRARY."
  ;; Strip off the extension to take advantage of library suffixes in
  ;; the call to `locate-file'.
  (if (string-match "\\.el\\(c\\(\\..*\\)?\\)?\\'" library)
      (setq library (replace-match "" t t library)))
  (or (locate-file library
		   (or find-function-source-path load-path)
		   (append (find-library-suffixes) load-file-rep-suffixes))
      (error "Can't find library %s" library)))

(defvar find-function-C-source-directory
  (let ((dir (expand-file-name "src" source-directory)))
    (when (and (file-directory-p dir) (file-readable-p dir))
      dir))
  "Directory where the C source files of Emacs can be found.
If nil, do not try to find the source code of functions and variables
defined in C.")

(defun find-function-C-source (fun-or-var file type)
  "Find the source location where FUN-OR-VAR is defined in FILE.
TYPE should be nil to find a function, or `defvar' to find a variable."
  (unless find-function-C-source-directory
    (setq find-function-C-source-directory
	  (read-directory-name "Emacs C source dir: " nil nil t)))
  (setq file (expand-file-name file find-function-C-source-directory))
  (unless (file-readable-p file)
    (error "The C source file %s is not available"
	   (file-name-nondirectory file)))
  (unless type
    (setq fun-or-var (indirect-function fun-or-var)))
  (with-current-buffer (find-file-noselect file)
    (goto-char (point-min))
    (unless (re-search-forward
	     (if type
		 (concat "DEFVAR[A-Z_]*[ \t\n]*([ \t\n]*\""
			 (regexp-quote (symbol-name fun-or-var))
			 "\"")
	       (concat "DEFUN[ \t\n]*([ \t\n]*\""
		       (regexp-quote (subr-name fun-or-var))
		       "\""))
	     nil t)
      (error "Can't find source for %s" fun-or-var))
    (cons (current-buffer) (match-beginning 0))))

;;;###autoload
(defun find-library (library)
  "Find the elisp source of LIBRARY."
  (interactive
   (list
    (completing-read "Library name: "
		     'locate-file-completion
		     (cons (or find-function-source-path load-path)
			   (find-library-suffixes)))))
  (let ((buf (find-file-noselect (find-library-name library))))
    (condition-case nil (switch-to-buffer buf) (error (pop-to-buffer buf)))))

;;;###autoload
(defun find-function-search-for-symbol (symbol type library)
  "Search for SYMBOL's definition of type TYPE in LIBRARY.
If TYPE is nil, look for a function definition.
Otherwise, TYPE specifies the kind of definition,
and it is interpreted via `find-function-regexp-alist'.
The search is done in the source for library LIBRARY."
  (if (null library)
      (error "Don't know where `%s' is defined" symbol))
  ;; Some functions are defined as part of the construct
  ;; that defines something else.
  (while (and (symbolp symbol) (get symbol 'definition-name))
    (setq symbol (get symbol 'definition-name)))
  (if (string-match "\\`src/\\(.*\\.c\\)\\'" library)
      (find-function-C-source symbol (match-string 1 library) type)
    (if (string-match "\\.el\\(c\\)\\'" library)
	(setq library (substring library 0 (match-beginning 1))))
    (let* ((filename (find-library-name library))
	   (regexp-symbol (cdr (assq type find-function-regexp-alist))))
      (with-current-buffer (find-file-noselect filename)
	(let ((regexp (format (symbol-value regexp-symbol)
			      (regexp-quote (symbol-name symbol))))
	      (case-fold-search))
	  (with-syntax-table emacs-lisp-mode-syntax-table
	    (goto-char (point-min))
	    (if (or (re-search-forward regexp nil t)
                    ;; `regexp' matches definitions using known forms like
                    ;; `defun', or `defvar'.  But some functions/variables
                    ;; are defined using special macros (or functions), so
                    ;; if `regexp' can't find the definition, we look for
                    ;; something of the form "(SOMETHING <symbol> ...)".
                    ;; This fails to distinguish function definitions from
                    ;; variable declarations (or even uses thereof), but is
                    ;; a good pragmatic fallback.
		    (re-search-forward
		     (concat "^([^ ]+" find-function-space-re "['(]?"
			     (regexp-quote (symbol-name symbol))
			     "\\_>")
		     nil t))
		(progn
		  (beginning-of-line)
		  (cons (current-buffer) (point)))
	      (error "Cannot find definition of `%s' in library `%s'"
		     symbol library))))))))

;;;###autoload
(defun find-function-noselect (function)
  "Return a pair (BUFFER . POINT) pointing to the definition of FUNCTION.

Finds the source file containing the definition of FUNCTION
in a buffer and the point of the definition.  The buffer is
not selected.

If the file where FUNCTION is defined is not known, then it is
searched for in `find-function-source-path' if non nil, otherwise
in `load-path'."
  (if (not function)
      (error "You didn't specify a function"))
  (let ((def (symbol-function function))
	aliases)
    (while (symbolp def)
      (or (eq def function)
	  (if aliases
	      (setq aliases (concat aliases
				    (format ", which is an alias for `%s'"
					    (symbol-name def))))
	    (setq aliases (format "`%s' an alias for `%s'"
				  function (symbol-name def)))))
      (setq function (symbol-function function)
	    def (symbol-function function)))
    (if aliases
	(message "%s" aliases))
    (let ((library
	   (cond ((eq (car-safe def) 'autoload)
		  (nth 1 def))
		 ((subrp def)
		  (help-C-file-name def 'subr))
		 ((symbol-file function 'defun)))))
      (find-function-search-for-symbol function nil library))))

(defun find-function-read (&optional type)
  "Read and return an interned symbol, defaulting to the one near point.

If TYPE is nil, insist on a symbol with a function definition.
Otherwise TYPE should be `defvar' or `defface'.
If TYPE is nil, defaults using `function-called-at-point',
otherwise uses `variable-at-point'."
  (let ((symb (if (null type)
		  (function-called-at-point)
		(if (eq type 'defvar)
		    (variable-at-point)
		  (variable-at-point t))))
	(predicate (cdr (assq type '((nil . fboundp) (defvar . boundp)
				     (defface . facep)))))
	(prompt (cdr (assq type '((nil . "function") (defvar . "variable")
				  (defface . "face")))))
	(enable-recursive-minibuffers t)
	val)
    (if (equal symb 0)
	(setq symb nil))
    (setq val (completing-read
	       (concat "Find "
		       prompt
		       (if symb
			   (format " (default %s)" symb))
		       ": ")
	       obarray predicate t nil))
    (list (if (equal val "")
	      symb
	    (intern val)))))

(defun find-function-do-it (symbol type switch-fn)
  "Find Emacs Lisp SYMBOL in a buffer and display it.
TYPE is nil to search for a function definition,
or else `defvar' or `defface'.

The variable `find-function-recenter-line' controls how
to recenter the display.  SWITCH-FN is the function to call
to display and select the buffer.
See also `find-function-after-hook'.

Set mark before moving, if the buffer already existed."
  (let* ((orig-point (point))
	(orig-buf (window-buffer))
	(orig-buffers (buffer-list))
	(buffer-point (save-excursion
			(find-definition-noselect symbol type)))
	(new-buf (car buffer-point))
	(new-point (cdr buffer-point)))
    (when buffer-point
      (when (memq new-buf orig-buffers)
	(push-mark orig-point))
      (funcall switch-fn new-buf)
      (goto-char new-point)
      (recenter find-function-recenter-line)
      (run-hooks 'find-function-after-hook))))

;;;###autoload
(defun find-function (function)
  "Find the definition of the FUNCTION near point.

Finds the source file containing the definition of the function
near point (selected by `function-called-at-point') in a buffer and
places point before the definition.
Set mark before moving, if the buffer already existed.

The library where FUNCTION is defined is searched for in
`find-function-source-path', if non nil, otherwise in `load-path'.
See also `find-function-recenter-line' and `find-function-after-hook'."
  (interactive (find-function-read))
  (find-function-do-it function nil 'switch-to-buffer))

;;;###autoload
(defun find-function-other-window (function)
  "Find, in another window, the definition of FUNCTION near point.

See `find-function' for more details."
  (interactive (find-function-read))
  (find-function-do-it function nil 'switch-to-buffer-other-window))

;;;###autoload
(defun find-function-other-frame (function)
  "Find, in another frame, the definition of FUNCTION near point.

See `find-function' for more details."
  (interactive (find-function-read))
  (find-function-do-it function nil 'switch-to-buffer-other-frame))

;;;###autoload
(defun find-variable-noselect (variable &optional file)
  "Return a pair `(BUFFER . POINT)' pointing to the definition of VARIABLE.

Finds the library containing the definition of VARIABLE in a buffer and
the point of the definition.  The buffer is not selected.

The library where VARIABLE is defined is searched for in FILE or
`find-function-source-path', if non nil, otherwise in `load-path'."
  (if (not variable)
      (error "You didn't specify a variable")
    (let ((library (or file
                       (symbol-file variable 'defvar)
                       (help-C-file-name variable 'var))))
      (find-function-search-for-symbol variable 'defvar library))))

;;;###autoload
(defun find-variable (variable)
  "Find the definition of the VARIABLE near point.

Finds the library containing the definition of the variable
near point (selected by `variable-at-point') in a buffer and
places point before the definition.

Set mark before moving, if the buffer already existed.

The library where VARIABLE is defined is searched for in
`find-function-source-path', if non nil, otherwise in `load-path'.
See also `find-function-recenter-line' and `find-function-after-hook'."
  (interactive (find-function-read 'defvar))
  (find-function-do-it variable 'defvar 'switch-to-buffer))

;;;###autoload
(defun find-variable-other-window (variable)
  "Find, in another window, the definition of VARIABLE near point.

See `find-variable' for more details."
  (interactive (find-function-read 'defvar))
  (find-function-do-it variable 'defvar 'switch-to-buffer-other-window))

;;;###autoload
(defun find-variable-other-frame (variable)
  "Find, in another frame, the definition of VARIABLE near point.

See `find-variable' for more details."
  (interactive (find-function-read 'defvar))
  (find-function-do-it variable 'defvar 'switch-to-buffer-other-frame))

;;;###autoload
(defun find-definition-noselect (symbol type &optional file)
  "Return a pair `(BUFFER . POINT)' pointing to the definition of SYMBOL.
TYPE says what type of definition: nil for a function, `defvar' for a
variable, `defface' for a face.  This function does not switch to the
buffer nor display it.

The library where SYMBOL is defined is searched for in FILE or
`find-function-source-path', if non nil, otherwise in `load-path'."
  (cond
   ((not symbol)
    (error "You didn't specify a symbol"))
   ((null type)
    (find-function-noselect symbol))
   ((eq type 'defvar)
    (find-variable-noselect symbol file))
   (t
    (let ((library (or file (symbol-file symbol type))))
      (find-function-search-for-symbol symbol type library)))))

;; For symmetry, this should be called find-face; but some programs
;; assume that, if that name is defined, it means something else.
;;;###autoload
(defun find-face-definition (face)
  "Find the definition of FACE.  FACE defaults to the name near point.

Finds the Emacs Lisp library containing the definition of the face
near point (selected by `variable-at-point') in a buffer and
places point before the definition.

Set mark before moving, if the buffer already existed.

The library where FACE is defined is searched for in
`find-function-source-path', if non nil, otherwise in `load-path'.
See also `find-function-recenter-line' and `find-function-after-hook'."
  (interactive (find-function-read 'defface))
  (find-function-do-it face 'defface 'switch-to-buffer))

;;;###autoload
(defun find-function-on-key (key)
  "Find the function that KEY invokes.  KEY is a string.
Set mark before moving, if the buffer already existed."
  (interactive "kFind function on key: ")
  (let (defn)
    (save-excursion
      (let* ((event (and (eventp key) (aref key 0))) ; Null event OK below.
	     (start (event-start event))
	     (modifiers (event-modifiers event))
	     (window (and (or (memq 'click modifiers) (memq 'down modifiers)
			      (memq 'drag modifiers))
			  (posn-window start))))
	;; For a mouse button event, go to the button it applies to
	;; to get the right key bindings.  And go to the right place
	;; in case the keymap depends on where you clicked.
	(when (windowp window)
	  (set-buffer (window-buffer window))
	  (goto-char (posn-point start)))
	(setq defn (key-binding key))))
    (let ((key-desc (key-description key)))
      (if (or (null defn) (integerp defn))
	  (message "%s is unbound" key-desc)
	(if (consp defn)
	    (message "%s runs %s" key-desc (prin1-to-string defn))
	  (find-function-other-window defn))))))

;;;###autoload
(defun find-function-at-point ()
  "Find directly the function at point in the other window."
  (interactive)
  (let ((symb (function-called-at-point)))
    (when symb
      (find-function-other-window symb))))

;;;###autoload
(defun find-variable-at-point ()
  "Find directly the variable at point in the other window."
  (interactive)
  (let ((symb (variable-at-point)))
    (when (and symb (not (equal symb 0)))
      (find-variable-other-window symb))))

;;;###autoload
(defun find-function-setup-keys ()
  "Define some key bindings for the find-function family of functions."
  (define-key ctl-x-map "F" 'find-function)
  (define-key ctl-x-4-map "F" 'find-function-other-window)
  (define-key ctl-x-5-map "F" 'find-function-other-frame)
  (define-key ctl-x-map "K" 'find-function-on-key)
  (define-key ctl-x-map "V" 'find-variable)
  (define-key ctl-x-4-map "V" 'find-variable-other-window)
  (define-key ctl-x-5-map "V" 'find-variable-other-frame))

(provide 'find-func)

;; arch-tag: 43ecd81c-74dc-4d9a-8f63-a61e55670d64
;;; find-func.el ends here