;;; nadvice.el --- Light-weight advice primitives for Elisp functions -*- lexical-binding: t -*-
-;; Copyright (C) 2012 Free Software Foundation, Inc.
+;; Copyright (C) 2012-2013 Free Software Foundation, Inc.
;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
;; Keywords: extensions, lisp, tools
;; This package lets you add behavior (which we call "piece of advice") to
;; existing functions, like the old `advice.el' package, but with much fewer
-;; bells ans whistles. It comes in 2 parts:
+;; bells and whistles. It comes in 2 parts:
;;
;; - The first part lets you add/remove functions, similarly to
;; add/remove-hook, from any "place" (i.e. as accepted by `setf') that
;; holds a function.
;; This part provides mainly 2 macros: `add-function' and `remove-function'.
;;
-;; - The second part provides `add-advice' and `remove-advice' which are
+;; - The second part provides `advice-add' and `advice-remove' which are
;; refined version of the previous macros specially tailored for the case
;; where the place that we want to modify is a `symbol-function'.
'((:around "\300\301\302\003#\207" 5)
(:before "\300\301\002\"\210\300\302\002\"\207" 4)
(:after "\300\302\002\"\300\301\003\"\210\207" 5)
+ (:override "\300\301\ 2\"\207" 4)
(:after-until "\300\302\002\"\206\013\000\300\301\002\"\207" 4)
(:after-while "\300\302\002\"\205\013\000\300\301\002\"\207" 4)
(:before-until "\300\301\002\"\206\013\000\300\302\002\"\207" 4)
- (:before-while "\300\301\002\"\205\013\000\300\302\002\"\207" 4))
+ (:before-while "\300\301\002\"\205\013\000\300\302\002\"\207" 4)
+ (:filter-args "\300\302\301\ 3!\"\207" 5)
+ (:filter-return "\301\300\302\ 3\"!\207" 5))
"List of descriptions of how to add a function.
Each element has the form (WHERE BYTECODE STACK) where:
WHERE is a keyword indicating where the function is added.
(propertize "Advised function"
'dynamic-docstring-function #'advice--make-docstring)) ;; )
+(defun advice-eval-interactive-spec (spec)
+ "Evaluate the interactive spec SPEC."
+ (cond
+ ((stringp spec)
+ ;; There's no direct access to the C code (in call-interactively) that
+ ;; processes those specs, but that shouldn't stop us, should it?
+ ;; FIXME: Despite appearances, this is not faithful: SPEC and
+ ;; (advice-eval-interactive-spec SPEC) will behave subtly differently w.r.t
+ ;; command-history (and maybe a few other details).
+ (call-interactively `(lambda (&rest args) (interactive ,spec) args)))
+ ;; ((functionp spec) (funcall spec))
+ (t (eval spec))))
+
(defun advice--make-interactive-form (function main)
- ;; TODO: Make it possible to do around-like advising on the
- ;; interactive forms (bug#12844).
;; TODO: make it so that interactive spec can be a constant which
;; dynamically checks the advice--car/cdr to do its job.
- ;; TODO: Implement interactive-read-args:
- ;;(when (or (commandp function) (commandp main))
- ;; `(interactive-read-args
- ;; (cadr (or (interactive-form function) (interactive-form main)))))
- ;; FIXME: This loads autoloaded functions too eagerly.
+ ;; For that, advice-eval-interactive-spec needs to be more faithful.
+ ;; FIXME: The calls to interactive-form below load autoloaded functions
+ ;; too eagerly.
+ (let ((fspec (cadr (interactive-form function))))
+ (when (eq 'function (car-safe fspec)) ;; Macroexpanded lambda?
+ (setq fspec (nth 1 fspec)))
+ (if (functionp fspec)
+ `(funcall ',fspec
+ ',(cadr (interactive-form main)))
(cadr (or (interactive-form function)
- (interactive-form main))))
+ (interactive-form main))))))
(defsubst advice--make-1 (byte-code stack-depth function main props)
"Build a function value that adds FUNCTION to MAIN."
(advice--make-1 (nth 1 desc) (nth 2 desc)
function main props)))
-(defun advice--member-p (function definition)
+(defun advice--member-p (function name definition)
(let ((found nil))
(while (and (not found) (advice--p definition))
(if (or (equal function (advice--car definition))
- (equal function (cdr (assq 'name (advice--props definition)))))
- (setq found t)
+ (when name
+ (equal name (cdr (assq 'name (advice--props definition))))))
+ (setq found definition)
(setq definition (advice--cdr definition))))
found))
-;;;###autoload
-(defun advice--remove-function (flist function)
+(defun advice--tweak (flist tweaker)
(if (not (advice--p flist))
- flist
+ (funcall tweaker nil flist nil)
(let ((first (advice--car flist))
+ (rest (advice--cdr flist))
(props (advice--props flist)))
- (if (or (equal function first)
- (equal function (cdr (assq 'name props))))
- (advice--cdr flist)
- (let* ((rest (advice--cdr flist))
- (nrest (advice--remove-function rest function)))
- (if (eq rest nrest) flist
- (advice--make-1 (aref flist 1) (aref flist 3)
- first nrest props)))))))
+ (let ((val (funcall tweaker first rest props)))
+ (if val (car val)
+ (let ((nrest (advice--tweak rest tweaker)))
+ (if (eq rest nrest) flist
+ (advice--make-1 (aref flist 1) (aref flist 3)
+ first nrest props))))))))
+
+;;;###autoload
+(defun advice--remove-function (flist function)
+ (advice--tweak flist
+ (lambda (first rest props)
+ (cond ((not first) rest)
+ ((or (equal function first)
+ (equal function (cdr (assq 'name props))))
+ (list rest))))))
+
+(defvar advice--buffer-local-function-sample nil)
+
+(defun advice--set-buffer-local (var val)
+ (if (function-equal val advice--buffer-local-function-sample)
+ (kill-local-variable var)
+ (set (make-local-variable var) val)))
+
+;;;###autoload
+(defun advice--buffer-local (var)
+ "Buffer-local value of VAR, presumed to contain a function."
+ (declare (gv-setter advice--set-buffer-local))
+ (if (local-variable-p var) (symbol-value var)
+ (setq advice--buffer-local-function-sample
+ (lambda (&rest args) (apply (default-value var) args)))))
;;;###autoload
(defmacro add-function (where place function &optional props)
;; TODO:
- ;; - provide something like `around' for interactive forms.
- ;; - provide some kind of buffer-local functionality at least when `place'
- ;; is a variable.
- ;; - obsolete with-wrapper-hook (mostly requires buffer-local support).
;; - provide some kind of control over ordering. E.g. debug-on-entry, ELP
;; and tracing want to stay first.
- ;; - maybe also let `where' specify some kind of predicate and use it
+ ;; - maybe let `where' specify some kind of predicate and use it
;; to implement things like mode-local or eieio-defmethod.
+ ;; Of course, that only makes sense if the predicates of all advices can
+ ;; be combined and made more efficient.
;; :before is like a normal add-hook on a normal hook.
;; :before-while is like add-hook on run-hook-with-args-until-failure.
;; :before-until is like add-hook on run-hook-with-args-until-success.
`:before' (lambda (&rest r) (apply FUNCTION r) (apply OLDFUN r))
`:after' (lambda (&rest r) (prog1 (apply OLDFUN r) (apply FUNCTION r)))
`:around' (lambda (&rest r) (apply FUNCTION OLDFUN r))
+`:override' (lambda (&rest r) (apply FUNCTION r))
`:before-while' (lambda (&rest r) (and (apply FUNCTION r) (apply OLDFUN r)))
`:before-until' (lambda (&rest r) (or (apply FUNCTION r) (apply OLDFUN r)))
`:after-while' (lambda (&rest r) (and (apply OLDFUN r) (apply FUNCTION r)))
`:after-until' (lambda (&rest r) (or (apply OLDFUN r) (apply FUNCTION r)))
+`:filter-args' (lambda (&rest r) (apply OLDFUN (funcall FUNCTION r)))
+`:filter-return'(lambda (&rest r) (funcall FUNCTION (apply OLDFUN r)))
If FUNCTION was already added, do nothing.
PROPS is an alist of additional properties, among which the following have
a special meaning:
-- `name': a string or symbol. It can be used to refer to this piece of advice."
+- `name': a string or symbol. It can be used to refer to this piece of advice.
+
+If PLACE is a simple variable, only its global value will be affected.
+Use (local 'VAR) if you want to apply FUNCTION to VAR buffer-locally.
+
+If one of FUNCTION or OLDFUN is interactive, then the resulting function
+is also interactive. There are 3 cases:
+- FUNCTION is not interactive: the interactive spec of OLDFUN is used.
+- The interactive spec of FUNCTION is itself a function: it should take one
+ argument (the interactive spec of OLDFUN, which it can pass to
+ `advice-eval-interactive-spec') and return the list of arguments to use.
+- Else, use the interactive spec of FUNCTION and ignore the one of OLDFUN."
(declare (debug t)) ;;(indent 2)
+ (cond ((eq 'local (car-safe place))
+ (setq place `(advice--buffer-local ,@(cdr place))))
+ ((symbolp place)
+ (setq place `(default-value ',place))))
`(advice--add-function ,where (gv-ref ,place) ,function ,props))
;;;###autoload
(defun advice--add-function (where ref function props)
- (unless (advice--member-p function (gv-deref ref))
+ (let ((a (advice--member-p function (cdr (assq 'name props))
+ (gv-deref ref))))
+ (when a
+ ;; The advice is already present. Remove the old one, first.
+ (setf (gv-deref ref)
+ (advice--remove-function (gv-deref ref) (advice--car a))))
(setf (gv-deref ref)
(advice--make where function (gv-deref ref) props))))
+;;;###autoload
(defmacro remove-function (place function)
"Remove the FUNCTION piece of advice from PLACE.
If FUNCTION was not added to PLACE, do nothing.
Instead of FUNCTION being the actual function, it can also be the `name'
of the piece of advice."
(declare (debug t))
+ (cond ((eq 'local (car-safe place))
+ (setq place `(advice--buffer-local ,@(cdr place))))
+ ((symbolp place)
+ (error "Use (default-value '%S) or (local '%S)" place place)))
(gv-letplace (getter setter) place
(macroexp-let2 nil new `(advice--remove-function ,getter ,function)
`(unless (eq ,new ,getter) ,(funcall setter new)))))
;;;; Specific application of add-function to `symbol-function' for advice.
(defun advice--subst-main (old new)
- (if (not (advice--p old))
- new
- (let* ((first (advice--car old))
- (rest (advice--cdr old))
- (props (advice--props old))
- (nrest (advice--subst-main rest new)))
- (if (equal rest nrest) old
- (advice--make-1 (aref old 1) (aref old 3)
- first nrest props)))))
+ (advice--tweak old
+ (lambda (first _rest _props) (if (not first) new))))
+
+(defun advice--normalize (symbol def)
+ (cond
+ ((special-form-p def)
+ ;; Not worth the trouble trying to handle this, I think.
+ (error "advice-add failure: %S is a special form" symbol))
+ ((and (symbolp def)
+ (eq 'macro (car-safe (ignore-errors (indirect-function def)))))
+ (let ((newval (cons 'macro (cdr (indirect-function def)))))
+ (put symbol 'advice--saved-rewrite (cons def newval))
+ newval))
+ ;; `f' might be a pure (hence read-only) cons!
+ ((and (eq 'macro (car-safe def))
+ (not (ignore-errors (setcdr def (cdr def)) t)))
+ (cons 'macro (cdr def)))
+ (t def)))
+
+(defsubst advice--strip-macro (x)
+ (if (eq 'macro (car-safe x)) (cdr x) x))
(defun advice--defalias-fset (fsetfun symbol newdef)
- (let* ((olddef (if (fboundp symbol) (symbol-function symbol)))
+ (when (get symbol 'advice--saved-rewrite)
+ (put symbol 'advice--saved-rewrite nil))
+ (setq newdef (advice--normalize symbol newdef))
+ (let* ((olddef (advice--strip-macro
+ (if (fboundp symbol) (symbol-function symbol))))
(oldadv
(cond
- ((null (get symbol 'advice--pending))
- (or olddef
- (progn
- (message "Delayed advice activation failed for %s: no data"
- symbol)
- nil)))
- ((or (not olddef) (autoloadp olddef))
- (prog1 (get symbol 'advice--pending)
- (put symbol 'advice--pending nil)))
+ ((null (get symbol 'advice--pending))
+ (or olddef
+ (progn
+ (message "Delayed advice activation failed for %s: no data"
+ symbol)
+ nil)))
+ ((or (not olddef) (autoloadp olddef))
+ (prog1 (get symbol 'advice--pending)
+ (put symbol 'advice--pending nil)))
(t (message "Dropping left-over advice--pending for %s" symbol)
(put symbol 'advice--pending nil)
olddef))))
- (funcall (or fsetfun #'fset) symbol (advice--subst-main oldadv newdef))))
+ (let* ((snewdef (advice--strip-macro newdef))
+ (snewadv (advice--subst-main oldadv snewdef)))
+ (funcall (or fsetfun #'fset) symbol
+ (if (eq snewdef newdef) snewadv (cons 'macro snewadv))))))
;;;###autoload
;; - change all defadvice in lisp/**/*.el.
;; - rewrite advice.el on top of this.
;; - obsolete advice.el.
- ;; To make advice.el and nadvice.el interoperate properly I see 2 different
- ;; ways:
- ;; - keep them separate: complete the defalias-fset-function setter with
- ;; a matching accessor which both nadvice.el and advice.el will have to use
- ;; in place of symbol-function. This can probably be made to work, but
- ;; they have to agree on a "protocol".
- ;; - layer advice.el on top of nadvice.el. I prefer this approach. the
- ;; simplest way is to make advice.el build one ad-Advice-foo function for
- ;; each advised function which is advice-added/removed whenever ad-activate
- ;; ad-deactivate is called.
- (let ((f (and (fboundp symbol) (symbol-function symbol))))
- (cond
- ((special-form-p f)
- ;; Not worth the trouble trying to handle this, I think.
- (error "add-advice failure: %S is a special form" symbol))
- ((and (symbolp f)
- (eq 'macro (car-safe (ignore-errors (indirect-function f)))))
- (let ((newval (cons 'macro (cdr (indirect-function f)))))
- (put symbol 'advice--saved-rewrite (cons f newval))
- (fset symbol newval)))
- ;; `f' might be a pure (hence read-only) cons!
- ((and (eq 'macro (car-safe f)) (not (ignore-errors (setcdr f (cdr f)) t)))
- (fset symbol (cons 'macro (cdr f))))
- ))
- (let ((f (and (fboundp symbol) (symbol-function symbol))))
+ (let* ((f (and (fboundp symbol) (symbol-function symbol)))
+ (nf (advice--normalize symbol f)))
+ (unless (eq f nf) ;; Most importantly, if nf == nil!
+ (fset symbol nf))
(add-function where (cond
- ((eq (car-safe f) 'macro) (cdr f))
- ;; If the function is not yet defined, we can't yet
- ;; install the advice.
- ;; FIXME: If it's an autoloaded command, we also
- ;; have a problem because we need to load the
- ;; command to build the interactive-form.
- ((or (not f) (and (autoloadp f))) ;; (commandp f)
+ ((eq (car-safe nf) 'macro) (cdr nf))
+ ;; Reasons to delay installation of the advice:
+ ;; - If the function is not yet defined, installing
+ ;; the advice would affect `fboundp'ness.
+ ;; - If it's an autoloaded command,
+ ;; advice--make-interactive-form would end up
+ ;; loading the command eagerly.
+ ;; - `autoload' does nothing if the function is
+ ;; not an autoload or undefined.
+ ((or (not nf) (autoloadp nf))
(get symbol 'advice--pending))
(t (symbol-function symbol)))
function props)
function)
(unless (advice--p
(if (eq (car-safe f) 'macro) (cdr f) (symbol-function symbol)))
- ;; Not adviced any more.
+ ;; Not advised any more.
(remove-function (get symbol 'defalias-fset-function)
#'advice--defalias-fset)
(if (eq (symbol-function symbol)
;; (setq def (advice--cdr def)))))
;;;###autoload
-(defun advice-member-p (function symbol)
- "Return non-nil if advice FUNCTION has been added to function SYMBOL.
-Instead of FUNCTION being the actual function, it can also be the `name'
+(defun advice-member-p (advice function-name)
+ "Return non-nil if ADVICE has been added to FUNCTION-NAME.
+Instead of ADVICE being the actual function, it can also be the `name'
of the piece of advice."
- (advice--member-p function
- (or (get symbol 'advice--pending)
- (if (fboundp symbol) (symbol-function symbol)))))
+ (advice--member-p advice advice
+ (or (get function-name 'advice--pending)
+ (advice--strip-macro
+ (if (fboundp function-name)
+ (symbol-function function-name))))))
+
+;; When code is advised, called-interactively-p needs to be taught to skip
+;; the advising frames.
+;; FIXME: This Major Ugly Hack won't handle calls to called-interactively-p
+;; done from the advised function if the deepest advice is an around advice!
+;; In other cases (calls from an advice or calls from the advised function when
+;; the deepest advice is not an around advice), it should hopefully get
+;; it right.
+(add-hook 'called-interactively-p-functions
+ #'advice--called-interactively-skip)
+(defun advice--called-interactively-skip (origi frame1 frame2)
+ (let* ((i origi)
+ (get-next-frame
+ (lambda ()
+ (setq frame1 frame2)
+ (setq frame2 (internal--called-interactively-p--get-frame i))
+ ;; (message "Advice Frame %d = %S" i frame2)
+ (setq i (1+ i)))))
+ (when (and (eq (nth 1 frame2) 'apply)
+ (progn
+ (funcall get-next-frame)
+ (advice--p (indirect-function (nth 1 frame2)))))
+ (funcall get-next-frame)
+ ;; If we now have the symbol, this was the head advice and
+ ;; we're done.
+ (while (advice--p (nth 1 frame1))
+ ;; This was an inner advice called from some earlier advice.
+ ;; The stack frames look different depending on the particular
+ ;; kind of the earlier advice.
+ (let ((inneradvice (nth 1 frame1)))
+ (if (and (eq (nth 1 frame2) 'apply)
+ (progn
+ (funcall get-next-frame)
+ (advice--p (indirect-function
+ (nth 1 frame2)))))
+ ;; The earlier advice was something like a before/after
+ ;; advice where the "next" code is called directly by the
+ ;; advice--p object.
+ (funcall get-next-frame)
+ ;; It's apparently an around advice, where the "next" is
+ ;; called by the body of the advice in any way it sees fit,
+ ;; so we need to skip the frames of that body.
+ (while
+ (progn
+ (funcall get-next-frame)
+ (not (and (eq (nth 1 frame2) 'apply)
+ (eq (nth 3 frame2) inneradvice)))))
+ (funcall get-next-frame)
+ (funcall get-next-frame))))
+ (- i origi 1))))
(provide 'nadvice)