;;; cl-generic.el --- CLOS-style generic functions for Elisp -*- lexical-binding: t; -*-
-;; Copyright (C) 2015 Free Software Foundation, Inc.
+;; Copyright (C) 2015-2016 Free Software Foundation, Inc.
;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
;; Version: 1.0
;; - The standard method combination supports ":extra STRING" qualifiers
;; which simply allows adding more methods for the same
;; specializers&qualifiers.
+;; - Methods can dispatch on the context. For that, a method needs to specify
+;; context arguments, introduced by `&context' (which need to come right
+;; after the mandatory arguments and before anything like
+;; &optional/&rest/&key). Each context argument is given as (EXP SPECIALIZER)
+;; which means that EXP is taken as an expression which computes some context
+;; and this value is then used to dispatch.
+;; E.g. (foo &context (major-mode (eql c-mode))) is an arglist specifying
+;; that this method will only be applicable when `major-mode' has value
+;; `c-mode'.
;; Efficiency considerations: overall, I've made an effort to make this fairly
;; efficient for the expected case (e.g. no constant redefinition of methods).
;; TODO:
;;
-;; - A generic "filter" generalizer (e.g. could be used to cleanly adds methods
+;; - A generic "filter" generalizer (e.g. could be used to cleanly add methods
;; to cl-generic-combine-methods with a specializer that says it applies only
;; when some particular qualifier is used).
-;; - A way to dispatch on the context (e.g. the major-mode, some global
-;; variable, you name it).
;;; Code:
;; usually be simplified, or even completely skipped.
(eval-when-compile (require 'cl-lib))
+(eval-when-compile (require 'cl-macs)) ;For cl--find-class.
(eval-when-compile (require 'pcase))
(cl-defstruct (cl--generic-generalizer
(:constructor nil)
(:constructor cl-generic-make-generalizer
- (priority tagcode-function specializers-function)))
+ (name priority tagcode-function specializers-function)))
+ (name nil :type string)
(priority nil :type integer)
tagcode-function
specializers-function)
-(defconst cl--generic-t-generalizer
- (cl-generic-make-generalizer
- 0 (lambda (_name) nil) (lambda (_tag) '(t))))
+
+(defmacro cl-generic-define-generalizer
+ (name priority tagcode-function specializers-function)
+ "Define a new kind of generalizer.
+NAME is the name of the variable that will hold it.
+PRIORITY defines which generalizer takes precedence.
+ The catch-all generalizer has priority 0.
+ Then `eql' generalizer has priority 100.
+TAGCODE-FUNCTION takes as first argument a varname and should return
+ a chunk of code that computes the tag of the value held in that variable.
+ Further arguments are reserved for future use.
+SPECIALIZERS-FUNCTION takes as first argument a tag value TAG
+ and should return a list of specializers that match TAG.
+ Further arguments are reserved for future use."
+ (declare (indent 1) (debug (symbolp body)))
+ `(defconst ,name
+ (cl-generic-make-generalizer
+ ',name ,priority ,tagcode-function ,specializers-function)))
+
+(cl-generic-define-generalizer cl--generic-t-generalizer
+ 0 (lambda (_name &rest _) nil) (lambda (_tag &rest _) '(t)))
(cl-defstruct (cl--generic-method
(:constructor nil)
(defmacro cl--generic (name)
`(get ,name 'cl--generic))
-(defun cl-generic-ensure-function (name)
+(defun cl-generic-ensure-function (name &optional noerror)
(let (generic
(origname name))
(while (and (null (setq generic (cl--generic name)))
(fboundp name)
+ (null noerror)
(symbolp (symbol-function name)))
(setq name (symbol-function name)))
(unless (or (not (fboundp name))
(autoloadp (symbol-function name))
- (and (functionp name) generic))
+ (and (functionp name) generic)
+ noerror)
(error "%s is already defined as something else than a generic function"
origname))
(if generic
(defalias name (cl--generic-make-function generic)))
generic))
-(defun cl--generic-setf-rewrite (name)
- (let* ((setter (intern (format "cl-generic-setter--%s" name)))
- (exp `(unless (eq ',setter (get ',name 'cl-generic-setter))
- ;; (when (get ',name 'gv-expander)
- ;; (error "gv-expander conflicts with (setf %S)" ',name))
- (setf (get ',name 'cl-generic-setter) ',setter)
- (gv-define-setter ,name (val &rest args)
- (cons ',setter (cons val args))))))
- ;; Make sure `setf' can be used right away, e.g. in the body of the method.
- (eval exp t)
- (cons setter exp)))
-
;;;###autoload
(defmacro cl-defgeneric (name args &rest options-and-methods)
"Create a generic function NAME.
- (declare DECLARATIONS)
- (:argument-precedence-order &rest ARGS)
- (:method [QUALIFIERS...] ARGS &rest BODY)
-BODY, if present, is used as the body of a default method.
+DEFAULT-BODY, if present, is used as the body of a default method.
-\(fn NAME ARGS [DOC-STRING] [OPTIONS-AND-METHODS...] &rest BODY)"
+\(fn NAME ARGS [DOC-STRING] [OPTIONS-AND-METHODS...] &rest DEFAULT-BODY)"
(declare (indent 2) (doc-string 3))
(let* ((doc (if (stringp (car-safe options-and-methods))
(pop options-and-methods)))
(when options-and-methods
;; Anything remaining is assumed to be a default method body.
(push `(,args ,@options-and-methods) methods))
+ (when (eq 'setf (car-safe name))
+ (require 'gv)
+ (setq name (gv-setter (cadr name))))
`(progn
- ,(when (eq 'setf (car-safe name))
- (pcase-let ((`(,setter . ,code) (cl--generic-setf-rewrite
- (cadr name))))
- (setq name setter)
- code))
,@(mapcar (lambda (declaration)
(let ((f (cdr (assq (car declaration)
defun-declarations-alist))))
,@(mapcar (lambda (method) `(cl-defmethod ,name ,@method))
(nreverse methods)))))
-(defun cl--generic-mandatory-args (args)
- (let ((res ()))
- (while (not (memq (car args) '(nil &rest &optional &key)))
- (push (pop args) res))
- (nreverse res)))
-
;;;###autoload
(defun cl-generic-define (name args options)
- (let ((generic (cl-generic-ensure-function name))
- (mandatory (cl--generic-mandatory-args args))
- (apo (assq :argument-precedence-order options)))
- (setf (cl--generic-dispatches generic) nil)
+ (pcase-let* ((generic (cl-generic-ensure-function name 'noerror))
+ (`(,spec-args . ,_) (cl--generic-split-args args))
+ (mandatory (mapcar #'car spec-args))
+ (apo (assq :argument-precedence-order options)))
+ (unless (fboundp name)
+ ;; If the generic function was fmakunbound, throw away previous methods.
+ (setf (cl--generic-dispatches generic) nil)
+ (setf (cl--generic-method-table generic) nil))
(when apo
(dolist (arg (cdr apo))
(let ((pos (memq arg mandatory)))
(unless pos (error "%S is not a mandatory argument" arg))
- (push (list (- (length mandatory) (length pos)))
- (cl--generic-dispatches generic)))))
- (setf (cl--generic-method-table generic) nil)
+ (let* ((argno (- (length mandatory) (length pos)))
+ (dispatches (cl--generic-dispatches generic))
+ (dispatch (or (assq argno dispatches) (list argno))))
+ (setf (cl--generic-dispatches generic)
+ (cons dispatch (delq dispatch dispatches)))))))
(setf (cl--generic-options generic) options)
(cl--generic-make-function generic)))
This macro can only be used within the lexical scope of a cl-generic method."
(error "cl-generic-current-method-specializers used outside of a method"))
+(defmacro cl-generic-define-context-rewriter (name args &rest body)
+ "Define a special kind of context named NAME.
+Whenever a context specializer of the form (NAME . ARGS) appears,
+the specializer used will be the one returned by BODY."
+ (declare (debug (&define name lambda-list def-body)) (indent defun))
+ `(eval-and-compile
+ (put ',name 'cl-generic--context-rewriter
+ (lambda ,args ,@body))))
+
(eval-and-compile ;Needed while compiling the cl-defmethod calls below!
(defun cl--generic-fgrep (vars sexp) ;Copied from pcase.el.
"Check which of the symbols VARS appear in SEXP."
(and (memq sexp vars) (not (memq sexp res)) (push sexp res))
res))
- (defun cl--generic-lambda (args body)
- "Make the lambda expression for a method with ARGS and BODY."
+ (defun cl--generic-split-args (args)
+ "Return (SPEC-ARGS . PLAIN-ARGS)."
(let ((plain-args ())
(specializers nil)
(mandatory t))
(dolist (arg args)
(push (pcase arg
((or '&optional '&rest '&key) (setq mandatory nil) arg)
- ((and `(,name . ,type) (guard mandatory))
+ ('&context
+ (unless mandatory
+ (error "&context not immediately after mandatory args"))
+ (setq mandatory 'context) nil)
+ ((let 'nil mandatory) arg)
+ ((let 'context mandatory)
+ (unless (consp arg)
+ (error "Invalid &context arg: %S" arg))
+ (let* ((name (car arg))
+ (rewriter
+ (and (symbolp name)
+ (get name 'cl-generic--context-rewriter))))
+ (if rewriter (setq arg (apply rewriter (cdr arg)))))
+ (push `((&context . ,(car arg)) . ,(cadr arg)) specializers)
+ nil)
+ (`(,name . ,type)
(push (cons name (car type)) specializers)
name)
- (_ arg))
+ (_
+ (push (cons arg t) specializers)
+ arg))
plain-args))
- (setq plain-args (nreverse plain-args))
- (let ((fun `(cl-function (lambda ,plain-args ,@body)))
- (macroenv (cons `(cl-generic-current-method-specializers
- . ,(lambda () specializers))
- macroexpand-all-environment)))
- (require 'cl-lib) ;Needed to expand `cl-flet' and `cl-function'.
- ;; First macroexpand away the cl-function stuff (e.g. &key and
- ;; destructuring args, `declare' and whatnot).
- (pcase (macroexpand fun macroenv)
- (`#'(lambda ,args . ,body)
- (let* ((parsed-body (macroexp-parse-body body))
- (cnm (make-symbol "cl--cnm"))
- (nmp (make-symbol "cl--nmp"))
- (nbody (macroexpand-all
- `(cl-flet ((cl-call-next-method ,cnm)
- (cl-next-method-p ,nmp))
- ,@(cdr parsed-body))
- macroenv))
- ;; FIXME: Rather than `grep' after the fact, the
- ;; macroexpansion should directly set some flag when cnm
- ;; is used.
- ;; FIXME: Also, optimize the case where call-next-method is
- ;; only called with explicit arguments.
- (uses-cnm (cl--generic-fgrep (list cnm nmp) nbody)))
- (cons (not (not uses-cnm))
- `#'(lambda (,@(if uses-cnm (list cnm)) ,@args)
- ,@(car parsed-body)
- ,(if (not (memq nmp uses-cnm))
- nbody
- `(let ((,nmp (lambda ()
- (cl--generic-isnot-nnm-p ,cnm))))
- ,nbody))))))
- (f (error "Unexpected macroexpansion result: %S" f)))))))
+ (cons (nreverse specializers)
+ (nreverse (delq nil plain-args)))))
+ (defun cl--generic-lambda (args body)
+ "Make the lambda expression for a method with ARGS and BODY."
+ (pcase-let* ((`(,spec-args . ,plain-args)
+ (cl--generic-split-args args))
+ (fun `(cl-function (lambda ,plain-args ,@body)))
+ (macroenv (cons `(cl-generic-current-method-specializers
+ . ,(lambda () spec-args))
+ macroexpand-all-environment)))
+ (require 'cl-lib) ;Needed to expand `cl-flet' and `cl-function'.
+ ;; First macroexpand away the cl-function stuff (e.g. &key and
+ ;; destructuring args, `declare' and whatnot).
+ (pcase (macroexpand fun macroenv)
+ (`#'(lambda ,args . ,body)
+ (let* ((parsed-body (macroexp-parse-body body))
+ (cnm (make-symbol "cl--cnm"))
+ (nmp (make-symbol "cl--nmp"))
+ (nbody (macroexpand-all
+ `(cl-flet ((cl-call-next-method ,cnm)
+ (cl-next-method-p ,nmp))
+ ,@(cdr parsed-body))
+ macroenv))
+ ;; FIXME: Rather than `grep' after the fact, the
+ ;; macroexpansion should directly set some flag when cnm
+ ;; is used.
+ ;; FIXME: Also, optimize the case where call-next-method is
+ ;; only called with explicit arguments.
+ (uses-cnm (cl--generic-fgrep (list cnm nmp) nbody)))
+ (cons (not (not uses-cnm))
+ `#'(lambda (,@(if uses-cnm (list cnm)) ,@args)
+ ,@(car parsed-body)
+ ,(if (not (memq nmp uses-cnm))
+ nbody
+ `(let ((,nmp (lambda ()
+ (cl--generic-isnot-nnm-p ,cnm))))
+ ,nbody))))))
+ (f (error "Unexpected macroexpansion result: %S" f))))))
+
+(put 'cl-defmethod 'function-documentation
+ '(cl--generic-make-defmethod-docstring))
+
+(defun cl--generic-make-defmethod-docstring ()
+ ;; FIXME: Copy&paste from pcase--make-docstring.
+ (let* ((main (documentation (symbol-function 'cl-defmethod) 'raw))
+ (ud (help-split-fundoc main 'cl-defmethod)))
+ ;; So that eg emacs -Q -l cl-lib --eval "(documentation 'pcase)" works,
+ ;; where cl-lib is anything using pcase-defmacro.
+ (require 'help-fns)
+ (with-temp-buffer
+ (insert (or (cdr ud) main))
+ (insert "\n\n\tCurrently supported forms for TYPE:\n\n")
+ (dolist (method (reverse (cl--generic-method-table
+ (cl--generic 'cl-generic-generalizers))))
+ (let* ((info (cl--generic-method-info method)))
+ (when (nth 2 info)
+ (insert (nth 2 info) "\n\n"))))
+ (let ((combined-doc (buffer-string)))
+ (if ud (help-add-fundoc-usage combined-doc (car ud)) combined-doc)))))
;;;###autoload
(defmacro cl-defmethod (name args &rest body)
"Define a new method for generic function NAME.
I.e. it defines the implementation of NAME to use for invocations where the
-value of the dispatch argument matches the specified TYPE.
-The dispatch argument has to be one of the mandatory arguments, and
-all methods of NAME have to use the same argument for dispatch.
-The dispatch argument and TYPE are specified in ARGS where the corresponding
+values of the dispatch arguments match the specified TYPEs.
+The dispatch arguments have to be among the mandatory arguments, and
+all methods of NAME have to use the same set of arguments for dispatch.
+Each dispatch argument and TYPE are specified in ARGS where the corresponding
formal argument appears as (VAR TYPE) rather than just VAR.
The optional second argument QUALIFIER is a specifier that
:after - Method will be called after the primary
:around - Method will be called around everything else
The absence of QUALIFIER means this is a \"primary\" method.
+The set of acceptable qualifiers and their meaning is defined
+\(and can be extended) by the methods of `cl-generic-combine-methods'.
-Other than a type, TYPE can also be of the form `(eql VAL)' in
-which case this method will be invoked when the argument is `eql' to VAL.
+ARGS can also include so-called context specializers, introduced by
+`&context' (which should appear right after the mandatory arguments,
+before any &optional or &rest). They have the form (EXPR TYPE) where
+EXPR is an Elisp expression whose value should match TYPE for the
+method to be applicable.
+
+The set of acceptable TYPEs (also called \"specializers\") is defined
+\(and can be extended) by the various methods of `cl-generic-generalizers'.
\(fn NAME [QUALIFIER] ARGS &rest [DOCSTRING] BODY)"
(declare (doc-string 3) (indent 2)
list ; arguments
[ &optional stringp ] ; documentation string
def-body))) ; part to be debugged
- (let ((qualifiers nil)
- (setfizer (if (eq 'setf (car-safe name))
- ;; Call it before we call cl--generic-lambda.
- (cl--generic-setf-rewrite (cadr name)))))
+ (let ((qualifiers nil))
(while (not (listp args))
(push args qualifiers)
(setq args (pop body)))
+ (when (eq 'setf (car-safe name))
+ (require 'gv)
+ (setq name (gv-setter (cadr name))))
(pcase-let* ((`(,uses-cnm . ,fun) (cl--generic-lambda args body)))
`(progn
- ,(when setfizer
- (setq name (car setfizer))
- (cdr setfizer))
,(and (get name 'byte-obsolete-info)
(or (not (fboundp 'byte-compile-warning-enabled-p))
(byte-compile-warning-enabled-p 'obsolete))
;; function, so warnings like "not known to be defined" are fair game.
;; But in practice, it's common to use `cl-defmethod'
;; without a previous `cl-defgeneric'.
- (declare-function ,name "")
+ ;; The ",'" is a no-op that pacifies check-declare.
+ (,'declare-function ,name "")
(cl-generic-define-method ',name ',(nreverse qualifiers) ',args
,uses-cnm ,fun)))))
;;;###autoload
(defun cl-generic-define-method (name qualifiers args uses-cnm function)
- (let* ((generic (cl-generic-ensure-function name))
- (mandatory (cl--generic-mandatory-args args))
- (specializers
- (mapcar (lambda (arg) (if (consp arg) (cadr arg) t)) mandatory))
- (method (cl--generic-make-method
- specializers qualifiers uses-cnm function))
- (mt (cl--generic-method-table generic))
- (me (cl--generic-member-method specializers qualifiers mt))
- (dispatches (cl--generic-dispatches generic))
- (i 0))
- (dolist (specializer specializers)
- (let* ((generalizers (cl-generic-generalizers specializer))
- (x (assq i dispatches)))
+ (pcase-let*
+ ((generic (cl-generic-ensure-function name))
+ (`(,spec-args . ,_) (cl--generic-split-args args))
+ (specializers (mapcar (lambda (spec-arg)
+ (if (eq '&context (car-safe (car spec-arg)))
+ spec-arg (cdr spec-arg)))
+ spec-args))
+ (method (cl--generic-make-method
+ specializers qualifiers uses-cnm function))
+ (mt (cl--generic-method-table generic))
+ (me (cl--generic-member-method specializers qualifiers mt))
+ (dispatches (cl--generic-dispatches generic))
+ (i 0))
+ (dolist (spec-arg spec-args)
+ (let* ((key (if (eq '&context (car-safe (car spec-arg)))
+ (car spec-arg) i))
+ (generalizers (cl-generic-generalizers (cdr spec-arg)))
+ (x (assoc key dispatches)))
(unless x
- (setq x (cons i (cl-generic-generalizers t)))
+ (setq x (cons key (cl-generic-generalizers t)))
(setf (cl--generic-dispatches generic)
(setq dispatches (cons x dispatches))))
(dolist (generalizer generalizers)
(> (cl--generic-generalizer-priority x)
(cl--generic-generalizer-priority y)))))))
(setq i (1+ i))))
- (if me (setcar me method)
- (setf (cl--generic-method-table generic) (cons method mt)))
- (cl-pushnew `(cl-defmethod . (,(cl--generic-name generic) . ,specializers))
+ ;; We used to (setcar me method), but that can cause false positives in
+ ;; the hash-consing table of the method-builder (bug#20644).
+ ;; See also the related FIXME in cl--generic-build-combined-method.
+ (setf (cl--generic-method-table generic)
+ (if (null me)
+ (cons method mt)
+ ;; Keep the ordering; important for methods with :extra qualifiers.
+ (mapcar (lambda (x) (if (eq x (car me)) method x)) mt)))
+ (cl-pushnew `(cl-defmethod . (,(cl--generic-name generic)
+ ,qualifiers . ,specializers))
current-load-list :test #'equal)
;; FIXME: Try to avoid re-constructing a new function if the old one
;; is still valid (e.g. still empty method cache)?
;; the generic function.
current-load-list)
;; For aliases, cl--generic-name gives us the actual name.
- (defalias (cl--generic-name generic) gfun))))
+ (let ((purify-flag
+ ;; BEWARE! Don't purify this function definition, since that leads
+ ;; to memory corruption if the hash-tables it holds are modified
+ ;; (the GC doesn't trace those pointers).
+ nil))
+ ;; But do use `defalias', so that it interacts properly with nadvice,
+ ;; e.g. for tracing/debug-on-entry.
+ (defalias (cl--generic-name generic) gfun)))))
(defmacro cl--generic-with-memoization (place &rest code)
(declare (indent 1) (debug t))
(defun cl--generic-get-dispatcher (dispatch)
(cl--generic-with-memoization
(gethash dispatch cl--generic-dispatchers)
+ ;; (message "cl--generic-get-dispatcher (%S)" dispatch)
(let* ((dispatch-arg (car dispatch))
(generalizers (cdr dispatch))
(lexical-binding t)
'arg))
generalizers))
(typescodes
- (mapcar (lambda (generalizer)
- `(funcall ',(cl--generic-generalizer-specializers-function
- generalizer)
- ,(funcall (cl--generic-generalizer-tagcode-function
- generalizer)
- 'arg)))
- generalizers))
+ (mapcar
+ (lambda (generalizer)
+ `(funcall ',(cl--generic-generalizer-specializers-function
+ generalizer)
+ ,(funcall (cl--generic-generalizer-tagcode-function
+ generalizer)
+ 'arg)))
+ generalizers))
(tag-exp
;; Minor optimization: since this tag-exp is
;; only used to lookup the method-cache, it
`(or ,@(if (macroexp-const-p (car (last tagcodes)))
(butlast tagcodes)
tagcodes)))
- (extraargs ()))
- (dotimes (_ dispatch-arg)
- (push (make-symbol "arg") extraargs))
+ (fixedargs '(arg))
+ (dispatch-idx dispatch-arg)
+ (bindings nil))
+ (when (eq '&context (car-safe dispatch-arg))
+ (setq bindings `((arg ,(cdr dispatch-arg))))
+ (setq fixedargs nil)
+ (setq dispatch-idx 0))
+ (dotimes (i dispatch-idx)
+ (push (make-symbol (format "arg%d" (- dispatch-idx i 1))) fixedargs))
;; FIXME: For generic functions with a single method (or with 2 methods,
;; one of which always matches), using a tagcode + hash-table is
;; overkill: better just use a `cl-typep' test.
(byte-compile
`(lambda (generic dispatches-left methods)
(let ((method-cache (make-hash-table :test #'eql)))
- (lambda (,@extraargs arg &rest args)
- (apply (cl--generic-with-memoization
- (gethash ,tag-exp method-cache)
- (cl--generic-cache-miss
- generic ',dispatch-arg dispatches-left methods
- ,(if (cdr typescodes)
- `(append ,@typescodes) (car typescodes))))
- ,@extraargs arg args))))))))
+ (lambda (,@fixedargs &rest args)
+ (let ,bindings
+ (apply (cl--generic-with-memoization
+ (gethash ,tag-exp method-cache)
+ (cl--generic-cache-miss
+ generic ',dispatch-arg dispatches-left methods
+ ,(if (cdr typescodes)
+ `(append ,@typescodes) (car typescodes))))
+ ,@fixedargs args)))))))))
(defun cl--generic-make-function (generic)
(cl--generic-make-next-function generic
(progn
(while (and dispatches
(let ((x (nth 1 (car dispatches))))
- ;; No need to dispatch for `t' specializers.
+ ;; No need to dispatch for t specializers.
(or (null x) (equal x cl--generic-t-generalizer))))
(setq dispatches (cdr dispatches)))
(pop dispatches))))
(setq fun (cl-generic-call-method generic method fun)))
fun)))))
+(defun cl--generic-arg-specializer (method dispatch-arg)
+ (or (if (integerp dispatch-arg)
+ (nth dispatch-arg
+ (cl--generic-method-specializers method))
+ (cdr (assoc dispatch-arg
+ (cl--generic-method-specializers method))))
+ t))
+
(defun cl--generic-cache-miss (generic
dispatch-arg dispatches-left methods-left types)
(let ((methods '()))
(dolist (method methods-left)
- (let* ((specializer (or (nth dispatch-arg
- (cl--generic-method-specializers method))
- t))
+ (let* ((specializer (cl--generic-arg-specializer method dispatch-arg))
(m (member specializer types)))
(when m
(push (cons (length m) method) methods))))
This is because the method-cache is only indexed with the first non-nil
tag (by order of decreasing priority).")
-
(cl-defgeneric cl-generic-combine-methods (generic methods)
"Build the effective method made of METHODS.
It should return a function that expects the same arguments as the methods, and
The function can use `cl-generic-call-method' to create functions that call those
methods.")
-;; Temporary definition to let the next defmethod succeed.
-(fset 'cl-generic-generalizers
- (lambda (_specializer) (list cl--generic-t-generalizer)))
-(fset 'cl-generic-combine-methods
- #'cl--generic-standard-method-combination)
+(unless (ignore-errors (cl-generic-generalizers t))
+ ;; Temporary definition to let the next defmethod succeed.
+ (fset 'cl-generic-generalizers
+ (lambda (specializer)
+ (if (eq t specializer) (list cl--generic-t-generalizer))))
+ (fset 'cl-generic-combine-methods #'cl--generic-standard-method-combination))
(cl-defmethod cl-generic-generalizers (specializer)
- "Support for the catch-all `t' specializer."
+ "Support for the catch-all t specializer which always matches."
(if (eq specializer t) (list cl--generic-t-generalizer)
(error "Unknown specializer %S" specializer)))
+(eval-when-compile
+ ;; This macro is brittle and only really important in order to be
+ ;; able to preload cl-generic without also preloading the byte-compiler,
+ ;; So we use `eval-when-compile' so as not keep it available longer than
+ ;; strictly needed.
+(defmacro cl--generic-prefill-dispatchers (arg-or-context specializer)
+ (unless (integerp arg-or-context)
+ (setq arg-or-context `(&context . ,arg-or-context)))
+ (unless (fboundp 'cl--generic-get-dispatcher)
+ (require 'cl-generic))
+ (let ((fun (cl--generic-get-dispatcher
+ `(,arg-or-context ,@(cl-generic-generalizers specializer)
+ ,cl--generic-t-generalizer))))
+ ;; Recompute dispatch at run-time, since the generalizers may be slightly
+ ;; different (e.g. byte-compiled rather than interpreted).
+ ;; FIXME: There is a risk that the run-time generalizer is not equivalent
+ ;; to the compile-time one, in which case `fun' may not be correct
+ ;; any more!
+ `(let ((dispatch `(,',arg-or-context
+ ,@(cl-generic-generalizers ',specializer)
+ ,cl--generic-t-generalizer)))
+ ;; (message "Prefilling for %S with \n%S" dispatch ',fun)
+ (puthash dispatch ',fun cl--generic-dispatchers)))))
+
(cl-defmethod cl-generic-combine-methods (generic methods)
"Standard support for :after, :before, :around, and `:extra NAME' qualifiers."
(cl--generic-standard-method-combination generic methods))
;;; Define some pre-defined generic functions, used internally.
-(define-error 'cl-no-method "No method for %S")
-(define-error 'cl-no-next-method "No next method for %S" 'cl-no-method)
-(define-error 'cl-no-primary-method "No primary method for %S" 'cl-no-method)
-(define-error 'cl-no-applicable-method "No applicable method for %S"
+(define-error 'cl-no-method "No method")
+(define-error 'cl-no-next-method "No next method" 'cl-no-method)
+(define-error 'cl-no-primary-method "No primary method" 'cl-no-method)
+(define-error 'cl-no-applicable-method "No applicable method"
'cl-no-method)
(cl-defgeneric cl-no-next-method (generic method &rest args)
specializers qualifiers
(cl--generic-method-table (cl--generic generic)))))
-(defalias 'cl-method-qualifiers 'cl--generic-method-qualifiers)
-
;;; Add support for describe-function
(defun cl--generic-search-method (met-name)
+ "For `find-function-regexp-alist'. Searches for a cl-defmethod.
+MET-NAME is a cons (SYMBOL . SPECIALIZERS)."
(let ((base-re (concat "(\\(?:cl-\\)?defmethod[ \t]+"
(regexp-quote (format "%s" (car met-name)))
"\\_>")))
nil t)
(re-search-forward base-re nil t))))
+;; WORKAROUND: This can't be a defconst due to bug#21237.
+(defvar cl--generic-find-defgeneric-regexp "(\\(?:cl-\\)?defgeneric[ \t]+%s\\>")
(with-eval-after-load 'find-func
(defvar find-function-regexp-alist)
(add-to-list 'find-function-regexp-alist
- `(cl-defmethod . ,#'cl--generic-search-method)))
+ `(cl-defmethod . ,#'cl--generic-search-method))
+ (add-to-list 'find-function-regexp-alist
+ `(cl-defgeneric . cl--generic-find-defgeneric-regexp)))
(defun cl--generic-method-info (method)
(let* ((specializers (cl--generic-method-specializers method))
(add-hook 'help-fns-describe-function-functions #'cl--generic-describe)
(defun cl--generic-describe (function)
+ ;; Supposedly this is called from help-fns, so help-fns should be loaded at
+ ;; this point.
+ (declare-function help-fns-short-filename "help-fns" (filename))
(let ((generic (if (symbolp function) (cl--generic function))))
(when generic
(require 'help-mode) ;Needed for `help-function-def' button!
(let* ((info (cl--generic-method-info method)))
;; FIXME: Add hyperlinks for the types as well.
(insert (format "%s%S" (nth 0 info) (nth 1 info)))
- (let* ((met-name (cons function
- (cl--generic-method-specializers method)))
+ (let* ((met-name `(,function
+ ,(cl--generic-method-qualifiers method)
+ . ,(cl--generic-method-specializers method)))
(file (find-lisp-object-file-name met-name 'cl-defmethod)))
(when file
- (insert " in `")
+ (insert (substitute-command-keys " in `"))
(help-insert-xref-button (help-fns-short-filename file)
'help-function-def met-name file
'cl-defmethod)
- (insert "'.\n")))
+ (insert (substitute-command-keys "'.\n"))))
(insert "\n" (or (nth 2 info) "Undocumented") "\n\n")))))))
+(defun cl--generic-specializers-apply-to-type-p (specializers type)
+ "Return non-nil if a method with SPECIALIZERS applies to TYPE."
+ (let ((applies nil))
+ (dolist (specializer specializers)
+ (if (memq (car-safe specializer) '(subclass eieio--static))
+ (setq specializer (nth 1 specializer)))
+ ;; Don't include the methods that are "too generic", such as those
+ ;; applying to `eieio-default-superclass'.
+ (and (not (memq specializer '(t eieio-default-superclass)))
+ (or (equal type specializer)
+ (when (symbolp specializer)
+ (let ((sclass (cl--find-class specializer))
+ (tclass (cl--find-class type)))
+ (when (and sclass tclass)
+ (member specializer (cl--generic-class-parents tclass))))))
+ (setq applies t)))
+ applies))
+
+(defun cl-generic-all-functions (&optional type)
+ "Return a list of all generic functions.
+Optional TYPE argument returns only those functions that contain
+methods for TYPE."
+ (let ((l nil))
+ (mapatoms
+ (lambda (symbol)
+ (let ((generic (and (fboundp symbol) (cl--generic symbol))))
+ (and generic
+ (catch 'found
+ (if (null type) (throw 'found t))
+ (dolist (method (cl--generic-method-table generic))
+ (if (cl--generic-specializers-apply-to-type-p
+ (cl--generic-method-specializers method) type)
+ (throw 'found t))))
+ (push symbol l)))))
+ l))
+
+(defun cl--generic-method-documentation (function type)
+ "Return info for all methods of FUNCTION (a symbol) applicable to TYPE.
+The value returned is a list of elements of the form
+\(QUALIFIERS ARGS DOC)."
+ (let ((generic (cl--generic function))
+ (docs ()))
+ (when generic
+ (dolist (method (cl--generic-method-table generic))
+ (when (cl--generic-specializers-apply-to-type-p
+ (cl--generic-method-specializers method) type)
+ (push (cl--generic-method-info method) docs))))
+ docs))
+
;;; Support for (head <val>) specializers.
;; For both the `eql' and the `head' specializers, the dispatch
(defvar cl--generic-head-used (make-hash-table :test #'eql))
-(defconst cl--generic-head-generalizer
- (cl-generic-make-generalizer
- 80 (lambda (name) `(gethash (car-safe ,name) cl--generic-head-used))
- (lambda (tag) (if (eq (car-safe tag) 'head) (list tag)))))
+(cl-generic-define-generalizer cl--generic-head-generalizer
+ 80 (lambda (name &rest _) `(gethash (car-safe ,name) cl--generic-head-used))
+ (lambda (tag &rest _) (if (eq (car-safe tag) 'head) (list tag))))
(cl-defmethod cl-generic-generalizers :extra "head" (specializer)
- "Support for the `(head VAL)' specializers."
+ "Support for (head VAL) specializers.
+These match if the argument is a cons cell whose car is `eql' to VAL."
;; We have to implement `head' here using the :extra qualifier,
;; since we can't use the `head' specializer to implement itself.
(if (not (eq (car-safe specializer) 'head))
(gethash (cadr specializer) cl--generic-head-used) specializer)
(list cl--generic-head-generalizer)))
+(cl--generic-prefill-dispatchers 0 (head eql))
+
;;; Support for (eql <val>) specializers.
(defvar cl--generic-eql-used (make-hash-table :test #'eql))
-(defconst cl--generic-eql-generalizer
- (cl-generic-make-generalizer
- 100 (lambda (name) `(gethash ,name cl--generic-eql-used))
- (lambda (tag) (if (eq (car-safe tag) 'eql) (list tag)))))
+(cl-generic-define-generalizer cl--generic-eql-generalizer
+ 100 (lambda (name &rest _) `(gethash ,name cl--generic-eql-used))
+ (lambda (tag &rest _) (if (eq (car-safe tag) 'eql) (list tag))))
(cl-defmethod cl-generic-generalizers ((specializer (head eql)))
- "Support for the `(eql VAL)' specializers."
+ "Support for (eql VAL) specializers.
+These match if the argument is `eql' to VAL."
(puthash (cadr specializer) specializer cl--generic-eql-used)
(list cl--generic-eql-generalizer))
+(cl--generic-prefill-dispatchers 0 (eql nil))
+(cl--generic-prefill-dispatchers window-system (eql nil))
+(cl--generic-prefill-dispatchers (terminal-parameter nil 'xterm--get-selection)
+ (eql nil))
+(cl--generic-prefill-dispatchers (terminal-parameter nil 'xterm--set-selection)
+ (eql nil))
+
;;; Support for cl-defstructs specializers.
-(defun cl--generic-struct-tag (name)
+(defun cl--generic-struct-tag (name &rest _)
;; It's tempting to use (and (vectorp ,name) (aref ,name 0))
;; but that would suffer from some problems:
;; - the vector may have size 0.
`(and (vectorp ,name)
(> (length ,name) 0)
(let ((tag (aref ,name 0)))
- (if (eq (symbol-function tag) :quick-object-witness-check)
- tag))))
-
-(defun cl--generic-struct-specializers (tag)
+ (and (symbolp tag)
+ (eq (symbol-function tag) :quick-object-witness-check)
+ tag))))
+
+(defun cl--generic-class-parents (class)
+ (let ((parents ())
+ (classes (list class)))
+ ;; BFS precedence. FIXME: Use a topological sort.
+ (while (let ((class (pop classes)))
+ (cl-pushnew (cl--class-name class) parents)
+ (setq classes
+ (append classes
+ (cl--class-parents class)))))
+ (nreverse parents)))
+
+(defun cl--generic-struct-specializers (tag &rest _)
(and (symbolp tag) (boundp tag)
(let ((class (symbol-value tag)))
(when (cl-typep class 'cl-structure-class)
- (let ((types ())
- (classes (list class)))
- ;; BFS precedence.
- (while (let ((class (pop classes)))
- (push (cl--class-name class) types)
- (setq classes
- (append classes
- (cl--class-parents class)))))
- (nreverse types))))))
-
-(defconst cl--generic-struct-generalizer
- (cl-generic-make-generalizer
- 50 #'cl--generic-struct-tag
- #'cl--generic-struct-specializers))
+ (cl--generic-class-parents class)))))
+
+(cl-generic-define-generalizer cl--generic-struct-generalizer
+ 50 #'cl--generic-struct-tag
+ #'cl--generic-struct-specializers)
(cl-defmethod cl-generic-generalizers :extra "cl-struct" (type)
- "Support for dispatch on cl-struct types."
+ "Support for dispatch on types defined by `cl-defstruct'."
(or
(when (symbolp type)
;; Use the "cl--struct-class*" (inlinable) functions/macros rather than
(list cl--generic-struct-generalizer))))
(cl-call-next-method)))
+(cl--generic-prefill-dispatchers 0 cl--generic-generalizer)
+
;;; Dispatch on "system types".
(defconst cl--generic-typeof-types
(sequence)
(number)))
-(defconst cl--generic-typeof-generalizer
- (cl-generic-make-generalizer
- ;; FIXME: We could also change `type-of' to return `null' for nil.
- 10 (lambda (name) `(if ,name (type-of ,name) 'null))
- (lambda (tag) (and (symbolp tag) (assq tag cl--generic-typeof-types)))))
+(cl-generic-define-generalizer cl--generic-typeof-generalizer
+ ;; FIXME: We could also change `type-of' to return `null' for nil.
+ 10 (lambda (name &rest _) `(if ,name (type-of ,name) 'null))
+ (lambda (tag &rest _)
+ (and (symbolp tag) (assq tag cl--generic-typeof-types))))
(cl-defmethod cl-generic-generalizers :extra "typeof" (type)
- "Support for dispatch on builtin types."
+ "Support for dispatch on builtin types.
+See the full list and their hierarchy in `cl--generic-typeof-types'."
;; FIXME: Add support for other types accepted by `cl-typep' such
;; as `character', `atom', `face', `function', ...
(or
(and (assq type cl--generic-typeof-types)
(progn
- (if (memq type '(vector array sequence))
- (message "`%S' also matches CL structs and EIEIO classes" type))
+ ;; FIXME: While this wrinkle in the semantics can be occasionally
+ ;; problematic, this warning is more often annoying than helpful.
+ ;;(if (memq type '(vector array sequence))
+ ;; (message "`%S' also matches CL structs and EIEIO classes"
+ ;; type))
(list cl--generic-typeof-generalizer)))
(cl-call-next-method)))
-;;; Just for kicks: dispatch on major-mode
-;;
-;; Here's how you'd use it:
-;; (cl-defmethod foo ((x (major-mode text-mode)) y z) ...)
-;; And then
-;; (foo 'major-mode toto titi)
-;;
-;; FIXME: Better would be to do that via dispatch on an "implicit argument".
-;; E.g. (cl-defmethod foo (y z &context (major-mode text-mode)) ...)
-
-;; (defvar cl--generic-major-modes (make-hash-table :test #'eq))
-;;
-;; (add-function :before-until cl-generic-generalizer-function
-;; #'cl--generic-major-mode-tagcode)
-;; (defun cl--generic-major-mode-tagcode (type name)
-;; (if (eq 'major-mode (car-safe type))
-;; `(50 . (if (eq ,name 'major-mode)
-;; (cl--generic-with-memoization
-;; (gethash major-mode cl--generic-major-modes)
-;; `(cl--generic-major-mode . ,major-mode))))))
-;;
-;; (add-function :before-until cl-generic-tag-types-function
-;; #'cl--generic-major-mode-types)
-;; (defun cl--generic-major-mode-types (tag)
-;; (when (eq (car-safe tag) 'cl--generic-major-mode)
-;; (if (eq tag 'fundamental-mode) '(fundamental-mode t)
-;; (let ((types `((major-mode ,(cdr tag)))))
-;; (while (get (car types) 'derived-mode-parent)
-;; (push (list 'major-mode (get (car types) 'derived-mode-parent))
-;; types))
-;; (unless (eq 'fundamental-mode (car types))
-;; (push '(major-mode fundamental-mode) types))
-;; (nreverse types)))))
+(cl--generic-prefill-dispatchers 0 integer)
+
+;;; Dispatch on major mode.
+
+;; Two parts:
+;; - first define a specializer (derived-mode <mode>) to match symbols
+;; representing major modes, while obeying the major mode hierarchy.
+;; - then define a context-rewriter so you can write
+;; "&context (major-mode c-mode)" rather than
+;; "&context (major-mode (derived-mode c-mode))".
+
+(defun cl--generic-derived-specializers (mode &rest _)
+ ;; FIXME: Handle (derived-mode <mode1> ... <modeN>)
+ (let ((specializers ()))
+ (while mode
+ (push `(derived-mode ,mode) specializers)
+ (setq mode (get mode 'derived-mode-parent)))
+ (nreverse specializers)))
+
+(cl-generic-define-generalizer cl--generic-derived-generalizer
+ 90 (lambda (name) `(and (symbolp ,name) (functionp ,name) ,name))
+ #'cl--generic-derived-specializers)
+
+(cl-defmethod cl-generic-generalizers ((_specializer (head derived-mode)))
+ "Support for (derived-mode MODE) specializers.
+Used internally for the (major-mode MODE) context specializers."
+ (list cl--generic-derived-generalizer))
+
+(cl-generic-define-context-rewriter major-mode (mode &rest modes)
+ `(major-mode ,(if (consp mode)
+ ;;E.g. could be (eql ...)
+ (progn (cl-assert (null modes)) mode)
+ `(derived-mode ,mode . ,modes))))
;; Local variables:
;; generated-autoload-file: "cl-loaddefs.el"