;;; 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
;; 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:
(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))))
;;;###autoload
(defun cl-generic-define (name args options)
- (pcase-let* ((generic (cl-generic-ensure-function name))
+ (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)))
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."
((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)
,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'.
+
+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.
-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.
+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)))))
(setq i (1+ i))))
;; We used to (setcar me method), but that can cause false positives in
;; the hash-consing table of the method-builder (bug#20644).
- ;; See the related FIXME in cl--generic-build-combined-method.
- (setf (cl--generic-method-table generic) (cons method (delq (car me) mt)))
- (cl-pushnew `(cl-defmethod . (,(cl--generic-name generic) . ,specializers))
+ ;; 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)?
(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 (if (integerp dispatch-arg)
- (nth dispatch-arg
- (cl--generic-method-specializers method))
- (cdr (assoc 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)))
;;; 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)
;;; 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))
(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 (substitute-command-keys " in ‘"))
+ (insert (substitute-command-keys " in `"))
(help-insert-xref-button (help-fns-short-filename file)
'help-function-def met-name file
'cl-defmethod)
- (insert (substitute-command-keys "’.\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)
(setq applies t)))
applies))
-(defun cl--generic-all-functions (&optional type)
+(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."
(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))
(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))))
+ (and (symbolp tag)
+ (eq (symbol-function tag) :quick-object-witness-check)
+ tag))))
(defun cl--generic-class-parents (class)
(let ((parents ())
(cl--class-parents class)))))
(nreverse parents)))
-(defun cl--generic-struct-specializers (tag)
+(defun cl--generic-struct-specializers (tag &rest _)
(and (symbolp tag) (boundp tag)
(let ((class (symbol-value tag)))
(when (cl-typep class 'cl-structure-class)
(cl--generic-class-parents class)))))
-(defconst cl--generic-struct-generalizer
- (cl-generic-make-generalizer
- 50 #'cl--generic-struct-tag
- #'cl--generic-struct-specializers))
+(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
(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)))
(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"
;; End: