diff options
Diffstat (limited to 'lisp/emacs-lisp/macroexp.el')
| -rw-r--r-- | lisp/emacs-lisp/macroexp.el | 248 |
1 files changed, 179 insertions, 69 deletions
diff --git a/lisp/emacs-lisp/macroexp.el b/lisp/emacs-lisp/macroexp.el index 21c351159c2..65a72aa5312 100644 --- a/lisp/emacs-lisp/macroexp.el +++ b/lisp/emacs-lisp/macroexp.el @@ -1,4 +1,4 @@ -;;; macroexp.el --- Additional macro-expansion support -*- lexical-binding: t -*- +;;; macroexp.el --- Additional macro-expansion support -*- lexical-binding: t; coding: utf-8 -*- ;; ;; Copyright (C) 2004-2012 Free Software Foundation, Inc. ;; @@ -29,13 +29,11 @@ ;;; Code: -(eval-when-compile (require 'cl)) - ;; Bound by the top-level `macroexpand-all', and modified to include any ;; macros defined by `defmacro'. (defvar macroexpand-all-environment nil) -(defun maybe-cons (car cdr original-cons) +(defun macroexp--cons (car cdr original-cons) "Return (CAR . CDR), using ORIGINAL-CONS if possible." (if (and (eq car (car original-cons)) (eq cdr (cdr original-cons))) original-cons @@ -43,9 +41,9 @@ ;; We use this special macro to iteratively process forms and share list ;; structure of the result with the input. Doing so recursively using -;; `maybe-cons' results in excessively deep recursion for very long +;; `macroexp--cons' results in excessively deep recursion for very long ;; input forms. -(defmacro macroexp-accumulate (var+list &rest body) +(defmacro macroexp--accumulate (var+list &rest body) "Return a list of the results of evaluating BODY for each element of LIST. Evaluate BODY with VAR bound to each `car' from LIST, in turn. Return a list of the values of the final form in BODY. @@ -65,7 +63,7 @@ result will be eq to LIST). (,unshared nil) (,tail ,shared) ,var ,new-el) - (while ,tail + (while (consp ,tail) (setq ,var (car ,tail) ,new-el (progn ,@body)) (unless (eq ,var ,new-el) @@ -76,27 +74,33 @@ result will be eq to LIST). (setq ,tail (cdr ,tail))) (nconc (nreverse ,unshared) ,shared)))) -(defun macroexpand-all-forms (forms &optional skip) +(defun macroexp--all-forms (forms &optional skip) "Return FORMS with macros expanded. FORMS is a list of forms. If SKIP is non-nil, then don't expand that many elements at the start of FORMS." - (macroexp-accumulate (form forms) + (macroexp--accumulate (form forms) (if (or (null skip) (zerop skip)) - (macroexpand-all-1 form) + (macroexp--expand-all form) (setq skip (1- skip)) form))) -(defun macroexpand-all-clauses (clauses &optional skip) +(defun macroexp--all-clauses (clauses &optional skip) "Return CLAUSES with macros expanded. CLAUSES is a list of lists of forms; any clause that's not a list is ignored. If SKIP is non-nil, then don't expand that many elements at the start of each clause." - (macroexp-accumulate (clause clauses) + (macroexp--accumulate (clause clauses) (if (listp clause) - (macroexpand-all-forms clause skip) + (macroexp--all-forms clause skip) clause))) -(defun macroexpand-all-1 (form) +(defun macroexp--compiler-macro (handler form) + (condition-case err + (apply handler form (cdr form)) + (error (message "Compiler-macro error for %S: %S" (car form) err) + form))) + +(defun macroexp--expand-all (form) "Expand all macros in FORM. This is an internal version of `macroexpand-all'. Assumes the caller has bound `macroexpand-all-environment'." @@ -105,7 +109,7 @@ Assumes the caller has bound `macroexpand-all-environment'." ;; generates exceedingly deep expansions from relatively shallow input ;; forms. We just process it `in reverse' -- first we expand all the ;; arguments, _then_ we expand the top-level definition. - (macroexpand (macroexpand-all-forms form 1) + (macroexpand (macroexp--all-forms form 1) macroexpand-all-environment) ;; Normal form; get its expansion, and then expand arguments. (let ((new-form (macroexpand form macroexpand-all-environment))) @@ -118,48 +122,34 @@ Assumes the caller has bound `macroexpand-all-environment'." (setq form new-form)) (pcase form (`(cond . ,clauses) - (maybe-cons 'cond (macroexpand-all-clauses clauses) form)) + (macroexp--cons 'cond (macroexp--all-clauses clauses) form)) (`(condition-case . ,(or `(,err ,body . ,handlers) dontcare)) - (maybe-cons + (macroexp--cons 'condition-case - (maybe-cons err - (maybe-cons (macroexpand-all-1 body) - (macroexpand-all-clauses handlers 1) + (macroexp--cons err + (macroexp--cons (macroexp--expand-all body) + (macroexp--all-clauses handlers 1) (cddr form)) (cdr form)) form)) - (`(defmacro ,name . ,args-and-body) - (push (cons name (cons 'lambda args-and-body)) - macroexpand-all-environment) - (let ((n 3)) - ;; Don't macroexpand `declare' since it should really be "expanded" - ;; away when `defmacro' is expanded, but currently defmacro is not - ;; itself a macro. So both `defmacro' and `declare' need to be - ;; handled directly in bytecomp.el. - ;; FIXME: Maybe a simpler solution is to (defalias 'declare 'quote). - (while (or (stringp (nth n form)) - (eq (car-safe (nth n form)) 'declare)) - (setq n (1+ n))) - (macroexpand-all-forms form n))) - (`(defun . ,_) (macroexpand-all-forms form 3)) - (`(,(or `defvar `defconst) . ,_) (macroexpand-all-forms form 2)) + (`(,(or `defvar `defconst) . ,_) (macroexp--all-forms form 2)) (`(function ,(and f `(lambda . ,_))) - (maybe-cons 'function - (maybe-cons (macroexpand-all-forms f 2) + (macroexp--cons 'function + (macroexp--cons (macroexp--all-forms f 2) nil (cdr form)) form)) (`(,(or `function `quote) . ,_) form) (`(,(and fun (or `let `let*)) . ,(or `(,bindings . ,body) dontcare)) - (maybe-cons fun - (maybe-cons (macroexpand-all-clauses bindings 1) - (macroexpand-all-forms body) + (macroexp--cons fun + (macroexp--cons (macroexp--all-clauses bindings 1) + (macroexp--all-forms body) (cdr form)) form)) (`(,(and fun `(lambda . ,_)) . ,args) ;; Embedded lambda in function position. - (maybe-cons (macroexpand-all-forms fun 2) - (macroexpand-all-forms args) + (macroexp--cons (macroexp--all-forms fun 2) + (macroexp--all-forms args) form)) ;; The following few cases are for normal function calls that ;; are known to funcall one of their arguments. The byte @@ -175,41 +165,58 @@ Assumes the caller has bound `macroexpand-all-environment'." (format "%s quoted with ' rather than with #'" (list 'lambda (nth 1 f) '...)) t) - ;; We don't use `maybe-cons' since there's clearly a change. + ;; We don't use `macroexp--cons' since there's clearly a change. (cons fun - (cons (macroexpand-all-1 (list 'function f)) - (macroexpand-all-forms args)))) + (cons (macroexp--expand-all (list 'function f)) + (macroexp--all-forms args)))) ;; Second arg is a function: (`(,(and fun (or `sort)) ,arg1 ',(and f `(lambda . ,_)) . ,args) (byte-compile-log-warning (format "%s quoted with ' rather than with #'" (list 'lambda (nth 1 f) '...)) t) - ;; We don't use `maybe-cons' since there's clearly a change. + ;; We don't use `macroexp--cons' since there's clearly a change. (cons fun - (cons (macroexpand-all-1 arg1) - (cons (macroexpand-all-1 + (cons (macroexp--expand-all arg1) + (cons (macroexp--expand-all (list 'function f)) - (macroexpand-all-forms args))))) - ;; Macro expand compiler macros. This cannot be delayed to - ;; byte-optimize-form because the output of the compiler-macro can - ;; use macros. - ;; FIXME: Don't depend on CL. - (`(,(pred (lambda (fun) - (and (symbolp fun) - (eq (get fun 'byte-compile) - 'cl-byte-compile-compiler-macro) - (functionp 'compiler-macroexpand)))) - . ,_) - (let ((newform (with-no-warnings (compiler-macroexpand form)))) - (if (eq form newform) - (macroexpand-all-forms form 1) - (macroexpand-all-1 newform)))) - (`(,_ . ,_) - ;; For every other list, we just expand each argument (for - ;; setq/setq-default this works alright because the variable names - ;; are symbols). - (macroexpand-all-forms form 1)) + (macroexp--all-forms args))))) + (`(,func . ,_) + ;; Macro expand compiler macros. This cannot be delayed to + ;; byte-optimize-form because the output of the compiler-macro can + ;; use macros. + (let ((handler nil)) + (while (and (symbolp func) + (not (setq handler (get func 'compiler-macro))) + (fboundp func)) + ;; Follow the sequence of aliases. + (setq func (symbol-function func))) + (if (null handler) + ;; No compiler macro. We just expand each argument (for + ;; setq/setq-default this works alright because the variable names + ;; are symbols). + (macroexp--all-forms form 1) + ;; If the handler is not loaded yet, try (auto)loading the + ;; function itself, which may in turn load the handler. + (when (and (not (functionp handler)) + (fboundp func) (eq (car-safe (symbol-function func)) + 'autoload)) + (ignore-errors + (load (nth 1 (symbol-function func)) + 'noerror 'nomsg))) + (let ((newform (macroexp--compiler-macro handler form))) + (if (eq form newform) + ;; The compiler macro did not find anything to do. + (if (equal form (setq newform (macroexp--all-forms form 1))) + form + ;; Maybe after processing the args, some new opportunities + ;; appeared, so let's try the compiler macro again. + (setq form (macroexp--compiler-macro handler newform)) + (if (eq newform form) + newform + (macroexp--expand-all newform))) + (macroexp--expand-all newform)))))) + (t form)))) ;;;###autoload @@ -219,7 +226,110 @@ If no macros are expanded, FORM is returned unchanged. The second optional arg ENVIRONMENT specifies an environment of macro definitions to shadow the loaded ones for use in file byte-compilation." (let ((macroexpand-all-environment environment)) - (macroexpand-all-1 form))) + (macroexp--expand-all form))) + +;;; Handy functions to use in macros. + +(defun macroexp-progn (exps) + "Return an expression equivalent to `(progn ,@EXPS)." + (if (cdr exps) `(progn ,@exps) (car exps))) + +(defun macroexp-unprogn (exp) + "Turn EXP into a list of expressions to execute in sequence." + (if (eq (car-safe exp) 'progn) (cdr exp) (list exp))) + +(defun macroexp-let* (bindings exp) + "Return an expression equivalent to `(let* ,bindings ,exp)." + (cond + ((null bindings) exp) + ((eq 'let* (car-safe exp)) `(let* (,@bindings ,@(cadr exp)) ,@(cddr exp))) + (t `(let* ,bindings ,exp)))) + +(defun macroexp-if (test then else) + "Return an expression equivalent to `(if ,test ,then ,else)." + (cond + ((eq (car-safe else) 'if) + (if (equal test (nth 1 else)) + ;; Doing a test a second time: get rid of the redundancy. + `(if ,test ,then ,@(nthcdr 3 else)) + `(cond (,test ,then) + (,(nth 1 else) ,(nth 2 else)) + (t ,@(nthcdr 3 else))))) + ((eq (car-safe else) 'cond) + `(cond (,test ,then) + ;; Doing a test a second time: get rid of the redundancy, as above. + ,@(remove (assoc test else) (cdr else)))) + ;; Invert the test if that lets us reduce the depth of the tree. + ((memq (car-safe then) '(if cond)) (macroexp-if `(not ,test) else then)) + (t `(if ,test ,then ,else)))) + +(defmacro macroexp-let2 (test var exp &rest exps) + "Bind VAR to a copyable expression that returns the value of EXP. +This is like `(let ((v ,EXP)) ,EXPS) except that `v' is a new generated +symbol which EXPS can find in VAR. +TEST should be the name of a predicate on EXP checking whether the `let' can +be skipped; if nil, as is usual, `macroexp-const-p' is used." + (declare (indent 3) (debug (sexp sexp form body))) + (let ((bodysym (make-symbol "body")) + (expsym (make-symbol "exp"))) + `(let* ((,expsym ,exp) + (,var (if (funcall #',(or test #'macroexp-const-p) ,expsym) + ,expsym (make-symbol ,(symbol-name var)))) + (,bodysym ,(macroexp-progn exps))) + (if (eq ,var ,expsym) ,bodysym + (macroexp-let* (list (list ,var ,expsym)) + ,bodysym))))) + +(defun macroexp--maxsize (exp size) + (cond ((< size 0) size) + ((symbolp exp) (1- size)) + ((stringp exp) (- size (/ (length exp) 16))) + ((vectorp exp) + (dotimes (i (length exp)) + (setq size (macroexp--maxsize (aref exp i) size))) + (1- size)) + ((consp exp) + ;; We could try to be more clever with quote&function, + ;; but it is difficult to do so correctly, and it's not obvious that + ;; it would be worth the effort. + (dolist (e exp) + (setq size (macroexp--maxsize e size))) + (1- size)) + (t -1))) + +(defun macroexp-small-p (exp) + "Return non-nil if EXP can be considered small." + (> (macroexp--maxsize exp 10) 0)) + +(defsubst macroexp--const-symbol-p (symbol &optional any-value) + "Non-nil if SYMBOL is constant. +If ANY-VALUE is nil, only return non-nil if the value of the symbol is the +symbol itself." + (or (memq symbol '(nil t)) + (keywordp symbol) + (if any-value + (or (memq symbol byte-compile-const-variables) + ;; FIXME: We should provide a less intrusive way to find out + ;; if a variable is "constant". + (and (boundp symbol) + (condition-case nil + (progn (set symbol (symbol-value symbol)) nil) + (setting-constant t))))))) + +(defun macroexp-const-p (exp) + "Return non-nil if EXP will always evaluate to the same value." + (cond ((consp exp) (or (eq (car exp) 'quote) + (and (eq (car exp) 'function) + (symbolp (cadr exp))))) + ;; It would sometimes make sense to pass `any-value', but it's not + ;; always safe since a "constant" variable may not actually always have + ;; the same value. + ((symbolp exp) (macroexp--const-symbol-p exp)) + (t t))) + +(defun macroexp-copyable-p (exp) + "Return non-nil if EXP can be copied without extra cost." + (or (symbolp exp) (macroexp-const-p exp))) (provide 'macroexp) |