-;;; macroexp.el --- Additional macro-expansion support -*- lexical-binding: t -*-
+;;; macroexp.el --- Additional macro-expansion support -*- lexical-binding: t; coding: utf-8 -*-
;;
-;; Copyright (C) 2004-2011 Free Software Foundation, Inc.
+;; Copyright (C) 2004-2013 Free Software Foundation, Inc.
;;
;; Author: Miles Bader <miles@gnu.org>
;; Keywords: lisp, compiler, macros
;;; 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
;; 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.
(,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)
(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--funcall-if-compiled (_form)
+ "Pseudo function used internally by macroexp to delay warnings.
+The purpose is to delay warnings to bytecomp.el, so they can use things
+like `byte-compile-log-warning' to get better file-and-line-number data
+and also to avoid outputting the warning during normal execution."
+ nil)
+(put 'macroexp--funcall-if-compiled 'byte-compile
+ (lambda (form)
+ (funcall (eval (cadr form)))
+ (byte-compile-constant nil)))
+
+(defun macroexp--warn-and-return (msg form)
+ (let ((when-compiled (lambda () (byte-compile-log-warning msg t))))
+ (cond
+ ((null msg) form)
+ ;; FIXME: ¡¡Major Ugly Hack!! To determine whether the output of this
+ ;; macro-expansion will be processed by the byte-compiler, we check
+ ;; circumstantial evidence.
+ ((member '(declare-function . byte-compile-macroexpand-declare-function)
+ macroexpand-all-environment)
+ `(progn
+ (macroexp--funcall-if-compiled ',when-compiled)
+ ,form))
+ (t
+ (message "%s%s" (if (stringp load-file-name)
+ (concat (file-relative-name load-file-name) ": ")
+ "")
+ msg)
+ form))))
+
+(defun macroexp--obsolete-warning (fun obsolescence-data type)
+ (let ((instead (car obsolescence-data))
+ (asof (nth 2 obsolescence-data)))
+ (format "`%s' is an obsolete %s%s%s" fun type
+ (if asof (concat " (as of " asof ")") "")
+ (cond ((stringp instead) (concat "; " instead))
+ (instead (format "; use `%s' instead." instead))
+ (t ".")))))
+
+(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'."
;; 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)))
- (when (and (not (eq form new-form)) ;It was a macro call.
- (car-safe form)
- (symbolp (car form))
- (get (car form) 'byte-obsolete-info)
- (fboundp 'byte-compile-warn-obsolete))
- (byte-compile-warn-obsolete (car form)))
- (setq form new-form))
+ (let ((new-form
+ (macroexpand form macroexpand-all-environment)))
+ (setq form
+ (if (and (not (eq form new-form)) ;It was a macro call.
+ (car-safe form)
+ (symbolp (car form))
+ (get (car form) 'byte-obsolete-info)
+ (or (not (fboundp 'byte-compile-warning-enabled-p))
+ (byte-compile-warning-enabled-p 'obsolete)))
+ (let* ((fun (car form))
+ (obsolete (get fun 'byte-obsolete-info)))
+ (macroexp--warn-and-return
+ (macroexp--obsolete-warning
+ fun obsolete
+ (if (symbolp (symbol-function fun))
+ "alias" "macro"))
+ new-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
;; here, so that any code that cares about the difference will
;; see the same transformation.
;; First arg is a function:
- (`(,(and fun (or `apply `mapcar `mapatoms `mapconcat `mapc))
+ (`(,(and fun (or `funcall `apply `mapcar `mapatoms `mapconcat `mapc))
',(and f `(lambda . ,_)) . ,args)
- ;; We don't use `maybe-cons' since there's clearly a change.
- (cons fun
- (cons (macroexpand-all-1 (list 'function f))
- (macroexpand-all-forms args))))
+ (macroexp--warn-and-return
+ (format "%s quoted with ' rather than with #'"
+ (list 'lambda (nth 1 f) '...))
+ (macroexp--expand-all `(,fun ,f . ,args))))
;; Second arg is a function:
(`(,(and fun (or `sort)) ,arg1 ',(and f `(lambda . ,_)) . ,args)
- ;; We don't use `maybe-cons' since there's clearly a change.
- (cons fun
- (cons (macroexpand-all-1 arg1)
- (cons (macroexpand-all-1
- (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--warn-and-return
+ (format "%s quoted with ' rather than with #'"
+ (list 'lambda (nth 1 f) '...))
+ (macroexp--expand-all `(,fun ,arg1 ,f . ,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 (function-get func 'compiler-macro)))
+ (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.
+ (unless (functionp handler)
+ (ignore-errors
+ (autoload-do-load (indirect-function func) func)))
+ (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
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)))
+
+;;; Load-time macro-expansion.
+
+;; Because macro-expansion used to be more lazy, eager macro-expansion
+;; tends to bump into previously harmless/unnoticeable cyclic-dependencies.
+;; So, we have to delay macro-expansion like we used to when we detect
+;; such a cycle, and we also want to help coders resolve those cycles (since
+;; they can be non-obvious) by providing a usefully trimmed backtrace
+;; (hopefully) highlighting the problem.
+
+(defun macroexp--backtrace ()
+ "Return the Elisp backtrace, more recent frames first."
+ (let ((bt ())
+ (i 0))
+ (while
+ (let ((frame (backtrace-frame i)))
+ (when frame
+ (push frame bt)
+ (setq i (1+ i)))))
+ (nreverse bt)))
+
+(defun macroexp--trim-backtrace-frame (frame)
+ (pcase frame
+ (`(,_ macroexpand (,head . ,_) . ,_) `(macroexpand (,head …)))
+ (`(,_ internal-macroexpand-for-load (,head ,second . ,_) . ,_)
+ (if (or (symbolp second)
+ (and (eq 'quote (car-safe second))
+ (symbolp (cadr second))))
+ `(macroexpand-all (,head ,second …))
+ '(macroexpand-all …)))
+ (`(,_ load-with-code-conversion ,name . ,_)
+ `(load ,(file-name-nondirectory name)))))
+
+(defvar macroexp--pending-eager-loads nil
+ "Stack of files currently undergoing eager macro-expansion.")
+
+(defun internal-macroexpand-for-load (form)
+ ;; Called from the eager-macroexpansion in readevalloop.
+ (cond
+ ;; Don't repeat the same warning for every top-level element.
+ ((eq 'skip (car macroexp--pending-eager-loads)) form)
+ ;; If we detect a cycle, skip macro-expansion for now, and output a warning
+ ;; with a trimmed backtrace.
+ ((and load-file-name (member load-file-name macroexp--pending-eager-loads))
+ (let* ((bt (delq nil
+ (mapcar #'macroexp--trim-backtrace-frame
+ (macroexp--backtrace))))
+ (elem `(load ,(file-name-nondirectory load-file-name)))
+ (tail (member elem (cdr (member elem bt)))))
+ (if tail (setcdr tail (list '…)))
+ (if (eq (car-safe (car bt)) 'macroexpand-all) (setq bt (cdr bt)))
+ (message "Warning: Eager macro-expansion skipped due to cycle:\n %s"
+ (mapconcat #'prin1-to-string (nreverse bt) " => "))
+ (push 'skip macroexp--pending-eager-loads)
+ form))
+ (t
+ (condition-case err
+ (let ((macroexp--pending-eager-loads
+ (cons load-file-name macroexp--pending-eager-loads)))
+ (macroexpand-all form))
+ (error
+ ;; Hopefully this shouldn't happen thanks to the cycle detection,
+ ;; but in case it does happen, let's catch the error and give the
+ ;; code a chance to macro-expand later.
+ (message "Eager macro-expansion failure: %S" err)
+ form)))))
+
+;; ¡¡¡ Big Ugly Hack !!!
+;; src/bootstrap-emacs is mostly used to compile .el files, so it needs
+;; macroexp, bytecomp, cconv, and byte-opt to be fast. Generally this is done
+;; by compiling those files first, but this only makes a difference if those
+;; files are not preloaded. But macroexp.el is preloaded so we reload it if
+;; the current version is interpreted and there's a compiled version available.
+(eval-when-compile
+ (add-hook 'emacs-startup-hook
+ (lambda ()
+ (and (not (byte-code-function-p
+ (symbol-function 'macroexpand-all)))
+ (locate-library "macroexp.elc")
+ (load "macroexp.elc")))))
(provide 'macroexp)