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a9de04fa | 1 | ;;; macroexp.el --- Additional macro-expansion support -*- lexical-binding: t -*- |
4d449b11 | 2 | ;; |
acaf905b | 3 | ;; Copyright (C) 2004-2012 Free Software Foundation, Inc. |
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4 | ;; |
5 | ;; Author: Miles Bader <miles@gnu.org> | |
6 | ;; Keywords: lisp, compiler, macros | |
7 | ||
8 | ;; This file is part of GNU Emacs. | |
9 | ||
d6cba7ae | 10 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
4d449b11 | 11 | ;; it under the terms of the GNU General Public License as published by |
d6cba7ae GM |
12 | ;; the Free Software Foundation, either version 3 of the License, or |
13 | ;; (at your option) any later version. | |
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14 | |
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
d6cba7ae | 21 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
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22 | |
23 | ;;; Commentary: | |
24 | ;; | |
25 | ;; This file contains macro-expansions functions that are not defined in | |
26 | ;; the Lisp core, namely `macroexpand-all', which expands all macros in | |
27 | ;; a form, not just a top-level one. | |
28 | ;; | |
29 | ||
30 | ;;; Code: | |
31 | ||
32 | ;; Bound by the top-level `macroexpand-all', and modified to include any | |
33 | ;; macros defined by `defmacro'. | |
34 | (defvar macroexpand-all-environment nil) | |
35 | ||
fa779ab0 | 36 | (defun macroexp--cons (car cdr original-cons) |
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37 | "Return (CAR . CDR), using ORIGINAL-CONS if possible." |
38 | (if (and (eq car (car original-cons)) (eq cdr (cdr original-cons))) | |
39 | original-cons | |
40 | (cons car cdr))) | |
41 | ||
42 | ;; We use this special macro to iteratively process forms and share list | |
43 | ;; structure of the result with the input. Doing so recursively using | |
fa779ab0 | 44 | ;; `macroexp--cons' results in excessively deep recursion for very long |
4d449b11 | 45 | ;; input forms. |
fa779ab0 | 46 | (defmacro macroexp--accumulate (var+list &rest body) |
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47 | "Return a list of the results of evaluating BODY for each element of LIST. |
48 | Evaluate BODY with VAR bound to each `car' from LIST, in turn. | |
49 | Return a list of the values of the final form in BODY. | |
50 | The list structure of the result will share as much with LIST as | |
51 | possible (for instance, when BODY just returns VAR unchanged, the | |
5de35ba4 RS |
52 | result will be eq to LIST). |
53 | ||
54 | \(fn (VAR LIST) BODY...)" | |
6fe79b7c | 55 | (declare (indent 1)) |
5de35ba4 RS |
56 | (let ((var (car var+list)) |
57 | (list (cadr var+list)) | |
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58 | (shared (make-symbol "shared")) |
59 | (unshared (make-symbol "unshared")) | |
60 | (tail (make-symbol "tail")) | |
61 | (new-el (make-symbol "new-el"))) | |
62 | `(let* ((,shared ,list) | |
63 | (,unshared nil) | |
64 | (,tail ,shared) | |
65 | ,var ,new-el) | |
61b108cc | 66 | (while (consp ,tail) |
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67 | (setq ,var (car ,tail) |
68 | ,new-el (progn ,@body)) | |
69 | (unless (eq ,var ,new-el) | |
70 | (while (not (eq ,shared ,tail)) | |
71 | (push (pop ,shared) ,unshared)) | |
72 | (setq ,shared (cdr ,shared)) | |
73 | (push ,new-el ,unshared)) | |
74 | (setq ,tail (cdr ,tail))) | |
75 | (nconc (nreverse ,unshared) ,shared)))) | |
4d449b11 | 76 | |
fa779ab0 | 77 | (defun macroexp--all-forms (forms &optional skip) |
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78 | "Return FORMS with macros expanded. FORMS is a list of forms. |
79 | If SKIP is non-nil, then don't expand that many elements at the start of | |
80 | FORMS." | |
fa779ab0 | 81 | (macroexp--accumulate (form forms) |
4d449b11 | 82 | (if (or (null skip) (zerop skip)) |
fa779ab0 | 83 | (macroexp--expand-all form) |
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84 | (setq skip (1- skip)) |
85 | form))) | |
86 | ||
fa779ab0 | 87 | (defun macroexp--all-clauses (clauses &optional skip) |
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88 | "Return CLAUSES with macros expanded. |
89 | CLAUSES is a list of lists of forms; any clause that's not a list is ignored. | |
90 | If SKIP is non-nil, then don't expand that many elements at the start of | |
91 | each clause." | |
fa779ab0 | 92 | (macroexp--accumulate (clause clauses) |
4d449b11 | 93 | (if (listp clause) |
fa779ab0 | 94 | (macroexp--all-forms clause skip) |
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95 | clause))) |
96 | ||
fa779ab0 | 97 | (defun macroexp--expand-all (form) |
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98 | "Expand all macros in FORM. |
99 | This is an internal version of `macroexpand-all'. | |
100 | Assumes the caller has bound `macroexpand-all-environment'." | |
101 | (if (and (listp form) (eq (car form) 'backquote-list*)) | |
102 | ;; Special-case `backquote-list*', as it is normally a macro that | |
103 | ;; generates exceedingly deep expansions from relatively shallow input | |
104 | ;; forms. We just process it `in reverse' -- first we expand all the | |
105 | ;; arguments, _then_ we expand the top-level definition. | |
fa779ab0 | 106 | (macroexpand (macroexp--all-forms form 1) |
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107 | macroexpand-all-environment) |
108 | ;; Normal form; get its expansion, and then expand arguments. | |
a9de04fa SM |
109 | (let ((new-form (macroexpand form macroexpand-all-environment))) |
110 | (when (and (not (eq form new-form)) ;It was a macro call. | |
111 | (car-safe form) | |
112 | (symbolp (car form)) | |
113 | (get (car form) 'byte-obsolete-info) | |
114 | (fboundp 'byte-compile-warn-obsolete)) | |
115 | (byte-compile-warn-obsolete (car form))) | |
116 | (setq form new-form)) | |
6fe79b7c SM |
117 | (pcase form |
118 | (`(cond . ,clauses) | |
fa779ab0 | 119 | (macroexp--cons 'cond (macroexp--all-clauses clauses) form)) |
6fe79b7c | 120 | (`(condition-case . ,(or `(,err ,body . ,handlers) dontcare)) |
fa779ab0 | 121 | (macroexp--cons |
6fe79b7c | 122 | 'condition-case |
fa779ab0 SM |
123 | (macroexp--cons err |
124 | (macroexp--cons (macroexp--expand-all body) | |
125 | (macroexp--all-clauses handlers 1) | |
6fe79b7c SM |
126 | (cddr form)) |
127 | (cdr form)) | |
128 | form)) | |
fa779ab0 | 129 | (`(,(or `defvar `defconst) . ,_) (macroexp--all-forms form 2)) |
6fe79b7c | 130 | (`(function ,(and f `(lambda . ,_))) |
fa779ab0 SM |
131 | (macroexp--cons 'function |
132 | (macroexp--cons (macroexp--all-forms f 2) | |
6fe79b7c SM |
133 | nil |
134 | (cdr form)) | |
135 | form)) | |
136 | (`(,(or `function `quote) . ,_) form) | |
137 | (`(,(and fun (or `let `let*)) . ,(or `(,bindings . ,body) dontcare)) | |
fa779ab0 SM |
138 | (macroexp--cons fun |
139 | (macroexp--cons (macroexp--all-clauses bindings 1) | |
140 | (macroexp--all-forms body) | |
6fe79b7c SM |
141 | (cdr form)) |
142 | form)) | |
143 | (`(,(and fun `(lambda . ,_)) . ,args) | |
144 | ;; Embedded lambda in function position. | |
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145 | (macroexp--cons (macroexp--all-forms fun 2) |
146 | (macroexp--all-forms args) | |
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147 | form)) |
148 | ;; The following few cases are for normal function calls that | |
149 | ;; are known to funcall one of their arguments. The byte | |
150 | ;; compiler has traditionally handled these functions specially | |
151 | ;; by treating a lambda expression quoted by `quote' as if it | |
152 | ;; were quoted by `function'. We make the same transformation | |
153 | ;; here, so that any code that cares about the difference will | |
154 | ;; see the same transformation. | |
155 | ;; First arg is a function: | |
9c848d8a | 156 | (`(,(and fun (or `funcall `apply `mapcar `mapatoms `mapconcat `mapc)) |
876c194c | 157 | ',(and f `(lambda . ,_)) . ,args) |
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158 | (byte-compile-log-warning |
159 | (format "%s quoted with ' rather than with #'" | |
160 | (list 'lambda (nth 1 f) '...)) | |
161 | t) | |
fa779ab0 | 162 | ;; We don't use `macroexp--cons' since there's clearly a change. |
6fe79b7c | 163 | (cons fun |
fa779ab0 SM |
164 | (cons (macroexp--expand-all (list 'function f)) |
165 | (macroexp--all-forms args)))) | |
6fe79b7c | 166 | ;; Second arg is a function: |
876c194c | 167 | (`(,(and fun (or `sort)) ,arg1 ',(and f `(lambda . ,_)) . ,args) |
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168 | (byte-compile-log-warning |
169 | (format "%s quoted with ' rather than with #'" | |
170 | (list 'lambda (nth 1 f) '...)) | |
171 | t) | |
fa779ab0 | 172 | ;; We don't use `macroexp--cons' since there's clearly a change. |
6fe79b7c | 173 | (cons fun |
fa779ab0 SM |
174 | (cons (macroexp--expand-all arg1) |
175 | (cons (macroexp--expand-all | |
6fe79b7c | 176 | (list 'function f)) |
fa779ab0 | 177 | (macroexp--all-forms args))))) |
57a7d507 SM |
178 | (`(,func . ,_) |
179 | ;; Macro expand compiler macros. This cannot be delayed to | |
180 | ;; byte-optimize-form because the output of the compiler-macro can | |
181 | ;; use macros. | |
182 | (let ((handler nil)) | |
183 | (while (and (symbolp func) | |
184 | (not (setq handler (get func 'compiler-macro))) | |
185 | (fboundp func) | |
186 | (or (not (eq (car-safe (symbol-function func)) | |
187 | 'autoload)) | |
53aacf21 | 188 | (ignore-errors |
b7bb5838 SM |
189 | (load (nth 1 (symbol-function func)) |
190 | 'noerror 'nomsg)))) | |
57a7d507 SM |
191 | ;; Follow the sequence of aliases. |
192 | (setq func (symbol-function func))) | |
193 | (if (null handler) | |
194 | ;; No compiler macro. We just expand each argument (for | |
195 | ;; setq/setq-default this works alright because the variable names | |
196 | ;; are symbols). | |
fa779ab0 | 197 | (macroexp--all-forms form 1) |
53aacf21 SM |
198 | (let ((newform (condition-case err |
199 | (apply handler form (cdr form)) | |
200 | (error (message "Compiler-macro error: %S" err) | |
201 | form)))) | |
57a7d507 SM |
202 | (if (eq form newform) |
203 | ;; The compiler macro did not find anything to do. | |
fa779ab0 | 204 | (if (equal form (setq newform (macroexp--all-forms form 1))) |
57a7d507 SM |
205 | form |
206 | ;; Maybe after processing the args, some new opportunities | |
207 | ;; appeared, so let's try the compiler macro again. | |
53aacf21 SM |
208 | (setq form (condition-case err |
209 | (apply handler newform (cdr newform)) | |
210 | (error (message "Compiler-macro error: %S" err) | |
211 | newform))) | |
212 | (if (eq newform form) | |
57a7d507 | 213 | newform |
fa779ab0 SM |
214 | (macroexp--expand-all newform))) |
215 | (macroexp--expand-all newform)))))) | |
57a7d507 | 216 | |
6fe79b7c | 217 | (t form)))) |
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218 | |
219 | ;;;###autoload | |
220 | (defun macroexpand-all (form &optional environment) | |
221 | "Return result of expanding macros at all levels in FORM. | |
222 | If no macros are expanded, FORM is returned unchanged. | |
223 | The second optional arg ENVIRONMENT specifies an environment of macro | |
224 | definitions to shadow the loaded ones for use in file byte-compilation." | |
225 | (let ((macroexpand-all-environment environment)) | |
fa779ab0 | 226 | (macroexp--expand-all form))) |
4d449b11 | 227 | |
4dd1c416 SM |
228 | ;;; Handy functions to use in macros. |
229 | ||
230 | (defun macroexp-progn (exps) | |
231 | "Return an expression equivalent to `(progn ,@EXPS)." | |
232 | (if (cdr exps) `(progn ,@exps) (car exps))) | |
233 | ||
de7e2b36 SM |
234 | (defun macroexp-unprogn (exp) |
235 | "Turn EXP into a list of expressions to execute in sequence." | |
236 | (if (eq (car-safe exp) 'progn) (cdr exp) (list exp))) | |
237 | ||
4dd1c416 SM |
238 | (defun macroexp-let* (bindings exp) |
239 | "Return an expression equivalent to `(let* ,bindings ,exp)." | |
240 | (cond | |
241 | ((null bindings) exp) | |
242 | ((eq 'let* (car-safe exp)) `(let* (,@bindings ,@(cadr exp)) ,@(cddr exp))) | |
243 | (t `(let* ,bindings ,exp)))) | |
244 | ||
245 | (defun macroexp-if (test then else) | |
246 | "Return an expression equivalent to `(if ,test ,then ,else)." | |
247 | (cond | |
248 | ((eq (car-safe else) 'if) | |
249 | (if (equal test (nth 1 else)) | |
250 | ;; Doing a test a second time: get rid of the redundancy. | |
251 | `(if ,test ,then ,@(nthcdr 3 else)) | |
252 | `(cond (,test ,then) | |
253 | (,(nth 1 else) ,(nth 2 else)) | |
254 | (t ,@(nthcdr 3 else))))) | |
255 | ((eq (car-safe else) 'cond) | |
256 | `(cond (,test ,then) | |
257 | ;; Doing a test a second time: get rid of the redundancy, as above. | |
258 | ,@(remove (assoc test else) (cdr else)))) | |
259 | ;; Invert the test if that lets us reduce the depth of the tree. | |
260 | ((memq (car-safe then) '(if cond)) (macroexp-if `(not ,test) else then)) | |
261 | (t `(if ,test ,then ,else)))) | |
262 | ||
263 | (defmacro macroexp-let² (test var exp &rest exps) | |
264 | "Bind VAR to a copyable expression that returns the value of EXP. | |
265 | This is like `(let ((v ,EXP)) ,EXPS) except that `v' is a new generated | |
266 | symbol which EXPS can find in VAR. | |
267 | TEST should be the name of a predicate on EXP checking whether the `let' can | |
268 | be skipped; if nil, as is usual, `macroexp-const-p' is used." | |
269 | (declare (indent 3) (debug (sexp form sexp body))) | |
270 | (let ((bodysym (make-symbol "body")) | |
271 | (expsym (make-symbol "exp"))) | |
272 | `(let* ((,expsym ,exp) | |
273 | (,var (if (,(or test #'macroexp-const-p) ,expsym) | |
274 | ,expsym (make-symbol "x"))) | |
275 | (,bodysym ,(macroexp-progn exps))) | |
276 | (if (eq ,var ,expsym) ,bodysym | |
277 | (macroexp-let* (list (list ,var ,expsym)) | |
278 | ,bodysym))))) | |
279 | ||
280 | (defsubst macroexp--const-symbol-p (symbol &optional any-value) | |
281 | "Non-nil if SYMBOL is constant. | |
282 | If ANY-VALUE is nil, only return non-nil if the value of the symbol is the | |
283 | symbol itself." | |
284 | (or (memq symbol '(nil t)) | |
285 | (keywordp symbol) | |
286 | (if any-value | |
287 | (or (memq symbol byte-compile-const-variables) | |
288 | ;; FIXME: We should provide a less intrusive way to find out | |
289 | ;; if a variable is "constant". | |
290 | (and (boundp symbol) | |
291 | (condition-case nil | |
292 | (progn (set symbol (symbol-value symbol)) nil) | |
293 | (setting-constant t))))))) | |
294 | ||
295 | (defun macroexp-const-p (exp) | |
296 | "Return non-nil if EXP will always evaluate to the same value." | |
297 | (cond ((consp exp) (or (eq (car exp) 'quote) | |
298 | (and (eq (car exp) 'function) | |
299 | (symbolp (cadr exp))))) | |
300 | ;; It would sometimes make sense to pass `any-value', but it's not | |
301 | ;; always safe since a "constant" variable may not actually always have | |
302 | ;; the same value. | |
303 | ((symbolp exp) (macroexp--const-symbol-p exp)) | |
304 | (t t))) | |
305 | ||
306 | (defun macroexp-copyable-p (exp) | |
307 | "Return non-nil if EXP can be copied without extra cost." | |
308 | (or (symbolp exp) (macroexp-const-p exp))) | |
309 | ||
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310 | (provide 'macroexp) |
311 | ||
4d449b11 | 312 | ;;; macroexp.el ends here |