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1 | ;;; macroexp.el --- Additional macro-expansion support |
2 | ;; | |
8b72699e | 3 | ;; Copyright (C) 2004, 2005, 2006, 2007, 2008 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 | ||
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
e0085d62 | 12 | ;; the Free Software Foundation; either version 3, or (at your option) |
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13 | ;; any later version. |
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 | |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
3a35cf56 LK |
22 | ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
23 | ;; Boston, MA 02110-1301, USA. | |
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24 | |
25 | ;;; Commentary: | |
26 | ;; | |
27 | ;; This file contains macro-expansions functions that are not defined in | |
28 | ;; the Lisp core, namely `macroexpand-all', which expands all macros in | |
29 | ;; a form, not just a top-level one. | |
30 | ;; | |
31 | ||
32 | ;;; Code: | |
33 | ||
34 | ;; Bound by the top-level `macroexpand-all', and modified to include any | |
35 | ;; macros defined by `defmacro'. | |
36 | (defvar macroexpand-all-environment nil) | |
37 | ||
38 | (defun maybe-cons (car cdr original-cons) | |
39 | "Return (CAR . CDR), using ORIGINAL-CONS if possible." | |
40 | (if (and (eq car (car original-cons)) (eq cdr (cdr original-cons))) | |
41 | original-cons | |
42 | (cons car cdr))) | |
43 | ||
44 | ;; We use this special macro to iteratively process forms and share list | |
45 | ;; structure of the result with the input. Doing so recursively using | |
46 | ;; `maybe-cons' results in excessively deep recursion for very long | |
47 | ;; input forms. | |
5de35ba4 | 48 | (defmacro macroexp-accumulate (var+list &rest body) |
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49 | "Return a list of the results of evaluating BODY for each element of LIST. |
50 | Evaluate BODY with VAR bound to each `car' from LIST, in turn. | |
51 | Return a list of the values of the final form in BODY. | |
52 | The list structure of the result will share as much with LIST as | |
53 | possible (for instance, when BODY just returns VAR unchanged, the | |
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54 | result will be eq to LIST). |
55 | ||
56 | \(fn (VAR LIST) BODY...)" | |
57 | (let ((var (car var+list)) | |
58 | (list (cadr var+list)) | |
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59 | (shared (make-symbol "shared")) |
60 | (unshared (make-symbol "unshared")) | |
61 | (tail (make-symbol "tail")) | |
62 | (new-el (make-symbol "new-el"))) | |
63 | `(let* ((,shared ,list) | |
64 | (,unshared nil) | |
65 | (,tail ,shared) | |
66 | ,var ,new-el) | |
67 | (while ,tail | |
68 | (setq ,var (car ,tail) | |
69 | ,new-el (progn ,@body)) | |
70 | (unless (eq ,var ,new-el) | |
71 | (while (not (eq ,shared ,tail)) | |
72 | (push (pop ,shared) ,unshared)) | |
73 | (setq ,shared (cdr ,shared)) | |
74 | (push ,new-el ,unshared)) | |
75 | (setq ,tail (cdr ,tail))) | |
76 | (nconc (nreverse ,unshared) ,shared)))) | |
77 | (put 'macroexp-accumulate 'lisp-indent-function 1) | |
78 | ||
79 | (defun macroexpand-all-forms (forms &optional skip) | |
80 | "Return FORMS with macros expanded. FORMS is a list of forms. | |
81 | If SKIP is non-nil, then don't expand that many elements at the start of | |
82 | FORMS." | |
83 | (macroexp-accumulate (form forms) | |
84 | (if (or (null skip) (zerop skip)) | |
85 | (macroexpand-all-1 form) | |
86 | (setq skip (1- skip)) | |
87 | form))) | |
88 | ||
89 | (defun macroexpand-all-clauses (clauses &optional skip) | |
90 | "Return CLAUSES with macros expanded. | |
91 | CLAUSES is a list of lists of forms; any clause that's not a list is ignored. | |
92 | If SKIP is non-nil, then don't expand that many elements at the start of | |
93 | each clause." | |
3731a850 | 94 | (macroexp-accumulate (clause clauses) |
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95 | (if (listp clause) |
96 | (macroexpand-all-forms clause skip) | |
97 | clause))) | |
98 | ||
99 | (defun macroexpand-all-1 (form) | |
100 | "Expand all macros in FORM. | |
101 | This is an internal version of `macroexpand-all'. | |
102 | Assumes the caller has bound `macroexpand-all-environment'." | |
103 | (if (and (listp form) (eq (car form) 'backquote-list*)) | |
104 | ;; Special-case `backquote-list*', as it is normally a macro that | |
105 | ;; generates exceedingly deep expansions from relatively shallow input | |
106 | ;; forms. We just process it `in reverse' -- first we expand all the | |
107 | ;; arguments, _then_ we expand the top-level definition. | |
108 | (macroexpand (macroexpand-all-forms form 1) | |
109 | macroexpand-all-environment) | |
110 | ;; Normal form; get its expansion, and then expand arguments. | |
111 | (setq form (macroexpand form macroexpand-all-environment)) | |
112 | (if (consp form) | |
113 | (let ((fun (car form))) | |
114 | (cond | |
115 | ((eq fun 'cond) | |
116 | (maybe-cons fun (macroexpand-all-clauses (cdr form)) form)) | |
117 | ((eq fun 'condition-case) | |
118 | (maybe-cons | |
119 | fun | |
120 | (maybe-cons (cadr form) | |
121 | (maybe-cons (macroexpand-all-1 (nth 2 form)) | |
122 | (macroexpand-all-clauses (nthcdr 3 form) 1) | |
123 | (cddr form)) | |
124 | (cdr form)) | |
125 | form)) | |
126 | ((eq fun 'defmacro) | |
127 | (push (cons (cadr form) (cons 'lambda (cddr form))) | |
128 | macroexpand-all-environment) | |
129 | (macroexpand-all-forms form 3)) | |
130 | ((eq fun 'defun) | |
131 | (macroexpand-all-forms form 3)) | |
132 | ((memq fun '(defvar defconst)) | |
133 | (macroexpand-all-forms form 2)) | |
134 | ((eq fun 'function) | |
135 | (if (and (consp (cadr form)) (eq (car (cadr form)) 'lambda)) | |
136 | (maybe-cons fun | |
137 | (maybe-cons (macroexpand-all-forms (cadr form) 2) | |
138 | nil | |
139 | (cadr form)) | |
140 | form) | |
141 | form)) | |
142 | ((memq fun '(let let*)) | |
143 | (maybe-cons fun | |
144 | (maybe-cons (macroexpand-all-clauses (cadr form) 1) | |
145 | (macroexpand-all-forms (cddr form)) | |
146 | (cdr form)) | |
147 | form)) | |
148 | ((eq fun 'quote) | |
149 | form) | |
150 | ((and (consp fun) (eq (car fun) 'lambda)) | |
151 | ;; embedded lambda | |
152 | (maybe-cons (macroexpand-all-forms fun 2) | |
153 | (macroexpand-all-forms (cdr form)) | |
154 | form)) | |
155 | ;; The following few cases are for normal function calls that | |
156 | ;; are known to funcall one of their arguments. The byte | |
157 | ;; compiler has traditionally handled these functions specially | |
158 | ;; by treating a lambda expression quoted by `quote' as if it | |
159 | ;; were quoted by `function'. We make the same transformation | |
160 | ;; here, so that any code that cares about the difference will | |
161 | ;; see the same transformation. | |
162 | ;; First arg is a function: | |
163 | ((and (memq fun '(apply mapcar mapatoms mapconcat mapc)) | |
164 | (consp (cadr form)) | |
165 | (eq (car (cadr form)) 'quote)) | |
166 | ;; We don't use `maybe-cons' since there's clearly a change. | |
167 | (cons fun | |
168 | (cons (macroexpand-all-1 (cons 'function (cdr (cadr form)))) | |
169 | (macroexpand-all-forms (cddr form))))) | |
170 | ;; Second arg is a function: | |
171 | ((and (eq fun 'sort) | |
172 | (consp (nth 2 form)) | |
173 | (eq (car (nth 2 form)) 'quote)) | |
174 | ;; We don't use `maybe-cons' since there's clearly a change. | |
175 | (cons fun | |
176 | (cons (macroexpand-all-1 (cadr form)) | |
177 | (cons (macroexpand-all-1 | |
178 | (cons 'function (cdr (nth 2 form)))) | |
179 | (macroexpand-all-forms (nthcdr 3 form)))))) | |
180 | (t | |
181 | ;; For everything else, we just expand each argument (for | |
182 | ;; setq/setq-default this works alright because the variable names | |
183 | ;; are symbols). | |
184 | (macroexpand-all-forms form 1)))) | |
185 | form))) | |
186 | ||
187 | ;;;###autoload | |
188 | (defun macroexpand-all (form &optional environment) | |
189 | "Return result of expanding macros at all levels in FORM. | |
190 | If no macros are expanded, FORM is returned unchanged. | |
191 | The second optional arg ENVIRONMENT specifies an environment of macro | |
192 | definitions to shadow the loaded ones for use in file byte-compilation." | |
193 | (let ((macroexpand-all-environment environment)) | |
194 | (macroexpand-all-1 form))) | |
195 | ||
196 | (provide 'macroexp) | |
197 | ||
cbee283d | 198 | ;; arch-tag: af9b8c24-c196-43bc-91e1-a3570790fa5a |
4d449b11 | 199 | ;;; macroexp.el ends here |