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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 | ||
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 | ||
36 | (defun maybe-cons (car cdr original-cons) | |
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 | |
44 | ;; `maybe-cons' results in excessively deep recursion for very long | |
45 | ;; input forms. | |
5de35ba4 | 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 | |
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52 | result will be eq to LIST). |
53 | ||
54 | \(fn (VAR LIST) BODY...)" | |
55 | (let ((var (car var+list)) | |
56 | (list (cadr var+list)) | |
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57 | (shared (make-symbol "shared")) |
58 | (unshared (make-symbol "unshared")) | |
59 | (tail (make-symbol "tail")) | |
60 | (new-el (make-symbol "new-el"))) | |
61 | `(let* ((,shared ,list) | |
62 | (,unshared nil) | |
63 | (,tail ,shared) | |
64 | ,var ,new-el) | |
65 | (while ,tail | |
66 | (setq ,var (car ,tail) | |
67 | ,new-el (progn ,@body)) | |
68 | (unless (eq ,var ,new-el) | |
69 | (while (not (eq ,shared ,tail)) | |
70 | (push (pop ,shared) ,unshared)) | |
71 | (setq ,shared (cdr ,shared)) | |
72 | (push ,new-el ,unshared)) | |
73 | (setq ,tail (cdr ,tail))) | |
74 | (nconc (nreverse ,unshared) ,shared)))) | |
75 | (put 'macroexp-accumulate 'lisp-indent-function 1) | |
76 | ||
77 | (defun macroexpand-all-forms (forms &optional skip) | |
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." | |
81 | (macroexp-accumulate (form forms) | |
82 | (if (or (null skip) (zerop skip)) | |
83 | (macroexpand-all-1 form) | |
84 | (setq skip (1- skip)) | |
85 | form))) | |
86 | ||
87 | (defun macroexpand-all-clauses (clauses &optional skip) | |
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." | |
3731a850 | 92 | (macroexp-accumulate (clause clauses) |
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93 | (if (listp clause) |
94 | (macroexpand-all-forms clause skip) | |
95 | clause))) | |
96 | ||
97 | (defun macroexpand-all-1 (form) | |
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. | |
106 | (macroexpand (macroexpand-all-forms form 1) | |
107 | macroexpand-all-environment) | |
108 | ;; Normal form; get its expansion, and then expand arguments. | |
109 | (setq form (macroexpand form macroexpand-all-environment)) | |
110 | (if (consp form) | |
111 | (let ((fun (car form))) | |
112 | (cond | |
113 | ((eq fun 'cond) | |
114 | (maybe-cons fun (macroexpand-all-clauses (cdr form)) form)) | |
115 | ((eq fun 'condition-case) | |
116 | (maybe-cons | |
117 | fun | |
118 | (maybe-cons (cadr form) | |
119 | (maybe-cons (macroexpand-all-1 (nth 2 form)) | |
120 | (macroexpand-all-clauses (nthcdr 3 form) 1) | |
121 | (cddr form)) | |
122 | (cdr form)) | |
123 | form)) | |
124 | ((eq fun 'defmacro) | |
125 | (push (cons (cadr form) (cons 'lambda (cddr form))) | |
126 | macroexpand-all-environment) | |
127 | (macroexpand-all-forms form 3)) | |
128 | ((eq fun 'defun) | |
129 | (macroexpand-all-forms form 3)) | |
130 | ((memq fun '(defvar defconst)) | |
131 | (macroexpand-all-forms form 2)) | |
132 | ((eq fun 'function) | |
133 | (if (and (consp (cadr form)) (eq (car (cadr form)) 'lambda)) | |
134 | (maybe-cons fun | |
135 | (maybe-cons (macroexpand-all-forms (cadr form) 2) | |
136 | nil | |
137 | (cadr form)) | |
138 | form) | |
139 | form)) | |
140 | ((memq fun '(let let*)) | |
141 | (maybe-cons fun | |
142 | (maybe-cons (macroexpand-all-clauses (cadr form) 1) | |
143 | (macroexpand-all-forms (cddr form)) | |
144 | (cdr form)) | |
145 | form)) | |
146 | ((eq fun 'quote) | |
147 | form) | |
148 | ((and (consp fun) (eq (car fun) 'lambda)) | |
149 | ;; embedded lambda | |
150 | (maybe-cons (macroexpand-all-forms fun 2) | |
151 | (macroexpand-all-forms (cdr form)) | |
152 | form)) | |
153 | ;; The following few cases are for normal function calls that | |
154 | ;; are known to funcall one of their arguments. The byte | |
155 | ;; compiler has traditionally handled these functions specially | |
156 | ;; by treating a lambda expression quoted by `quote' as if it | |
157 | ;; were quoted by `function'. We make the same transformation | |
158 | ;; here, so that any code that cares about the difference will | |
159 | ;; see the same transformation. | |
160 | ;; First arg is a function: | |
161 | ((and (memq fun '(apply mapcar mapatoms mapconcat mapc)) | |
162 | (consp (cadr form)) | |
163 | (eq (car (cadr form)) 'quote)) | |
164 | ;; We don't use `maybe-cons' since there's clearly a change. | |
165 | (cons fun | |
166 | (cons (macroexpand-all-1 (cons 'function (cdr (cadr form)))) | |
167 | (macroexpand-all-forms (cddr form))))) | |
168 | ;; Second arg is a function: | |
169 | ((and (eq fun 'sort) | |
170 | (consp (nth 2 form)) | |
171 | (eq (car (nth 2 form)) 'quote)) | |
172 | ;; We don't use `maybe-cons' since there's clearly a change. | |
173 | (cons fun | |
174 | (cons (macroexpand-all-1 (cadr form)) | |
175 | (cons (macroexpand-all-1 | |
176 | (cons 'function (cdr (nth 2 form)))) | |
177 | (macroexpand-all-forms (nthcdr 3 form)))))) | |
178 | (t | |
179 | ;; For everything else, we just expand each argument (for | |
180 | ;; setq/setq-default this works alright because the variable names | |
181 | ;; are symbols). | |
182 | (macroexpand-all-forms form 1)))) | |
183 | form))) | |
184 | ||
185 | ;;;###autoload | |
186 | (defun macroexpand-all (form &optional environment) | |
187 | "Return result of expanding macros at all levels in FORM. | |
188 | If no macros are expanded, FORM is returned unchanged. | |
189 | The second optional arg ENVIRONMENT specifies an environment of macro | |
190 | definitions to shadow the loaded ones for use in file byte-compilation." | |
191 | (let ((macroexpand-all-environment environment)) | |
192 | (macroexpand-all-1 form))) | |
193 | ||
194 | (provide 'macroexp) | |
195 | ||
cbee283d | 196 | ;; arch-tag: af9b8c24-c196-43bc-91e1-a3570790fa5a |
4d449b11 | 197 | ;;; macroexp.el ends here |