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861345b4 | 1 | ;;; -*-lisp-*- |
2 | ;;; | |
3 | ;;; $Id$ | |
4 | ;;; | |
5 | ;;; Basic definitions | |
6 | ;;; | |
7 | ;;; (c) 2005 Mark Wooding | |
8 | ;;; | |
9 | ||
10 | ;;;----- Licensing notice --------------------------------------------------- | |
11 | ;;; | |
12 | ;;; This program is free software; you can redistribute it and/or modify | |
13 | ;;; it under the terms of the GNU General Public License as published by | |
14 | ;;; the Free Software Foundation; either version 2 of the License, or | |
15 | ;;; (at your option) any later version. | |
16 | ;;; | |
17 | ;;; This program is distributed in the hope that it will be useful, | |
18 | ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ;;; GNU General Public License for more details. | |
21 | ;;; | |
22 | ;;; You should have received a copy of the GNU General Public License | |
23 | ;;; along with this program; if not, write to the Free Software Foundation, | |
24 | ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | ||
02866e07 MW |
26 | ;;;-------------------------------------------------------------------------- |
27 | ;;; Package things. | |
28 | ||
861345b4 | 29 | (defpackage #:mdw.base |
30 | (:use #:common-lisp) | |
31 | (:export #:compile-time-defun | |
32 | #:show | |
4b6a6387 | 33 | #:stringify #:mappend #:listify #:fix-pair #:pairify #:parse-body |
861345b4 | 34 | #:whitespace-char-p |
35 | #:slot-uninitialized | |
560e1186 | 36 | #:nlet #:while #:case2 #:ecase2 |
861345b4 | 37 | #:with-gensyms #:let*/gensyms #:with-places |
e979e568 MW |
38 | #:locp #:locf #:ref #:with-locatives |
39 | #:update-place #:update-place-after | |
7dcf04ad MW |
40 | #:incf-after #:decf-after |
41 | #:fixnump) | |
42 | #+cmu (:import-from #:extensions #:fixnump)) | |
43 | ||
861345b4 | 44 | (in-package #:mdw.base) |
45 | ||
02866e07 MW |
46 | ;;;-------------------------------------------------------------------------- |
47 | ;;; Some simple macros to get things going. | |
48 | ||
861345b4 | 49 | (defmacro compile-time-defun (name args &body body) |
50 | "Define a function which can be used by macros during the compilation | |
0ff9df03 | 51 | process." |
861345b4 | 52 | `(eval-when (:compile-toplevel :load-toplevel) |
53 | (defun ,name ,args ,@body))) | |
54 | ||
55 | (defmacro show (x) | |
56 | "Debugging tool: print the expression X and its value." | |
57 | (let ((tmp (gensym))) | |
58 | `(let ((,tmp ,x)) | |
59 | (format t "~&~S: ~S~%" ',x ,tmp) | |
60 | ,tmp))) | |
61 | ||
62 | (defun stringify (str) | |
63 | "Return a string representation of STR. Strings are returned unchanged; | |
0ff9df03 MW |
64 | symbols are converted to their names (unqualified!). Other objects are |
65 | converted to their print representations." | |
861345b4 | 66 | (typecase str |
67 | (string str) | |
68 | (symbol (symbol-name str)) | |
69 | (t (with-output-to-string (s) | |
70 | (princ str s))))) | |
02866e07 | 71 | |
4b6a6387 MW |
72 | (defun mappend (function list &rest more-lists) |
73 | "Apply FUNCTION to corresponding elements of LIST and MORE-LISTS, yielding | |
74 | a list. Return the concatenation of all the resulting lists. Like | |
75 | mapcan, but nondestructive." | |
76 | (apply #'append (apply #'mapcar function list more-lists))) | |
77 | ||
861345b4 | 78 | (compile-time-defun listify (x) |
79 | "If X is a (possibly empty) list, return X; otherwise return (list X)." | |
80 | (if (listp x) x (list x))) | |
02866e07 | 81 | |
861345b4 | 82 | (compile-time-defun do-fix-pair (x y defaultp) |
83 | "Helper function for fix-pair and pairify." | |
84 | (flet ((singleton (x) (values x (if defaultp y x)))) | |
85 | (cond ((atom x) (singleton x)) | |
86 | ((null (cdr x)) (singleton (car x))) | |
87 | ((atom (cdr x)) (values (car x) (cdr x))) | |
88 | ((cddr x) (error "Too many elements for a pair.")) | |
89 | (t (values (car x) (cadr x)))))) | |
02866e07 | 90 | |
861345b4 | 91 | (compile-time-defun fix-pair (x &optional (y nil defaultp)) |
92 | "Return two values extracted from X. It works as follows: | |
0ff9df03 MW |
93 | (A) -> A, Y |
94 | (A B) -> A, B | |
95 | (A B . C) -> error | |
96 | (A . B) -> A, B | |
97 | A -> A, Y | |
98 | where Y defaults to A if not specified." | |
861345b4 | 99 | (do-fix-pair x y defaultp)) |
02866e07 | 100 | |
861345b4 | 101 | (compile-time-defun pairify (x &optional (y nil defaultp)) |
102 | "As for fix-pair, but returns a list instead of two values." | |
103 | (multiple-value-call #'list (do-fix-pair x y defaultp))) | |
104 | ||
105 | (defun whitespace-char-p (ch) | |
106 | "Return whether CH is a whitespace character or not." | |
107 | (case ch | |
108 | ((#\space #\tab #\newline #\return #\vt #\formfeed) t) | |
109 | (t nil))) | |
110 | ||
111 | (declaim (ftype (function nil ()) slot-unitialized)) | |
112 | (defun slot-uninitialized () | |
113 | "A function which signals an error. Can be used as an initializer form in | |
0ff9df03 | 114 | structure definitions without doom ensuing." |
861345b4 | 115 | (error "No initializer for slot.")) |
116 | ||
e2a3c923 | 117 | (compile-time-defun parse-body (body &key (allow-docstring-p t)) |
9d3ccec7 | 118 | "Given a BODY (a list of forms), parses it into three sections: a |
0ff9df03 MW |
119 | docstring, a list of declarations (forms beginning with the symbol |
120 | `declare') and the body forms. The result is returned as three lists | |
121 | (even the docstring), suitable for interpolation into a backquoted list | |
e2a3c923 MW |
122 | using `@,'. If ALLOW-DOCSTRING-P is nil, docstrings aren't allowed at |
123 | all." | |
124 | (let ((doc nil) (decls nil)) | |
125 | (do ((forms body (cdr forms))) (nil) | |
126 | (let ((form (and forms (car forms)))) | |
127 | (cond ((and allow-docstring-p (not doc) (stringp form) (cdr forms)) | |
128 | (setf doc form)) | |
129 | ((and (consp form) | |
130 | (eq (car form) 'declare)) | |
131 | (setf decls (append decls (cdr form)))) | |
132 | (t (return (values (and doc (list doc)) | |
133 | (and decls (list (cons 'declare decls))) | |
134 | forms)))))))) | |
9d3ccec7 | 135 | |
7dcf04ad MW |
136 | #-cmu |
137 | (progn | |
138 | (declaim (inline fixnump)) | |
139 | (defun fixnump (object) | |
140 | "Answer non-nil if OBJECT is a fixnum, or nil if it isn't." | |
141 | (typep object 'fixnum))) | |
142 | ||
02866e07 MW |
143 | ;;;-------------------------------------------------------------------------- |
144 | ;;; Generating symbols. | |
145 | ||
861345b4 | 146 | (defmacro with-gensyms (syms &body body) |
147 | "Everyone's favourite macro helper." | |
148 | `(let (,@(mapcar (lambda (sym) `(,sym (gensym ,(symbol-name sym)))) | |
149 | (listify syms))) | |
150 | ,@body)) | |
151 | ||
152 | (defmacro let*/gensyms (binds &body body) | |
153 | "A macro helper. BINDS is a list of binding pairs (VAR VALUE), where VALUE | |
0ff9df03 MW |
154 | defaults to VAR. The result is that BODY is evaluated in a context where |
155 | each VAR is bound to a gensym, and in the final expansion, each of those | |
156 | gensyms will be bound to the corresponding VALUE." | |
861345b4 | 157 | (labels ((more (binds) |
158 | (let ((tmp (gensym "TMP")) (bind (car binds))) | |
159 | `((let ((,tmp ,(cadr bind)) | |
160 | (,(car bind) (gensym ,(symbol-name (car bind))))) | |
161 | `(let ((,,(car bind) ,,tmp)) | |
162 | ,,@(if (cdr binds) | |
163 | (more (cdr binds)) | |
164 | body))))))) | |
165 | (if (null binds) | |
166 | `(progn ,@body) | |
167 | (car (more (mapcar #'pairify (listify binds))))))) | |
168 | ||
02866e07 | 169 | ;;;-------------------------------------------------------------------------- |
f2d46aaa MW |
170 | ;;; Some simple yet useful control structures. |
171 | ||
172 | (defmacro nlet (name binds &body body) | |
173 | "Scheme's named let." | |
174 | (multiple-value-bind (vars vals) | |
175 | (loop for bind in binds | |
176 | for (var val) = (pairify bind nil) | |
177 | collect var into vars | |
178 | collect val into vals | |
179 | finally (return (values vars vals))) | |
180 | `(labels ((,name ,vars | |
181 | ,@body)) | |
182 | (,name ,@vals)))) | |
183 | ||
184 | (defmacro while (cond &body body) | |
185 | "If COND is false, evaluate to nil; otherwise evaluate BODY and try again." | |
186 | `(loop | |
93f04724 | 187 | (unless ,cond (return)) |
f2d46aaa MW |
188 | ,@body)) |
189 | ||
560e1186 MW |
190 | (compile-time-defun do-case2-like (kind vform clauses) |
191 | "Helper function for `case2' and `ecase2'." | |
192 | (with-gensyms (scrutinee argument) | |
193 | `(multiple-value-bind (,scrutinee ,argument) ,vform | |
194 | (declare (ignorable ,argument)) | |
195 | (,kind ,scrutinee | |
196 | ,@(mapcar (lambda (clause) | |
197 | (destructuring-bind | |
b3bc3745 | 198 | (cases (&optional varx vary) &rest forms) |
560e1186 MW |
199 | clause |
200 | `(,cases | |
b3bc3745 MW |
201 | ,@(if varx |
202 | (list `(let ((,(or vary varx) ,argument) | |
203 | ,@(and vary | |
204 | `((,varx ,scrutinee)))) | |
205 | ,@forms)) | |
560e1186 MW |
206 | forms)))) |
207 | clauses))))) | |
208 | ||
209 | (defmacro case2 (vform &body clauses) | |
210 | "VFORM is a form which evaluates to two values, SCRUTINEE and ARGUMENT. | |
b3bc3745 MW |
211 | The CLAUSES have the form (CASES ([[SCRUVAR] ARGVAR]) FORMS...), where a |
212 | standard `case' clause has the form (CASES FORMS...). The `case2' form | |
213 | evaluates the VFORM, and compares the SCRUTINEE to the various CASES, in | |
214 | order, just like `case'. If there is a match, then the corresponding | |
215 | FORMs are evaluated with ARGVAR bound to the ARGUMENT and SCRUVAR bound to | |
216 | the SCRUTINEE (where specified). Note the bizarre defaulting behaviour: | |
217 | ARGVAR is less optional than SCRUVAR." | |
560e1186 MW |
218 | (do-case2-like 'case vform clauses)) |
219 | ||
220 | (defmacro ecase2 (vform &body clauses) | |
221 | "Like `case2', but signals an error if no clause matches the SCRUTINEE." | |
222 | (do-case2-like 'ecase vform clauses)) | |
223 | ||
f2d46aaa | 224 | ;;;-------------------------------------------------------------------------- |
02866e07 MW |
225 | ;;; with-places |
226 | ||
861345b4 | 227 | (defmacro %place-ref (getform setform newtmp) |
228 | "Grim helper macro for with-places." | |
229 | (declare (ignore setform newtmp)) | |
230 | getform) | |
02866e07 | 231 | |
861345b4 | 232 | (define-setf-expander %place-ref (getform setform newtmp) |
233 | "Grim helper macro for with-places." | |
234 | (values nil nil newtmp setform getform)) | |
02866e07 | 235 | |
861345b4 | 236 | (defmacro with-places ((&key environment) places &body body) |
237 | "A hairy helper, for writing setf-like macros. PLACES is a list of binding | |
0ff9df03 MW |
238 | pairs (VAR PLACE), where PLACE defaults to VAR. The result is that BODY |
239 | is evaluated in a context where each VAR is bound to a gensym, and in the | |
240 | final expansion, each of those gensyms will be bound to a symbol-macro | |
241 | capable of reading or setting the value of the corresponding PLACE." | |
861345b4 | 242 | (if (null places) |
243 | `(progn ,@body) | |
244 | (let*/gensyms (environment) | |
245 | (labels | |
246 | ((more (places) | |
247 | (let ((place (car places))) | |
248 | (with-gensyms (tmp valtmps valforms | |
249 | newtmps setform getform) | |
250 | `((let ((,tmp ,(cadr place)) | |
251 | (,(car place) | |
252 | (gensym ,(symbol-name (car place))))) | |
253 | (multiple-value-bind | |
254 | (,valtmps ,valforms | |
255 | ,newtmps ,setform ,getform) | |
256 | (get-setf-expansion ,tmp | |
257 | ,environment) | |
258 | (list 'let* | |
259 | (mapcar #'list ,valtmps ,valforms) | |
260 | `(symbol-macrolet ((,,(car place) | |
261 | (%place-ref ,,getform | |
262 | ,,setform | |
263 | ,,newtmps))) | |
264 | ,,@(if (cdr places) | |
265 | (more (cdr places)) | |
266 | body)))))))))) | |
267 | (car (more (mapcar #'pairify (listify places)))))))) | |
268 | ||
02866e07 MW |
269 | ;;;-------------------------------------------------------------------------- |
270 | ;;; Update-in-place macros built using with-places. | |
271 | ||
e979e568 MW |
272 | (defmacro update-place (op place arg &environment env) |
273 | "Update PLACE with the value of OP PLACE ARG, returning the new value." | |
274 | (with-places (:environment env) (place) | |
275 | `(setf ,place (,op ,place ,arg)))) | |
02866e07 | 276 | |
e979e568 MW |
277 | (defmacro update-place-after (op place arg &environment env) |
278 | "Update PLACE with the value of OP PLACE ARG, returning the old value." | |
279 | (with-places (:environment env) (place) | |
280 | (with-gensyms (x) | |
281 | `(let ((,x ,place)) | |
02866e07 MW |
282 | (setf ,place (,op ,x ,arg)) |
283 | ,x)))) | |
284 | ||
e979e568 MW |
285 | (defmacro incf-after (place &optional (by 1)) |
286 | "Increment PLACE by BY, returning the old value." | |
287 | `(update-place-after + ,place ,by)) | |
02866e07 | 288 | |
e979e568 MW |
289 | (defmacro decf-after (place &optional (by 1)) |
290 | "Decrement PLACE by BY, returning the old value." | |
291 | `(update-place-after - ,place ,by)) | |
292 | ||
02866e07 MW |
293 | ;;;-------------------------------------------------------------------------- |
294 | ;;; Locatives. | |
e979e568 | 295 | |
861345b4 | 296 | (defstruct (loc (:predicate locp) (:constructor make-loc (reader writer))) |
297 | "Locative data type. See `locf' and `ref'." | |
298 | (reader (slot-uninitialized) :type function) | |
299 | (writer (slot-uninitialized) :type function)) | |
02866e07 | 300 | |
861345b4 | 301 | (defmacro locf (place &environment env) |
302 | "Slightly cheesy locatives. (locf PLACE) returns an object which, using | |
0ff9df03 MW |
303 | the `ref' function, can be used to read or set the value of PLACE. It's |
304 | cheesy because it uses closures rather than actually taking the address of | |
305 | something. Also, unlike Zetalisp, we don't overload `car' to do our dirty | |
306 | work." | |
861345b4 | 307 | (multiple-value-bind |
308 | (valtmps valforms newtmps setform getform) | |
309 | (get-setf-expansion place env) | |
310 | `(let* (,@(mapcar #'list valtmps valforms)) | |
311 | (make-loc (lambda () ,getform) | |
312 | (lambda (,@newtmps) ,setform))))) | |
02866e07 | 313 | |
861345b4 | 314 | (declaim (inline loc (setf loc))) |
02866e07 | 315 | |
861345b4 | 316 | (defun ref (loc) |
317 | "Fetch the value referred to by a locative." | |
318 | (funcall (loc-reader loc))) | |
02866e07 | 319 | |
861345b4 | 320 | (defun (setf ref) (new loc) |
321 | "Store a new value in the place referred to by a locative." | |
322 | (funcall (loc-writer loc) new)) | |
02866e07 | 323 | |
861345b4 | 324 | (defmacro with-locatives (locs &body body) |
325 | "LOCS is a list of items of the form (SYM [LOC-EXPR]), where SYM is a | |
0ff9df03 MW |
326 | symbol and LOC-EXPR evaluates to a locative. If LOC-EXPR is omitted, it |
327 | defaults to SYM. As an abbreviation for a common case, LOCS may be a | |
328 | symbol instead of a list. The BODY is evaluated in an environment where | |
329 | each SYM is a symbol macro which expands to (ref LOC-EXPR) -- or, in fact, | |
330 | something similar which doesn't break if LOC-EXPR has side-effects. Thus, | |
331 | references, including `setf' forms, fetch or modify the thing referred to | |
332 | by the LOC-EXPR. Useful for covering over where something uses a | |
333 | locative." | |
861345b4 | 334 | (setf locs (mapcar #'pairify (listify locs))) |
335 | (let ((tt (mapcar (lambda (l) (declare (ignore l)) (gensym)) locs)) | |
336 | (ll (mapcar #'cadr locs)) | |
337 | (ss (mapcar #'car locs))) | |
338 | `(let (,@(mapcar (lambda (tmp loc) `(,tmp ,loc)) tt ll)) | |
339 | (symbol-macrolet (,@(mapcar (lambda (sym tmp) | |
340 | `(,sym (ref ,tmp))) ss tt)) | |
341 | ,@body)))) | |
342 | ||
343 | ;;;----- That's all, folks -------------------------------------------------- |