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c0cd1b3e | 1 | ;;; GNU Guix --- Functional package management for GNU |
7874bbbb | 2 | ;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org> |
c0cd1b3e LC |
3 | ;;; |
4 | ;;; This file is part of GNU Guix. | |
5 | ;;; | |
6 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
7 | ;;; under the terms of the GNU General Public License as published by | |
8 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
9 | ;;; your option) any later version. | |
10 | ;;; | |
11 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
12 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | ;;; GNU General Public License for more details. | |
15 | ;;; | |
16 | ;;; You should have received a copy of the GNU General Public License | |
17 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
18 | ||
19 | (define-module (guix records) | |
20 | #:use-module (srfi srfi-1) | |
21 | #:use-module (srfi srfi-9) | |
22 | #:use-module (srfi srfi-26) | |
23 | #:use-module (ice-9 match) | |
fdc1bf65 LC |
24 | #:use-module (ice-9 regex) |
25 | #:use-module (ice-9 rdelim) | |
c0cd1b3e LC |
26 | #:export (define-record-type* |
27 | alist->record | |
fdc1bf65 | 28 | object->fields |
6692d845 | 29 | recutils->alist |
30 | match-record)) | |
c0cd1b3e LC |
31 | |
32 | ;;; Commentary: | |
33 | ;;; | |
34 | ;;; Utilities for dealing with Scheme records. | |
35 | ;;; | |
36 | ;;; Code: | |
37 | ||
b1353e7a LC |
38 | (define-syntax record-error |
39 | (syntax-rules () | |
40 | "Report a syntactic error in use of CONSTRUCTOR." | |
41 | ((_ constructor form fmt args ...) | |
42 | (syntax-violation constructor | |
43 | (format #f fmt args ...) | |
44 | form)))) | |
45 | ||
babc2c80 LC |
46 | (define (report-invalid-field-specifier name bindings) |
47 | "Report the first invalid binding among BINDINGS." | |
48 | (let loop ((bindings bindings)) | |
49 | (syntax-case bindings () | |
50 | (((field value) rest ...) ;good | |
51 | (loop #'(rest ...))) | |
52 | ((weird _ ...) ;weird! | |
53 | (syntax-violation name "invalid field specifier" #'weird))))) | |
54 | ||
7874bbbb LC |
55 | (define (print-record-abi-mismatch-error port key args |
56 | default-printer) | |
57 | (match args | |
58 | ((rtd . _) | |
59 | ;; The source file where this exception is thrown must be recompiled. | |
60 | (format port "ERROR: ~a: record ABI mismatch; recompilation needed" | |
61 | rtd)))) | |
62 | ||
63 | (set-exception-printer! 'record-abi-mismatch-error | |
64 | print-record-abi-mismatch-error) | |
65 | ||
66 | (define (current-abi-identifier type) | |
67 | "Return an identifier unhygienically derived from TYPE for use as its | |
68 | \"current ABI\" variable." | |
69 | (let ((type-name (syntax->datum type))) | |
70 | (datum->syntax | |
71 | type | |
72 | (string->symbol | |
73 | (string-append "% " (symbol->string type-name) | |
74 | " abi-cookie"))))) | |
75 | ||
76 | (define (abi-check type cookie) | |
77 | "Return syntax that checks that the current \"application binary | |
78 | interface\" (ABI) for TYPE is equal to COOKIE." | |
79 | (with-syntax ((current-abi (current-abi-identifier type))) | |
80 | #`(unless (eq? current-abi #,cookie) | |
81 | (throw 'record-abi-mismatch-error #,type)))) | |
82 | ||
39fc041a LC |
83 | (define-syntax make-syntactic-constructor |
84 | (syntax-rules () | |
85 | "Make the syntactic constructor NAME for TYPE, that calls CTOR, and | |
86 | expects all of EXPECTED fields to be initialized. DEFAULTS is the list of | |
87 | FIELD/DEFAULT-VALUE tuples, THUNKED is the list of identifiers of thunked | |
7874bbbb LC |
88 | fields, and DELAYED is the list of identifiers of delayed fields. |
89 | ||
90 | ABI-COOKIE is the cookie (an integer) against which to check the run-time ABI | |
91 | of TYPE matches the expansion-time ABI." | |
39fc041a | 92 | ((_ type name ctor (expected ...) |
7874bbbb | 93 | #:abi-cookie abi-cookie |
39fc041a LC |
94 | #:thunked thunked |
95 | #:delayed delayed | |
8a16d064 | 96 | #:innate innate |
39fc041a LC |
97 | #:defaults defaults) |
98 | (define-syntax name | |
99 | (lambda (s) | |
100 | (define (record-inheritance orig-record field+value) | |
101 | ;; Produce code that returns a record identical to ORIG-RECORD, | |
102 | ;; except that values for the FIELD+VALUE alist prevail. | |
103 | (define (field-inherited-value f) | |
104 | (and=> (find (lambda (x) | |
105 | (eq? f (car (syntax->datum x)))) | |
106 | field+value) | |
107 | car)) | |
108 | ||
109 | ;; Make sure there are no unknown field names. | |
110 | (let* ((fields (map (compose car syntax->datum) field+value)) | |
111 | (unexpected (lset-difference eq? fields '(expected ...)))) | |
112 | (when (pair? unexpected) | |
113 | (record-error 'name s "extraneous field initializers ~a" | |
114 | unexpected))) | |
115 | ||
cea25b08 | 116 | #`(make-struct/no-tail type |
39fc041a LC |
117 | #,@(map (lambda (field index) |
118 | (or (field-inherited-value field) | |
8a16d064 LC |
119 | (if (innate-field? field) |
120 | (wrap-field-value | |
121 | field (field-default-value field)) | |
122 | #`(struct-ref #,orig-record | |
123 | #,index)))) | |
39fc041a LC |
124 | '(expected ...) |
125 | (iota (length '(expected ...)))))) | |
126 | ||
127 | (define (thunked-field? f) | |
128 | (memq (syntax->datum f) 'thunked)) | |
129 | ||
130 | (define (delayed-field? f) | |
131 | (memq (syntax->datum f) 'delayed)) | |
132 | ||
8a16d064 LC |
133 | (define (innate-field? f) |
134 | (memq (syntax->datum f) 'innate)) | |
135 | ||
39fc041a LC |
136 | (define (wrap-field-value f value) |
137 | (cond ((thunked-field? f) | |
138 | #`(lambda () #,value)) | |
139 | ((delayed-field? f) | |
140 | #`(delay #,value)) | |
141 | (else value))) | |
142 | ||
b9c86473 LC |
143 | (define default-values |
144 | ;; List of symbol/value tuples. | |
145 | (map (match-lambda | |
146 | ((f v) | |
147 | (list (syntax->datum f) v))) | |
148 | #'defaults)) | |
149 | ||
150 | (define (field-default-value f) | |
151 | (car (assoc-ref default-values (syntax->datum f)))) | |
152 | ||
39fc041a LC |
153 | (define (field-bindings field+value) |
154 | ;; Return field to value bindings, for use in 'let*' below. | |
155 | (map (lambda (field+value) | |
156 | (syntax-case field+value () | |
157 | ((field value) | |
158 | #`(field | |
159 | #,(wrap-field-value #'field #'value))))) | |
160 | field+value)) | |
161 | ||
162 | (syntax-case s (inherit expected ...) | |
163 | ((_ (inherit orig-record) (field value) (... ...)) | |
164 | #`(let* #,(field-bindings #'((field value) (... ...))) | |
7874bbbb | 165 | #,(abi-check #'type abi-cookie) |
39fc041a LC |
166 | #,(record-inheritance #'orig-record |
167 | #'((field value) (... ...))))) | |
168 | ((_ (field value) (... ...)) | |
b9c86473 | 169 | (let ((fields (map syntax->datum #'(field (... ...))))) |
39fc041a | 170 | (define (field-value f) |
94df39cc LC |
171 | (or (find (lambda (x) |
172 | (eq? f (syntax->datum x))) | |
173 | #'(field (... ...))) | |
b9c86473 | 174 | (wrap-field-value f (field-default-value f)))) |
39fc041a | 175 | |
b9c86473 | 176 | (let ((fields (append fields (map car default-values)))) |
39fc041a LC |
177 | (cond ((lset= eq? fields '(expected ...)) |
178 | #`(let* #,(field-bindings | |
179 | #'((field value) (... ...))) | |
7874bbbb | 180 | #,(abi-check #'type abi-cookie) |
39fc041a LC |
181 | (ctor #,@(map field-value '(expected ...))))) |
182 | ((pair? (lset-difference eq? fields | |
183 | '(expected ...))) | |
184 | (record-error 'name s | |
185 | "extraneous field initializers ~a" | |
186 | (lset-difference eq? fields | |
187 | '(expected ...)))) | |
188 | (else | |
189 | (record-error 'name s | |
190 | "missing field initializers ~a" | |
191 | (lset-difference eq? | |
192 | '(expected ...) | |
babc2c80 LC |
193 | fields))))))) |
194 | ((_ bindings (... ...)) | |
195 | ;; One of BINDINGS doesn't match the (field value) pattern. | |
196 | ;; Report precisely which one is faulty, instead of letting the | |
197 | ;; "source expression failed to match any pattern" error. | |
198 | (report-invalid-field-specifier 'name | |
199 | #'(bindings (... ...)))))))))) | |
cf4efb39 | 200 | |
faef3b6a LC |
201 | (define-syntax-rule (define-field-property-predicate predicate property) |
202 | "Define PREDICATE as a procedure that takes a syntax object and, when passed | |
203 | a field specification, returns the field name if it has the given PROPERTY." | |
204 | (define (predicate s) | |
205 | (syntax-case s (property) | |
206 | ((field (property values (... ...)) _ (... ...)) | |
207 | #'field) | |
208 | ((field _ properties (... ...)) | |
209 | (predicate #'(field properties (... ...)))) | |
210 | (_ #f)))) | |
211 | ||
c0cd1b3e LC |
212 | (define-syntax define-record-type* |
213 | (lambda (s) | |
214 | "Define the given record type such that an additional \"syntactic | |
215 | constructor\" is defined, which allows instances to be constructed with named | |
e2540884 LC |
216 | field initializers, à la SRFI-35, as well as default values. An example use |
217 | may look like this: | |
218 | ||
219 | (define-record-type* <thing> thing make-thing | |
220 | thing? | |
221 | (name thing-name (default \"chbouib\")) | |
222 | (port thing-port | |
8a16d064 LC |
223 | (default (current-output-port)) (thunked)) |
224 | (loc thing-location (innate) (default (current-source-location)))) | |
e2540884 LC |
225 | |
226 | This example defines a macro 'thing' that can be used to instantiate records | |
227 | of this type: | |
228 | ||
229 | (thing | |
230 | (name \"foo\") | |
231 | (port (current-error-port))) | |
232 | ||
233 | The value of 'name' or 'port' could as well be omitted, in which case the | |
234 | default value specified in the 'define-record-type*' form is used: | |
235 | ||
236 | (thing) | |
237 | ||
238 | The 'port' field is \"thunked\", meaning that calls like '(thing-port x)' will | |
239 | actually compute the field's value in the current dynamic extent, which is | |
240 | useful when referring to fluids in a field's value. | |
241 | ||
310b32a2 LC |
242 | A field can also be marked as \"delayed\" instead of \"thunked\", in which |
243 | case its value is effectively wrapped in a (delay …) form. | |
244 | ||
e2540884 LC |
245 | It is possible to copy an object 'x' created with 'thing' like this: |
246 | ||
247 | (thing (inherit x) (name \"bar\")) | |
248 | ||
249 | This expression returns a new object equal to 'x' except for its 'name' | |
8a16d064 LC |
250 | field and its 'loc' field---the latter is marked as \"innate\", so it is not |
251 | inherited." | |
e2540884 | 252 | |
c0cd1b3e LC |
253 | (define (field-default-value s) |
254 | (syntax-case s (default) | |
255 | ((field (default val) _ ...) | |
256 | (list #'field #'val)) | |
792798f4 LC |
257 | ((field _ properties ...) |
258 | (field-default-value #'(field properties ...))) | |
c0cd1b3e LC |
259 | (_ #f))) |
260 | ||
faef3b6a LC |
261 | (define-field-property-predicate delayed-field? delayed) |
262 | (define-field-property-predicate thunked-field? thunked) | |
8a16d064 | 263 | (define-field-property-predicate innate-field? innate) |
c0cd1b3e | 264 | |
310b32a2 LC |
265 | (define (wrapped-field? s) |
266 | (or (thunked-field? s) (delayed-field? s))) | |
267 | ||
268 | (define (wrapped-field-accessor-name field) | |
c0cd1b3e | 269 | ;; Return the name (an unhygienic syntax object) of the "real" |
310b32a2 | 270 | ;; getter for field, which is assumed to be a wrapped field. |
c0cd1b3e | 271 | (syntax-case field () |
792798f4 | 272 | ((field get properties ...) |
c0cd1b3e LC |
273 | (let* ((getter (syntax->datum #'get)) |
274 | (real-getter (symbol-append '% getter '-real))) | |
275 | (datum->syntax #'get real-getter))))) | |
276 | ||
277 | (define (field-spec->srfi-9 field) | |
278 | ;; Convert a field spec of our style to a SRFI-9 field spec of the | |
279 | ;; form (field get). | |
280 | (syntax-case field () | |
792798f4 | 281 | ((name get properties ...) |
c0cd1b3e | 282 | #`(name |
310b32a2 LC |
283 | #,(if (wrapped-field? field) |
284 | (wrapped-field-accessor-name field) | |
c0cd1b3e LC |
285 | #'get))))) |
286 | ||
287 | (define (thunked-field-accessor-definition field) | |
288 | ;; Return the real accessor for FIELD, which is assumed to be a | |
289 | ;; thunked field. | |
290 | (syntax-case field () | |
291 | ((name get _ ...) | |
310b32a2 | 292 | (with-syntax ((real-get (wrapped-field-accessor-name field))) |
c0cd1b3e LC |
293 | #'(define-inlinable (get x) |
294 | ;; The real value of that field is a thunk, so call it. | |
295 | ((real-get x))))))) | |
296 | ||
310b32a2 LC |
297 | (define (delayed-field-accessor-definition field) |
298 | ;; Return the real accessor for FIELD, which is assumed to be a | |
299 | ;; delayed field. | |
300 | (syntax-case field () | |
301 | ((name get _ ...) | |
302 | (with-syntax ((real-get (wrapped-field-accessor-name field))) | |
303 | #'(define-inlinable (get x) | |
304 | ;; The real value of that field is a promise, so force it. | |
305 | (force (real-get x))))))) | |
306 | ||
7874bbbb LC |
307 | (define (compute-abi-cookie field-specs) |
308 | ;; Compute an "ABI cookie" for the given FIELD-SPECS. We use | |
309 | ;; 'string-hash' because that's a better hash function that 'hash' on a | |
310 | ;; list of symbols. | |
311 | (syntax-case field-specs () | |
312 | (((field get properties ...) ...) | |
313 | (string-hash (object->string | |
314 | (syntax->datum #'((field properties ...) ...))) | |
315 | most-positive-fixnum)))) | |
316 | ||
c0cd1b3e LC |
317 | (syntax-case s () |
318 | ((_ type syntactic-ctor ctor pred | |
792798f4 LC |
319 | (field get properties ...) ...) |
320 | (let* ((field-spec #'((field get properties ...) ...)) | |
9b543456 | 321 | (thunked (filter-map thunked-field? field-spec)) |
310b32a2 | 322 | (delayed (filter-map delayed-field? field-spec)) |
8a16d064 | 323 | (innate (filter-map innate-field? field-spec)) |
9b543456 | 324 | (defaults (filter-map field-default-value |
7874bbbb LC |
325 | #'((field properties ...) ...))) |
326 | (cookie (compute-abi-cookie field-spec))) | |
c0cd1b3e LC |
327 | (with-syntax (((field-spec* ...) |
328 | (map field-spec->srfi-9 field-spec)) | |
329 | ((thunked-field-accessor ...) | |
330 | (filter-map (lambda (field) | |
331 | (and (thunked-field? field) | |
332 | (thunked-field-accessor-definition | |
333 | field))) | |
310b32a2 LC |
334 | field-spec)) |
335 | ((delayed-field-accessor ...) | |
336 | (filter-map (lambda (field) | |
337 | (and (delayed-field? field) | |
338 | (delayed-field-accessor-definition | |
339 | field))) | |
c0cd1b3e LC |
340 | field-spec))) |
341 | #`(begin | |
342 | (define-record-type type | |
343 | (ctor field ...) | |
344 | pred | |
345 | field-spec* ...) | |
7874bbbb LC |
346 | (define #,(current-abi-identifier #'type) |
347 | #,cookie) | |
ad7c1a2c LC |
348 | thunked-field-accessor ... |
349 | delayed-field-accessor ... | |
39fc041a LC |
350 | (make-syntactic-constructor type syntactic-ctor ctor |
351 | (field ...) | |
7874bbbb | 352 | #:abi-cookie #,cookie |
39fc041a LC |
353 | #:thunked #,thunked |
354 | #:delayed #,delayed | |
8a16d064 | 355 | #:innate #,innate |
39fc041a | 356 | #:defaults #,defaults)))))))) |
c0cd1b3e | 357 | |
c8772a7a LC |
358 | (define* (alist->record alist make keys |
359 | #:optional (multiple-value-keys '())) | |
360 | "Apply MAKE to the values associated with KEYS in ALIST. Items in KEYS that | |
361 | are also in MULTIPLE-VALUE-KEYS are considered to occur possibly multiple | |
362 | times in ALIST, and thus their value is a list." | |
363 | (let ((args (map (lambda (key) | |
364 | (if (member key multiple-value-keys) | |
365 | (filter-map (match-lambda | |
366 | ((k . v) | |
367 | (and (equal? k key) v))) | |
368 | alist) | |
369 | (assoc-ref alist key))) | |
370 | keys))) | |
c0cd1b3e LC |
371 | (apply make args))) |
372 | ||
373 | (define (object->fields object fields port) | |
374 | "Write OBJECT (typically a record) as a series of recutils-style fields to | |
375 | PORT, according to FIELDS. FIELDS must be a list of field name/getter pairs." | |
376 | (let loop ((fields fields)) | |
377 | (match fields | |
378 | (() | |
379 | object) | |
380 | (((field . get) rest ...) | |
381 | (format port "~a: ~a~%" field (get object)) | |
382 | (loop rest))))) | |
383 | ||
fb519bd8 LC |
384 | (define %recutils-field-charset |
385 | ;; Valid characters starting a recutils field. | |
386 | ;; info "(recutils) Fields" | |
387 | (char-set-union char-set:upper-case | |
388 | char-set:lower-case | |
389 | (char-set #\%))) | |
836d10f1 | 390 | |
fdc1bf65 LC |
391 | (define (recutils->alist port) |
392 | "Read a recutils-style record from PORT and return it as a list of key/value | |
393 | pairs. Stop upon an empty line (after consuming it) or EOF." | |
394 | (let loop ((line (read-line port)) | |
395 | (result '())) | |
b7b88288 | 396 | (cond ((eof-object? line) |
fdc1bf65 | 397 | (reverse result)) |
b7b88288 LC |
398 | ((string-null? line) |
399 | (if (null? result) | |
400 | (loop (read-line port) result) ; leading space: ignore it | |
401 | (reverse result))) ; end-of-record marker | |
fdc1bf65 | 402 | (else |
fb519bd8 LC |
403 | ;; Now check the first character of LINE, since that's what the |
404 | ;; recutils manual says is enough. | |
405 | (let ((first (string-ref line 0))) | |
406 | (cond | |
407 | ((char-set-contains? %recutils-field-charset first) | |
408 | (let* ((colon (string-index line #\:)) | |
409 | (field (string-take line colon)) | |
410 | (value (string-trim (string-drop line (+ 1 colon))))) | |
411 | (loop (read-line port) | |
412 | (alist-cons field value result)))) | |
413 | ((eqv? first #\#) ;info "(recutils) Comments" | |
414 | (loop (read-line port) result)) | |
415 | ((eqv? first #\+) ;info "(recutils) Fields" | |
416 | (let ((new-line (if (string-prefix? "+ " line) | |
417 | (string-drop line 2) | |
418 | (string-drop line 1)))) | |
419 | (match result | |
420 | (((field . value) rest ...) | |
421 | (loop (read-line port) | |
422 | `((,field . ,(string-append value "\n" new-line)) | |
423 | ,@rest)))))) | |
424 | (else | |
425 | (error "unmatched line" line)))))))) | |
fdc1bf65 | 426 | |
6692d845 | 427 | (define-syntax match-record |
428 | (syntax-rules () | |
429 | "Bind each FIELD of a RECORD of the given TYPE to it's FIELD name. | |
430 | The current implementation does not support thunked and delayed fields." | |
431 | ((_ record type (field fields ...) body ...) | |
432 | (if (eq? (struct-vtable record) type) | |
433 | ;; TODO compute indices and report wrong-field-name errors at | |
434 | ;; expansion time | |
435 | ;; TODO support thunked and delayed fields | |
436 | (let ((field ((record-accessor type 'field) record))) | |
437 | (match-record record type (fields ...) body ...)) | |
438 | (throw 'wrong-type-arg record))) | |
439 | ((_ record type () body ...) | |
440 | (begin body ...)))) | |
441 | ||
c0cd1b3e | 442 | ;;; records.scm ends here |