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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> |
c2dcff41 | 3 | ;;; Copyright © 2018 Mark H Weaver <mhw@netris.org> |
c0cd1b3e LC |
4 | ;;; |
5 | ;;; This file is part of GNU Guix. | |
6 | ;;; | |
7 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
8 | ;;; under the terms of the GNU General Public License as published by | |
9 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
10 | ;;; your option) any later version. | |
11 | ;;; | |
12 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
13 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | ;;; GNU General Public License for more details. | |
16 | ;;; | |
17 | ;;; You should have received a copy of the GNU General Public License | |
18 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
19 | ||
20 | (define-module (guix records) | |
21 | #:use-module (srfi srfi-1) | |
22 | #:use-module (srfi srfi-9) | |
23 | #:use-module (srfi srfi-26) | |
24 | #:use-module (ice-9 match) | |
fdc1bf65 LC |
25 | #:use-module (ice-9 regex) |
26 | #:use-module (ice-9 rdelim) | |
c0cd1b3e LC |
27 | #:export (define-record-type* |
28 | alist->record | |
fdc1bf65 | 29 | object->fields |
6692d845 | 30 | recutils->alist |
31 | match-record)) | |
c0cd1b3e LC |
32 | |
33 | ;;; Commentary: | |
34 | ;;; | |
35 | ;;; Utilities for dealing with Scheme records. | |
36 | ;;; | |
37 | ;;; Code: | |
38 | ||
b1353e7a LC |
39 | (define-syntax record-error |
40 | (syntax-rules () | |
41 | "Report a syntactic error in use of CONSTRUCTOR." | |
42 | ((_ constructor form fmt args ...) | |
43 | (syntax-violation constructor | |
44 | (format #f fmt args ...) | |
45 | form)))) | |
46 | ||
babc2c80 LC |
47 | (define (report-invalid-field-specifier name bindings) |
48 | "Report the first invalid binding among BINDINGS." | |
49 | (let loop ((bindings bindings)) | |
50 | (syntax-case bindings () | |
51 | (((field value) rest ...) ;good | |
52 | (loop #'(rest ...))) | |
53 | ((weird _ ...) ;weird! | |
54 | (syntax-violation name "invalid field specifier" #'weird))))) | |
55 | ||
c2dcff41 LC |
56 | (define (report-duplicate-field-specifier name ctor) |
57 | "Report the first duplicate identifier among the bindings in CTOR." | |
58 | (syntax-case ctor () | |
59 | ((_ bindings ...) | |
60 | (let loop ((bindings #'(bindings ...)) | |
61 | (seen '())) | |
62 | (syntax-case bindings () | |
63 | (((field value) rest ...) | |
64 | (not (memq (syntax->datum #'field) seen)) | |
65 | (loop #'(rest ...) (cons (syntax->datum #'field) seen))) | |
66 | ((duplicate rest ...) | |
67 | (syntax-violation name "duplicate field initializer" | |
68 | #'duplicate)) | |
69 | (() | |
70 | #t)))))) | |
71 | ||
9768848a LC |
72 | (eval-when (expand load eval) |
73 | ;; The procedures below are needed both at run time and at expansion time. | |
74 | ||
75 | (define (current-abi-identifier type) | |
76 | "Return an identifier unhygienically derived from TYPE for use as its | |
7874bbbb | 77 | \"current ABI\" variable." |
9768848a LC |
78 | (let ((type-name (syntax->datum type))) |
79 | (datum->syntax | |
80 | type | |
81 | (string->symbol | |
82 | (string-append "% " (symbol->string type-name) | |
83 | " abi-cookie"))))) | |
7874bbbb | 84 | |
9768848a LC |
85 | (define (abi-check type cookie) |
86 | "Return syntax that checks that the current \"application binary | |
7874bbbb | 87 | interface\" (ABI) for TYPE is equal to COOKIE." |
9768848a LC |
88 | (with-syntax ((current-abi (current-abi-identifier type))) |
89 | #`(unless (eq? current-abi #,cookie) | |
de5cbd4a LC |
90 | ;; The source file where this exception is thrown must be |
91 | ;; recompiled. | |
92 | (throw 'record-abi-mismatch-error 'abi-check | |
93 | "~a: record ABI mismatch; recompilation needed" | |
8e1395be | 94 | (list #,type) '()))))) |
7874bbbb | 95 | |
39fc041a LC |
96 | (define-syntax make-syntactic-constructor |
97 | (syntax-rules () | |
98 | "Make the syntactic constructor NAME for TYPE, that calls CTOR, and | |
99 | expects all of EXPECTED fields to be initialized. DEFAULTS is the list of | |
100 | FIELD/DEFAULT-VALUE tuples, THUNKED is the list of identifiers of thunked | |
7874bbbb LC |
101 | fields, and DELAYED is the list of identifiers of delayed fields. |
102 | ||
103 | ABI-COOKIE is the cookie (an integer) against which to check the run-time ABI | |
104 | of TYPE matches the expansion-time ABI." | |
39fc041a | 105 | ((_ type name ctor (expected ...) |
7874bbbb | 106 | #:abi-cookie abi-cookie |
39fc041a LC |
107 | #:thunked thunked |
108 | #:delayed delayed | |
8a16d064 | 109 | #:innate innate |
39fc041a LC |
110 | #:defaults defaults) |
111 | (define-syntax name | |
112 | (lambda (s) | |
113 | (define (record-inheritance orig-record field+value) | |
114 | ;; Produce code that returns a record identical to ORIG-RECORD, | |
115 | ;; except that values for the FIELD+VALUE alist prevail. | |
116 | (define (field-inherited-value f) | |
117 | (and=> (find (lambda (x) | |
118 | (eq? f (car (syntax->datum x)))) | |
119 | field+value) | |
120 | car)) | |
121 | ||
122 | ;; Make sure there are no unknown field names. | |
123 | (let* ((fields (map (compose car syntax->datum) field+value)) | |
124 | (unexpected (lset-difference eq? fields '(expected ...)))) | |
125 | (when (pair? unexpected) | |
126 | (record-error 'name s "extraneous field initializers ~a" | |
127 | unexpected))) | |
128 | ||
cea25b08 | 129 | #`(make-struct/no-tail type |
39fc041a LC |
130 | #,@(map (lambda (field index) |
131 | (or (field-inherited-value field) | |
8a16d064 LC |
132 | (if (innate-field? field) |
133 | (wrap-field-value | |
134 | field (field-default-value field)) | |
135 | #`(struct-ref #,orig-record | |
136 | #,index)))) | |
39fc041a LC |
137 | '(expected ...) |
138 | (iota (length '(expected ...)))))) | |
139 | ||
140 | (define (thunked-field? f) | |
141 | (memq (syntax->datum f) 'thunked)) | |
142 | ||
143 | (define (delayed-field? f) | |
144 | (memq (syntax->datum f) 'delayed)) | |
145 | ||
8a16d064 LC |
146 | (define (innate-field? f) |
147 | (memq (syntax->datum f) 'innate)) | |
148 | ||
39fc041a LC |
149 | (define (wrap-field-value f value) |
150 | (cond ((thunked-field? f) | |
151 | #`(lambda () #,value)) | |
152 | ((delayed-field? f) | |
153 | #`(delay #,value)) | |
154 | (else value))) | |
155 | ||
b9c86473 LC |
156 | (define default-values |
157 | ;; List of symbol/value tuples. | |
158 | (map (match-lambda | |
159 | ((f v) | |
160 | (list (syntax->datum f) v))) | |
161 | #'defaults)) | |
162 | ||
163 | (define (field-default-value f) | |
164 | (car (assoc-ref default-values (syntax->datum f)))) | |
165 | ||
39fc041a LC |
166 | (define (field-bindings field+value) |
167 | ;; Return field to value bindings, for use in 'let*' below. | |
168 | (map (lambda (field+value) | |
169 | (syntax-case field+value () | |
170 | ((field value) | |
171 | #`(field | |
172 | #,(wrap-field-value #'field #'value))))) | |
173 | field+value)) | |
174 | ||
175 | (syntax-case s (inherit expected ...) | |
176 | ((_ (inherit orig-record) (field value) (... ...)) | |
177 | #`(let* #,(field-bindings #'((field value) (... ...))) | |
7874bbbb | 178 | #,(abi-check #'type abi-cookie) |
39fc041a LC |
179 | #,(record-inheritance #'orig-record |
180 | #'((field value) (... ...))))) | |
181 | ((_ (field value) (... ...)) | |
b9c86473 | 182 | (let ((fields (map syntax->datum #'(field (... ...))))) |
39fc041a | 183 | (define (field-value f) |
94df39cc LC |
184 | (or (find (lambda (x) |
185 | (eq? f (syntax->datum x))) | |
186 | #'(field (... ...))) | |
b9c86473 | 187 | (wrap-field-value f (field-default-value f)))) |
39fc041a | 188 | |
c2dcff41 LC |
189 | ;; Pass S to make sure source location info is preserved. |
190 | (report-duplicate-field-specifier 'name s) | |
191 | ||
b9c86473 | 192 | (let ((fields (append fields (map car default-values)))) |
39fc041a LC |
193 | (cond ((lset= eq? fields '(expected ...)) |
194 | #`(let* #,(field-bindings | |
195 | #'((field value) (... ...))) | |
7874bbbb | 196 | #,(abi-check #'type abi-cookie) |
39fc041a LC |
197 | (ctor #,@(map field-value '(expected ...))))) |
198 | ((pair? (lset-difference eq? fields | |
199 | '(expected ...))) | |
200 | (record-error 'name s | |
201 | "extraneous field initializers ~a" | |
202 | (lset-difference eq? fields | |
203 | '(expected ...)))) | |
204 | (else | |
205 | (record-error 'name s | |
206 | "missing field initializers ~a" | |
207 | (lset-difference eq? | |
208 | '(expected ...) | |
babc2c80 LC |
209 | fields))))))) |
210 | ((_ bindings (... ...)) | |
211 | ;; One of BINDINGS doesn't match the (field value) pattern. | |
212 | ;; Report precisely which one is faulty, instead of letting the | |
213 | ;; "source expression failed to match any pattern" error. | |
214 | (report-invalid-field-specifier 'name | |
215 | #'(bindings (... ...)))))))))) | |
cf4efb39 | 216 | |
faef3b6a LC |
217 | (define-syntax-rule (define-field-property-predicate predicate property) |
218 | "Define PREDICATE as a procedure that takes a syntax object and, when passed | |
219 | a field specification, returns the field name if it has the given PROPERTY." | |
220 | (define (predicate s) | |
221 | (syntax-case s (property) | |
222 | ((field (property values (... ...)) _ (... ...)) | |
223 | #'field) | |
224 | ((field _ properties (... ...)) | |
225 | (predicate #'(field properties (... ...)))) | |
226 | (_ #f)))) | |
227 | ||
c0cd1b3e LC |
228 | (define-syntax define-record-type* |
229 | (lambda (s) | |
230 | "Define the given record type such that an additional \"syntactic | |
231 | constructor\" is defined, which allows instances to be constructed with named | |
e2540884 LC |
232 | field initializers, à la SRFI-35, as well as default values. An example use |
233 | may look like this: | |
234 | ||
235 | (define-record-type* <thing> thing make-thing | |
236 | thing? | |
237 | (name thing-name (default \"chbouib\")) | |
238 | (port thing-port | |
8a16d064 LC |
239 | (default (current-output-port)) (thunked)) |
240 | (loc thing-location (innate) (default (current-source-location)))) | |
e2540884 LC |
241 | |
242 | This example defines a macro 'thing' that can be used to instantiate records | |
243 | of this type: | |
244 | ||
245 | (thing | |
246 | (name \"foo\") | |
247 | (port (current-error-port))) | |
248 | ||
249 | The value of 'name' or 'port' could as well be omitted, in which case the | |
250 | default value specified in the 'define-record-type*' form is used: | |
251 | ||
252 | (thing) | |
253 | ||
254 | The 'port' field is \"thunked\", meaning that calls like '(thing-port x)' will | |
255 | actually compute the field's value in the current dynamic extent, which is | |
256 | useful when referring to fluids in a field's value. | |
257 | ||
310b32a2 LC |
258 | A field can also be marked as \"delayed\" instead of \"thunked\", in which |
259 | case its value is effectively wrapped in a (delay …) form. | |
260 | ||
e2540884 LC |
261 | It is possible to copy an object 'x' created with 'thing' like this: |
262 | ||
263 | (thing (inherit x) (name \"bar\")) | |
264 | ||
265 | This expression returns a new object equal to 'x' except for its 'name' | |
8a16d064 LC |
266 | field and its 'loc' field---the latter is marked as \"innate\", so it is not |
267 | inherited." | |
e2540884 | 268 | |
c0cd1b3e LC |
269 | (define (field-default-value s) |
270 | (syntax-case s (default) | |
271 | ((field (default val) _ ...) | |
272 | (list #'field #'val)) | |
792798f4 LC |
273 | ((field _ properties ...) |
274 | (field-default-value #'(field properties ...))) | |
c0cd1b3e LC |
275 | (_ #f))) |
276 | ||
faef3b6a LC |
277 | (define-field-property-predicate delayed-field? delayed) |
278 | (define-field-property-predicate thunked-field? thunked) | |
8a16d064 | 279 | (define-field-property-predicate innate-field? innate) |
c0cd1b3e | 280 | |
310b32a2 LC |
281 | (define (wrapped-field? s) |
282 | (or (thunked-field? s) (delayed-field? s))) | |
283 | ||
284 | (define (wrapped-field-accessor-name field) | |
c0cd1b3e | 285 | ;; Return the name (an unhygienic syntax object) of the "real" |
310b32a2 | 286 | ;; getter for field, which is assumed to be a wrapped field. |
c0cd1b3e | 287 | (syntax-case field () |
792798f4 | 288 | ((field get properties ...) |
c0cd1b3e LC |
289 | (let* ((getter (syntax->datum #'get)) |
290 | (real-getter (symbol-append '% getter '-real))) | |
291 | (datum->syntax #'get real-getter))))) | |
292 | ||
293 | (define (field-spec->srfi-9 field) | |
294 | ;; Convert a field spec of our style to a SRFI-9 field spec of the | |
295 | ;; form (field get). | |
296 | (syntax-case field () | |
792798f4 | 297 | ((name get properties ...) |
c0cd1b3e | 298 | #`(name |
310b32a2 LC |
299 | #,(if (wrapped-field? field) |
300 | (wrapped-field-accessor-name field) | |
c0cd1b3e LC |
301 | #'get))))) |
302 | ||
303 | (define (thunked-field-accessor-definition field) | |
304 | ;; Return the real accessor for FIELD, which is assumed to be a | |
305 | ;; thunked field. | |
306 | (syntax-case field () | |
307 | ((name get _ ...) | |
310b32a2 | 308 | (with-syntax ((real-get (wrapped-field-accessor-name field))) |
c0cd1b3e LC |
309 | #'(define-inlinable (get x) |
310 | ;; The real value of that field is a thunk, so call it. | |
311 | ((real-get x))))))) | |
312 | ||
310b32a2 LC |
313 | (define (delayed-field-accessor-definition field) |
314 | ;; Return the real accessor for FIELD, which is assumed to be a | |
315 | ;; delayed field. | |
316 | (syntax-case field () | |
317 | ((name get _ ...) | |
318 | (with-syntax ((real-get (wrapped-field-accessor-name field))) | |
319 | #'(define-inlinable (get x) | |
320 | ;; The real value of that field is a promise, so force it. | |
321 | (force (real-get x))))))) | |
322 | ||
7874bbbb LC |
323 | (define (compute-abi-cookie field-specs) |
324 | ;; Compute an "ABI cookie" for the given FIELD-SPECS. We use | |
325 | ;; 'string-hash' because that's a better hash function that 'hash' on a | |
326 | ;; list of symbols. | |
327 | (syntax-case field-specs () | |
328 | (((field get properties ...) ...) | |
329 | (string-hash (object->string | |
330 | (syntax->datum #'((field properties ...) ...))) | |
331 | most-positive-fixnum)))) | |
332 | ||
c0cd1b3e LC |
333 | (syntax-case s () |
334 | ((_ type syntactic-ctor ctor pred | |
792798f4 LC |
335 | (field get properties ...) ...) |
336 | (let* ((field-spec #'((field get properties ...) ...)) | |
9b543456 | 337 | (thunked (filter-map thunked-field? field-spec)) |
310b32a2 | 338 | (delayed (filter-map delayed-field? field-spec)) |
8a16d064 | 339 | (innate (filter-map innate-field? field-spec)) |
9b543456 | 340 | (defaults (filter-map field-default-value |
7874bbbb LC |
341 | #'((field properties ...) ...))) |
342 | (cookie (compute-abi-cookie field-spec))) | |
c0cd1b3e LC |
343 | (with-syntax (((field-spec* ...) |
344 | (map field-spec->srfi-9 field-spec)) | |
345 | ((thunked-field-accessor ...) | |
346 | (filter-map (lambda (field) | |
347 | (and (thunked-field? field) | |
348 | (thunked-field-accessor-definition | |
349 | field))) | |
310b32a2 LC |
350 | field-spec)) |
351 | ((delayed-field-accessor ...) | |
352 | (filter-map (lambda (field) | |
353 | (and (delayed-field? field) | |
354 | (delayed-field-accessor-definition | |
355 | field))) | |
c0cd1b3e LC |
356 | field-spec))) |
357 | #`(begin | |
358 | (define-record-type type | |
359 | (ctor field ...) | |
360 | pred | |
361 | field-spec* ...) | |
7874bbbb LC |
362 | (define #,(current-abi-identifier #'type) |
363 | #,cookie) | |
ad7c1a2c LC |
364 | thunked-field-accessor ... |
365 | delayed-field-accessor ... | |
39fc041a LC |
366 | (make-syntactic-constructor type syntactic-ctor ctor |
367 | (field ...) | |
7874bbbb | 368 | #:abi-cookie #,cookie |
39fc041a LC |
369 | #:thunked #,thunked |
370 | #:delayed #,delayed | |
8a16d064 | 371 | #:innate #,innate |
39fc041a | 372 | #:defaults #,defaults)))))))) |
c0cd1b3e | 373 | |
c8772a7a LC |
374 | (define* (alist->record alist make keys |
375 | #:optional (multiple-value-keys '())) | |
376 | "Apply MAKE to the values associated with KEYS in ALIST. Items in KEYS that | |
377 | are also in MULTIPLE-VALUE-KEYS are considered to occur possibly multiple | |
378 | times in ALIST, and thus their value is a list." | |
379 | (let ((args (map (lambda (key) | |
380 | (if (member key multiple-value-keys) | |
381 | (filter-map (match-lambda | |
382 | ((k . v) | |
383 | (and (equal? k key) v))) | |
384 | alist) | |
385 | (assoc-ref alist key))) | |
386 | keys))) | |
c0cd1b3e LC |
387 | (apply make args))) |
388 | ||
389 | (define (object->fields object fields port) | |
390 | "Write OBJECT (typically a record) as a series of recutils-style fields to | |
391 | PORT, according to FIELDS. FIELDS must be a list of field name/getter pairs." | |
392 | (let loop ((fields fields)) | |
393 | (match fields | |
394 | (() | |
395 | object) | |
396 | (((field . get) rest ...) | |
397 | (format port "~a: ~a~%" field (get object)) | |
398 | (loop rest))))) | |
399 | ||
fb519bd8 LC |
400 | (define %recutils-field-charset |
401 | ;; Valid characters starting a recutils field. | |
402 | ;; info "(recutils) Fields" | |
403 | (char-set-union char-set:upper-case | |
404 | char-set:lower-case | |
405 | (char-set #\%))) | |
836d10f1 | 406 | |
fdc1bf65 LC |
407 | (define (recutils->alist port) |
408 | "Read a recutils-style record from PORT and return it as a list of key/value | |
409 | pairs. Stop upon an empty line (after consuming it) or EOF." | |
410 | (let loop ((line (read-line port)) | |
411 | (result '())) | |
b7b88288 | 412 | (cond ((eof-object? line) |
fdc1bf65 | 413 | (reverse result)) |
b7b88288 LC |
414 | ((string-null? line) |
415 | (if (null? result) | |
416 | (loop (read-line port) result) ; leading space: ignore it | |
417 | (reverse result))) ; end-of-record marker | |
fdc1bf65 | 418 | (else |
fb519bd8 LC |
419 | ;; Now check the first character of LINE, since that's what the |
420 | ;; recutils manual says is enough. | |
421 | (let ((first (string-ref line 0))) | |
422 | (cond | |
423 | ((char-set-contains? %recutils-field-charset first) | |
424 | (let* ((colon (string-index line #\:)) | |
425 | (field (string-take line colon)) | |
426 | (value (string-trim (string-drop line (+ 1 colon))))) | |
427 | (loop (read-line port) | |
428 | (alist-cons field value result)))) | |
429 | ((eqv? first #\#) ;info "(recutils) Comments" | |
430 | (loop (read-line port) result)) | |
431 | ((eqv? first #\+) ;info "(recutils) Fields" | |
432 | (let ((new-line (if (string-prefix? "+ " line) | |
433 | (string-drop line 2) | |
434 | (string-drop line 1)))) | |
435 | (match result | |
436 | (((field . value) rest ...) | |
437 | (loop (read-line port) | |
438 | `((,field . ,(string-append value "\n" new-line)) | |
439 | ,@rest)))))) | |
440 | (else | |
441 | (error "unmatched line" line)))))))) | |
fdc1bf65 | 442 | |
6692d845 | 443 | (define-syntax match-record |
444 | (syntax-rules () | |
445 | "Bind each FIELD of a RECORD of the given TYPE to it's FIELD name. | |
446 | The current implementation does not support thunked and delayed fields." | |
447 | ((_ record type (field fields ...) body ...) | |
448 | (if (eq? (struct-vtable record) type) | |
449 | ;; TODO compute indices and report wrong-field-name errors at | |
450 | ;; expansion time | |
451 | ;; TODO support thunked and delayed fields | |
452 | (let ((field ((record-accessor type 'field) record))) | |
453 | (match-record record type (fields ...) body ...)) | |
454 | (throw 'wrong-type-arg record))) | |
455 | ((_ record type () body ...) | |
456 | (begin body ...)))) | |
457 | ||
c0cd1b3e | 458 | ;;; records.scm ends here |