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