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76073d29 | 1 | ;;; GNU Guix --- Functional package management for GNU |
4071879c | 2 | ;;; Copyright © 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org> |
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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 json) | |
20 | #:use-module (json) | |
4071879c | 21 | #:use-module (srfi srfi-9)) |
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22 | |
23 | ;;; Commentary: | |
24 | ;;; | |
25 | ;;; Helpers to map JSON objects to SRFI-9 records. Taken from (guix swh). | |
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26 | ;;; This module is superseded by 'define-json-mapping' as found since version |
27 | ;;; 4.2.0 of Guile-JSON and will be removed once migration is complete. | |
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28 | ;;; |
29 | ;;; Code: | |
30 | ||
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31 | (define-syntax define-as-needed |
32 | (lambda (s) | |
33 | "Define the given syntax rule unless (json) already provides it." | |
34 | (syntax-case s () | |
35 | ((_ (macro args ...) body ...) | |
36 | (if (module-defined? (resolve-interface '(json)) | |
37 | (syntax->datum #'macro)) | |
38 | #'(eval-when (expand load eval) | |
39 | ;; Re-export MACRO from (json). | |
40 | (module-re-export! (current-module) '(macro))) | |
41 | #'(begin | |
42 | ;; Using Guile-JSON < 4.2.0, so provide our own MACRO. | |
43 | (define-syntax-rule (macro args ...) | |
44 | body ...) | |
45 | (eval-when (expand load eval) | |
46 | (module-export! (current-module) '(macro))))))))) | |
47 | ||
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48 | (define-syntax-rule (define-json-reader json->record ctor spec ...) |
49 | "Define JSON->RECORD as a procedure that converts a JSON representation, | |
50 | read from a port, string, or hash table, into a record created by CTOR and | |
51 | following SPEC, a series of field specifications." | |
52 | (define (json->record input) | |
53 | (let ((table (cond ((port? input) | |
54 | (json->scm input)) | |
55 | ((string? input) | |
56 | (json-string->scm input)) | |
57 | ((or (null? input) (pair? input)) | |
58 | input)))) | |
59 | (let-syntax ((extract-field (syntax-rules () | |
60 | ((_ table (field key json->value)) | |
61 | (json->value (assoc-ref table key))) | |
62 | ((_ table (field key)) | |
63 | (assoc-ref table key)) | |
64 | ((_ table (field)) | |
65 | (assoc-ref table | |
66 | (symbol->string 'field)))))) | |
67 | (ctor (extract-field table spec) ...))))) | |
68 | ||
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69 | ;; For some reason we cannot just have colliding definitions of |
70 | ;; 'define-json-mapping' (that leads to a build failure in users of this | |
71 | ;; module), hence the use of 'define-as-needed'. | |
72 | (define-as-needed (define-json-mapping rtd ctor pred json->record | |
73 | (field getter spec ...) ...) | |
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74 | "Define RTD as a record type with the given FIELDs and GETTERs, à la SRFI-9, |
75 | and define JSON->RECORD as a conversion from JSON to a record of this type." | |
76 | (begin | |
77 | (define-record-type rtd | |
78 | (ctor field ...) | |
79 | pred | |
80 | (field getter) ...) | |
81 | ||
82 | (define-json-reader json->record ctor | |
83 | (field spec ...) ...))) |