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92a4087b | 1 | ;;; GNU Guix --- Functional package management for GNU |
f06a26f5 | 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 repl) | |
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20 | #:use-module (srfi srfi-1) |
21 | #:use-module (srfi srfi-26) | |
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22 | #:use-module (ice-9 match) |
23 | #:export (send-repl-response | |
24 | machine-repl)) | |
25 | ||
26 | ;;; Commentary: | |
27 | ;;; | |
28 | ;;; This module implements the "machine-readable" REPL provided by | |
29 | ;;; 'guix repl -t machine'. It's a lightweight module meant to be | |
30 | ;;; embedded in any Guile process providing REPL functionality. | |
31 | ;;; | |
32 | ;;; Code: | |
33 | ||
34 | (define (self-quoting? x) | |
35 | "Return #t if X is self-quoting." | |
36 | (letrec-syntax ((one-of (syntax-rules () | |
37 | ((_) #f) | |
38 | ((_ pred rest ...) | |
39 | (or (pred x) | |
40 | (one-of rest ...)))))) | |
7abd5997 | 41 | (one-of symbol? string? keyword? pair? null? array? |
ab7010af | 42 | number? boolean? char?))) |
92a4087b | 43 | |
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44 | (define repl-prompt |
45 | ;; Current REPL prompt or #f. | |
46 | (make-parameter #f)) | |
47 | ||
48 | (define (stack->frames stack) | |
49 | "Return STACK's frames as a list." | |
50 | (unfold (cute >= <> (stack-length stack)) | |
51 | (cut stack-ref stack <>) | |
52 | 1+ | |
53 | 0)) | |
54 | ||
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55 | (define* (send-repl-response exp output |
56 | #:key (version '(0 0))) | |
92a4087b | 57 | "Write the response corresponding to the evaluation of EXP to PORT, an |
f06a26f5 | 58 | output port. VERSION is the client's protocol version we are targeting." |
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59 | (define (value->sexp value) |
60 | (if (self-quoting? value) | |
61 | `(value ,value) | |
62 | `(non-self-quoting ,(object-address value) | |
63 | ,(object->string value)))) | |
64 | ||
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65 | (define (frame->sexp frame) |
66 | `(,(frame-procedure-name frame) | |
67 | ,(match (frame-source frame) | |
68 | ((_ (? string? file) (? integer? line) . (? integer? column)) | |
69 | (list file line column)) | |
70 | (_ | |
71 | '(#f #f #f))))) | |
72 | ||
73 | (define (handle-exception key . args) | |
74 | (define reply | |
75 | (match version | |
76 | ((0 1 (? positive?) _ ...) | |
77 | ;; Protocol (0 1 1) and later. | |
78 | (let ((stack (if (repl-prompt) | |
79 | (make-stack #t handle-exception (repl-prompt)) | |
80 | (make-stack #t)))) | |
81 | `(exception (arguments ,key ,@(map value->sexp args)) | |
82 | (stack ,@(map frame->sexp (stack->frames stack)))))) | |
83 | (_ | |
84 | ;; Protocol (0 0). | |
85 | `(exception ,key ,@(map value->sexp args))))) | |
86 | ||
87 | (write reply output) | |
88 | (newline output) | |
89 | (force-output output)) | |
90 | ||
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91 | (catch #t |
92 | (lambda () | |
93 | (let ((results (call-with-values | |
94 | (lambda () | |
95 | (primitive-eval exp)) | |
96 | list))) | |
97 | (write `(values ,@(map value->sexp results)) | |
98 | output) | |
99 | (newline output) | |
100 | (force-output output))) | |
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101 | (const #t) |
102 | handle-exception)) | |
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103 | |
104 | (define* (machine-repl #:optional | |
105 | (input (current-input-port)) | |
106 | (output (current-output-port))) | |
107 | "Run a machine-usable REPL over ports INPUT and OUTPUT. | |
108 | ||
109 | The protocol of this REPL is meant to be machine-readable and provides proper | |
110 | support to represent multiple-value returns, exceptions, objects that lack a | |
111 | read syntax, and so on. As such it is more convenient and robust than parsing | |
112 | Guile's REPL prompt." | |
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113 | (define tag |
114 | (make-prompt-tag "repl-prompt")) | |
115 | ||
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116 | (define (loop exp version) |
117 | (match exp | |
118 | ((? eof-object?) #t) | |
119 | (exp | |
120 | (send-repl-response exp output | |
121 | #:version version) | |
122 | (loop (read input) version)))) | |
123 | ||
2b0a370d | 124 | (write `(repl-version 0 1 1) output) |
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125 | (newline output) |
126 | (force-output output) | |
127 | ||
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128 | ;; In protocol version (0 0), clients would not send their supported |
129 | ;; protocol version. Thus, the code below checks for two case: (1) a (0 0) | |
130 | ;; client that directly sends an expression to evaluate, and (2) a more | |
131 | ;; recent client that sends (() repl-version ...). This form is chosen to | |
132 | ;; be unambiguously distinguishable from a regular Scheme expression. | |
133 | ||
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134 | (call-with-prompt tag |
135 | (lambda () | |
136 | (parameterize ((repl-prompt tag)) | |
137 | (match (read input) | |
138 | ((() 'repl-version version ...) | |
139 | (loop (read input) version)) | |
140 | (exp | |
141 | (loop exp '(0 0)))))) | |
142 | (const #f))) |