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Diffstat (limited to 'gnu/services/configuration.scm')
| -rw-r--r-- | gnu/services/configuration.scm | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/gnu/services/configuration.scm b/gnu/services/configuration.scm new file mode 100644 index 0000000000..9f28aabc96 --- /dev/null +++ b/gnu/services/configuration.scm @@ -0,0 +1,205 @@ +;;; GNU Guix --- Functional package management for GNU +;;; Copyright © 2015 Andy Wingo <wingo@igalia.com> +;;; +;;; This file is part of GNU Guix. +;;; +;;; GNU Guix is free software; you can redistribute it and/or modify it +;;; under the terms of the GNU General Public License as published by +;;; the Free Software Foundation; either version 3 of the License, or (at +;;; your option) any later version. +;;; +;;; GNU Guix is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;;; GNU General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. + +(define-module (gnu services configuration) + #:use-module (guix packages) + #:use-module (guix records) + #:use-module (guix gexp) + #:autoload (texinfo) (texi-fragment->stexi) + #:autoload (texinfo serialize) (stexi->texi) + #:use-module (ice-9 match) + #:use-module ((srfi srfi-1) #:select (append-map)) + #:use-module (srfi srfi-34) + #:use-module (srfi srfi-35) + #:export (configuration-field + configuration-field-name + configuration-missing-field + configuration-field-error + serialize-configuration + define-configuration + validate-configuration + generate-documentation + serialize-field + serialize-string + serialize-name + serialize-space-separated-string-list + space-separated-string-list? + serialize-file-name + file-name? + serialize-boolean + serialize-package)) + +;;; Commentary: +;;; +;;; Syntax for creating Scheme bindings to complex configuration files. +;;; +;;; Code: + +(define-condition-type &configuration-error &error + configuration-error?) + +(define (configuration-error message) + (raise (condition (&message (message message)) + (&configuration-error)))) +(define (configuration-field-error field val) + (configuration-error + (format #f "Invalid value for field ~a: ~s" field val))) +(define (configuration-missing-field kind field) + (configuration-error + (format #f "~a configuration missing required field ~a" kind field))) + +(define-record-type* <configuration-field> + configuration-field make-configuration-field configuration-field? + (name configuration-field-name) + (type configuration-field-type) + (getter configuration-field-getter) + (predicate configuration-field-predicate) + (serializer configuration-field-serializer) + (default-value-thunk configuration-field-default-value-thunk) + (documentation configuration-field-documentation)) + +(define (serialize-configuration config fields) + (for-each (lambda (field) + ((configuration-field-serializer field) + (configuration-field-name field) + ((configuration-field-getter field) config))) + fields)) + +(define (validate-configuration config fields) + (for-each (lambda (field) + (let ((val ((configuration-field-getter field) config))) + (unless ((configuration-field-predicate field) val) + (configuration-field-error + (configuration-field-name field) val)))) + fields)) + +(define-syntax define-configuration + (lambda (stx) + (define (id ctx part . parts) + (let ((part (syntax->datum part))) + (datum->syntax + ctx + (match parts + (() part) + (parts (symbol-append part + (syntax->datum (apply id ctx parts)))))))) + (syntax-case stx () + ((_ stem (field (field-type def) doc) ...) + (with-syntax (((field-getter ...) + (map (lambda (field) + (id #'stem #'stem #'- field)) + #'(field ...))) + ((field-predicate ...) + (map (lambda (type) + (id #'stem type #'?)) + #'(field-type ...))) + ((field-serializer ...) + (map (lambda (type) + (id #'stem #'serialize- type)) + #'(field-type ...)))) + #`(begin + (define-record-type* #,(id #'stem #'< #'stem #'>) + #,(id #'stem #'% #'stem) + #,(id #'stem #'make- #'stem) + #,(id #'stem #'stem #'?) + (field field-getter (default def)) + ...) + (define #,(id #'stem #'stem #'-fields) + (list (configuration-field + (name 'field) + (type 'field-type) + (getter field-getter) + (predicate field-predicate) + (serializer field-serializer) + (default-value-thunk (lambda () def)) + (documentation doc)) + ...)) + (define-syntax-rule (stem arg (... ...)) + (let ((conf (#,(id #'stem #'% #'stem) arg (... ...)))) + (validate-configuration conf + #,(id #'stem #'stem #'-fields)) + conf)))))))) + +(define (uglify-field-name field-name) + (let ((str (symbol->string field-name))) + (string-concatenate + (map string-titlecase + (string-split (if (string-suffix? "?" str) + (substring str 0 (1- (string-length str))) + str) + #\-))))) + +(define (serialize-field field-name val) + (format #t "~a ~a\n" (uglify-field-name field-name) val)) + +(define (serialize-package field-name val) + #f) + +(define (serialize-string field-name val) + (serialize-field field-name val)) + +(define (space-separated-string-list? val) + (and (list? val) + (and-map (lambda (x) + (and (string? x) (not (string-index x #\space)))) + val))) +(define (serialize-space-separated-string-list field-name val) + (serialize-field field-name (string-join val " "))) + +(define (file-name? val) + (and (string? val) + (string-prefix? "/" val))) +(define (serialize-file-name field-name val) + (serialize-string field-name val)) + +(define (serialize-boolean field-name val) + (serialize-string field-name (if val "yes" "no"))) + +;; A little helper to make it easier to document all those fields. +(define (generate-documentation documentation documentation-name) + (define (str x) (object->string x)) + (define (generate configuration-name) + (match (assq-ref documentation configuration-name) + ((fields . sub-documentation) + `((para "Available " (code ,(str configuration-name)) " fields are:") + ,@(map + (lambda (f) + (let ((field-name (configuration-field-name f)) + (field-type (configuration-field-type f)) + (field-docs (cdr (texi-fragment->stexi + (configuration-field-documentation f)))) + (default (catch #t + (configuration-field-default-value-thunk f) + (lambda _ '%invalid)))) + (define (show-default? val) + (or (string? default) (number? default) (boolean? default) + (and (symbol? val) (not (eq? val '%invalid))) + (and (list? val) (and-map show-default? val)))) + `(deftypevr (% (category + (code ,(str configuration-name)) " parameter") + (data-type ,(str field-type)) + (name ,(str field-name))) + ,@field-docs + ,@(if (show-default? default) + `((para "Defaults to " (samp ,(str default)) ".")) + '()) + ,@(append-map + generate + (or (assq-ref sub-documentation field-name) '()))))) + fields))))) + (stexi->texi `(*fragment* . ,(generate documentation-name)))) |