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;;; 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-field-type
configuration-missing-field
configuration-field-error
configuration-field-serializer
configuration-field-getter
configuration-field-default-value-thunk
configuration-field-documentation
serialize-configuration
define-configuration
validate-configuration
generate-documentation
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 (serialize-package field-name val)
#f)
;; 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))))
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