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;;; -*- mode: scheme; coding: utf-8; -*-
;;;
;;; compat.scm -- Compatibility with Guile's `read-options' interface.
;;;
;;; Copyright 2005, 2010 Ludovic Courtès <ludo@gnu.org>
;;;
;;;
;;; This program 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.
;;;
;;; This program 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 this program; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
(define-module (system reader compat)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-17)
#:export (read-option-spec?
read-option-name read-option-takes-argument?
read-option-convert-proc
%read-options-spec lookup-read-option
clean-up-read-options))
;;; Author: Ludovic Courtès
;;;
;;; Commentary:
;;;
;;; This module provides helper functions to implement an interface
;;; compatible with Guile's `read-option' interface.
;;;
;;; Code:
;;;
;;; Read options.
;;;
;; Description of the various options of `read-options', i.e. whether they
;; need an additional argument or not.
(define-record-type <read-option-spec>
;; NAME names a standard Guile reader extension.
;; TAKES-ARG? is a boolean telling whether this extension takes an arg.
;; CONVERT-PROC is a procedure that takes two procedure with setters, one
;; to modify the reader options (as used in `(system reader
;; library)') and another to modify the `make-reader' options.
(make-read-option-spec name takes-arg? convert-proc)
read-option-spec?
(name read-option-name)
(takes-arg? read-option-takes-argument?)
(convert-proc read-option-convert-proc))
(define-macro (define-read-options name lst)
`(define ,name
(map (lambda (stuff)
(apply make-read-option-spec stuff))
,lst)))
(define-read-options %read-options-spec
;; Guile's standard reader options.
`((keywords #t ,(lambda (reader-options make-options value)
(case value
((prefix)
(set! (reader-options)
(cons 'colon-keywords
(reader-options))))
((#f)
(set! (reader-options)
(delq 'colon-keywords (reader-options))))
(else
(error "unsupported value for option `keywords'"
value)))))
(case-insensitive #f ,(lambda (reader-options make-options)
(set! (reader-options)
(cons 'case-insensitive
(reader-options)))))
(square-brackets #f ,(lambda (reader-options make-options)
(set! (reader-options)
(cons 'square-brackets
(reader-options)))))
(positions #f ,(lambda (read-options make-options)
(set! (make-options)
(cons 'reader/record-positions
(make-options)))))
(copy #f ,(lambda (read-options make-options)
(error "`(read-enable 'copy)' not implemented")))))
(define (lookup-read-option option-name)
"Look up read option named @var{option-name} (a symbol) among the list of
standard Guile reader options (see @inforef{Reader options, Guile's reader
options, guile}, for a list of options) and return a
@code{<read-option-spec>} object, or @code{#f} if not found."
(find (lambda (opt-spec)
(eq? (read-option-name opt-spec) option-name))
%read-options-spec))
(define (clean-up-read-options options)
"Process the new read options in @var{options}, a flat list, and return a
``cleaned'' flat list without duplicate options, etc."
(let loop ((result '())
(options options))
(if (null? options)
result
(let* ((opt (car options))
(opt-spec (lookup-read-option opt)))
(if (not opt-spec)
(error "unknown read option" opt)
(let ((takes-arg? (read-option-takes-argument? opt-spec)))
(if takes-arg?
(let ((value (memq opt result))
(new-value (cadr options)))
(if value
(set-cdr! value
(cons new-value (cddr value)))
(set! result
(append (list opt new-value) result))))
(if (not (memq opt result))
(set! result (append! result (list opt)))))
(loop result
(if takes-arg? (cddr options) (cdr options)))))))))
;;;
;;; Dynamically configurable `primitive-load'.
;;;
;; In Guile 1.7.2++, `current-reader' is a core binding bound to a fluid
;; whose value should be either `#f' or a `read'-like procedure. The value
;; of this fluid dictates the reader that is to be used by `primitive-load'.
;;
;; See:
;; http://lists.gnu.org/archive/html/guile-devel/2005-11/msg00006.html
;; http://lists.gnu.org/archive/html/guile-devel/2005-12/msg00062.html .
(if (not (defined? 'current-reader))
(begin ;; forward-compatible implementation
(module-define! the-root-module 'current-reader (make-fluid))
(fluid-set! current-reader #f)
(set! primitive-load
(lambda (file)
(with-input-from-file file
(lambda ()
(let loop ((sexp ((or (fluid-ref current-reader) read))))
(if (not (eof-object? sexp))
(begin
(primitive-eval sexp)
(loop ((or (fluid-ref current-reader)
read))))))))))))
;;; arch-tag: c9971617-3a90-4dbb-be3f-aa4b42d4f462
;;; compat.scm ends here
|
