-;;; srfi-39.scm --- Parameter objects
-
-;; Copyright (C) 2004, 2005, 2006, 2008 Free Software Foundation, Inc.
-;;
-;; This library is free software; you can redistribute it and/or
-;; modify it under the terms of the GNU Lesser General Public
-;; License as published by the Free Software Foundation; either
-;; version 2.1 of the License, or (at your option) any later version.
-;;
-;; This library 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
-;; Lesser General Public License for more details.
-;;
-;; You should have received a copy of the GNU Lesser General Public
-;; License along with this library; if not, write to the Free Software
-;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
-
-;;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
-;;; Date: 2004-05-05
-
-;;; Commentary:
-
-;; This is an implementation of SRFI-39 (Parameter objects).
-;;
-;; The implementation is based on Guile's fluid objects, and is, therefore,
-;; thread-safe (parameters are thread-local).
-;;
-;; In addition to the forms defined in SRFI-39 (`make-parameter',
-;; `parameterize'), a new procedure `with-parameters*' is provided.
-;; This procedures is analogous to `with-fluids*' but taking as first
-;; argument a list of parameter objects instead of a list of fluids.
-;;
-
-;;; Code:
-
-(define-module (srfi srfi-39)
- #:use-module (ice-9 syncase)
- #:use-module (srfi srfi-16)
-
- #:export (make-parameter)
- #:export-syntax (parameterize)
-
- ;; helper procedure not in srfi-39.
- #:export (with-parameters*)
- #:replace (current-input-port current-output-port current-error-port))
-
-;; Make 'srfi-39 available as a feature identifiere to `cond-expand'.
-;;
-(cond-expand-provide (current-module) '(srfi-39))
-
-(define make-parameter
- (case-lambda
- ((val) (make-parameter/helper val (lambda (x) x)))
- ((val conv) (make-parameter/helper val conv))))
-
-(define get-fluid-tag (lambda () 'get-fluid)) ;; arbitrary unique (as per eq?) value
-(define get-conv-tag (lambda () 'get-conv)) ;; arbitrary unique (as per eq?) value
-
-(define (make-parameter/helper val conv)
- (let ((value (make-fluid))
- (conv conv))
- (begin
- (fluid-set! value (conv val))
- (lambda new-value
- (cond
- ((null? new-value) (fluid-ref value))
- ((eq? (car new-value) get-fluid-tag) value)
- ((eq? (car new-value) get-conv-tag) conv)
- ((null? (cdr new-value)) (fluid-set! value (conv (car new-value))))
- (else (error "make-parameter expects 0 or 1 arguments" new-value)))))))
-
-(define-syntax parameterize
- (syntax-rules ()
- ((_ ((?param ?value) ...) ?body ...)
- (with-parameters* (list ?param ...)
- (list ?value ...)
- (lambda () ?body ...)))))
-
-(define (current-input-port . new-value)
- (if (null? new-value)
- ((@ (guile) current-input-port))
- (apply set-current-input-port new-value)))
-
-(define (current-output-port . new-value)
- (if (null? new-value)
- ((@ (guile) current-output-port))
- (apply set-current-output-port new-value)))
-
-(define (current-error-port . new-value)
- (if (null? new-value)
- ((@ (guile) current-error-port))
- (apply set-current-error-port new-value)))
-
-(define port-list
- (list current-input-port current-output-port current-error-port))
-
-;; There are no fluids behind current-input-port etc, so those parameter
-;; objects are picked out of the list and handled separately with a
-;; dynamic-wind to swap their values to and from a location (the "value"
-;; variable in the swapper procedure "let").
-;;
-;; current-input-port etc are already per-dynamic-root, so this arrangement
-;; works the same as a fluid. Perhaps they could become fluids for ease of
-;; implementation here.
-;;
-;; Notice the use of a param local variable for the swapper procedure. It
-;; ensures any application changes to the PARAMS list won't affect the
-;; winding.
-;;
-(define (with-parameters* params values thunk)
- (let more ((params params)
- (values values)
- (fluids '()) ;; fluids from each of PARAMS
- (convs '()) ;; VALUES with conversion proc applied
- (swapper noop)) ;; wind/unwind procedure for ports handling
- (if (null? params)
- (if (eq? noop swapper)
- (with-fluids* fluids convs thunk)
- (dynamic-wind
- swapper
- (lambda ()
- (with-fluids* fluids convs thunk))
- swapper))
- (if (memq (car params) port-list)
- (more (cdr params) (cdr values)
- fluids convs
- (let ((param (car params))
- (value (car values))
- (prev-swapper swapper))
- (lambda ()
- (set! value (param value))
- (prev-swapper))))
- (more (cdr params) (cdr values)
- (cons ((car params) get-fluid-tag) fluids)
- (cons (((car params) get-conv-tag) (car values)) convs)
- swapper)))))
+;;; srfi-39.scm --- Parameter objects
+
+;; Copyright (C) 2004, 2005, 2006, 2008, 2011 Free Software Foundation, Inc.
+;;
+;; This library is free software; you can redistribute it and/or
+;; modify it under the terms of the GNU Lesser General Public
+;; License as published by the Free Software Foundation; either
+;; version 3 of the License, or (at your option) any later version.
+;;
+;; This library 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
+;; Lesser General Public License for more details.
+;;
+;; You should have received a copy of the GNU Lesser General Public
+;; License along with this library; if not, write to the Free Software
+;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+;;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
+;;; Date: 2004-05-05
+
+;;; Commentary:
+
+;; This is an implementation of SRFI-39 (Parameter objects).
+;;
+;; The implementation is based on Guile's fluid objects, and is, therefore,
+;; thread-safe (parameters are thread-local).
+;;
+;; In addition to the forms defined in SRFI-39 (`make-parameter',
+;; `parameterize'), a new procedure `with-parameters*' is provided.
+;; This procedures is analogous to `with-fluids*' but taking as first
+;; argument a list of parameter objects instead of a list of fluids.
+;;
+
+;;; Code:
+
+(define-module (srfi srfi-39)
+ ;; helper procedure not in srfi-39.
+ #:export (with-parameters*)
+ #:re-export (make-parameter
+ parameterize
+ current-input-port current-output-port current-error-port))
+
+(define (with-parameters* params values thunk)
+ (let more ((params params)
+ (values values)
+ (fluids '()) ;; fluids from each of PARAMS
+ (convs '())) ;; VALUES with conversion proc applied
+ (if (null? params)
+ (with-fluids* fluids convs thunk)
+ (more (cdr params) (cdr values)
+ (cons (parameter-fluid (car params)) fluids)
+ (cons ((parameter-converter (car params)) (car values)) convs)))))
HCoop / bpt / guile.git / blobdiff