111 lines
3.4 KiB
Scheme
111 lines
3.4 KiB
Scheme
;;;; -*- mode: Scheme; indent-tabs-mode: nil; fill-column: 80; -*-
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;;;;
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;;;; Copyright © 2015 Rémi Delrue <asgeir@free.fr>
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;;;;
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;;;; This program is free software: you can redistribute it and/or modify
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;;;; it under the terms of the GNU General Public License as published by
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;;;; the Free Software Foundation, either version 3 of the License, or
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;;;; (at your option) any later version.
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;;;;
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;;;; This program is distributed in the hope that it will be useful,
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;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;;; GNU General Public License for more details.
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;;;;
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;;;; You should have received a copy of the GNU General Public License
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;;;; along with this program. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu gnunet binding-utils)
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#:use-module (ice-9 match)
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#:use-module ((srfi srfi-1) #:select (find))
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#:use-module (rnrs bytevectors)
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#:use-module (system foreign)
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#:export (getf
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interleave
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rassq
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rassq-ref
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rassv
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rassv-ref
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rassoc
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rassoc-ref
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destructuring-bind
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string->pointer*
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pointer->string*
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make-c-struct*
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or%
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and=>%))
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(define (getf plist value)
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(let ((entry (member value plist)))
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(if entry (cadr entry) #f)))
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;; reverse association lists
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(define-syntax-rule (define-assoc name name-ref test)
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(begin
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(define (name alist value)
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"Return the first entry in ALIST with the given VALUE."
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(find (match-lambda ((_ . val) (test value val))) alist))
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(define (name-ref alist value)
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"Return the key from the first entry in ALIST with the given VALUE."
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(car (or (name alist value) '(#f . #f))))))
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(define-assoc rassq rassq-ref eq?)
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(define-assoc rassv rassv-ref eqv?)
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(define-assoc rassoc rassoc-ref equal?)
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(define (interleave obj lst)
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"Interleaves OBJ in LST.
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(interleave '& '(kirk spock ahura sulu scotty))
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⇒
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(kirk & spock & ahura & sulu & scotty)"
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(define (%interleave lst)
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(if (null? lst)
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lst
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(cons obj (cons (car lst) (%interleave (cdr lst))))))
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(if (or (null? lst) (null? (cdr lst)))
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lst
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(cons (car lst) (%interleave (cdr lst)))))
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;;; FFI utilities
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(define (string->pointer* string)
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"Return a foreign pointer to a nul-terminated copy of STRING, or %null-pointer
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if STRING is empty (\"\")."
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(if (string=? "" string) %null-pointer (string->pointer string)))
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(define (pointer->string* ptr)
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(if (eq? %null-pointer ptr) #f (pointer->string ptr)))
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;; a variant of OR for foreign pointers.
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;; ex: (or% 'a 'b) → A
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;; (or% %null-pointer 'b) → B
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;; (or% %null-pointer %null-pointer) → #f
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(define-syntax or%
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(syntax-rules ()
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((_ x) (let ((x* x))
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(if (eq? %null-pointer x*)
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#f
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x*)))
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((_ x y ...) (let ((x* x))
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(if (eq? %null-pointer x*)
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(or% y ...)
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x*)))))
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;; a variant of and=> for foreign pointers.
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(define-syntax-rule (and=>% x f)
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(let ((x* x))
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(if (eq? %null-pointer x*)
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#f
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(f x*))))
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;;; Utilities
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(define-syntax-rule (destructuring-bind pattern value body body* ...)
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(match value (pattern body body* ...)))
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