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Diffstat (limited to 'sly/utils.scm')
-rw-r--r-- | sly/utils.scm | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/sly/utils.scm b/sly/utils.scm new file mode 100644 index 0000000..7bf38f7 --- /dev/null +++ b/sly/utils.scm @@ -0,0 +1,76 @@ +;;; Sly +;;; Copyright (C) 2013, 2014 David Thompson <dthompson2@worcester.edu> +;;; Copyright (C) 2014 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, see +;;; <http://www.gnu.org/licenses/>. + +;;; Commentary: +;; +;; Miscellaneous helper procedures. +;; +;;; Code: + +(define-module (sly utils) + #:use-module (srfi srfi-1) + #:use-module (rnrs arithmetic bitwise) + #:use-module (sly agenda) + #:export (any-equal? + logand? + define-guardian + memoize + forever + trampoline)) + +(define (any-equal? elem . args) + "Return #t if ELEM equals any of the elements in the list ARGS." + (any (lambda (e) (equal? elem e)) args)) + +(define (logand? . args) + "Return #t if the result of a bitwise AND of the integers in list +ARGS is non-zero." + (not (zero? (apply logand args)))) + +(define-syntax-rule (define-guardian name reaper) + "Define a new guardian called NAME and call REAPER when an object +within the guardian is GC'd. Reaping is ensured to happen from the +same thread that is running the game loop." + (begin + (define name (make-guardian)) + (schedule-each + (lambda () + (let reap ((obj (name))) + (when obj + (reaper obj) + (reap (name)))))))) + +(define (memoize proc) + "Return a memoizing version of PROC." + (let ((cache (make-hash-table))) + (lambda args + (let ((results (hash-ref cache args))) + (if results + (apply values results) + (let ((results (call-with-values (lambda () + (apply proc args)) + list))) + (hash-set! cache args results) + (apply values results))))))) + +(define-syntax-rule (forever body ...) + (while #t body ...)) + +(define-syntax-rule (trampoline proc) + (lambda args + (apply proc args))) |