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Diffstat (limited to 'sly/lru-cache.scm')
-rw-r--r-- | sly/lru-cache.scm | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/sly/lru-cache.scm b/sly/lru-cache.scm new file mode 100644 index 0000000..1a960a3 --- /dev/null +++ b/sly/lru-cache.scm @@ -0,0 +1,54 @@ +;;; Sly +;;; Copyright (C) 2014 David Thompson <dthompson2@worcester.edu> +;;; +;;; 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: +;; +;; Least recently used cache implementation. +;; +;;; Code: + +(define-module (sly lru-cache) + #:use-module (srfi srfi-1) + #:use-module (srfi srfi-9)) + +(define (memoize/lru proc max-size) + (let ((cache (make-hash-table)) + (keys '()) + (size 0)) + (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) + (set! size (1+ size)) + (apply values results))))))) + +(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))))))) |