add a simple cache

* tekuti/cache.scm: Add a simple cache.

Makefile.am

@@ -3,6 +3,7 @@ moddir=$(prefix)/share/guile/site
 SOURCES =					\
 	tekuti/base64.scm			\
 	tekuti/boot.scm				\
+	tekuti/cache.scm			\
 	tekuti/comment.scm			\
 	tekuti/config.scm			\
 	tekuti/filters.scm			\

tekuti/cache.scm

@@ -0,0 +1,47 @@
+;; Tekuti
+;; Copyright (C) 2010 Andy Wingo <wingo at pobox dot com>
+
+;; 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, contact:
+;;
+;; Free Software Foundation           Voice:  +1-617-542-5942
+;; 59 Temple Place - Suite 330        Fax:    +1-617-542-2652
+;; Boston, MA  02111-1307,  USA       gnu@gnu.org
+
+;;; Commentary:
+;;
+;; A cache for responses.
+;;
+;;; Code:
+
+(define-module (tekuti cache)
+  #:use-module (web request)
+  #:export (cache-hit?
+            cache-ref
+            cache-set))
+            
+(define (cache-hit? cache master request)
+  (and cache
+       (equal? (car cache) master)
+       (eq? (request-method request) 'GET)
+       (assoc (request-uri request) (cdr cache))
+       #t))
+
+(define (cache-ref cache master request)
+  (apply values (assoc-ref (cdr cache) (request-uri request))))
+
+(define (cache-set cache master request . args)
+  (append (if (and cache (< (length cache) 20))
+              cache
+              (list master))
+          (acons (request-uri request) args '())))