X-Git-Url: https://git.jsancho.org/?p=bongodb.git;a=blobdiff_plain;f=src%2Fbongodb.scm;h=6fc16fe0fcfababa251b2e7686263640e2a2cd18;hp=3cffa48d5ce6f7280958a00d1abf04ece8acc50b;hb=07eed7138a1b4aecb9d8ae0926ba22dc82ebe94e;hpb=9799d66d7e1538bbe2a672946ce80b49dc55ca84

diff --git a/src/bongodb.scm b/src/bongodb.scm
index 3cffa48..6fc16fe 100644
--- a/src/bongodb.scm
+++ b/src/bongodb.scm
@@ -24,7 +24,10 @@
 	    collection?
 	    count
 	    insert
-	    find))
+	    find
+	    $eq
+	    $exists
+	    $not))
 
 
 ;;; Collection Definition
@@ -75,15 +78,48 @@
 	       (apply insert (cons newcol (cdr documents)))
 	     (values rescol (cons docid docids)))))))
 
-(define (find col filter)
+(define (find col . filter)
   "Query the collection and return the documents that match with filter"
   (let ((table (get-table col)))
     (vhash-fold
-     (lambda (key value result) (cons (vhash->alist value) result))
+     (lambda (key document result)
+       (cond ((match-document? document filter)
+	      (cons (vhash->alist document) result))
+	     (else
+	      result)))
      '()
      table)))
 
+(define (match-document? document filter)
+  "Try to match the given document with a list of conditions"
+  (cond ((null? filter)
+	 #t)
+	(else
+	 (and
+	  ((car filter) document)
+	  (match-document? document (cdr filter))))))
+
+
+;;; Queries
+
+(define ($eq field value)
+  (lambda (document)
+    (let ((stored (vhash-assoc field document)))
+      (and stored
+	   (equal? (cdr stored) value)))))
+
+
+(define ($exists field)
+  (lambda (document)
+    (and (vhash-assoc field document)
+	 #t)))
+
+
+(define ($not expr)
+  (lambda (document)
+    (not (expr document))))
 
+	     
 ;;; Tools
 
 (define (vhash->alist vhash)