Advanced queries support

[bongodb.git] / src / bongodb.scm

diff --git a/src/bongodb.scm b/src/bongodb.scm
index 3cffa48d5ce6f7280958a00d1abf04ece8acc50b..6fc16fe0fcfababa251b2e7686263640e2a2cd18 100644 (file)
--- 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)