Writing support

[bongodb.git] / src / bongodb.scm

diff --git a/src/bongodb.scm b/src/bongodb.scm
index 3cffa48d5ce6f7280958a00d1abf04ece8acc50b..3e5dc680c115c49e5fa79f00eca1661e9952da90 100644 (file)
--- a/src/bongodb.scm
+++ b/src/bongodb.scm
@@ -24,7 +24,13 @@
            collection?
            count
            insert
-           find))
+           find
+           update
+           $eq
+           $exists
+           $not
+           $and
+           $set))
 
 
 ;;; Collection Definition
@@ -76,14 +82,73 @@
             (values rescol (cons docid docids)))))))
 
 (define (find col filter)
+  "Query the collection and return the documents that match with filter"
+  (map vhash->alist (inner-find col filter)))
+
+(define (inner-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 document result))
+            (else
+             result)))
      '()
      table)))
 
+(define (match-document? document filter)
+  "Try to match the given document with a given filter"
+  (cond ((equal? filter #t)
+        #t)
+       (else
+        (filter document))))
+
+(define (update col filter . changes)
+  "Update selected documents using the given filter"
+  (let ((documents (inner-find col filter)))
+    (apply insert (cons col (map (lambda (doc) (update-document doc changes)) documents)))))
+
+(define (update-document document changes)
+  "Update a document with the appropiate changes"
+  (cond ((null? changes)
+        document)
+       (else
+        (update-document ((car changes) document) (cdr changes)))))
+
+
+;;; 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))))
+
+(define-syntax $and
+  (syntax-rules ()
+    ((_ expr ...)
+     (lambda (document)
+       (and (expr document)
+           ...)))))
+
+
+;;; Updates
+
+(define ($set field value)
+  (lambda (document)
+    (vhash-cons field value document)))
 
+            
 ;;; Tools
 
 (define (vhash->alist vhash)