From 07eed7138a1b4aecb9d8ae0926ba22dc82ebe94e Mon Sep 17 00:00:00 2001
From: Javier Sancho <jsf@jsancho.org>
Date: Tue, 15 Mar 2016 01:10:40 +0100
Subject: [PATCH] Advanced queries support

---
 src/bongodb.scm  | 29 ++++++++++++++++++++++++++---
 tests/sample.scm | 15 +++++++++++----
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/src/bongodb.scm b/src/bongodb.scm
index e4df14b..6fc16fe 100644
--- a/src/bongodb.scm
+++ b/src/bongodb.scm
@@ -24,7 +24,10 @@
 	    collection?
 	    count
 	    insert
-	    find))
+	    find
+	    $eq
+	    $exists
+	    $not))
 
 
 ;;; Collection Definition
@@ -75,7 +78,7 @@
 	       (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
@@ -93,10 +96,30 @@
 	 #t)
 	(else
 	 (and
-	  (equal? (vhash-assoc (caar filter) document) (car filter))
+	  ((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)
diff --git a/tests/sample.scm b/tests/sample.scm
index 899c6e0..5054ffe 100644
--- a/tests/sample.scm
+++ b/tests/sample.scm
@@ -25,12 +25,19 @@
 (test-assert (collection? col))
 
 ; Insert
-(set! col (insert col '((a . 1) (b . 2)) '((a . 10) (b . 20)) '((a . 1) (b . "hello world"))))
+(set! col (insert col
+		  '((a . 1) (b . 2))
+		  '((a . 10) (b . 20))
+		  '((a . 1) (c . "hello world"))))
 (test-eqv 3 (count col))
 
 ; Search
-(test-eqv 2 (length (find col '((a . 1)))))
-(test-eqv 1 (length (find col '((a . 1) (b . 2)))))
-(test-eqv 0 (length (find col '((a . "test")))))
+(test-eqv 3 (length (find col)))
+(test-eqv 2 (length (find col ($eq 'a 1))))
+(test-eqv 1 (length (find col ($eq 'a 1) ($eq 'b 2))))
+(test-eqv 0 (length (find col ($eq 'a "test"))))
+
+(test-eqv 2 (length (find col ($exists 'b))))
+(test-eqv 2 (length (find col ($not ($exists 'c)))))
 
 (test-end "bongodb")
-- 
2.39.2