Add json-object-contains-key?, json-list-length, and json-key-not-found.

Update README accordingly and with add examples.

1 files changed, 22 insertions, 13 deletions

diff --git a/lib/zambyte/meta/sagittarius.scm b/lib/zambyte/meta/sagittarius.scm
index 3b5a741..97deb0b 100644
--- a/lib/zambyte/meta/sagittarius.scm
+++ b/lib/zambyte/meta/sagittarius.scm
@@ -2,17 +2,6 @@
 	(srfi 1)
 	(srfi 2))
 (begin
-  (define (string->json str)
-    (call-with-port (open-input-string str)
-      (lambda (port)
-	(json-read port))))
-
-  (define (json->string json)
-    (call-with-port (open-output-string)
-      (lambda (port)
-	(json-write json port)
-	(get-output-string port))))
-
   (define (json-object . pairs)
     (if (eq? (*json-map-type*) 'vector)
 	(apply vector pairs)
@@ -38,13 +27,33 @@
   (define (json-null? obj)
     (eq? obj json-null))
 
+  (define (json-object-contains-key? obj key)
+    (and (assoc key (json-object->alist obj)) #t))
+
+  (define (string->json str)
+    (call-with-port (open-input-string str)
+      (lambda (port)
+	(json-read port))))
+
+  (define (json->string json)
+    (call-with-port (open-output-string)
+      (lambda (port)
+	(json-write json port)
+	(get-output-string port))))
+
   (define (json-object-ref json key)
-    (and-let* ((pair (assoc key (json-object->alist json))))
-      (cdr pair)))
+    (or (and-let* ((pair (assoc key (json-object->alist json))))
+	  (cdr pair))
+	((json-key-not-found))))
 
   (define (json-list-ref json index)
     (list-ref (json-list->list json) index))
 
+  (define (json-list-length json)
+    (if (eq? (*json-map-type*) 'vector)
+	(length json)
+	(vector-length json)))
+
   (define (json-object->alist json)
     (if (eq? (*json-map-type*) 'vector)
 	(vector->list json)