1 files changed, 52 insertions, 0 deletions
diff --git a/src/util.js b/src/util.js
new file mode 100644
index 00000000..3113474b
--- /dev/null
+++ b/src/util.js
@@ -0,0 +1,52 @@
+"use strict"
+
+define(function() {
+
+    function set_from_array(a) {
+        var ret = {};
+        for (var k = 0; k < a.length; ++k) {
+            ret[a[k]] = 1;
+        }
+        return ret;
+    }
+
+    function set_from_object(o) {
+        var ret = {}
+        for ( var k in o) {
+            ret[k] = 1;
+        }
+        return ret;
+    }
+
+    function set_diff(sa, sb) {
+        var ret = {
+            a_b : [],
+            b_a : []
+        };
+        var i;
+        for (i in sa) {
+            if (!(i in sb)) {
+                ret.a_b.push(i);
+            }
+        }
+        for (i in sb) {
+            if (!(i in sa)) {
+                ret.b_a.push(i);
+            }
+        }
+        return ret;
+    }
+
+    function array_diff(aa, ab) {
+        var sa = set_from_array(aa);
+        var sb = set_from_array(ab);
+        return set_diff(sa, sb);
+    }
+
+    return {
+        set_from_array : set_from_array,
+        set_from_object : set_from_object,
+        set_diff : set_diff,
+        array_diff : array_diff
+    };
+});