orm add atomic set value

orm/orm_queryset.go

@@ -4,6 +4,36 @@ import (
 	"fmt"
 )
 
+type colValue struct {
+	value int64
+	opt   operator
+}
+
+type operator int
+
+const (
+	Col_Add operator = iota
+	Col_Minus
+	Col_Multiply
+	Col_Except
+)
+
+func ColValue(opt operator, value interface{}) interface{} {
+	switch opt {
+	case Col_Add, Col_Minus, Col_Multiply, Col_Except:
+	default:
+		panic(fmt.Errorf("orm.ColValue wrong operator"))
+	}
+	v, err := StrTo(ToStr(value)).Int64()
+	if err != nil {
+		panic(fmt.Errorf("orm.ColValue doesn't support non string/numeric type, %s", err))
+	}
+	var val colValue
+	val.value = v
+	val.opt = opt
+	return val
+}
+
 type querySet struct {
 	mi       *modelInfo
 	cond     *Condition