add order clause

client/orm/structs/order_phrase.go

@@ -0,0 +1,48 @@
+package structs
+
+import "fmt"
+
+type Sort int8
+
+const (
+	ASCENDING  Sort = 1
+	DESCENDING Sort = 2
+)
+
+type OrderClause struct {
+	Column string
+	Sort   Sort
+}
+
+var _ fmt.Stringer = new(OrderClause)
+
+func (o *OrderClause) String() string {
+	sort := ``
+	if o.Sort == ASCENDING {
+		sort = `ASC`
+	} else if o.Sort == DESCENDING {
+		sort = `DESC`
+	} else {
+		return fmt.Sprintf("%s", o.Column)
+	}
+	return fmt.Sprintf("%s %s", o.Column, sort)
+}
+
+func ParseOrderClause(expressions ...string) []*OrderClause {
+	var orders []*OrderClause
+	for _, expression := range expressions {
+		sort := ASCENDING
+		column := expression
+		if expression[0] == '-' {
+			sort = DESCENDING
+			column = expression[1:]
+		}
+
+		orders = append(orders, &OrderClause{
+			Column: column,
+			Sort:   sort,
+		})
+	}
+
+	return orders
+}