Refactoring to support parameterized queries.

sqlbuilder/order_by_clause.go

@@ -0,0 +1,46 @@
+package sqlbuilder
+
+import "github.com/dropbox/godropbox/errors"
+
+type OrderByClause interface {
+	Clause
+	isOrderByClauseType()
+}
+
+type isOrderByClause struct {
+}
+
+func (o *isOrderByClause) isOrderByClauseType() {
+}
+
+type orderByClause struct {
+	isOrderByClause
+	expression Expression
+	ascent     bool
+}
+
+func (o *orderByClause) Serialize(out *queryData, options ...serializeOption) error {
+	if o.expression == nil {
+		return errors.Newf("nil orderBy by clause.")
+	}
+
+	if err := o.expression.Serialize(out); err != nil {
+		return err
+	}
+
+	if o.ascent {
+		out.WriteString(" ASC")
+	} else {
+		out.WriteString(" DESC")
+	}
+
+	return nil
+}
+
+func Asc(expression Expression) OrderByClause {
+	return &orderByClause{expression: expression, ascent: true}
+}
+
+func Desc(expression Expression) OrderByClause {
+	return &orderByClause{expression: expression, ascent: false}
+}