simplify stringlist

common/serial/string.go

@@ -1,5 +1,9 @@
 package serial
 
+import (
+	"strings"
+)
+
 // An interface for any objects that has string presentation.
 type String interface {
 	String() string
@@ -7,6 +11,22 @@ type String interface {
 
 type StringLiteral string
 
+func NewStringLiteral(str String) StringLiteral {
+	return StringLiteral(str.String())
+}
+
 func (this StringLiteral) String() string {
 	return string(this)
 }
+
+func (this StringLiteral) ToLower() StringLiteral {
+	return StringLiteral(strings.ToLower(string(this)))
+}
+
+func (this StringLiteral) ToUpper() StringLiteral {
+	return StringLiteral(strings.ToUpper(string(this)))
+}
+
+func (this StringLiteral) TrimSpace() StringLiteral {
+	return StringLiteral(strings.TrimSpace(string(this)))
+}