Add parser.Tree.AddDeclaration()

parser/tree.go

@@ -34,3 +34,8 @@ func (this *Tree) Parse (name string, file io.Reader) error {
 	if err != nil { return err }
 	return parser.ParseInto(this)
 }
+
+// AddDeclaration adds a top-level entity to the tree.
+func (this *Tree) AddDeclaration (topLevel ...entity.TopLevel) {
+	this.Declarations = append(this.Declarations, topLevel...)
+}