Append author signatures directly via a struct func

const.go

@@ -36,4 +36,8 @@ const (
   // webfinger
   WebFingerOstatus = "http://ostatus.org/schema/1.0/subscribe"
   WebFingerHcard = "http://microformats.org/profile/hcard"
+
+  // signature types
+  AuthorSignatureType = iota
+  ParentAuthorSignatureType
 )

entity_comment.go

@@ -17,7 +17,10 @@ package federation
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //
 
-import "encoding/xml"
+import (
+  "encoding/xml"
+  "errors"
+)
 
 type EntityComment struct {
   XMLName xml.Name `xml:"comment"`
@@ -33,3 +36,19 @@ type EntityComment struct {
 func (e *EntityComment) SignatureOrder() string {
   return "author created_at guid parent_guid text"
 }
+
+func (e *EntityComment) AppendSignature(privKey, order string, typ int) error {
+  signature, err := AuthorSignature(*e, order, privKey)
+  if err != nil {
+    return err
+  }
+
+  if AuthorSignatureType == typ {
+    (*e).AuthorSignature = signature
+  } else if ParentAuthorSignatureType == typ {
+    (*e).ParentAuthorSignature = signature
+  } else {
+    return errors.New("Unsupported author signature type!")
+  }
+  return nil
+}

entity_like.go

@@ -17,7 +17,10 @@ package federation
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //
 
-import "encoding/xml"
+import (
+  "encoding/xml"
+  "errors"
+)
 
 type EntityLike struct {
   XMLName xml.Name `xml:"like"`
@@ -33,3 +36,19 @@ type EntityLike struct {
 func (e *EntityLike) SignatureOrder() string {
   return "positive guid parent_guid target_type author"
 }
+
+func (e *EntityLike) AppendSignature(privKey, order string, typ int) error {
+  signature, err := AuthorSignature(*e, privKey, order)
+  if err != nil {
+    return err
+  }
+
+  if AuthorSignatureType == typ {
+    (*e).AuthorSignature = signature
+  } else if ParentAuthorSignatureType == typ {
+    (*e).ParentAuthorSignature = signature
+  } else {
+    return errors.New("Unsupported author signature type!")
+  }
+  return nil
+}