[geary/mjog/rfc822-cleanup-part-n: 1/9] Composer.Widget: Convert references to a MessageIdList instance

[Michael Gratton <mjog src gnome org>]

commit b78dfe7cb88d198d2382a6db26128fd2c5609eee
Author: Michael Gratton <mike vee net>
Date:   Tue Jun 30 11:53:22 2020 +1000

    Composer.Widget: Convert references to a MessageIdList instance
    
    Using the high-level representation avoids having to re-parse and
    re-format the list.
    
    Update the util method Geary.RFC822.Utils.reply_references to support
    this.

 src/client/composer/composer-widget.vala | 10 ++++------
 src/engine/rfc822/rfc822-utils.vala      | 13 ++++---------
 2 files changed, 8 insertions(+), 15 deletions(-)
---
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index 19b853cbd..de2213857 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -341,7 +341,7 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
 
     private Gee.Set<Geary.RFC822.MessageID> in_reply_to = new Gee.HashSet<Geary.RFC822.MessageID>();
 
-    private string references { get; private set; }
+    private Geary.RFC822.MessageIDList? references = null;
 
     [GtkChild]
     private Gtk.Grid editor_container;
@@ -1143,7 +1143,7 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
                 if (referred.in_reply_to != null)
                     this.in_reply_to.add_all(referred.in_reply_to.get_all());
                 if (referred.references != null)
-                    this.references = referred.references.to_rfc822_string();
+                    this.references = referred.references;
                 if (referred.subject != null)
                     this.subject = referred.subject.value ?? "";
             break;
@@ -1373,10 +1373,8 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
                 new Geary.RFC822.MessageIDList(this.in_reply_to)
             );
 
-        if (!Geary.String.is_empty(this.references)) {
-            email.set_references(
-                new Geary.RFC822.MessageIDList.from_rfc822_string(this.references)
-            );
+        if (this.references != null) {
+            email.set_references(this.references);
         }
 
         email.attached_files.add_all(this.attached_files);
diff --git a/src/engine/rfc822/rfc822-utils.vala b/src/engine/rfc822/rfc822-utils.vala
index 51fae6a37..4e7d5b058 100644
--- a/src/engine/rfc822/rfc822-utils.vala
+++ b/src/engine/rfc822/rfc822-utils.vala
@@ -96,9 +96,9 @@ namespace Geary.RFC822.Utils {
         return new MailboxAddresses(result);
     }
 
-    public string reply_references(Email source) {
-        // generate list for References
-        var list = new Gee.ArrayList<MessageID>();
+    /** Generate a References header value in reply to a message. */
+    public MessageIDList? reply_references(Email source) {
+        var list = new Gee.LinkedList<MessageID>();
 
         // 1. Start with the source's References list
         if (source.references != null) {
@@ -119,12 +119,7 @@ namespace Geary.RFC822.Utils {
             list.add(source.message_id);
         }
 
-        string[] strings = new string[list.size];
-        for(int i = 0; i < list.size; ++i) {
-            strings[i] = list[i].value;
-        }
-
-        return (list.size > 0) ? string.joinv(" ", strings) : "";
+        return (list.is_empty) ? null : new MessageIDList(list);
     }
 
     public string email_addresses_for_reply(MailboxAddresses? addresses,