From f56b89dde3db4ed2948f360f5003528c85db1965 Mon Sep 17 00:00:00 2001
From: Manos Pitsidianakis <el13635@mail.ntua.gr>
Date: Wed, 6 Nov 2019 14:53:12 +0200
Subject: [PATCH] melib: add as_any() method to MailBackend trait

Cast the trait object into an &Any object. Then we can downcast it to
its actual type with downcast_ref().
---
 melib/src/backends.rs                 | 3 +++
 melib/src/backends/imap.rs            | 4 ++++
 melib/src/backends/maildir/backend.rs | 4 ++++
 melib/src/backends/mbox.rs            | 4 ++++
 4 files changed, 15 insertions(+)

diff --git a/melib/src/backends.rs b/melib/src/backends.rs
index 1649bad2..3bd39001 100644
--- a/melib/src/backends.rs
+++ b/melib/src/backends.rs
@@ -36,6 +36,7 @@ use self::maildir::MaildirType;
 #[cfg(feature = "mbox_backend")]
 use self::mbox::MboxType;
 use super::email::{Envelope, EnvelopeHash, Flag};
+use std::any::Any;
 use std::fmt;
 use std::fmt::Debug;
 use std::ops::Deref;
@@ -191,6 +192,8 @@ pub trait MailBackend: ::std::fmt::Debug + Send + Sync {
     fn folder_operation(&mut self, _path: &str, _op: FolderOperation) -> Result<()> {
         Ok(())
     }
+
+    fn as_any(&self) -> &dyn Any;
 }
 
 /// A `BackendOp` manages common operations for the various mail backends. They only live for the
diff --git a/melib/src/backends/imap.rs b/melib/src/backends/imap.rs
index 96addca3..aaad3d66 100644
--- a/melib/src/backends/imap.rs
+++ b/melib/src/backends/imap.rs
@@ -358,6 +358,10 @@ impl MailBackend for ImapType {
         }
         Ok(())
     }
+
+    fn as_any(&self) -> &dyn::std::any::Any {
+        self
+    }
 }
 
 macro_rules! get_conf_val {
diff --git a/melib/src/backends/maildir/backend.rs b/melib/src/backends/maildir/backend.rs
index 75a20aa3..7f198e3b 100644
--- a/melib/src/backends/maildir/backend.rs
+++ b/melib/src/backends/maildir/backend.rs
@@ -552,6 +552,10 @@ impl MailBackend for MaildirType {
             folder
         )))
     }
+
+    fn as_any(&self) -> &dyn::std::any::Any {
+        self
+    }
 }
 
 impl MaildirType {
diff --git a/melib/src/backends/mbox.rs b/melib/src/backends/mbox.rs
index 06d78df6..a1548f0b 100644
--- a/melib/src/backends/mbox.rs
+++ b/melib/src/backends/mbox.rs
@@ -548,6 +548,10 @@ impl MailBackend for MboxType {
     fn save(&self, _bytes: &[u8], _folder: &str, _flags: Option<Flag>) -> Result<()> {
         unimplemented!();
     }
+
+    fn as_any(&self) -> &dyn::std::any::Any {
+        self
+    }
 }
 
 impl MboxType {