backends: use IsSubscribedFn in method signatures

Despite having the IsSubscribedFn struct wrapper for closures that check
if a mailbox is subscribed or not, backend methods were still using
  Box<dyn Fn(... types. Switch to using the wrapper newtype everywhere.

Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is>

meli/src/accounts.rs

@@ -203,7 +203,7 @@ impl Account {
         let s = settings.clone();
         let backend = map.get(&settings.account().format)(
             settings.account(),
-            Box::new(move |path: &str| {
+            (Box::new(move |path: &str| {
                 // disjoint-capture-in-closures
                 let _ = &s;
                 s.account.subscribed_mailboxes.is_empty()
@@ -213,7 +213,8 @@ impl Account {
                         .subscribed_mailboxes
                         .iter()
                         .any(|m| path.fnmatches(m))
-            }),
+            }) as Box<dyn Fn(&str) -> bool + Send + Sync>)
+                .into(),
             event_consumer,
         )?;
 

meli/src/patch_retrieve.rs

@@ -79,7 +79,7 @@ pub trait PublicInbox {
             extra,
         };
 
-        NntpType::new(&account_conf, Box::new(|_| true), event_consumer)
+        NntpType::new(&account_conf, Default::default(), event_consumer)
     }
 }
 

meli/src/subcommands.rs

@@ -259,7 +259,7 @@ pub fn tool(path: Option<PathBuf>, opt: ToolOpt) -> Result<()> {
 
             let imap = melib::imap::ImapType::new(
                 &account_conf.account,
-                Box::new(|_| true),
+                Default::default(),
                 melib::BackendEventConsumer::new(std::sync::Arc::new(|_, _| ())),
             )?;
 

melib/src/backends.rs

@@ -62,11 +62,7 @@ pub mod prelude {
 use prelude::*;
 
 pub type BackendCreator = Box<
-    dyn Fn(
-        &AccountSettings,
-        Box<dyn Fn(&str) -> bool + Send + Sync>,
-        BackendEventConsumer,
-    ) -> Result<Box<dyn MailBackend>>,
+    dyn Fn(&AccountSettings, IsSubscribedFn, BackendEventConsumer) -> Result<Box<dyn MailBackend>>,
 >;
 
 pub type BackendValidateConfigFn = Box<dyn Fn(&mut AccountSettings) -> Result<()>>;
@@ -352,6 +348,24 @@ impl Deref for BackendEventConsumer {
     }
 }
 
+impl From<Arc<dyn Fn(AccountHash, BackendEvent) + Send + Sync>> for BackendEventConsumer {
+    fn from(val: Arc<dyn Fn(AccountHash, BackendEvent) + Send + Sync>) -> Self {
+        Self(val)
+    }
+}
+
+impl From<Box<dyn Fn(AccountHash, BackendEvent) + Send + Sync>> for BackendEventConsumer {
+    fn from(val: Box<dyn Fn(AccountHash, BackendEvent) + Send + Sync>) -> Self {
+        Self(val.into())
+    }
+}
+
+impl Default for BackendEventConsumer {
+    fn default() -> Self {
+        Self(Arc::new(|_, _| {}))
+    }
+}
+
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 pub enum FlagOp {
     Set(Flag),
@@ -821,7 +835,26 @@ impl LazyCountSet {
     }
 }
 
-pub struct IsSubscribedFn(pub Box<dyn Fn(&str) -> bool + Send + Sync>);
+#[derive(Clone)]
+pub struct IsSubscribedFn(Arc<dyn Fn(&str) -> bool + Send + Sync>);
+
+impl From<Arc<dyn Fn(&str) -> bool + Send + Sync>> for IsSubscribedFn {
+    fn from(val: Arc<dyn Fn(&str) -> bool + Send + Sync>) -> Self {
+        Self(val)
+    }
+}
+
+impl From<Box<dyn Fn(&str) -> bool + Send + Sync>> for IsSubscribedFn {
+    fn from(val: Box<dyn Fn(&str) -> bool + Send + Sync>) -> Self {
+        Self(val.into())
+    }
+}
+
+impl Default for IsSubscribedFn {
+    fn default() -> Self {
+        Self(Arc::new(|_| true))
+    }
+}
 
 impl std::fmt::Debug for IsSubscribedFn {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
@@ -830,8 +863,9 @@ impl std::fmt::Debug for IsSubscribedFn {
 }
 
 impl std::ops::Deref for IsSubscribedFn {
-    type Target = Box<dyn Fn(&str) -> bool + Send + Sync>;
-    fn deref(&self) -> &Box<dyn Fn(&str) -> bool + Send + Sync> {
-        &self.0
+    type Target = dyn Fn(&str) -> bool + Send + Sync;
+
+    fn deref(&self) -> &Self::Target {
+        self.0.as_ref()
     }
 }

melib/src/imap/mod.rs

@@ -240,7 +240,7 @@ impl UIDStore {
 
 #[derive(Debug)]
 pub struct ImapType {
-    pub _is_subscribed: Arc<IsSubscribedFn>,
+    pub _is_subscribed: IsSubscribedFn,
     pub connection: Arc<FutureMutex<ImapConnection>>,
     pub server_conf: ImapServerConf,
     pub uid_store: Arc<UIDStore>,
@@ -1359,7 +1359,7 @@ impl MailBackend for ImapType {
 impl ImapType {
     pub fn new(
         s: &AccountSettings,
-        is_subscribed: Box<dyn Fn(&str) -> bool + Send + Sync>,
+        is_subscribed: IsSubscribedFn,
         event_consumer: BackendEventConsumer,
     ) -> Result<Box<Self>> {
         let server_hostname = get_conf_val!(s["server_hostname"])?;
@@ -1439,7 +1439,7 @@ impl ImapType {
 
         Ok(Box::new(Self {
             server_conf,
-            _is_subscribed: Arc::new(IsSubscribedFn(is_subscribed)),
+            _is_subscribed: is_subscribed,
             connection: Arc::new(FutureMutex::new(connection)),
             uid_store,
         }))

melib/src/jmap/mod.rs

@@ -293,7 +293,7 @@ pub struct Store {
     pub mailboxes_index: Arc<RwLock<HashMap<MailboxHash, HashSet<EnvelopeHash>>>>,
     pub mailbox_state: Arc<FutureMutex<State<mailbox::MailboxObject>>>,
     pub online_status: OnlineStatus,
-    pub is_subscribed: Arc<IsSubscribedFn>,
+    pub is_subscribed: IsSubscribedFn,
     pub core_capabilities: Arc<Mutex<IndexMap<String, CapabilitiesObject>>>,
     pub event_consumer: BackendEventConsumer,
 }
@@ -1261,7 +1261,7 @@ impl MailBackend for JmapType {
 impl JmapType {
     pub fn new(
         s: &AccountSettings,
-        is_subscribed: Box<dyn Fn(&str) -> bool + Send + Sync>,
+        is_subscribed: IsSubscribedFn,
         event_consumer: BackendEventConsumer,
     ) -> Result<Box<Self>> {
         let online_status = OnlineStatus(Arc::new(FutureMutex::new((
@@ -1278,7 +1278,7 @@ impl JmapType {
             extra_identities: s.extra_identities.clone(),
             online_status,
             event_consumer,
-            is_subscribed: Arc::new(IsSubscribedFn(is_subscribed)),
+            is_subscribed,
             collection: Collection::default(),
             core_capabilities: Arc::new(Mutex::new(IndexMap::default())),
             byte_cache: Default::default(),

melib/src/maildir/backend.rs

@@ -142,6 +142,7 @@ pub struct MaildirType {
     pub mailbox_index: Arc<Mutex<HashMap<EnvelopeHash, MailboxHash>>>,
     pub hash_indexes: HashIndexes,
     pub event_consumer: BackendEventConsumer,
+    pub is_subscribed: IsSubscribedFn,
     pub collection: Collection,
     pub path: PathBuf,
     pub config: Arc<Configuration>,
@@ -596,7 +597,7 @@ impl MailBackend for MaildirType {
 impl MaildirType {
     pub fn new(
         settings: &AccountSettings,
-        is_subscribed: Box<dyn Fn(&str) -> bool>,
+        is_subscribed: IsSubscribedFn,
         event_consumer: BackendEventConsumer,
     ) -> Result<Box<Self>> {
         let config = Arc::new(Configuration::new(settings)?);
@@ -745,6 +746,7 @@ impl MaildirType {
         Ok(Box::new(Self {
             name: settings.name.to_string(),
             mailboxes,
+            is_subscribed,
             hash_indexes: Arc::new(Mutex::new(hash_indexes)),
             mailbox_index: Default::default(),
             event_consumer,

melib/src/mbox/mod.rs

@@ -1276,7 +1276,7 @@ macro_rules! get_conf_val {
 impl MboxType {
     pub fn new(
         s: &AccountSettings,
-        _is_subscribed: Box<dyn Fn(&str) -> bool>,
+        _is_subscribed: IsSubscribedFn,
         event_consumer: BackendEventConsumer,
     ) -> Result<Box<Self>> {
         let path = Path::new(s.root_mailbox.as_str()).expand();

melib/src/nntp/mod.rs

@@ -131,6 +131,7 @@ pub struct UIDStore {
     pub store: Arc<FutureMutex<Option<store::Store>>>,
     pub mailboxes: Arc<FutureMutex<HashMap<MailboxHash, NntpMailbox>>>,
     pub is_online: Arc<FutureMutex<(Instant, Result<()>)>>,
+    pub is_subscribed: IsSubscribedFn,
     pub event_consumer: BackendEventConsumer,
 }
 
@@ -155,17 +156,16 @@ impl UIDStore {
                 Instant::now(),
                 Err(Error::new("Account is uninitialised.")),
             ))),
+            is_subscribed: IsSubscribedFn::default(),
         }
     }
 }
 
 #[derive(Debug)]
 pub struct NntpType {
-    pub _is_subscribed: Arc<IsSubscribedFn>,
     pub connection: Arc<FutureMutex<NntpConnection>>,
     pub server_conf: NntpServerConf,
     pub uid_store: Arc<UIDStore>,
-    pub _can_create_flags: Arc<Mutex<bool>>,
 }
 
 impl MailBackend for NntpType {
@@ -651,7 +651,7 @@ impl MailBackend for NntpType {
 impl NntpType {
     pub fn new(
         s: &AccountSettings,
-        is_subscribed: Box<dyn Fn(&str) -> bool + Send + Sync>,
+        is_subscribed: IsSubscribedFn,
         event_consumer: BackendEventConsumer,
     ) -> Result<Box<Self>> {
         let server_hostname = get_conf_val!(s["server_hostname"])?;
@@ -735,14 +735,13 @@ impl NntpType {
             } else {
                 Default::default()
             },
+            is_subscribed,
             ..UIDStore::new(account_hash, account_name, event_consumer)
         });
         let connection = NntpConnection::new_connection(&server_conf, uid_store.clone());
 
         Ok(Box::new(Self {
             server_conf,
-            _is_subscribed: Arc::new(IsSubscribedFn(is_subscribed)),
-            _can_create_flags: Arc::new(Mutex::new(false)),
             connection: Arc::new(FutureMutex::new(connection)),
             uid_store,
         }))

melib/src/notmuch/mod.rs

@@ -274,7 +274,7 @@ impl NotmuchDb {
 
     pub fn new(
         s: &AccountSettings,
-        _is_subscribed: Box<dyn Fn(&str) -> bool>,
+        _is_subscribed: IsSubscribedFn,
         event_consumer: BackendEventConsumer,
     ) -> Result<Box<Self>> {
         let mut dlpath = Cow::Borrowed(Self::DEFAULT_DYLIB_NAME);