actix-tls release candidate prep (#422)

actix-tls/src/connect/connect_addrs.rs

@@ -0,0 +1,82 @@
+use std::{
+    collections::{vec_deque, VecDeque},
+    fmt, iter,
+    net::SocketAddr,
+};
+
+#[derive(Debug, Clone, Eq, PartialEq, Hash)]
+pub(crate) enum ConnectAddrs {
+    None,
+    One(SocketAddr),
+    // TODO: consider using smallvec
+    Multi(VecDeque<SocketAddr>),
+}
+
+impl ConnectAddrs {
+    pub(crate) fn is_unresolved(&self) -> bool {
+        matches!(self, Self::None)
+    }
+
+    pub(crate) fn is_resolved(&self) -> bool {
+        !self.is_unresolved()
+    }
+}
+
+impl Default for ConnectAddrs {
+    fn default() -> Self {
+        Self::None
+    }
+}
+
+impl From<Option<SocketAddr>> for ConnectAddrs {
+    fn from(addr: Option<SocketAddr>) -> Self {
+        match addr {
+            Some(addr) => ConnectAddrs::One(addr),
+            None => ConnectAddrs::None,
+        }
+    }
+}
+
+/// Iterator over addresses in a [`Connect`] request.
+#[derive(Clone)]
+pub(crate) enum ConnectAddrsIter<'a> {
+    None,
+    One(SocketAddr),
+    Multi(vec_deque::Iter<'a, SocketAddr>),
+    MultiOwned(vec_deque::IntoIter<SocketAddr>),
+}
+
+impl Iterator for ConnectAddrsIter<'_> {
+    type Item = SocketAddr;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match *self {
+            Self::None => None,
+            Self::One(addr) => {
+                *self = Self::None;
+                Some(addr)
+            }
+            Self::Multi(ref mut iter) => iter.next().copied(),
+            Self::MultiOwned(ref mut iter) => iter.next(),
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        match *self {
+            Self::None => (0, Some(0)),
+            Self::One(_) => (1, Some(1)),
+            Self::Multi(ref iter) => iter.size_hint(),
+            Self::MultiOwned(ref iter) => iter.size_hint(),
+        }
+    }
+}
+
+impl fmt::Debug for ConnectAddrsIter<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+impl iter::ExactSizeIterator for ConnectAddrsIter<'_> {}
+
+impl iter::FusedIterator for ConnectAddrsIter<'_> {}