1 files changed, 110 insertions, 0 deletions
diff --git a/src/flavors/never.rs b/src/flavors/never.rs
new file mode 100644
index 0000000..e49d214
--- /dev/null
+++ b/src/flavors/never.rs
@@ -0,0 +1,110 @@
+//! Channel that never delivers messages.
+//!
+//! Messages cannot be sent into this kind of channel.
+
+use std::marker::PhantomData;
+use std::time::Instant;
+
+use crate::context::Context;
+use crate::err::{RecvTimeoutError, TryRecvError};
+use crate::select::{Operation, SelectHandle, Token};
+use crate::utils;
+
+/// This flavor doesn't need a token.
+pub type NeverToken = ();
+
+/// Channel that never delivers messages.
+pub struct Channel<T> {
+    _marker: PhantomData<T>,
+}
+
+impl<T> Channel<T> {
+    /// Creates a channel that never delivers messages.
+    #[inline]
+    pub fn new() -> Self {
+        Channel {
+            _marker: PhantomData,
+        }
+    }
+
+    /// Attempts to receive a message without blocking.
+    #[inline]
+    pub fn try_recv(&self) -> Result<T, TryRecvError> {
+        Err(TryRecvError::Empty)
+    }
+
+    /// Receives a message from the channel.
+    #[inline]
+    pub fn recv(&self, deadline: Option<Instant>) -> Result<T, RecvTimeoutError> {
+        utils::sleep_until(deadline);
+        Err(RecvTimeoutError::Timeout)
+    }
+
+    /// Reads a message from the channel.
+    #[inline]
+    pub unsafe fn read(&self, _token: &mut Token) -> Result<T, ()> {
+        Err(())
+    }
+
+    /// Returns `true` if the channel is empty.
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        true
+    }
+
+    /// Returns `true` if the channel is full.
+    #[inline]
+    pub fn is_full(&self) -> bool {
+        true
+    }
+
+    /// Returns the number of messages in the channel.
+    #[inline]
+    pub fn len(&self) -> usize {
+        0
+    }
+
+    /// Returns the capacity of the channel.
+    #[inline]
+    pub fn capacity(&self) -> Option<usize> {
+        Some(0)
+    }
+}
+
+impl<T> SelectHandle for Channel<T> {
+    #[inline]
+    fn try_select(&self, _token: &mut Token) -> bool {
+        false
+    }
+
+    #[inline]
+    fn deadline(&self) -> Option<Instant> {
+        None
+    }
+
+    #[inline]
+    fn register(&self, _oper: Operation, _cx: &Context) -> bool {
+        self.is_ready()
+    }
+
+    #[inline]
+    fn unregister(&self, _oper: Operation) {}
+
+    #[inline]
+    fn accept(&self, token: &mut Token, _cx: &Context) -> bool {
+        self.try_select(token)
+    }
+
+    #[inline]
+    fn is_ready(&self) -> bool {
+        false
+    }
+
+    #[inline]
+    fn watch(&self, _oper: Operation, _cx: &Context) -> bool {
+        self.is_ready()
+    }
+
+    #[inline]
+    fn unwatch(&self, _oper: Operation) {}
+}