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use std::collections::BTreeSet;
use std::iter;
/// Message sent by a given source.
#[derive(Clone, Debug)]
pub struct SourcedMessage<M, N> {
/// The ID of the sender.
pub source: N,
/// The content of a message.
pub message: M,
}
/// The intended recipient(s) of a message.
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Target<N> {
/// The message must be sent to the nodes with the given IDs.
/// It is _not_ automatically sent to observers.
Nodes(BTreeSet<N>),
/// The message must be sent to all remote nodes except the passed nodes.
/// Useful for sending messages to observer nodes that aren't
/// present in a node's `all_ids()` list.
AllExcept(BTreeSet<N>),
}
impl<N: Ord> Target<N> {
/// Creates a new `Target` addressing all peers, including observers.
pub fn all() -> Self {
Target::AllExcept(BTreeSet::new())
}
/// Creates a new `Target` addressing a single peer.
pub fn node(node_id: N) -> Self {
Target::Nodes(iter::once(node_id).collect())
}
/// Returns a `TargetedMessage` with this target, and the given message.
pub fn message<M>(self, message: M) -> TargetedMessage<M, N> {
TargetedMessage {
target: self,
message,
}
}
/// Returns whether `node_id` is included in this target.
pub fn contains(&self, node_id: &N) -> bool {
match self {
Target::Nodes(ids) => ids.contains(node_id),
Target::AllExcept(ids) => !ids.contains(node_id),
}
}
}
/// Message with a designated target.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct TargetedMessage<M, N> {
/// The node or nodes that this message must be delivered to.
pub target: Target<N>,
/// The content of the message that must be serialized and sent to the target.
pub message: M,
}
impl<M, N> TargetedMessage<M, N> {
/// Applies the given transformation of messages, preserving the target.
pub fn map<T, F: FnOnce(M) -> T>(self, f: F) -> TargetedMessage<T, N> {
TargetedMessage {
target: self.target,
message: f(self.message),
}
}
}