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use crate::{address::AnyMessageBox, plugin::Message};
/// A message that can contain any other message
///
/// This is solely used in conjunction with [`AnyMessages`](crate::plugin::AnyMessages) and should not generally be used
/// otherwise.
///
/// To construct it, you will need to have a message and call [`AnyMessage::from_message`]
#[derive(Debug)]
pub struct AnyMessage(pub(crate) AnyMessageBox);
impl std::ops::Deref for AnyMessage {
type Target = dyn Message;
fn deref(&self) -> &Self::Target {
&*self.0
}
}
impl AnyMessage {
/// Construct a new [`AnyMessage`] from a message
pub fn from_message<M: Message>(m: M) -> Self {
AnyMessage(Box::new(m))
}
/// Try to downcast this message to a specific message
pub fn downcast<M: Message>(self) -> Result<M, Self> {
Ok(*self.0.downcast().map_err(AnyMessage)?)
}
/// Take out the raw boxed message
///
/// Note
///
/// This is an advanced API and should only be used if needed.
/// Prefer using `AnyMessage::downcast` if possible
pub fn into_raw(self) -> AnyMessageBox {
self.0
}
}
impl Message for AnyMessage {}
/// The type of a message as used by `tedge_api` to represent a type
#[derive(Debug, Clone)]
pub struct MessageType {
name: &'static str,
kind: MessageKind,
}
#[derive(Debug, Clone)]
enum MessageKind {
Wildcard,
Typed(std::any::TypeId),
}
impl MessageType {
/// Does this [`MessageType`] satisfy another [`MessageType`]
///
/// ## Note
/// A message type from [`AnyMessage`] acts as a 'wildcard', being satisfied by any other type
/// (even itself).
/// The reverse is not true, a specific type cannot be satisfied by a 'wildcard' (i.e.
/// [`AnyMessage`]).
///
/// [`MessageType::satisfy`] is thus reflexive but not symmetric nor transitive, meaning that it cannot be
/// used for `PartialEq`.
#[must_use]
pub fn satisfy(&self, other: &Self) -> bool {
match (&self.kind, &other.kind) {
(MessageKind::Wildcard, _) => true,
(_, MessageKind::Wildcard) => false,
(MessageKind::Typed(ty_l), MessageKind::Typed(ty_r)) => ty_l.eq(ty_r),
}
}
/// Get the [`MessageType`] for a `M`:[`Message`]
#[must_use]
pub fn for_message<M: Message>() -> Self {
let id = std::any::TypeId::of::<M>();
MessageType {
name: std::any::type_name::<M>(),
kind: if id == std::any::TypeId::of::<AnyMessage>() {
MessageKind::Wildcard
} else {
MessageKind::Typed(id)
},
}
}
/// Get the type's name
#[must_use]
pub fn name(&self) -> &str {
self.name
}
}
/// A message to tell the core to stop thin-edge
#[derive(Debug)]
pub struct StopCore;
impl Message for StopCore {}
crate::make_receiver_bundle!(pub struct CoreMessages(StopCore));
#[cfg(test)]
mod tests {
use crate::Message;
use super::{AnyMessage, MessageType};
#[derive(Debug)]
struct Bar;
impl Message for Bar {}
#[derive(Debug)]
struct Foo;
impl Message for Foo {}
#[test]
fn assert_satisfy_laws_for_types() {
let bar_type = MessageType::for_message::<Bar>();
let any_message_type = MessageType::for_message::<AnyMessage>();
let foo_type = MessageType::for_message::<Foo>();
assert!(any_message_type.satisfy(&bar_type));
assert!(any_message_type.satisfy(&foo_type));
assert!(!bar_type.satisfy(&any_message_type));
assert!(!bar_type.satisfy(&foo_type));
}
}
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