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use crate::command::HandleCommand; use crate::event::{DomainEventView, NewEvent, Sequence}; use serde::de::DeserializeOwned; use serde::{Deserialize, Serialize}; use std::fmt::{self, Debug, Display}; #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)] pub struct Generation(u64); impl Default for Generation { fn default() -> Self { Self(0) } } impl Display for Generation { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "{}", self.0) } } impl Generation { pub fn number(self) -> u64 { self.0 } pub fn increment(&mut self) { self.0 = self.0.wrapping_add(1); } } impl From<Sequence> for Generation { fn from(sequence: Sequence) -> Self { Self(sequence.number()) } } pub trait AggregateType { fn aggregate_type() -> &'static str { std::any::type_name::<Self>() } } pub trait WithAggregateId { type Id: Debug + Clone + PartialEq + Serialize + DeserializeOwned; fn aggregate_id(&self) -> &Self::Id; } pub type AggregateIdOf<A> = <A as WithAggregateId>::Id; pub trait AggregateState { fn generation(&self) -> Generation; fn generation_mut(&mut self) -> &mut Generation; } pub trait Aggregate<E> where E: 'static, Self: 'static + Sized + WithAggregateId, { fn apply_event(&mut self, event: DomainEventView<'_, E, Self>); fn apply_all_events<'a>( &mut self, events: impl IntoIterator<Item = DomainEventView<'a, E, Self>>, ) { events.into_iter().for_each(|e| self.apply_event(e)) } } pub trait InitializeAggregate { type State: WithAggregateId; fn initialize(aggregate_id: AggregateIdOf<Self::State>) -> Self::State; } #[derive(Debug, Clone, PartialEq)] pub struct VersionedAggregate<S> { generation: Generation, state: S, } impl<S> VersionedAggregate<S> { pub fn restore(generation_number: u64, state: S) -> Self { Self { generation: Generation(generation_number), state, } } pub fn unwrap(self) -> S { self.state } pub fn generation(&self) -> Generation { self.generation } pub fn state(&self) -> &S { &self.state } } impl<S> InitializeAggregate for VersionedAggregate<S> where S: WithAggregateId + InitializeAggregate<State = S>, { type State = Self; fn initialize(aggregate_id: AggregateIdOf<Self::State>) -> Self::State { Self { generation: Generation::default(), state: S::initialize(aggregate_id), } } } impl<S> AggregateType for VersionedAggregate<S> {} impl<S> AggregateState for VersionedAggregate<S> { fn generation(&self) -> Generation { self.generation } fn generation_mut(&mut self) -> &mut Generation { &mut self.generation } } impl<S> WithAggregateId for VersionedAggregate<S> where S: WithAggregateId, { type Id = <S as WithAggregateId>::Id; fn aggregate_id(&self) -> &Self::Id { self.state.aggregate_id() } } impl<E, S> Aggregate<E> for VersionedAggregate<S> where E: 'static, S: Aggregate<E> + AggregateType, { fn apply_event(&mut self, event: DomainEventView<'_, E, Self>) { let inner_data = event.data; self.state.apply_event(event.transmute(inner_data)); self.generation.increment(); } } impl<C, S> HandleCommand<C, Self> for VersionedAggregate<S> where S: HandleCommand<C, S>, S: WithAggregateId, { type Event = <S as HandleCommand<C, S>>::Event; type Error = <S as HandleCommand<C, S>>::Error; type Context = <S as HandleCommand<C, S>>::Context; fn handle_command( &self, command: C, context: &Self::Context, ) -> Result<Vec<NewEvent<Self::Event, Self>>, Self::Error> { self.state.handle_command(command, context).map(|events| { events .into_iter() .map(|NewEvent { aggregate_id, data }| NewEvent { aggregate_id, data }) .collect::<Vec<_>>() }) } } #[cfg(test)] mod tests;