Trait Host 

pub trait Host: BaseHost {
    // Required methods
    fn get_mast_forest(
        &self,
        node_digest: &Word,
    ) -> impl FutureMaybeSend<Option<Arc<MastForest>>>;
    fn on_event(
        &mut self,
        process: &ProcessorState<'_>,
    ) -> impl FutureMaybeSend<Result<Vec<AdviceMutation>, Box<dyn Error + Sync + Send>>>;
}

Defines an async interface by which the VM can interact with the host during execution.

This mirrors the historic async host surface while allowing the sync-first core to depend on [BaseHost].

Required Methods

fn get_mast_forest( &self, node_digest: &Word, ) -> impl FutureMaybeSend<Option<Arc<MastForest>>>

Returns MAST forest corresponding to the specified digest, or None if the MAST forest for this digest could not be found in this host.

fn on_event( &mut self, process: &ProcessorState<'_>, ) -> impl FutureMaybeSend<Result<Vec<AdviceMutation>, Box<dyn Error + Sync + Send>>>

Handles the event emitted from the VM and provides advice mutations to be applied to the advice provider.

The event ID is available at the top of the stack (position 0) when this handler is called. This allows the handler to access both the event ID and any additional context data that may have been pushed onto the stack prior to the emit operation.

Implementation notes

• Extract the event ID via EventId::from_felt(process.get_stack_item(0))
• Return errors without event names or IDs - the caller will enrich them via [BaseHost::resolve_event()]
• System events (IDs 0-255) are handled by the VM before calling this method

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<T> Host for T

where T: SyncHost,