Struct EventStream 

pub struct EventStream { /* private fields */ }

Available on crate feature streaming only.

Typed stream of StreamEvents yielded from a streaming Messages request.

Implements futures_util::Stream so callers can iterate event-by-event, or call Self::aggregate to drive the stream to completion and reconstruct a full Message.

Optional callback hooks can be attached via the on_* builder methods; they fire only during Self::aggregate (the raw Stream path is unaffected). Useful for token-by-token UI updates without pattern-matching StreamEvent yourself.

Mid-stream connection failures are not retried – doing so would silently drop content. See crate::error::Error::is_retryable.

Implementations

impl EventStream

pub fn on_text_delta<F>(self, handler: F) -> Self

where F: FnMut(&str) + Send + 'static,

Attach a handler fired on each text-delta inside a text content block. The closure receives only the new chunk; the running concatenation is available via the final Message returned by Self::aggregate.

pub fn on_tool_use_complete<F>(self, handler: F) -> Self

where F: FnMut(&str, &str, &Value) + Send + 'static,

Attach a handler fired when a tool_use content block finishes streaming (its input JSON is fully reconstructed). The closure receives (id, name, &input). Also fires for server_tool_use blocks (e.g. web search invocations).

pub fn on_thinking_delta<F>(self, handler: F) -> Self

where F: FnMut(&str) + Send + 'static,

Attach a handler fired on each delta inside a thinking block.

pub fn on_message_stop<F>(self, handler: F) -> Self

where F: FnMut(&Usage) + Send + 'static,

Attach a handler fired once when the stream’s final message_stop event arrives. Receives the cumulative Usage from the message.

pub fn on_error<F>(self, handler: F) -> Self

where F: FnMut(&Error) + Send + 'static,

Attach a handler fired when the server emits an error stream event or when a stream-parse failure escapes mid-aggregation. The closure runs before the error propagates back to the caller of Self::aggregate.

pub async fn aggregate(self) -> Result<Message>

Drive the stream to completion and return the reconstructed Message.

Equivalent to using messages.create(...) non-streamed – the same final Message payload is produced. If callback hooks were attached via the on_* builder methods, they fire as their corresponding events are processed.

Trait Implementations

impl Debug for EventStream

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Stream for EventStream

type Item = Result<StreamEvent, Error>

Values yielded by the stream.

fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.