Enum MaybeFuture

pub enum MaybeFuture<'a, T, E> {
    Result(Result<T, E>),
    Future(BoxFuture<'a, Result<T, E>>),
}

Available on crate feature async only.

A type that can represent either an immediate result or a future.

When the async feature is enabled, MaybeFuture is an enum that can hold either an immediate Result<T, E> or a boxed future that will eventually resolve to a Result<T, E>. This allows the same API to handle both synchronous and asynchronous operations seamlessly.

Type Parameters

• 'a - The lifetime of the future
• T - The success type
• E - The error type

Variants

• Result(Result<T, E>) - An immediate result
• Future(BoxFuture<'a, Result<T, E>>) - A future that will resolve to a result

Feature-Dependent Behavior

This type has different definitions depending on feature flags:

• Without async feature: Type alias to Result<T, E>
• With async feature: Enum with Result and Future variants (this definition)

See the module documentation for more details about feature-dependent behavior.

Examples

Working with immediate results

use cel_cxx::MaybeFuture;

let immediate: MaybeFuture<'_, i32, &str> = MaybeFuture::Result(Ok(42));
assert!(immediate.is_result());
assert_eq!(immediate.into_result().unwrap().unwrap(), 42);

Working with futures

use cel_cxx::MaybeFuture;
use futures::future::BoxFuture;

let future_result: BoxFuture<'_, Result<i32, &str>> =
    Box::pin(async { Ok(42) });
let maybe_future: MaybeFuture<'_, i32, &str> =
    MaybeFuture::Future(future_result);

assert!(maybe_future.is_future());
let result = maybe_future.into_future().unwrap().await.unwrap();
assert_eq!(result, 42);

Variants

Result(Result<T, E>)

An immediate result value.

Future(BoxFuture<'a, Result<T, E>>)

A future that will resolve to a result value.

Implementations

impl<'a, T, E> MaybeFuture<'a, T, E>

pub fn is_result(&self) -> bool

Returns true if this is an immediate result.

Examples

use cel_cxx::MaybeFuture;

let immediate: MaybeFuture<'_, i32, &str> = MaybeFuture::Result(Ok(42));
assert!(immediate.is_result());

pub fn is_future(&self) -> bool

Returns true if this is a future.

Examples

use cel_cxx::MaybeFuture;
use futures::future::BoxFuture;

let future: BoxFuture<'_, Result<i32, &str>> = Box::pin(async { Ok(42) });
let maybe_future: MaybeFuture<'_, i32, &str> = MaybeFuture::Future(future);
assert!(maybe_future.is_future());

pub fn result_ref(&self) -> Option<&Result<T, E>>

Returns a reference to the result if this is an immediate result.

Examples

use cel_cxx::MaybeFuture;

let immediate: MaybeFuture<'_, i32, &str> = MaybeFuture::Result(Ok(42));
assert_eq!(immediate.result_ref().unwrap().as_ref().unwrap(), &42);

pub fn future_ref(&self) -> Option<&BoxFuture<'a, Result<T, E>>>

Returns a reference to the future if this is a future.

Examples

use cel_cxx::MaybeFuture;
use futures::future::BoxFuture;

let future: BoxFuture<'_, Result<i32, &str>> = Box::pin(async { Ok(42) });
let maybe_future: MaybeFuture<'_, i32, &str> = MaybeFuture::Future(future);
assert!(maybe_future.future_ref().is_some());

pub fn result_mut(&mut self) -> Option<&mut Result<T, E>>

Returns a mutable reference to the result if this is an immediate result.

pub fn future_mut(&mut self) -> Option<&mut BoxFuture<'a, Result<T, E>>>

Returns a mutable reference to the future if this is a future.

pub fn into_result(self) -> Option<Result<T, E>>

Consumes this value and returns the result if it’s an immediate result.

Examples

use cel_cxx::MaybeFuture;

let immediate: MaybeFuture<'_, i32, &str> = MaybeFuture::Result(Ok(42));
let result = immediate.into_result().unwrap();
assert_eq!(result.unwrap(), 42);

pub fn into_future(self) -> Option<BoxFuture<'a, Result<T, E>>>

Consumes this value and returns the future if it’s a future.

Examples

use cel_cxx::MaybeFuture;
use futures::future::BoxFuture;

let future: BoxFuture<'_, Result<i32, &str>> = Box::pin(async { Ok(42) });
let maybe_future: MaybeFuture<'_, i32, &str> = MaybeFuture::Future(future);
let extracted_future = maybe_future.into_future().unwrap();
let result = extracted_future.await.unwrap();
assert_eq!(result, 42);

pub fn expect_result(self, msg: &str) -> Result<T, E>

Extracts the result, panicking if this is a future.

Panics

Panics if this MaybeFuture contains a future rather than an immediate result.

Examples

use cel_cxx::MaybeFuture;

let immediate: MaybeFuture<'_, i32, &str> = MaybeFuture::Result(Ok(42));
let result = immediate.expect_result("Expected immediate result");
assert_eq!(result.unwrap(), 42);

pub fn expect_future(self, msg: &str) -> BoxFuture<'a, Result<T, E>>

Extracts the future, panicking if this is an immediate result.

Panics

Panics if this MaybeFuture contains an immediate result rather than a future.

Examples

use cel_cxx::MaybeFuture;
use futures::future::BoxFuture;

let future: BoxFuture<'_, Result<i32, &str>> = Box::pin(async { Ok(42) });
let maybe_future: MaybeFuture<'_, i32, &str> = MaybeFuture::Future(future);
let extracted_future = maybe_future.expect_future("Expected future");
let result = extracted_future.await.unwrap();
assert_eq!(result, 42);

pub fn unwrap_result(self) -> Result<T, E>

Extracts the result, panicking if this is a future.

This is equivalent to expect_result but with a default panic message.

Panics

Panics if this MaybeFuture contains a future rather than an immediate result.

pub fn unwrap_future(self) -> BoxFuture<'a, Result<T, E>>

Extracts the future, panicking if this is an immediate result.

This is equivalent to expect_future but with a default panic message.

Panics

Panics if this MaybeFuture contains an immediate result rather than a future.

Trait Implementations

impl<'a, T: Debug, E: Debug> Debug for MaybeFuture<'a, T, E>

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

Formats the value using the given formatter.

impl<'a, Fut, T, E> From<Pin<Box<Fut>>> for MaybeFuture<'a, T, E>

where Fut: Future<Output = Result<T, E>> + Send + 'a,

fn from(f: Pin<Box<Fut>>) -> Self

Converts to this type from the input type.

impl<'a, T, E> From<Result<T, E>> for MaybeFuture<'a, T, E>

fn from(t: Result<T, E>) -> Self

Converts to this type from the input type.