[][src]Trait next_gen::Generator

pub trait Generator {
    type Yield;
    type Return;
    fn resume(self: Pin<&mut Self>) -> GeneratorState<Self::Yield, Self::Return>;

The trait implemented by GeneratorFns.

Generators, also commonly referred to as coroutines, provide an ergonomic definition for iterators and other primitives, allowing to write iterators and iterator adapters in a much more imperative way, which may sometimes improve the readability of such iterators / iterator adapters.


use ::next_gen::{prelude::*, GeneratorState};

fn main ()
    fn generator_fn () -> &'static str
        return "foo"

    mk_gen!(let mut generator = generator_fn());

    match generator.as_mut().resume() {
        | GeneratorState::Yield(1) => {}
        | _ => panic!("unexpected return from resume"),
    match generator.as_mut().resume() {
        | GeneratorState::Return("foo") => {}
        | _ => panic!("unexpected yield from resume"),

Associated Types

type Yield

The type of value this generator yields.

This associated type corresponds to the yield_! expression and the values which are allowed to be returned each time a generator yields. For example an iterator-as-a-generator would likely have this type as T, the type being iterated over.

type Return

The type of value this generator returns.

This corresponds to the type returned from a generator either with a return statement or implicitly as the last expression of a generator literal.

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Required methods

fn resume(self: Pin<&mut Self>) -> GeneratorState<Self::Yield, Self::Return>

Resumes the execution of this generator.

This function will resume execution of the generator or start execution if it hasn't already. This call will return back into the generator's last suspension point, resuming execution from the latest yield_!. The generator will continue executing until it either yields or returns, at which point this function will return.

Return value

The GeneratorState enum returned from this function indicates what state the generator is in upon returning.

If the Yield variant is returned then the generator has reached a suspension point and a value has been yielded out. Generators in this state are available for resumption at a later point.

If Return is returned then the generator has completely finished with the value provided. It is invalid for the generator to be resumed again.


This function may panic if it is called after the Return variant has been returned previously. While generator literals in the language are guaranteed to panic on resuming after Return, this is not guaranteed for all implementations of the Generator trait.

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Implementations on Foreign Types

impl<'a, G: ?Sized + 'a> Generator for Pin<&'a mut G> where
    G: Generator

type Yield = G::Yield

type Return = G::Return

impl<'a, G: ?Sized + 'a> Generator for &'a mut G where
    G: Generator + Unpin

type Yield = G::Yield

type Return = G::Return

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impl<Item, F: Future> Generator for GeneratorFn<Item, F>[src]

type Yield = Item

type Return = F::Output

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