generator_extensions 0.1.1

Basic extensions to Generator types to bring parity with Iterators.
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//
// Copyright (C) 2020 Nathan Sharp.
//
// This file is available under either the terms of the Apache License, Version
// 2.0 or the MIT License, at your discretion.
//

use core::ops::GeneratorState;
use core::pin::Pin;

use super::*;

#[derive(PartialEq, Eq)]
struct TestItemA {}

#[derive(PartialEq, Eq)]
struct TestItemB {}

struct TestIterator {
    count: usize,
}

impl TestIterator {
    pub fn new() -> Self {
        Self { count: 0 }
    }
}

impl Iterator for TestIterator {
    type Item = TestItemA;

    fn next(&mut self) -> Option<Self::Item> {
        if self.count < 2 {
            self.count += 1;
            Some(TestItemA {})
        } else {
            None
        }
    }
}

struct TestGenerator {
    count: usize,
}

impl TestGenerator {
    pub fn new() -> Self {
        Self { count: 0 }
    }
}

impl Generator<()> for TestGenerator {
    type Yield = TestItemA;
    type Return = TestItemB;

    fn resume(self: Pin<&mut Self>, _arg: ()) -> GeneratorState<Self::Yield, Self::Return> {
        let me = self.get_mut();

        if me.count < 2 {
            me.count += 1;
            GeneratorState::Yielded(TestItemA {})
        } else {
            GeneratorState::Complete(TestItemB {})
        }
    }
}

#[test]
fn iter_as_gen() {
    let mut gen = &mut TestIterator::new().into_generator();

    assert!(gen.resume(()) == GeneratorState::Yielded(TestItemA {}));
    assert!(gen.resume(()) == GeneratorState::Yielded(TestItemA {}));
    assert!(gen.resume(()) == GeneratorState::Complete(()));
}

#[test]
fn gen_as_states_iter() {
    let mut gen = TestGenerator::new();
    let mut states = gen.states();
    let mut iter = states.iter();

    assert!(iter.next() == Some(GeneratorState::Yielded(TestItemA {})));
    assert!(iter.next() == Some(GeneratorState::Yielded(TestItemA {})));
    assert!(iter.next() == Some(GeneratorState::Complete(TestItemB {})));
    assert!(iter.next() == None);
}