pushgen 0.0.2

Push-style design pattern for processing of ranges and data-streams.
Documentation 
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use crate::{Generator, GeneratorResult, ValueResult};

/// Implements a mapped generator. See [`.map()`](crate::GeneratorExt::map) for details.
#[derive(Clone)]
pub struct Map<Gen, Func> {
    source: Gen,
    transform: Func,
}

impl<Gen, Func, Out> Map<Gen, Func>
where
    Gen: Generator,
    Func: FnMut(Gen::Output) -> Out,
{
    #[inline]
    pub fn new(source: Gen, transform: Func) -> Self {
        Self { source, transform }
    }
}

impl<Gen, Func, Out> Generator for Map<Gen, Func>
where
    Gen: Generator,
    Func: FnMut(Gen::Output) -> Out,
{
    type Output = Out;

    #[inline]
    fn run(&mut self, mut output: impl FnMut(Self::Output) -> ValueResult) -> GeneratorResult {
        let transform = &mut self.transform;
        self.source.run(move |value| output(transform(value)))
    }

    #[inline]
    fn try_advance(&mut self, n: core::num::NonZeroUsize) -> (usize, GeneratorResult) {
        self.source.try_advance(n)
    }
}

#[cfg(test)]
mod tests {
    use crate::test::StoppingGen;
    use crate::{GeneratorExt, GeneratorResult};

    #[test]
    fn spuriously_stopping() {
        let data = [1, 2, 3];

        for x in 0..data.len() {
            let mut gen = StoppingGen::new(x as i32, &data).map(|x| x * 2);
            let mut output = Vec::new();
            let result = gen.for_each(|x| output.push(x));
            assert_eq!(result, GeneratorResult::Stopped);
            let result = gen.for_each(|x| output.push(x));
            assert_eq!(result, GeneratorResult::Complete);
            assert_eq!(output, [2 * 1, 2 * 2, 2 * 3]);
        }
    }
}