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use crate::{Generator, GeneratorResult, ValueResult};
use core::num::NonZeroUsize;
pub struct Inspect<Src, F> {
source: Src,
inspector: F,
}
impl<Src, F> Inspect<Src, F> {
pub(crate) fn new(source: Src, inspector: F) -> Self {
Self { source, inspector }
}
}
impl<Src, F> Generator for Inspect<Src, F>
where
Src: Generator,
F: FnMut(&Src::Output),
{
type Output = Src::Output;
#[inline]
fn run(&mut self, mut output: impl FnMut(Self::Output) -> ValueResult) -> GeneratorResult {
let inspector = &mut self.inspector;
self.source.run(|x| {
inspector(&x);
output(x)
})
}
#[inline]
fn try_advance(&mut self, n: NonZeroUsize) -> (usize, GeneratorResult) {
self.source.try_advance(n)
}
}
#[cfg(test)]
mod tests {
use crate::{GeneratorExt, SliceGenerator};
#[test]
fn inspect() {
let a = [1, 4, 2, 3];
let mut before_filter = Vec::new();
let mut after_filter = Vec::new();
let sum: i32 = SliceGenerator::new(&a)
.cloned()
.inspect(|x| before_filter.push(*x))
.filter(|x| x % 2 == 0)
.inspect(|x| after_filter.push(*x))
.sum();
assert_eq!(sum, 6);
assert_eq!(before_filter, [1, 4, 2, 3]);
assert_eq!(after_filter, [4, 2]);
}
}