iter-opt-filter  

This crate adds an optional filter to iterators. The problem this attempts to solve is the combination of multiple filters that can be enabled/disabled at runtime.

Example

use iter_opt_filter::IteratorOptionalFilterExt;

let mut iter = (0..3)
    .optional_filter(Some(|&item: &usize| item % 2 == 0))
    .optional_filter(None::<fn(&usize) -> bool>)
    .optional_filter(Some(|&item: &usize| item > 1));

assert_eq!(iter.next(), Some(2));
assert_eq!(iter.next(), None);