rust/protover: add ProtoSet::and_not_in()

//! Sets for lazily storing ordered, non-overlapping ranges of integers.

use std::cmp;

use std::iter;

use std::slice;

use std::str::FromStr;

use std::u32;

        expanded.retain(f);

        *self = expanded.into();

    }

    /// Returns all the `Version`s in `self` which are not also in the `other`

    /// `ProtoSet`.

    ///

    /// # Examples

    ///

    /// ```

    /// # use protover::errors::ProtoverError;

    /// use protover::protoset::ProtoSet;

    ///

    /// # fn do_test() -> Result<bool, ProtoverError> {

    /// let protoset: ProtoSet = "1,3-6,10-12,15-16".parse()?;

    /// let other: ProtoSet = "2,5-7,9-11,14-20".parse()?;

    ///

    /// let subset: ProtoSet = protoset.and_not_in(&other);

    ///

    /// assert_eq!(subset.expand(), vec![1, 3, 4, 12]);

    /// #

    /// # Ok(true)

    /// # }

    /// # fn main() { do_test(); }  // wrap the test so we can use the ? operator

    /// ```

    pub fn and_not_in(&self, other: &Self) -> Self {

        if self.is_empty() || other.is_empty() {

            return self.clone();

        }

        let pairs = self.iter().flat_map(|&(lo, hi)| {

            let the_end = (hi + 1, hi + 1); // special case to mark the end of the range.

            let excluded_ranges = other

                .iter()

                .cloned() // have to be owned tuples, to match iter::once(the_end).

                .skip_while(move|&(_, hi2)| hi2 < lo) // skip the non-overlapping ranges.

                .take_while(move|&(lo2, _)| lo2 <= hi) // take all the overlapping ones.

                .chain(iter::once(the_end));

            let mut nextlo = lo;

            excluded_ranges.filter_map(move |(excluded_lo, excluded_hi)| {

                let pair = if nextlo < excluded_lo {

                    Some((nextlo, excluded_lo - 1))

                } else {

                    None

                };

                nextlo = cmp::min(excluded_hi, u32::MAX - 1) + 1;

                pair

            })

        });

        let pairs = pairs.collect();

        ProtoSet::is_ok(ProtoSet{ pairs }).expect("should be already sorted")

    }

}

impl FromStr for ProtoSet {