Method union

src/expr/src/interpret.rs:50–79

(self, other: Values<'a>)

    }

    fn union(self, other: Values<'a>) -> Values<'a> {
        match (self, other) {
            (Values::Empty, r) => r,
            (r, Values::Empty) => r,
            (Values::Within(a0, a1), Values::Within(b0, b1)) => {
                Values::Within(a0.min(b0), a1.max(b1))
            }
            (Values::Nested(a), Values::Nested(mut b)) => {
                // `Nested(map)` treats keys missing from `map` as fully unconstrained, so a
                // key present in only one side of the union must be treated as `anything`
                // on the other side. Because `x ∪ anything = anything`, such keys drop
                // out of the merged map (the Nested default is already "anything").
                let mut merged = BTreeMap::new();
                for (key, a_spec) in a {
                    if let Some(b_spec) = b.remove(&key) {
                        let unioned = a_spec.union(b_spec);
                        if unioned != ResultSpec::anything() {
                            merged.insert(key, unioned);
                        }
                    }
                }
                if merged.is_empty() {
                    Values::All
                } else {
                    Values::Nested(merged)
                }
            }
            _ => Values::All,
        }
    }

    fn intersect(self, other: Values<'a>) -> Values<'a> {
        match (self, other) {