Function hir_difference

regex/regex-syntax/src/hir/translate.rs:1328–1348

(expr1: Hir, expr2: Hir)

    }

    fn hir_difference(expr1: Hir, expr2: Hir) -> Hir {
        use hir::Class::{Bytes, Unicode};

        match (expr1.into_kind(), expr2.into_kind()) {
            (
                HirKind::Class(Unicode(mut c1)),
                HirKind::Class(Unicode(c2)),
            ) => {
                c1.difference(&c2);
                Hir::class(hir::Class::Unicode(c1))
            }
            (
                HirKind::Class(Bytes(mut c1)),
                HirKind::Class(Bytes(c2)),
            ) => {
                c1.difference(&c2);
                Hir::class(hir::Class::Bytes(c1))
            }
            _ => panic!("cannot difference non-class Hir exprs"),
        }
    }

    fn hir_anchor(anchor: hir::Anchor) -> Hir {
        Hir::anchor(anchor)