fn _push()

in sgx_tstd/src/path.rs [1228:1297]
53 lines of code
16 McCabe index (conditional complexity)

    fn _push(&mut self, path: &Path) {
        // in general, a separator is needed if the rightmost byte is not a separator
        let mut need_sep = self.as_mut_vec().last().map(|c| !is_sep_byte(*c)).unwrap_or(false);

        // in the special case of `C:` on Windows, do *not* add a separator
        let comps = self.components();

        if comps.prefix_len() > 0
            && comps.prefix_len() == comps.path.len()
            && comps.prefix.unwrap().is_drive()
        {
            need_sep = false
        }

        // absolute `path` replaces `self`
        if path.is_absolute() || path.prefix().is_some() {
            self.as_mut_vec().truncate(0);

        // verbatim paths need . and .. removed
        } else if comps.prefix_verbatim() && !path.inner.is_empty() {
            let mut buf: Vec<_> = comps.collect();
            for c in path.components() {
                match c {
                    Component::RootDir => {
                        buf.truncate(1);
                        buf.push(c);
                    }
                    Component::CurDir => (),
                    Component::ParentDir => {
                        if let Some(Component::Normal(_)) = buf.last() {
                            buf.pop();
                        }
                    }
                    _ => buf.push(c),
                }
            }

            let mut res = OsString::new();
            let mut need_sep = false;

            for c in buf {
                if need_sep && c != Component::RootDir {
                    res.push(MAIN_SEP_STR);
                }
                res.push(c.as_os_str());

                need_sep = match c {
                    Component::RootDir => false,
                    Component::Prefix(prefix) => {
                        !prefix.parsed.is_drive() && prefix.parsed.len() > 0
                    }
                    _ => true,
                }
            }

            self.inner = res;
            return;

        // `path` has a root but no prefix, e.g., `\windows` (Windows only)
        } else if path.has_root() {
            let prefix_len = self.components().prefix_remaining();
            self.as_mut_vec().truncate(prefix_len);

        // `path` is a pure relative path
        } else if need_sep {
            self.inner.push(MAIN_SEP_STR);
        }

        self.inner.push(path);
    }