fn ensure_correct_interface_name()

in crates/zbus_names/src/interface_name.rs [181:234]

• 49 lines of code
• 14 McCabe index (conditional complexity)

fn ensure_correct_interface_name(name: &str) -> Result<()> {
    // Rules
    //
    // * Only ASCII alphanumeric or `_`.
    // * Must not begin with a `.`.
    // * Must contain at least one `.`.
    // * Each element must:
    //   * not begin with a digit.
    //   * be 1 character (so name must be minimum 3 characters long).
    // * <= 255 characters.
    if name.len() < 3 {
        return Err(Error::InvalidInterfaceName(format!(
            "`{}` is {} characters long, which is smaller than minimum allowed (3)",
            name,
            name.len(),
        )));
    } else if name.len() > 255 {
        return Err(Error::InvalidInterfaceName(format!(
            "`{}` is {} characters long, which is longer than maximum allowed (255)",
            name,
            name.len(),
        )));
    }

    let mut prev = None;
    let mut no_dot = true;
    for c in name.chars() {
        if c == '.' {
            if prev.is_none() || prev == Some('.') {
                return Err(Error::InvalidInterfaceName(String::from(
                    "must not contain a double `.`",
                )));
            }

            if no_dot {
                no_dot = false;
            }
        } else if c.is_ascii_digit() && (prev.is_none() || prev == Some('.')) {
            return Err(Error::InvalidInterfaceName(String::from(
                "each element must not start with a digit",
            )));
        } else if !c.is_ascii_alphanumeric() && c != '_' {
            return Err(Error::InvalidInterfaceName(format!("`{c}` character not allowed")));
        }

        prev = Some(c);
    }

    if no_dot {
        return Err(Error::InvalidInterfaceName(String::from("must contain at least 1 `.`")));
    }

    Ok(())
}