use std::error::Error; use std::fmt::{self, Display}; #[derive(Debug, PartialEq)] pub enum ParserError { InvalidLanguage, InvalidSubtag, } impl Error for ParserError {} impl Display for ParserError { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { let value = match self { ParserError::InvalidLanguage => "The given language subtag is invalid", ParserError::InvalidSubtag => "Invalid subtag", }; f.write_str(value) } }