/// Bump the current position in the source string by one character,
/// returning the current character or an unexpected end of file error.
Bump the current position in the source string by one character,
returning the current character or an unexpected end of file error.
Bump the current position in the source string by one character returning the current character or an unexpected end of file error .
fn expect_advance(&mut self) -> Result<char, Diagnostic<FileSpan>> {
        self.advance().ok_or_else(|| {
            Diagnostic::new_error("unexpected end of file")
                .with_label(Label::new_primary(self.eof_span()))
        })
    }
fn expect_advance ( & mut self ) -> Result < char , Diagnostic < FileSpan > > { self . advance ( ) . ok_or_else ( | | { Diagnostic :: new_error ( " " ) . with_label ( Label :: new_primary ( self . eof_span ( ) ) ) } ) }
Bump the current position in the source string by one character,
returning the current character or an unexpected end of file error.
Bump the current position in the source string by one character returning the current character or an unexpected end of file error .
&mut self