use std::fmt;
pub fn to_escaped_string<T: fmt::Debug>(x: &T) -> String {
use std::fmt::Write;
let mut buf = String::new();
let _ = buf.write_fmt(format_args!("{:?}", x));
buf.shrink_to_fit();
buf.chars().flat_map(|c| c.escape_default()).collect()
}
pub fn lower_ascii_letter(c: char) -> Option<char> {
match c {
'a' ... 'z' => Some(c),
'A' ... 'Z' => Some((c as u8 - b'A' + b'a') as char),
_ => None
}
}
pub fn is_ascii_alnum(c: char) -> bool {
matches!(c, '0'...'9' | 'a'...'z' | 'A'...'Z')
}
pub fn is_ascii_whitespace(c: char) -> bool {
matches!(c, '\t' | '\r' | '\n' | '\x0C' | ' ')
}
#[cfg(test)]
#[allow(non_snake_case)]
mod test {
use super::{is_ascii_alnum, lower_ascii_letter};
test_eq!(lower_letter_a_is_a, lower_ascii_letter('a'), Some('a'));
test_eq!(lower_letter_A_is_a, lower_ascii_letter('A'), Some('a'));
test_eq!(lower_letter_symbol_is_None, lower_ascii_letter('!'), None);
test_eq!(lower_letter_nonascii_is_None, lower_ascii_letter('\u{a66e}'), None);
test_eq!(is_alnum_a, is_ascii_alnum('a'), true);
test_eq!(is_alnum_A, is_ascii_alnum('A'), true);
test_eq!(is_alnum_1, is_ascii_alnum('1'), true);
test_eq!(is_not_alnum_symbol, is_ascii_alnum('!'), false);
test_eq!(is_not_alnum_nonascii, is_ascii_alnum('\u{a66e}'), false);
}