str_to_bytes 0.2.3

use regex::Regex;

/// Check if a string match a decimal number representation.
///
/// Examples:
/// ```rust
/// use str_to_bytes::is_decimal;
///
/// assert!(is_decimal("11"));
/// assert!(is_decimal("1424"));
/// assert!(is_decimal("0x33") == false);
/// ```
pub fn is_decimal(s: &str) -> bool {
    let re = Regex::new(r"^[0-9]+$").unwrap();

    re.is_match(s)
}

/// Parse a string representing a decimal number into a Vec<u8>.
///
/// Always use if is_decimal() returns true on that string.
///
/// Examples:
/// ```rust
/// use str_to_bytes::{is_decimal, parse_decimal};
///
/// let dec_str: &str = "4124";
/// if str_to_bytes::is_decimal(dec_str) {
///     let bytes = parse_decimal(dec_str);
///     println!("{:?}", bytes);
/// }
/// ```
pub fn parse_decimal(n: &str) -> Vec<u8> {
    let val = n.parse::<u64>().expect("Not a decimal number");

    let mut bytes: Vec<u8> = Vec::new();
    bytes.extend_from_slice(&val.to_be_bytes());

    while bytes.len() > 1 && bytes[0] == 0 {
        bytes.remove(0);
    }

    bytes
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_decimal() {
        assert!(is_decimal("0"));
        assert!(is_decimal("1"));
        assert!(is_decimal("12"));
        assert!(is_decimal("31"));

        // empty
        assert!(is_decimal("") == false);

        // any size should work
        assert!(is_decimal("12"));
        assert!(is_decimal("1"));
        assert!(is_decimal("0"));
        assert!(is_decimal("18130184813"));
        assert!(is_decimal("189120931130184813"));

        // simple decimal
        assert_eq!(parse_decimal("10"), [10]);
        assert_eq!(parse_decimal("6"), [6]);
        assert_eq!(parse_decimal("1"), [1]);
        assert_eq!(parse_decimal("256"), [1, 0]);

        // multi bytes
        assert_eq!(parse_decimal("1024"), [0b100, 0]);
        assert_eq!(
            parse_decimal("123456789"),
            [0b111, 0b01011011, 0b11001101, 0b00010101]
        );
    }
}