string_to_num/
lib.rs

1pub trait ParseNum {
2    /// Parse string to number
3    ///
4    /// This trait is default implemented for  [str](std::str), so both `str`
5    /// and `String` type can use this method
6    ///
7    /// Unlike [from_str_radix](num::Num::from_str_radix) where user must
8    /// provide a radix, this method support auto hex, dec, oct, bin detection
9    ///
10    /// # Examples
11    ///
12    /// ```rust
13    /// use string_to_num::ParseNum;
14    ///
15    /// assert_eq!("0".parse_num::<i32>().unwrap(), 0i32);
16    /// assert_eq!("10".parse_num::<f32>().unwrap(), 10f32);
17    ///
18    /// assert_eq!("0x01".parse_num::<u16>().unwrap(), 1u16);
19    /// assert_eq!("0xFF".parse_num::<f64>().unwrap(), 255f64);
20    /// assert_eq!("0b1111".parse_num::<u8>().unwrap(), 0b1111u8);
21    /// assert_eq!("0o1463".parse_num::<u16>().unwrap(), 0o1463u16);
22    ///
23    /// assert_eq!("0XfF".to_string().parse_num::<f64>().unwrap(), 255f64);
24    /// assert_eq!("0B1111".to_string().parse_num::<u8>().unwrap(), 0b1111u8);
25    /// assert_eq!("0O1463".to_string().parse_num::<u16>().unwrap(), 0o1463u16);
26    /// ```
27    fn parse_num<T: num::Num>(&self) -> Result<T, T::FromStrRadixErr>;
28}
29
30// impl for str so both str and String can use this impl
31impl ParseNum for str {
32    fn parse_num<T: num::Num>(&self) -> Result<T, T::FromStrRadixErr> {
33        // Check prefix, if no prefix, assume decimal
34        let (radix, trimmed_str) =
35            if self.starts_with("0x") || self.starts_with("0X") {
36                (16, &self[2..])
37            } else if self.starts_with("0b") || self.starts_with("0B") {
38                (2, &self[2..])
39            } else if self.starts_with("0o") || self.starts_with("0O") {
40                (8, &self[2..])
41            } else {
42                (10, self)
43            };
44
45        T::from_str_radix(trimmed_str, radix)
46    }
47}
48
49#[cfg(test)]
50mod test {
51    use super::ParseNum;
52
53    #[test]
54    fn conversion() {
55        assert_eq!("0".parse_num::<i32>().unwrap(), 0i32);
56        assert_eq!("10".parse_num::<f32>().unwrap(), 10f32);
57
58        assert_eq!("0x01".parse_num::<u16>().unwrap(), 1u16);
59        assert_eq!("0xFF".parse_num::<f64>().unwrap(), 255f64);
60        assert_eq!("0b1111".parse_num::<u8>().unwrap(), 0b1111u8);
61        assert_eq!("0o1463".parse_num::<u16>().unwrap(), 0o1463u16);
62
63        assert_eq!("0XfF".parse_num::<f64>().unwrap(), 255f64);
64        assert_eq!("0B1111".parse_num::<u8>().unwrap(), 0b1111u8);
65        assert_eq!("0O1463".parse_num::<u16>().unwrap(), 0o1463u16);
66    }
67
68    #[test]
69    fn fails() {
70        assert!("".parse_num::<i8>().is_err());
71        assert!("0b".parse_num::<u8>().is_err());
72        assert!("0o".parse_num::<i16>().is_err());
73        assert!("0x".parse_num::<u16>().is_err());
74
75        assert!("a".parse_num::<i8>().is_err());
76        assert!("0b2".parse_num::<u8>().is_err());
77        assert!("0o8".parse_num::<i16>().is_err());
78        assert!("0xg".parse_num::<u16>().is_err());
79    }
80}
string_to_num/lib.rs

string_to_num/
lib.rs
