1use nom::branch::alt; 2use nom::bytes::complete::tag; 3use nom::character::streaming::digit1 as digit; 4use nom::combinator::{map, map_res, opt, recognize}; 5use nom::sequence::{delimited, pair}; 6use nom::IResult; 7 8use std::str; 9use std::str::FromStr; 10 11fn unsigned_float(i: &[u8]) -> IResult<&[u8], f32> { 12 let float_bytes = recognize(alt(( 13 delimited(digit, tag("."), opt(digit)), 14 delimited(opt(digit), tag("."), digit), 15 ))); 16 let float_str = map_res(float_bytes, str::from_utf8); 17 map_res(float_str, FromStr::from_str)(i) 18} 19 20fn float(i: &[u8]) -> IResult<&[u8], f32> { 21 map( 22 pair(opt(alt((tag("+"), tag("-")))), unsigned_float), 23 |(sign, value)| { 24 sign 25 .and_then(|s| if s[0] == b'-' { Some(-1f32) } else { None }) 26 .unwrap_or(1f32) 27 * value 28 }, 29 )(i) 30} 31 32#[test] 33fn unsigned_float_test() { 34 assert_eq!(unsigned_float(&b"123.456;"[..]), Ok((&b";"[..], 123.456))); 35 assert_eq!(unsigned_float(&b"0.123;"[..]), Ok((&b";"[..], 0.123))); 36 assert_eq!(unsigned_float(&b"123.0;"[..]), Ok((&b";"[..], 123.0))); 37 assert_eq!(unsigned_float(&b"123.;"[..]), Ok((&b";"[..], 123.0))); 38 assert_eq!(unsigned_float(&b".123;"[..]), Ok((&b";"[..], 0.123))); 39} 40 41#[test] 42fn float_test() { 43 assert_eq!(float(&b"123.456;"[..]), Ok((&b";"[..], 123.456))); 44 assert_eq!(float(&b"+123.456;"[..]), Ok((&b";"[..], 123.456))); 45 assert_eq!(float(&b"-123.456;"[..]), Ok((&b";"[..], -123.456))); 46} 47