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use nom::branch::alt;
use nom::bytes::complete::tag;
use nom::character::streaming::digit1 as digit;
use nom::combinator::{map, map_res, opt, recognize};
use nom::sequence::{delimited, pair};
use nom::IResult;
use std::str;
use std::str::FromStr;
fn unsigned_float(i: &[u8]) -> IResult<&[u8], f32> {
let float_bytes = recognize(alt((
delimited(digit, tag("."), opt(digit)),
delimited(opt(digit), tag("."), digit),
)));
let float_str = map_res(float_bytes, str::from_utf8);
map_res(float_str, FromStr::from_str)(i)
}
fn float(i: &[u8]) -> IResult<&[u8], f32> {
map(
pair(opt(alt((tag("+"), tag("-")))), unsigned_float),
|(sign, value)| {
sign
.and_then(|s| if s[0] == b'-' { Some(-1f32) } else { None })
.unwrap_or(1f32)
* value
},
)(i)
}
#[test]
fn unsigned_float_test() {
assert_eq!(unsigned_float(&b"123.456;"[..]), Ok((&b";"[..], 123.456)));
assert_eq!(unsigned_float(&b"0.123;"[..]), Ok((&b";"[..], 0.123)));
assert_eq!(unsigned_float(&b"123.0;"[..]), Ok((&b";"[..], 123.0)));
assert_eq!(unsigned_float(&b"123.;"[..]), Ok((&b";"[..], 123.0)));
assert_eq!(unsigned_float(&b".123;"[..]), Ok((&b";"[..], 0.123)));
}
#[test]
fn float_test() {
assert_eq!(float(&b"123.456;"[..]), Ok((&b";"[..], 123.456)));
assert_eq!(float(&b"+123.456;"[..]), Ok((&b";"[..], 123.456)));
assert_eq!(float(&b"-123.456;"[..]), Ok((&b";"[..], -123.456)));
}