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