1 unstable release
0.1.1 | Jul 29, 2019 |
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#17 in #special
5KB
nom-both
Extension of nom to provide special both_
parsers.
Requirement
nom must be 5.0.0 or later. nom-both can be applied to function-style parser only.
Usage
[dependencies]
nom-both = "0.1.1"
Example
nom-both provide both_opt
and both_alt
parser.
both_opt
means that the parser tries both argument parser and skip.
both_alt
means that the parser tries both 1st argument parser and 2nd argument parser.
use nom::branch::*;
use nom::bytes::complete::*;
use nom::IResult;
use nom_both::both_parser;
#[both_parser]
pub fn both_opt_parser(s: &str) -> IResult<&str, Option<&str>> {
let (s, _) = tag("1")(s)?;
let (s, x) = both_opt(tag("2"))(s)?;
let (s, _) = tag("2")(s)?;
let (s, _) = tag("3")(s)?;
Ok((s, x))
}
#[both_parser]
pub fn both_alt_parser(s: &str) -> IResult<&str, &str> {
let (s, _) = tag("1")(s)?;
let (s, x) = both_alt(tag("22"), tag("2"))(s)?;
let (s, _) = tag("2")(s)?;
let (s, _) = tag("3")(s)?;
Ok((s, x))
}
#[test]
fn test() {
let ret = both_opt_parser("123");
assert_eq!("None", format!("{:?}", ret.unwrap().1));
let ret = both_alt_parser("1223");
assert_eq!("\"2\"", format!("{:?}", ret.unwrap().1));
}
both_opt_parser
is expanded as below:
pub fn both_opt_parser(s: &str) -> IResult<&str, Option<&str>> {
alt((
{ |s| {
let (s, _) = tag("1")(s)?;
let (s, x) = nom_both::some(tag("2"))(s)?;
let (s, _) = tag("2")(s)?;
let (s, _) = tag("3")(s)?;
Ok((s, x))
} },
{ |s| {
let (s, _) = tag("1")(s)?;
let (s, x) = nom_both::none(tag("2"))(s)?;
let (s, _) = tag("2")(s)?;
let (s, _) = tag("3")(s)?;
Ok((s, x))
} },
))(s)
}
both_alt_parser
is expanded as below:
pub fn both_opt_parser(s: &str) -> IResult<&str, Option<&str>> {
alt((
{ |s| {
let (s, _) = tag("1")(s)?;
let (s, x) = nom_both::alt_left(tag("22"), tag("2"))(s)?;
let (s, _) = tag("2")(s)?;
let (s, _) = tag("3")(s)?;
Ok((s, x))
} },
{ |s| {
let (s, _) = tag("1")(s)?;
let (s, x) = nom_both::alt_right(tag("22"), tag("2"))(s)?;
let (s, _) = tag("2")(s)?;
let (s, _) = tag("3")(s)?;
Ok((s, x))
} },
))(s)
}
License
Licensed under either of
- Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
Dependencies
~3MB
~64K SLoC