1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

use std::marker::PhantomData;
use std::fmt::Debug;

use crate::*;

/// Returns `Ok(())` if successful, `Err(Error)` otherwise. Doesn't consume input.
#[derive(Debug, Clone, Copy, Default)]
pub struct Must<T : Parse> {

	phantom_data: PhantomData<T>,

}

impl<T : Parse> Parse for Must<T> {

	type Target = ();

	fn parse_from(parser: &mut Parser) -> Result<Self::Target> {
		
		match parser.clone().parse::<T>() {

			Ok(_) => Ok(()),
			Err(_) => Err(Error::new::<Self>(parser))

		}

	}

}