utils/parser/
then.rs

1#![allow(non_snake_case)]
2
3use crate::parser::{ParseResult, Parser};
4
5pub trait Then<P: Parser, T: Parser>: Parser {
6    fn then(parser: P, then: T) -> Self;
7}
8
9#[derive(Copy, Clone)]
10pub enum Unimplemented {}
11impl Parser for Unimplemented {
12    type Output<'i> = Unimplemented;
13    type Then<T: Parser> = Unimplemented;
14
15    fn parse<'i>(&self, _: &'i [u8]) -> ParseResult<'i, Self::Output<'i>> {
16        unimplemented!();
17    }
18}
19impl<P: Parser, T: Parser> Then<P, T> for Unimplemented {
20    fn then(_: P, _: T) -> Self {
21        unimplemented!();
22    }
23}
24
25macro_rules! then_impl {
26    (
27        $name:ident<$_:ident> => [$($t:ident),+],
28        $next_name:ident<$next_t:ident> => $($tail:tt)*
29    ) => {
30        #[derive(Copy, Clone)]
31        pub struct $name<$($t),+>{
32            $($t: $t,)+
33        }
34        impl<$($t: Parser),+> Parser for $name<$($t),+> {
35            type Output<'i> = ($($t::Output<'i>),+);
36            type Then<T: Parser> = $next_name<$($t),+, T>;
37
38            #[inline(always)]
39            fn parse<'i>(&self, input: &'i [u8]) -> ParseResult<'i, Self::Output<'i>> {
40                $(let ($t, input) = self.$t.parse(input)?;)+
41                Ok((($($t),+), input))
42            }
43        }
44        impl<$($t: Parser),+, T: Parser> Then<$name<$($t),+>, T> for $next_name<$($t),+, T> {
45            fn then(parser: $name<$($t),+>, next: T) -> Self {
46                Self{$($t: parser.$t),+, $next_t: next}
47            }
48        }
49        then_impl!{$next_name<$next_t> => $($tail)*}
50    };
51    (
52        $name:ident<$_:ident> => [$($t:ident),+],
53    ) => {
54        #[derive(Copy, Clone)]
55        pub struct $name<$($t),+>{
56            $($t: $t,)+
57        }
58        impl<$($t: Parser),+> Parser for $name<$($t),+> {
59            type Output<'i> = ($($t::Output<'i>),+);
60            type Then<T: Parser> = Unimplemented;
61
62            #[inline(always)]
63            fn parse<'i>(&self, input: &'i [u8]) -> ParseResult<'i, Self::Output<'i>> {
64                $(let ($t, input) = self.$t.parse(input)?;)+
65                Ok((($($t),+), input))
66            }
67        }
68    };
69}
70
71then_impl! {
72    Then2<B> => [A, B],
73    Then3<C> => [A, B, C],
74    Then4<D> => [A, B, C, D],
75    Then5<E> => [A, B, C, D, E],
76    Then6<F> => [A, B, C, D, E, F],
77    Then7<G> => [A, B, C, D, E, F, G],
78    Then8<H> => [A, B, C, D, E, F, G, H],
79}
80
81impl<A: Parser, B: Parser> Then<A, B> for Then2<A, B> {
82    fn then(parser: A, then: B) -> Self {
83        Then2 { A: parser, B: then }
84    }
85}
utils/parser/then.rs

utils/parser/
then.rs
