diff options
Diffstat (limited to 'iter_patterns')
| -rw-r--r-- | iter_patterns/src/lib.rs | 95 |
1 files changed, 90 insertions, 5 deletions
diff --git a/iter_patterns/src/lib.rs b/iter_patterns/src/lib.rs index 10679aa..a4be783 100644 --- a/iter_patterns/src/lib.rs +++ b/iter_patterns/src/lib.rs @@ -1,4 +1,4 @@ -#![feature(slice_patterns)] +#![feature(slice_patterns, bind_by_move_pattern_guards)] /* Destructure an iterator using the syntax of slice_patterns. * Wraps the match body in `Some` if there was a match; returns @@ -35,6 +35,21 @@ macro_rules! destructure_iter { $($rest)* ) }; + // Special variable length pattern with a common unary variant + (@match_forwards, $iter:expr, ($body:expr), $variant:ident ($x:ident).., $($rest:tt)*) => { + $crate::destructure_iter!(@match_backwards, + $iter, + ({ + let $x = $iter + .map(|x| match x { + $variant(y) => y, + _ => unreachable!(), + }); + $body + }), + $($rest)* + ) + }; // Variable length pattern without a binder (@match_forwards, $iter:expr, ($body:expr), .., $($rest:tt)*) => { $crate::destructure_iter!(@match_backwards, @@ -117,6 +132,71 @@ macro_rules! destructure_iter { */ #[macro_export] macro_rules! match_vec { + // Variable length pattern + (@make_pat; ($($acc:tt)*), $x:ident.., $($rest:tt)*) => { + $crate::match_vec!(@make_pat; + ($($acc)*, $x..), + $($rest)* + ) + }; + // Special variable length pattern with a common unary variant + (@make_pat; ($($acc:tt)*), $variant:ident ($x:ident).., $($rest:tt)*) => { + $crate::match_vec!(@make_pat; + ($($acc)*, $x..), + $($rest)* + ) + }; + // Variable length pattern without a binder + (@make_pat; ($($acc:tt)*), .., $($rest:tt)*) => { + $crate::match_vec!(@make_pat; + ($($acc)*, ..), + $($rest)* + ) + }; + // Single item pattern + (@make_pat; ($($acc:tt)*), $x:pat, $($rest:tt)*) => { + $crate::match_vec!(@make_pat; + ($($acc)*, $x), + $($rest)* + ) + }; + (@make_pat; (, $($acc:tt)*), $(,)*) => { + [$($acc)*] + }; + (@make_pat; ($($acc:tt)*), $(,)*) => { + [$($acc)*] + }; + + (@make_filter; $x:ident.., $($rest:tt)*) => { + $crate::match_vec!(@make_filter; + $($rest)* + ) + }; + (@make_filter; $variant:ident ($x:ident).., $($rest:tt)*) => { + $x.iter() + .all(|x| match x { + $variant(_) => true, + _ => false, + }) + && + $crate::match_vec!(@make_filter; + $($rest)* + ) + }; + (@make_filter; .., $($rest:tt)*) => { + $crate::match_vec!(@make_filter; + $($rest)* + ) + }; + (@make_filter; $x:pat, $($rest:tt)*) => { + $crate::match_vec!(@make_filter; + $($rest)* + ) + }; + (@make_filter; $(,)*) => { + true + }; + ($arg:expr; $( [$($args:tt)*] => $body:expr ),* $(,)*) => { { let vec = $arg; @@ -126,7 +206,10 @@ macro_rules! match_vec { #[allow(unused_variables, unreachable_patterns)] match vec.as_slice() { $( - [$($args)*] => { + $crate::match_vec!(@make_pat; (), $($args)*,) + if + $crate::match_vec!(@make_filter; $($args)*,) + => { // Actually consume the values #[allow(unused_mut)] let mut iter = vec.into_iter(); @@ -179,7 +262,8 @@ fn test() { [Some(_x), None] => 2, [None, Some(y)] => 1, [None, _y..] => 3, - [_x.., Some(y), Some(z)] => y - z, + [_x.., Some(y), Some(z), None] => y - z, + [Some(ys)..] => ys.sum(), [] => 0, [..] => -1, ) @@ -189,10 +273,11 @@ fn test() { assert_eq!(test(vec![Some(0), None, None]), 4); assert_eq!(test(vec![Some(0), None]), 2); assert_eq!(test(vec![None, Some(0)]), 1); - assert_eq!(test(vec![Some(1), Some(2), Some(5), Some(14)]), -9); + assert_eq!(test(vec![Some(1), Some(2), Some(5), Some(14), None]), -9); + assert_eq!(test(vec![Some(1), Some(2), Some(3), Some(4)]), 10); assert_eq!(test(vec![None]), 3); assert_eq!(test(vec![]), 0); - assert_eq!(test(vec![Some(0)]), -1); + assert_eq!(test(vec![Some(0), None, Some(1)]), -1); // Test move out of pattern struct Foo; |