diff options
Diffstat (limited to 'iter_patterns')
| -rw-r--r-- | iter_patterns/Cargo.toml | 9 | ||||
| -rw-r--r-- | iter_patterns/src/lib.rs | 261 |
2 files changed, 0 insertions, 270 deletions
diff --git a/iter_patterns/Cargo.toml b/iter_patterns/Cargo.toml deleted file mode 100644 index 5a4c45f..0000000 --- a/iter_patterns/Cargo.toml +++ /dev/null @@ -1,9 +0,0 @@ -[package] -name = "iter_patterns" -version = "0.1.0" -authors = ["Nadrieril <nadrieril@users.noreply.github.com>"] -license = "BSD-2-Clause" -edition = "2018" - -[lib] -doctest = false diff --git a/iter_patterns/src/lib.rs b/iter_patterns/src/lib.rs deleted file mode 100644 index 0672499..0000000 --- a/iter_patterns/src/lib.rs +++ /dev/null @@ -1,261 +0,0 @@ -#![feature(slice_patterns)] - -/* Destructure an iterator using the syntax of slice_patterns. - * Wraps the match body in `Some` if there was a match; returns - * `None` otherwise. - * Contrary to slice_patterns, this allows moving out - * of the iterator. - * A variable length pattern (`x..`) is only allowed as the last - * pattern, unless the iterator is double-ended. - * - * Example: - * ``` - * let vec = vec![Some(1), Some(2), None]; - * - * destructure_iter!(vec.into_iter(); - * [Some(x), y.., z] => { - * // x: usize - * // y: impl Iterator<Option<usize>> - * // z: Option<usize> - * } - * ) - * ``` - * -*/ -#[macro_export] -macro_rules! destructure_iter { - // Variable length pattern - (@match_forwards, $iter:expr, ($body:expr), $x:ident.., $($rest:tt)*) => { - $crate::destructure_iter!(@match_backwards, - $iter, - ({ - let $x = $iter; - $body - }), - $($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, - $iter, - ($body), - $($rest)* - ) - }; - // Single item pattern - (@match_forwards, $iter:expr, ($body:expr), $x:pat, $($rest:tt)*) => { - if let std::option::Option::Some($x) = $iter.next() { - $crate::destructure_iter!(@match_forwards, - $iter, - ($body), - $($rest)* - ) - } else { - std::option::Option::None - } - }; - // Single item pattern after a variable length one: declare reversed and take from the end - (@match_backwards, $iter:expr, ($body:expr), $x:pat, $($rest:tt)*) => { - $crate::destructure_iter!(@match_backwards, $iter, ( - if let std::option::Option::Some($x) = $iter.next_back() { - $body - } else { - std::option::Option::None - } - ), $($rest)*) - }; - - // Check no elements remain - (@match_forwards, $iter:expr, ($body:expr) $(,)*) => { - if $iter.next().is_some() { - std::option::Option::None - } else { - $body - } - }; - // After a variable length pattern, everything has already been consumed - (@match_backwards, $iter:expr, ($body:expr) $(,)*) => { - $body - }; - - ($iter:expr; [$($args:tt)*] => $body:expr) => { - { - #[allow(unused_mut)] - let mut iter = $iter; - $crate::destructure_iter!(@match_forwards, - iter, - (std::option::Option::Some($body)), - $($args)*, - ) - } - }; -} - -/* Pattern-match on a vec using the syntax of slice_patterns. - * Wraps the match body in `Some` if there was a match; returns - * `None` otherwise. - * A variable length pattern (`x..`) returns an iterator. - * - * Example: - * ``` - * let vec = vec![Some(1), Some(2), None]; - * - * match_vec!(vec; - * [Some(x), y.., z] => { - * // x: usize - * // y: impl Iterator<Option<usize>> - * // z: Option<usize> - * } - * [x, Some(0)] => { - * // x: Option<usize> - * }, - * [..] => { } - * ) - * ``` - * -*/ -#[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)*) => { - { - // Circumvent https://github.com/rust-lang/rust/issues/59803 - let is_all_variant = || $x.iter() - .all(|x| match x { - $variant(_) => true, - _ => false, - }); - is_all_variant() - } - && - $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; - // Match as references to decide which branch to take - // I think `match_default_bindings` should make this always work but - // there may be some patterns this doesn't capture. - #[allow(unused_variables, unreachable_patterns)] - match vec.as_slice() { - $( - $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(); - $crate::destructure_iter!(iter; [$($args)*] => $body) - } - )* - _ => std::option::Option::None, - } - } - }; -} - -#[test] -fn test() { - let test = |v: Vec<Option<isize>>| { - match_vec!(v.into_iter(); - [Some(_x), None, None] => 4, - [Some(_x), None] => 2, - [None, Some(y)] => 1, - [None, _y..] => 3, - [_x.., Some(y), Some(z), None] => y - z, - [Some(ys)..] => ys.sum(), - [] => 0, - [..] => -1, - ) - .unwrap() - }; - - 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), 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), None, Some(1)]), -1); - - // Test move out of pattern - struct Foo; - let _: (Foo, Foo) = match_vec!(vec![Some(Foo), Some(Foo)].into_iter(); - [Some(f1), Some(f2)] => (f1, f2), - ) - .unwrap(); -} |