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authorNadrieril2019-03-27 01:35:01 +0100
committerNadrieril2019-03-27 01:35:32 +0100
commit345e9d23f8b8e6e7d5fb6eb3071b46c7f6fba420 (patch)
tree17b89f8ee12cc918db39fbd413effad6fa657ffb /iter_patterns
parentf358a9b1a7b05e300cdab41f2903187227564aa9 (diff)
Integrate the special patterns from match_children!() into iter_patterns
Considerably simplifies parser macros
Diffstat (limited to '')
-rw-r--r--iter_patterns/src/lib.rs95
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;