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Merged
merged 2 commits into from
Mar 10, 2022
Merged

Improve extension_trait! #1005

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21fb4ac
Remove two useless rules from `extension_trait!`.
nnethercote Mar 10, 2022
db7c194
Move the `extension_trait!` accumulator to the end of the rules.
nnethercote Mar 10, 2022
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32 changes: 12 additions & 20 deletions src/utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -281,7 +281,7 @@ macro_rules! extension_trait {
#[cfg(feature = "docs")]
#[doc = $doc]
pub trait $name {
extension_trait!(@doc () $($body_base)* $($body_ext)*);
extension_trait!(@doc [$($body_base)* $($body_ext)*] -> []);
}

// When not rendering docs, re-export the base trait from the futures crate.
Expand All @@ -291,7 +291,7 @@ macro_rules! extension_trait {
// The extension trait that adds methods to any type implementing the base trait.
#[doc = $doc_ext]
pub trait $ext: $name {
extension_trait!(@ext () $($body_ext)*);
extension_trait!(@ext [$($body_ext)*] -> []);
}

// Blanket implementation of the extension trait for any type implementing the base trait.
Expand All @@ -302,32 +302,24 @@ macro_rules! extension_trait {
};

// Parse the return type in an extension method.
(@doc ($($head:tt)*) -> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*) => {
extension_trait!(@doc ($($head)* -> owned::ImplFuture<$out>) $($tail)*);
(@doc [-> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@doc [$($tail)*] -> [$($accum)* -> owned::ImplFuture<$out>]);
};
(@ext ($($head:tt)*) -> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*) => {
extension_trait!(@ext ($($head)* -> $f) $($tail)*);
};

// Parse the return type in an extension method.
(@doc ($($head:tt)*) -> impl Future<Output = $out:ty> + $lt:lifetime [$f:ty] $($tail:tt)*) => {
extension_trait!(@doc ($($head)* -> borrowed::ImplFuture<$lt, $out>) $($tail)*);
};
(@ext ($($head:tt)*) -> impl Future<Output = $out:ty> + $lt:lifetime [$f:ty] $($tail:tt)*) => {
extension_trait!(@ext ($($head)* -> $f) $($tail)*);
(@ext [-> impl Future<Output = $out:ty> $(+ $lt:lifetime)? [$f:ty] $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@ext [$($tail)*] -> [$($accum)* -> $f]);
};

// Parse a token.
(@doc ($($head:tt)*) $token:tt $($tail:tt)*) => {
extension_trait!(@doc ($($head)* $token) $($tail)*);
(@doc [$token:tt $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@doc [$($tail)*] -> [$($accum)* $token]);
};
(@ext ($($head:tt)*) $token:tt $($tail:tt)*) => {
extension_trait!(@ext ($($head)* $token) $($tail)*);
(@ext [$token:tt $($tail:tt)*] -> [$($accum:tt)*]) => {
extension_trait!(@ext [$($tail)*] -> [$($accum)* $token]);
};

// Handle the end of the token list.
(@doc ($($head:tt)*)) => { $($head)* };
(@ext ($($head:tt)*)) => { $($head)* };
(@doc [] -> [$($accum:tt)*]) => { $($accum)* };
(@ext [] -> [$($accum:tt)*]) => { $($accum)* };

// Parse imports at the beginning of the macro.
($import:item $($tail:tt)*) => {
Expand Down