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Implement Hash for tuples of up to arity 12. Also change the style to be consistent with core::tuple #16033

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Merged
merged 1 commit into from
Jul 29, 2014
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Implement Hash for tuples of up to arity 12. Also change the style to be consistent with core::tuple #16033

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29 changes: 18 additions & 11 deletions src/libcollections/hash/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -155,29 +155,36 @@ macro_rules! impl_hash_tuple(
}
);

($A:ident $($B:ident)*) => (
impl<
S: Writer,
$A: Hash<S> $(, $B: Hash<S>)*
> Hash<S> for ($A, $($B),*) {
( $($name:ident)+) => (
impl<S: Writer, $($name: Hash<S>),*> Hash<S> for ($($name,)*) {
#[allow(uppercase_variables)]
#[inline]
fn hash(&self, state: &mut S) {
match *self {
(ref $A, $(ref $B),*) => {
$A.hash(state);
($(ref $name,)*) => {
$(
$B.hash(state);
$name.hash(state);
)*
}
}
}
}

impl_hash_tuple!($($B)*)
);
)

impl_hash_tuple!(a0 a1 a2 a3 a4 a5 a6 a7)
impl_hash_tuple!()
impl_hash_tuple!(A)
impl_hash_tuple!(A B)
impl_hash_tuple!(A B C)
impl_hash_tuple!(A B C D)
impl_hash_tuple!(A B C D E)
impl_hash_tuple!(A B C D E F)
impl_hash_tuple!(A B C D E F G)
impl_hash_tuple!(A B C D E F G H)
impl_hash_tuple!(A B C D E F G H I)
impl_hash_tuple!(A B C D E F G H I J)
impl_hash_tuple!(A B C D E F G H I J K)
impl_hash_tuple!(A B C D E F G H I J K L)
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Why move from the one line invocation to 12 lines of invocations?

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Maybe this is really silly, but with one line invocation and a recursive macro it ends up coming out like:

impl Trait for (A, B, C, D)
impl Trait for (B, C, D)
impl Trait for (C, D)
impl Trait for (D,)

I want it to come out

impl Trait for (A,)
impl Trait for (A, B)
impl Trait for (A, B, C)
impl Trait for (A, B, C, D)

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In that case, could the recursive macro invocation be placed first?

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That will help a bit, but it will still expand to

impl Trait for (D,)
impl Trait for (C, D)
impl Trait for (B, C, D)
impl Trait for (A, B, C, D)

I was mostly doing it so that the implementation for a 1-tuple would use "A", for a 2-tuple would use "A, B", for a 3-tuple would use "A, B, C", etc. Maybe this is too minor to worry about.

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Oh well :(


impl<'a, S: Writer, T: Hash<S>> Hash<S> for &'a [T] {
#[inline]
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