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Implement tuples using recursion #95914

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Apr 13, 2022
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Implement tuples using recursion #95914

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141 changes: 74 additions & 67 deletions library/core/src/tuple.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,68 +3,88 @@
use crate::cmp::Ordering::*;
use crate::cmp::*;

// macro for implementing n-ary tuple functions and operations
// Recursive macro for implementing n-ary tuple functions and operations
//
// Also provides implementations for tuples with lesser arity. For example, tuple_impls!(A B C)
// will implement everything for (A, B, C), (A, B) and (A,).
macro_rules! tuple_impls {
( $( ( $( $T:ident )+ ) )+ ) => {
$(
#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:PartialEq),+> PartialEq for ($($T,)+) where last_type!($($T,)+): ?Sized {
#[inline]
fn eq(&self, other: &($($T,)+)) -> bool {
$( ${ignore(T)} self.${index()} == other.${index()} )&&+
}
#[inline]
fn ne(&self, other: &($($T,)+)) -> bool {
$( ${ignore(T)} self.${index()} != other.${index()} )||+
}
// Stopping criteria (1-ary tuple)
($T:ident) => {
tuple_impls!(@impl $T);
};
// Running criteria (n-ary tuple, with n >= 2)
($T:ident $( $U:ident )+) => {
tuple_impls!($( $U )+);
tuple_impls!(@impl $T $( $U )+);
};
// "Private" internal implementation
(@impl $( $T:ident )+) => {
#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:PartialEq),+> PartialEq for ($($T,)+)
where
last_type!($($T,)+): ?Sized
{
#[inline]
fn eq(&self, other: &($($T,)+)) -> bool {
$( ${ignore(T)} self.${index()} == other.${index()} )&&+
}
#[inline]
fn ne(&self, other: &($($T,)+)) -> bool {
$( ${ignore(T)} self.${index()} != other.${index()} )||+
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:Eq),+> Eq for ($($T,)+) where last_type!($($T,)+): ?Sized {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:Eq),+> Eq for ($($T,)+)
where
last_type!($($T,)+): ?Sized
{}

#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:PartialOrd + PartialEq),+> PartialOrd for ($($T,)+)
where
last_type!($($T,)+): ?Sized
{
#[inline]
fn partial_cmp(&self, other: &($($T,)+)) -> Option<Ordering> {
lexical_partial_cmp!($( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn lt(&self, other: &($($T,)+)) -> bool {
lexical_ord!(lt, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn le(&self, other: &($($T,)+)) -> bool {
lexical_ord!(le, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn ge(&self, other: &($($T,)+)) -> bool {
lexical_ord!(ge, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn gt(&self, other: &($($T,)+)) -> bool {
lexical_ord!(gt, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:PartialOrd + PartialEq),+> PartialOrd for ($($T,)+)
where
last_type!($($T,)+): ?Sized
{
#[inline]
fn partial_cmp(&self, other: &($($T,)+)) -> Option<Ordering> {
lexical_partial_cmp!($( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn lt(&self, other: &($($T,)+)) -> bool {
lexical_ord!(lt, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn le(&self, other: &($($T,)+)) -> bool {
lexical_ord!(le, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn ge(&self, other: &($($T,)+)) -> bool {
lexical_ord!(ge, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[inline]
fn gt(&self, other: &($($T,)+)) -> bool {
lexical_ord!(gt, $( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:Ord),+> Ord for ($($T,)+) where last_type!($($T,)+): ?Sized {
#[inline]
fn cmp(&self, other: &($($T,)+)) -> Ordering {
lexical_cmp!($( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:Ord),+> Ord for ($($T,)+)
where
last_type!($($T,)+): ?Sized
{
#[inline]
fn cmp(&self, other: &($($T,)+)) -> Ordering {
lexical_cmp!($( ${ignore(T)} self.${index()}, other.${index()} ),+)
}
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:Default),+> Default for ($($T,)+) {
#[inline]
fn default() -> ($($T,)+) {
($({ let x: $T = Default::default(); x},)+)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<$($T:Default),+> Default for ($($T,)+) {
#[inline]
fn default() -> ($($T,)+) {
($({ let x: $T = Default::default(); x},)+)
}
)+
}
}
}

Expand Down Expand Up @@ -105,17 +125,4 @@ macro_rules! last_type {
($a:ident, $($rest_a:ident,)+) => { last_type!($($rest_a,)+) };
}

tuple_impls! {
(A)
(A B)
(A B C)
(A B C D)
(A B C D E)
(A B C D E F)
(A B C D E F G)
(A B C D E F G H)
(A B C D E F G H I)
(A B C D E F G H I J)
(A B C D E F G H I J K)
(A B C D E F G H I J K L)
}
tuple_impls!(A B C D E F G H I J K L);