```1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
```
``````// See src/libstd/primitive_docs.rs for documentation.

use crate::cmp::Ordering::*;
use crate::cmp::*;

// 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 {
// 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 )+) => {
maybe_tuple_doc! {
\$(\$T)+ @
#[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()} )||+
}
}
}

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

maybe_tuple_doc! {
\$(\$T)+ @
#[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()} ),+)
}
}
}

maybe_tuple_doc! {
\$(\$T)+ @
#[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()} ),+)
}
}
}

maybe_tuple_doc! {
\$(\$T)+ @
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_default_impls", issue = "87864")]
impl<\$(\$T: ~const Default),+> const Default for (\$(\$T,)+) {
#[inline]
fn default() -> (\$(\$T,)+) {
(\$({ let x: \$T = Default::default(); x},)+)
}
}
}
}
}

// If this is a unary tuple, it adds a doc comment.
// Otherwise, it hides the docs entirely.
macro_rules! maybe_tuple_doc {
(\$a:ident @ #[\$meta:meta] \$item:item) => {
#[doc = "This trait is implemented for tuples up to twelve items long."]
#[\$meta]
\$item
};
(\$a:ident \$(\$rest_a:ident)+ @ #[\$meta:meta] \$item:item) => {
#[doc(hidden)]
#[\$meta]
\$item
};
}

// Constructs an expression that performs a lexical ordering using method \$rel.
// The values are interleaved, so the macro invocation for
// `(a1, a2, a3) < (b1, b2, b3)` would be `lexical_ord!(lt, a1, b1, a2, b2,
// a3, b3)` (and similarly for `lexical_cmp`)
macro_rules! lexical_ord {
(\$rel: ident, \$a:expr, \$b:expr, \$(\$rest_a:expr, \$rest_b:expr),+) => {
if \$a != \$b { lexical_ord!(\$rel, \$a, \$b) }
else { lexical_ord!(\$rel, \$(\$rest_a, \$rest_b),+) }
};
(\$rel: ident, \$a:expr, \$b:expr) => { (\$a) . \$rel (& \$b) };
}

macro_rules! lexical_partial_cmp {
(\$a:expr, \$b:expr, \$(\$rest_a:expr, \$rest_b:expr),+) => {
match (\$a).partial_cmp(&\$b) {
Some(Equal) => lexical_partial_cmp!(\$(\$rest_a, \$rest_b),+),
ordering   => ordering
}
};
(\$a:expr, \$b:expr) => { (\$a).partial_cmp(&\$b) };
}

macro_rules! lexical_cmp {
(\$a:expr, \$b:expr, \$(\$rest_a:expr, \$rest_b:expr),+) => {
match (\$a).cmp(&\$b) {
Equal => lexical_cmp!(\$(\$rest_a, \$rest_b),+),
ordering   => ordering
}
};
(\$a:expr, \$b:expr) => { (\$a).cmp(&\$b) };
}

macro_rules! last_type {
(\$a:ident,) => { \$a };
(\$a:ident, \$(\$rest_a:ident,)+) => { last_type!(\$(\$rest_a,)+) };
}

tuple_impls!(E D C B A Z Y X W V U T);
``````