core/
tuple.rs

1// See core/src/primitive_docs.rs for documentation.
2
3use crate::cell::CloneFromCell;
4use crate::cmp::Ordering::{self, *};
5use crate::marker::{ConstParamTy_, StructuralPartialEq};
6use crate::ops::ControlFlow::{self, Break, Continue};
7
8// Recursive macro for implementing n-ary tuple functions and operations
9//
10// Also provides implementations for tuples with lesser arity. For example, tuple_impls!(A B C)
11// will implement everything for (A, B, C), (A, B) and (A,).
12macro_rules! tuple_impls {
13    // Stopping criteria (1-ary tuple)
14    ($T:ident) => {
15        tuple_impls!(@impl $T);
16    };
17    // Running criteria (n-ary tuple, with n >= 2)
18    ($T:ident $( $U:ident )+) => {
19        tuple_impls!($( $U )+);
20        tuple_impls!(@impl $T $( $U )+);
21    };
22    // "Private" internal implementation
23    (@impl $( $T:ident )+) => {
24        maybe_tuple_doc! {
25            $($T)+ @
26            #[stable(feature = "rust1", since = "1.0.0")]
27            #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
28            impl<$($T: [const] PartialEq),+> const PartialEq for ($($T,)+) {
29                #[inline]
30                fn eq(&self, other: &($($T,)+)) -> bool {
31                    $( ${ignore($T)} self.${index()} == other.${index()} )&&+
32                }
33                #[inline]
34                fn ne(&self, other: &($($T,)+)) -> bool {
35                    $( ${ignore($T)} self.${index()} != other.${index()} )||+
36                }
37            }
38        }
39
40        maybe_tuple_doc! {
41            $($T)+ @
42            #[stable(feature = "rust1", since = "1.0.0")]
43            #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
44            impl<$($T: [const] Eq),+> const Eq for ($($T,)+)
45            {}
46        }
47
48        maybe_tuple_doc! {
49            $($T)+ @
50            #[unstable(feature = "min_adt_const_params", issue = "154042")]
51            impl<$($T: ConstParamTy_),+> ConstParamTy_ for ($($T,)+)
52            {}
53        }
54
55        maybe_tuple_doc! {
56            $($T)+ @
57            #[unstable(feature = "structural_match", issue = "31434")]
58            impl<$($T),+> StructuralPartialEq for ($($T,)+)
59            {}
60        }
61
62        maybe_tuple_doc! {
63            $($T)+ @
64            #[stable(feature = "rust1", since = "1.0.0")]
65            #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
66            impl<$($T: [const] PartialOrd),+> const PartialOrd for ($($T,)+)
67            {
68                #[inline]
69                fn partial_cmp(&self, other: &($($T,)+)) -> Option<Ordering> {
70                    lexical_partial_cmp!($( ${ignore($T)} self.${index()}, other.${index()} ),+)
71                }
72                #[inline]
73                fn lt(&self, other: &($($T,)+)) -> bool {
74                    lexical_ord!(lt, __chaining_lt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
75                }
76                #[inline]
77                fn le(&self, other: &($($T,)+)) -> bool {
78                    lexical_ord!(le, __chaining_le, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
79                }
80                #[inline]
81                fn ge(&self, other: &($($T,)+)) -> bool {
82                    lexical_ord!(ge, __chaining_ge, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
83                }
84                #[inline]
85                fn gt(&self, other: &($($T,)+)) -> bool {
86                    lexical_ord!(gt, __chaining_gt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
87                }
88                #[inline]
89                fn __chaining_lt(&self, other: &($($T,)+)) -> ControlFlow<bool> {
90                    lexical_chain!(__chaining_lt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
91                }
92                #[inline]
93                fn __chaining_le(&self, other: &($($T,)+)) -> ControlFlow<bool> {
94                    lexical_chain!(__chaining_le, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
95                }
96                #[inline]
97                fn __chaining_gt(&self, other: &($($T,)+)) -> ControlFlow<bool> {
98                    lexical_chain!(__chaining_gt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
99                }
100                #[inline]
101                fn __chaining_ge(&self, other: &($($T,)+)) -> ControlFlow<bool> {
102                    lexical_chain!(__chaining_ge, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
103                }
104            }
105        }
106
107        maybe_tuple_doc! {
108            $($T)+ @
109            #[stable(feature = "rust1", since = "1.0.0")]
110            #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
111            impl<$($T: [const] Ord),+> const Ord for ($($T,)+)
112            {
113                #[inline]
114                fn cmp(&self, other: &($($T,)+)) -> Ordering {
115                    lexical_cmp!($( ${ignore($T)} self.${index()}, other.${index()} ),+)
116                }
117            }
118        }
119
120        maybe_tuple_doc! {
121            $($T)+ @
122            #[stable(feature = "rust1", since = "1.0.0")]
123            impl<$($T: Default),+> Default for ($($T,)+) {
124                #[inline]
125                fn default() -> ($($T,)+) {
126                    ($({ let x: $T = Default::default(); x},)+)
127                }
128            }
129        }
130
131        maybe_tuple_doc! {
132            $($T)+ @
133            #[stable(feature = "array_tuple_conv", since = "1.71.0")]
134            // can't do const From due to https://github.com/rust-lang/rust/issues/144280
135            impl<T> From<[T; ${count($T)}]> for ($(${ignore($T)} T,)+) {
136                #[inline]
137                #[allow(non_snake_case)]
138                fn from(array: [T; ${count($T)}]) -> Self {
139                    let [$($T,)+] = array;
140                    ($($T,)+)
141                }
142            }
143        }
144
145        maybe_tuple_doc! {
146            $($T)+ @
147            #[stable(feature = "array_tuple_conv", since = "1.71.0")]
148            // can't do const From due to https://github.com/rust-lang/rust/issues/144280
149            impl<T> From<($(${ignore($T)} T,)+)> for [T; ${count($T)}] {
150                #[inline]
151                #[allow(non_snake_case)]
152                fn from(tuple: ($(${ignore($T)} T,)+)) -> Self {
153                    let ($($T,)+) = tuple;
154                    [$($T,)+]
155                }
156            }
157        }
158
159        maybe_tuple_doc! {
160            $($T)+ @
161            // SAFETY: tuples introduce no additional indirection, so they can be copied whenever T
162            // can.
163            #[unstable(feature = "cell_get_cloned", issue = "145329")]
164            unsafe impl<$($T: CloneFromCell),+> CloneFromCell for ($($T,)+)
165            {}
166        }
167    }
168}
169
170// If this is a unary tuple, it adds a doc comment.
171// Otherwise, it hides the docs entirely.
172macro_rules! maybe_tuple_doc {
173    ($a:ident @ #[$meta:meta] $item:item) => {
174        #[doc(fake_variadic)]
175        #[doc = "This trait is implemented for tuples up to twelve items long."]
176        #[$meta]
177        $item
178    };
179    ($a:ident $($rest_a:ident)+ @ #[$meta:meta] $item:item) => {
180        #[doc(hidden)]
181        #[$meta]
182        $item
183    };
184}
185
186// Constructs an expression that performs a lexical ordering using method `$rel`.
187// The values are interleaved, so the macro invocation for
188// `(a1, a2, a3) < (b1, b2, b3)` would be `lexical_ord!(lt, opt_is_lt, a1, b1,
189// a2, b2, a3, b3)` (and similarly for `lexical_cmp`)
190//
191// `$chain_rel` is the chaining method from `PartialOrd` to use for all but the
192// final value, to produce better results for simple primitives.
193macro_rules! lexical_ord {
194    ($rel: ident, $chain_rel: ident, $a:expr, $b:expr, $($rest_a:expr, $rest_b:expr),+) => {{
195        match PartialOrd::$chain_rel(&$a, &$b) {
196            Break(val) => val,
197            Continue(()) => lexical_ord!($rel, $chain_rel, $($rest_a, $rest_b),+),
198        }
199    }};
200    ($rel: ident, $chain_rel: ident, $a:expr, $b:expr) => {
201        // Use the specific method for the last element
202        PartialOrd::$rel(&$a, &$b)
203    };
204}
205
206// Same parameter interleaving as `lexical_ord` above
207macro_rules! lexical_chain {
208    ($chain_rel: ident, $a:expr, $b:expr $(,$rest_a:expr, $rest_b:expr)*) => {{
209        PartialOrd::$chain_rel(&$a, &$b)?;
210        lexical_chain!($chain_rel $(,$rest_a, $rest_b)*)
211    }};
212    ($chain_rel: ident) => {
213        Continue(())
214    };
215}
216
217macro_rules! lexical_partial_cmp {
218    ($a:expr, $b:expr, $($rest_a:expr, $rest_b:expr),+) => {
219        match ($a).partial_cmp(&$b) {
220            Some(Equal) => lexical_partial_cmp!($($rest_a, $rest_b),+),
221            ordering => ordering
222        }
223    };
224    ($a:expr, $b:expr) => { ($a).partial_cmp(&$b) };
225}
226
227macro_rules! lexical_cmp {
228    ($a:expr, $b:expr, $($rest_a:expr, $rest_b:expr),+) => {
229        match ($a).cmp(&$b) {
230            Equal => lexical_cmp!($($rest_a, $rest_b),+),
231            ordering => ordering
232        }
233    };
234    ($a:expr, $b:expr) => { ($a).cmp(&$b) };
235}
236
237tuple_impls!(E D C B A Z Y X W V U T);
core/tuple.rs

core/
tuple.rs
