core/
tuple.rs

1// See core/src/primitive_docs.rs for documentation.
2
3use crate::cmp::Ordering::{self, *};
4use crate::marker::{ConstParamTy_, StructuralPartialEq};
5use crate::ops::ControlFlow::{self, Break, Continue};
6
7// Recursive macro for implementing n-ary tuple functions and operations
8//
9// Also provides implementations for tuples with lesser arity. For example, tuple_impls!(A B C)
10// will implement everything for (A, B, C), (A, B) and (A,).
11macro_rules! tuple_impls {
12    // Stopping criteria (1-ary tuple)
13    ($T:ident) => {
14        tuple_impls!(@impl $T);
15    };
16    // Running criteria (n-ary tuple, with n >= 2)
17    ($T:ident $( $U:ident )+) => {
18        tuple_impls!($( $U )+);
19        tuple_impls!(@impl $T $( $U )+);
20    };
21    // "Private" internal implementation
22    (@impl $( $T:ident )+) => {
23        maybe_tuple_doc! {
24            $($T)+ @
25            #[stable(feature = "rust1", since = "1.0.0")]
26            #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
27            impl<$($T: [const] PartialEq),+> const PartialEq for ($($T,)+) {
28                #[inline]
29                fn eq(&self, other: &($($T,)+)) -> bool {
30                    $( ${ignore($T)} self.${index()} == other.${index()} )&&+
31                }
32                #[inline]
33                fn ne(&self, other: &($($T,)+)) -> bool {
34                    $( ${ignore($T)} self.${index()} != other.${index()} )||+
35                }
36            }
37        }
38
39        maybe_tuple_doc! {
40            $($T)+ @
41            #[stable(feature = "rust1", since = "1.0.0")]
42            #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
43            impl<$($T: [const] Eq),+> const Eq for ($($T,)+)
44            {}
45        }
46
47        maybe_tuple_doc! {
48            $($T)+ @
49            #[unstable(feature = "adt_const_params", issue = "95174")]
50            #[unstable_feature_bound(unsized_const_params)]
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($T)} T,)+)) -> Self {
153                    let ($($T,)+) = tuple;
154                    [$($T,)+]
155                }
156            }
157        }
158    }
159}
160
161// If this is a unary tuple, it adds a doc comment.
162// Otherwise, it hides the docs entirely.
163macro_rules! maybe_tuple_doc {
164    ($a:ident @ #[$meta:meta] $item:item) => {
165        #[doc(fake_variadic)]
166        #[doc = "This trait is implemented for tuples up to twelve items long."]
167        #[$meta]
168        $item
169    };
170    ($a:ident $($rest_a:ident)+ @ #[$meta:meta] $item:item) => {
171        #[doc(hidden)]
172        #[$meta]
173        $item
174    };
175}
176
177// Constructs an expression that performs a lexical ordering using method `$rel`.
178// The values are interleaved, so the macro invocation for
179// `(a1, a2, a3) < (b1, b2, b3)` would be `lexical_ord!(lt, opt_is_lt, a1, b1,
180// a2, b2, a3, b3)` (and similarly for `lexical_cmp`)
181//
182// `$chain_rel` is the chaining method from `PartialOrd` to use for all but the
183// final value, to produce better results for simple primitives.
184macro_rules! lexical_ord {
185    ($rel: ident, $chain_rel: ident, $a:expr, $b:expr, $($rest_a:expr, $rest_b:expr),+) => {{
186        match PartialOrd::$chain_rel(&$a, &$b) {
187            Break(val) => val,
188            Continue(()) => lexical_ord!($rel, $chain_rel, $($rest_a, $rest_b),+),
189        }
190    }};
191    ($rel: ident, $chain_rel: ident, $a:expr, $b:expr) => {
192        // Use the specific method for the last element
193        PartialOrd::$rel(&$a, &$b)
194    };
195}
196
197// Same parameter interleaving as `lexical_ord` above
198macro_rules! lexical_chain {
199    ($chain_rel: ident, $a:expr, $b:expr $(,$rest_a:expr, $rest_b:expr)*) => {{
200        PartialOrd::$chain_rel(&$a, &$b)?;
201        lexical_chain!($chain_rel $(,$rest_a, $rest_b)*)
202    }};
203    ($chain_rel: ident) => {
204        Continue(())
205    };
206}
207
208macro_rules! lexical_partial_cmp {
209    ($a:expr, $b:expr, $($rest_a:expr, $rest_b:expr),+) => {
210        match ($a).partial_cmp(&$b) {
211            Some(Equal) => lexical_partial_cmp!($($rest_a, $rest_b),+),
212            ordering => ordering
213        }
214    };
215    ($a:expr, $b:expr) => { ($a).partial_cmp(&$b) };
216}
217
218macro_rules! lexical_cmp {
219    ($a:expr, $b:expr, $($rest_a:expr, $rest_b:expr),+) => {
220        match ($a).cmp(&$b) {
221            Equal => lexical_cmp!($($rest_a, $rest_b),+),
222            ordering => ordering
223        }
224    };
225    ($a:expr, $b:expr) => { ($a).cmp(&$b) };
226}
227
228tuple_impls!(E D C B A Z Y X W V U T);
core/tuple.rs

core/
tuple.rs
