core/
tuple.rs

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1// See core/src/primitive_docs.rs for documentation.
2
3use crate::cmp::Ordering::{self, *};
4use crate::marker::{ConstParamTy_, StructuralPartialEq, UnsizedConstParamTy};
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            impl<$($T: PartialEq),+> PartialEq for ($($T,)+) {
27                #[inline]
28                fn eq(&self, other: &($($T,)+)) -> bool {
29                    $( ${ignore($T)} self.${index()} == other.${index()} )&&+
30                }
31                #[inline]
32                fn ne(&self, other: &($($T,)+)) -> bool {
33                    $( ${ignore($T)} self.${index()} != other.${index()} )||+
34                }
35            }
36        }
37
38        maybe_tuple_doc! {
39            $($T)+ @
40            #[stable(feature = "rust1", since = "1.0.0")]
41            impl<$($T: Eq),+> Eq for ($($T,)+)
42            {}
43        }
44
45        maybe_tuple_doc! {
46            $($T)+ @
47            #[unstable(feature = "adt_const_params", issue = "95174")]
48            impl<$($T: ConstParamTy_),+> ConstParamTy_ for ($($T,)+)
49            {}
50        }
51
52        maybe_tuple_doc! {
53            $($T)+ @
54            #[unstable(feature = "unsized_const_params", issue = "95174")]
55            impl<$($T: UnsizedConstParamTy),+> UnsizedConstParamTy for ($($T,)+)
56            {}
57        }
58
59        maybe_tuple_doc! {
60            $($T)+ @
61            #[unstable(feature = "structural_match", issue = "31434")]
62            impl<$($T),+> StructuralPartialEq for ($($T,)+)
63            {}
64        }
65
66        maybe_tuple_doc! {
67            $($T)+ @
68            #[stable(feature = "rust1", since = "1.0.0")]
69            impl<$($T: PartialOrd),+> PartialOrd for ($($T,)+)
70            {
71                #[inline]
72                fn partial_cmp(&self, other: &($($T,)+)) -> Option<Ordering> {
73                    lexical_partial_cmp!($( ${ignore($T)} self.${index()}, other.${index()} ),+)
74                }
75                #[inline]
76                fn lt(&self, other: &($($T,)+)) -> bool {
77                    lexical_ord!(lt, __chaining_lt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
78                }
79                #[inline]
80                fn le(&self, other: &($($T,)+)) -> bool {
81                    lexical_ord!(le, __chaining_le, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
82                }
83                #[inline]
84                fn ge(&self, other: &($($T,)+)) -> bool {
85                    lexical_ord!(ge, __chaining_ge, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
86                }
87                #[inline]
88                fn gt(&self, other: &($($T,)+)) -> bool {
89                    lexical_ord!(gt, __chaining_gt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
90                }
91                #[inline]
92                fn __chaining_lt(&self, other: &($($T,)+)) -> ControlFlow<bool> {
93                    lexical_chain!(__chaining_lt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
94                }
95                #[inline]
96                fn __chaining_le(&self, other: &($($T,)+)) -> ControlFlow<bool> {
97                    lexical_chain!(__chaining_le, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
98                }
99                #[inline]
100                fn __chaining_gt(&self, other: &($($T,)+)) -> ControlFlow<bool> {
101                    lexical_chain!(__chaining_gt, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
102                }
103                #[inline]
104                fn __chaining_ge(&self, other: &($($T,)+)) -> ControlFlow<bool> {
105                    lexical_chain!(__chaining_ge, $( ${ignore($T)} self.${index()}, other.${index()} ),+)
106                }
107            }
108        }
109
110        maybe_tuple_doc! {
111            $($T)+ @
112            #[stable(feature = "rust1", since = "1.0.0")]
113            impl<$($T: Ord),+> Ord for ($($T,)+)
114            {
115                #[inline]
116                fn cmp(&self, other: &($($T,)+)) -> Ordering {
117                    lexical_cmp!($( ${ignore($T)} self.${index()}, other.${index()} ),+)
118                }
119            }
120        }
121
122        maybe_tuple_doc! {
123            $($T)+ @
124            #[stable(feature = "rust1", since = "1.0.0")]
125            impl<$($T: Default),+> Default for ($($T,)+) {
126                #[inline]
127                fn default() -> ($($T,)+) {
128                    ($({ let x: $T = Default::default(); x},)+)
129                }
130            }
131        }
132
133        maybe_tuple_doc! {
134            $($T)+ @
135            #[stable(feature = "array_tuple_conv", since = "1.71.0")]
136            impl<T> From<[T; ${count($T)}]> for ($(${ignore($T)} T,)+) {
137                #[inline]
138                #[allow(non_snake_case)]
139                fn from(array: [T; ${count($T)}]) -> Self {
140                    let [$($T,)+] = array;
141                    ($($T,)+)
142                }
143            }
144        }
145
146        maybe_tuple_doc! {
147            $($T)+ @
148            #[stable(feature = "array_tuple_conv", since = "1.71.0")]
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
