facet_core/impls_core/
tuple.rs

1use core::{fmt, mem};
2
3use crate::{
4    Characteristic, Facet, MarkerTraits, Repr, Shape, StructKind, StructType, Type, TypeNameOpts,
5    UserType, VTableView, ValueVTable, types::field_in_type,
6};
7
8#[inline(always)]
9pub fn write_type_name_list(
10    f: &mut fmt::Formatter<'_>,
11    opts: TypeNameOpts,
12    open: &'static str,
13    delimiter: &'static str,
14    close: &'static str,
15    shapes: &'static [&'static Shape],
16) -> fmt::Result {
17    f.pad(open)?;
18    if let Some(opts) = opts.for_children() {
19        for (index, shape) in shapes.iter().enumerate() {
20            if index > 0 {
21                f.pad(delimiter)?;
22            }
23            shape.write_type_name(f, opts)?;
24        }
25    } else {
26        write!(f, "…")?;
27    }
28    f.pad(close)?;
29    Ok(())
30}
31
32macro_rules! impl_facet_for_tuple {
33    // Used to implement the next bigger tuple type, by taking the next typename & associated index
34    // out of `remaining`, if it exists.
35    {
36        continue from ($($elems:ident.$idx:tt,)+),
37        remaining ()
38    } => {};
39    {
40        continue from ($($elems:ident.$idx:tt,)+),
41        remaining ($next:ident.$nextidx:tt, $($remaining:ident.$remainingidx:tt,)*)
42    } => {
43        impl_facet_for_tuple! {
44            impl ($($elems.$idx,)+ $next.$nextidx,),
45            remaining ($($remaining.$remainingidx,)*)
46        }
47    };
48    // Handle commas correctly for the debug implementation
49    { debug on $f:ident { $first:stmt; } } => {
50        write!($f, "(")?;
51        $first
52        write!($f, ",)")
53    };
54    // Actually generate the trait implementation, and keep the remaining possible elements around
55    {
56        impl ($($elems:ident.$idx:tt,)+),
57        remaining ($($remaining:ident.$remainingidx:tt,)*)
58    } => {
59        unsafe impl<'a $(, $elems)+> Facet<'a> for ($($elems,)+)
60        where
61            $($elems: Facet<'a>,)+
62        {
63
64            const SHAPE: &'static Shape = &const {
65                Shape::builder_for_sized::<Self>()
66                    .vtable(
67                        ValueVTable::builder::<Self>()
68                            .type_name(|f, opts| {
69                                write_type_name_list(f, opts, "(", ", ", ")", &[$($elems::SHAPE),+])
70                            })
71                            .drop_in_place(Some(|data| unsafe { data.drop_in_place::<Self>() }))
72                            .marker_traits(                                MarkerTraits::all()
73                                    $(.intersection($elems::SHAPE.vtable.marker_traits()))+
74                            )
75                            .default_in_place({
76                                let elem_shapes = const { &[$($elems::SHAPE),+] };
77                                if Characteristic::all_default(elem_shapes) {
78                                    Some(|mut dst| {
79                                        $(
80                                            unsafe {
81                                                (<VTableView<$elems>>::of().default_in_place().unwrap())(
82                                                    dst.field_uninit_at(mem::offset_of!(Self, $idx))
83                                                );
84                                            }
85                                        )+
86
87                                        unsafe { dst.assume_init().into() }
88                                    })
89                                } else {
90                                    None
91                                }
92                            })
93                            .build()
94                    )
95                    .type_identifier(const {
96                        let fields = [
97                            $(field_in_type!(Self, $idx),)+
98                        ];
99                        if fields.len() == 1 {
100                            "(_)"
101                        } else {
102                            "(…)"
103                        }
104                    })
105                    .ty(Type::User(UserType::Struct(StructType {
106                        repr: Repr::default(),
107                        kind: StructKind::Tuple,
108                        fields: &const {[
109                            $(field_in_type!(Self, $idx),)+
110                        ]}
111                    })))
112                    .build()
113            };
114        }
115
116        impl_facet_for_tuple! {
117            continue from ($($elems.$idx,)+),
118            remaining ($($remaining.$remainingidx,)*)
119        }
120    };
121    // The entry point into this macro, all smaller tuple types get implemented as well.
122    { ($first:ident.$firstidx:tt $(, $remaining:ident.$remainingidx:tt)* $(,)?) } => {
123        impl_facet_for_tuple! {
124            impl ($first.$firstidx,),
125            remaining ($($remaining.$remainingidx,)*)
126        }
127    };
128}
129
130#[cfg(feature = "tuples-12")]
131impl_facet_for_tuple! {
132    (T0.0, T1.1, T2.2, T3.3, T4.4, T5.5, T6.6, T7.7, T8.8, T9.9, T10.10, T11.11)
133}
134
135#[cfg(not(feature = "tuples-12"))]
136impl_facet_for_tuple! {
137    (T0.0, T1.1, T2.2, T3.3)
138}
facet_core/impls_core/tuple.rs

facet_core/impls_core/
tuple.rs
