facet_core/impls_core/

tuple.rs

use core::{cmp::Ordering, fmt, mem};

use crate::{
    Characteristic, Facet, MarkerTraits, Repr, Shape, StructKind, StructType, Type, TypeNameOpts,
    UserType, VTableView, ValueVTable, types::field_in_type,
};

#[inline(always)]
pub fn write_type_name_list(
    f: &mut fmt::Formatter<'_>,
    opts: TypeNameOpts,
    open: &'static str,
    delimiter: &'static str,
    close: &'static str,
    shapes: &'static [&'static Shape],
) -> fmt::Result {
    f.pad(open)?;
    if let Some(opts) = opts.for_children() {
        for (index, shape) in shapes.iter().enumerate() {
            if index > 0 {
                f.pad(delimiter)?;
            }
            shape.write_type_name(f, opts)?;
        }
    } else {
        write!(f, "⋯")?;
    }
    f.pad(close)?;
    Ok(())
}

macro_rules! impl_facet_for_tuple {
    // Used to implement the next bigger tuple type, by taking the next typename & associated index
    // out of `remaining`, if it exists.
    {
        continue from ($($elems:ident.$idx:tt,)+),
        remaining ()
    } => {};
    {
        continue from ($($elems:ident.$idx:tt,)+),
        remaining ($next:ident.$nextidx:tt, $($remaining:ident.$remainingidx:tt,)*)
    } => {
        impl_facet_for_tuple! {
            impl ($($elems.$idx,)+ $next.$nextidx,),
            remaining ($($remaining.$remainingidx,)*)
        }
    };
    // Handle commas correctly for the debug implementation
    { debug on $f:ident { $first:stmt; } } => {
        write!($f, "(")?;
        $first
        write!($f, ",)")
    };
    { debug on $f:ident { $first:stmt; $($stmt:stmt;)+ } } => {
        write!($f, "(")?;
        $first
        $(
            write!($f, ", ")?;
            $stmt
        )+
        write!($f, ")")
    };
    // Common structure of eq, partial_ord & ord
    { ord on ($($elems:ident.$idx:tt,)+), $cmp:ident($a:ident, $b:ident), eq = $eq:expr } => {{
        $(
            unsafe {
                let ordering = (<VTableView<$elems>>::of().$cmp().unwrap_unchecked())(
                    &$a.$idx,
                    &$b.$idx,
                );

                if ordering != $eq {
                    return ordering;
                }
            }
        )+

        $eq
    }};
    // Actually generate the trait implementation, and keep the remaining possible elements around
    {
        impl ($($elems:ident.$idx:tt,)+),
        remaining ($($remaining:ident.$remainingidx:tt,)*)
    } => {
        unsafe impl<'a $(, $elems)+> Facet<'a> for ($($elems,)+)
        where
            $($elems: Facet<'a>,)+
        {
            const VTABLE: &'static ValueVTable = &const {
                ValueVTable::builder::<Self>()
                    .type_name(|f, opts| {
                        write_type_name_list(f, opts, "(", ", ", ")", &[$($elems::SHAPE),+])
                    })
                    .drop_in_place(|| Some(|data| unsafe { data.drop_in_place::<Self>() }))
                    .marker_traits(||
                        MarkerTraits::all()
                            $(.intersection($elems::SHAPE.vtable.marker_traits()))+
                    )
                    .debug(|| {
                        let elem_shapes = const { &[$($elems::SHAPE),+] };
                        if Characteristic::Debug.all(elem_shapes) {
                            Some(|value, f| {
                                impl_facet_for_tuple! {
                                    debug on f {
                                        $(
                                            (<VTableView<$elems>>::of().debug().unwrap())(
                                                &value.$idx,
                                                f,
                                            )?;
                                        )+
                                    }
                                }
                            })
                        } else {
                            None
                        }
                    })
                    .default_in_place(|| {
                        let elem_shapes = const { &[$($elems::SHAPE),+] };
                        if Characteristic::all_default(elem_shapes) {
                            Some(|mut dst| {
                                $(
                                    unsafe {
                                        (<VTableView<$elems>>::of().default_in_place().unwrap())(
                                            dst.field_uninit_at(mem::offset_of!(Self, $idx))
                                        );
                                    }
                                )+

                                unsafe { dst.assume_init() }
                            })
                        } else {
                            None
                        }
                    })
                    // .clone_into(|| {
                    //     let elem_shapes = const { &[$($elems::SHAPE),+] };
                    //     if Characteristic::Clone.all(elem_shapes) {
                    //         Some(|src, dst| {
                    //             $({
                    //                 let offset = mem::offset_of!(Self, $idx);
                    //                 unsafe {
                    //                     (<VTableView<$elems>>::of().clone_into().unwrap())(
                    //                         src.field(offset),
                    //                         dst.field_uninit_at(offset),
                    //                     );
                    //                 }
                    //             })+

                    //             unsafe { dst.assume_init() }
                    //         })
                    //     } else {
                    //         None
                    //     }
                    // })
                    .partial_eq(|| {
                        let elem_shapes = const { &[$($elems::SHAPE),+] };
                        if Characteristic::all_partial_eq(elem_shapes) {
                            Some(|a, b| impl_facet_for_tuple! {
                                ord on ($($elems.$idx,)+),
                                partial_eq(a, b),
                                eq = true
                            })
                        } else {
                            None
                        }
                    })
                    .partial_ord(|| {
                        let elem_shapes = const { &[$($elems::SHAPE),+] };
                        if Characteristic::all_partial_ord(elem_shapes) {
                            Some(|a, b| impl_facet_for_tuple! {
                                ord on ($($elems.$idx,)+),
                                partial_ord(a, b),
                                eq = Some(Ordering::Equal)
                            })
                        } else {
                            None
                        }
                    })
                    .ord(|| {
                        let elem_shapes = const { &[$($elems::SHAPE),+] };
                        if Characteristic::all_ord(elem_shapes) {
                            Some(|a, b| impl_facet_for_tuple! {
                                ord on ($($elems.$idx,)+),
                                ord(a, b),
                                eq = Ordering::Equal
                            })
                        } else {
                            None
                        }
                    })
                    .hash(|| {
                        let elem_shapes = const { &[$($elems::SHAPE),+] };
                        if Characteristic::all_hash(elem_shapes) {
                            Some(|value, hasher_this, hasher_write_fn| {
                                $(
                                    (<VTableView<$elems>>::of().hash().unwrap())(
                                        &value.$idx,
                                        hasher_this,
                                        hasher_write_fn,
                                    );
                                )+
                            })
                        } else {
                            None
                        }
                    })
                    .build()
            };

            const SHAPE: &'static Shape<'static> = &const {
                Shape::builder_for_sized::<Self>()
                    .type_identifier(const {
                        let fields = [
                            $(field_in_type!(Self, $idx),)+
                        ];
                        if fields.len() == 1 {
                            "(_)"
                        } else {
                            "(⋯)"
                        }
                    })
                    .ty(Type::User(UserType::Struct(StructType {
                        repr: Repr::default(),
                        kind: StructKind::Tuple,
                        fields: &const {[
                            $(field_in_type!(Self, $idx),)+
                        ]}
                    })))
                    .build()
            };
        }

        impl_facet_for_tuple! {
            continue from ($($elems.$idx,)+),
            remaining ($($remaining.$remainingidx,)*)
        }
    };
    // The entry point into this macro, all smaller tuple types get implemented as well.
    { ($first:ident.$firstidx:tt $(, $remaining:ident.$remainingidx:tt)* $(,)?) } => {
        impl_facet_for_tuple! {
            impl ($first.$firstidx,),
            remaining ($($remaining.$remainingidx,)*)
        }
    };
}

#[cfg(feature = "tuples-12")]
impl_facet_for_tuple! {
    (T0.0, T1.1, T2.2, T3.3, T4.4, T5.5, T6.6, T7.7, T8.8, T9.9, T10.10, T11.11)
}

#[cfg(not(feature = "tuples-12"))]
impl_facet_for_tuple! {
    (T0.0, T1.1, T2.2, T3.3)
}