Macro path_tuple

macro_rules! path_tuple {
    () => { ... };
    ($($expr:expr),* $(,)?) => { ... };
}

For manually constructing a FieldPathSet to access up to 64 fields.

Example

This demonstrates how to construct a FieldPathSet to access over 8 fields.

use structural::{ FieldPathSet, StructuralExt, path_tuple, ts };

let this = ('a', 'b', 3, 5, "foo", "bar", false, true, Some(8), Some(13));

// If you access up to 8 fields with `FieldPathSet::large(path_tuple!(....))`,
// then accessor methods return non-nested tuples.
{
    let path8 = FieldPathSet::large(path_tuple!(
        ts!(0), ts!(1), ts!(2), ts!(3), ts!(4), ts!(5), ts!(6), ts!(7)
    ));
    assert_eq!(
        this.fields(path8),
        (&'a', &'b', &3, &5, &"foo", &"bar", &false, &true)
    );
}

// If you access more than 8 fields with `FieldPathSet::large(path_tuple!(....))`,
// then accessor methods return nested tuples. 8 elements each.
{
    let path10 = FieldPathSet::large(path_tuple!(
        ts!(0), ts!(1), ts!(2), ts!(3), ts!(4), ts!(5), ts!(6), ts!(7),
        ts!(8), ts!(9),
    ));
    assert_eq!(
        this.fields(path10),
        (
            (&'a', &'b', &3, &5, &"foo", &"bar", &false, &true),
            (&Some(8), &Some(13))
        ),
    );
    assert_eq!(
        this.cloned_fields(path10),
        (
            ('a', 'b', 3, 5, "foo", "bar", false, true),
            (Some(8), Some(13))
        ),
    );
}

Example

This demnstrates what the macro expands into:

use structural::path_tuple;

assert_eq!( path_tuple!(), () );

assert_eq!( path_tuple!(1), ((1,),) );

assert_eq!( path_tuple!(1, 2), ((1, 2),) );

assert_eq!(
    path_tuple!(0, 1, 2, 3, 4, 5, 6, 7),
    ((0, 1, 2, 3, 4, 5, 6, 7),),
);

assert_eq!(
    path_tuple!(0, 1, 2, 3, 4, 5, 6, 7, 8),
    ((0, 1, 2, 3, 4, 5, 6, 7), (8,)),
);

assert_eq!(
    path_tuple!(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15),
    (
        (0, 1, 2, 3, 4, 5, 6, 7),
        (8, 9, 10, 11, 12, 13, 14, 15),
    ),
);

assert_eq!(
    path_tuple!(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16),
    (
        (0, 1, 2, 3, 4, 5, 6, 7),
        (8, 9, 10, 11, 12, 13, 14, 15),
        (16,),
    )
);