rust/tests/ui/macros/rfc-3086-metavar-expr/count-and-length-are-distinct.rs

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// run-pass
#![feature(macro_metavar_expr)]
fn main() {
macro_rules! one_nested_count_and_length {
( $( [ $( $l:literal ),* ] ),* ) => {
[
// outer-most repetition
$(
// inner-most repetition
$(
${ignore(l)} ${index()}, ${length()},
)*
${count(l)}, ${index()}, ${length()},
)*
${count(l)},
]
};
}
assert_eq!(
one_nested_count_and_length!(["foo"], ["bar", "baz"]),
[
// # ["foo"]
// ## inner-most repetition (first iteration)
//
// `index` is 0 because this is the first inner-most iteration.
// `length` is 1 because there is only one inner-most repetition, "foo".
0, 1,
// ## outer-most repetition (first iteration)
//
// `count` is 1 because of "foo", i,e, `$l` has only one repetition,
// `index` is 0 because this is the first outer-most iteration.
// `length` is 2 because there are 2 outer-most repetitions, ["foo"] and ["bar", "baz"]
1, 0, 2,
// # ["bar", "baz"]
// ## inner-most repetition (first iteration)
//
// `index` is 0 because this is the first inner-most iteration
// `length` is 2 because there are repetitions, "bar" and "baz"
0, 2,
// ## inner-most repetition (second iteration)
//
// `index` is 1 because this is the second inner-most iteration
// `length` is 2 because there are repetitions, "bar" and "baz"
1, 2,
// ## outer-most repetition (second iteration)
//
// `count` is 2 because of "bar" and "baz", i,e, `$l` has two repetitions,
// `index` is 1 because this is the second outer-most iteration
// `length` is 2 because there are 2 outer-most repetitions, ["foo"] and ["bar", "baz"]
2, 1, 2,
// # last count
// Because there are a total of 3 repetitions of `$l`, "foo", "bar" and "baz"
3,
]
);
// Based on the above explanation, the following macros should be straightforward
// Grouped from the outer-most to the inner-most
macro_rules! three_nested_count {
( $( { $( [ $( ( $( $i:ident )* ) )* ] )* } )* ) => {
&[
$( $( $(
&[
${ignore(i)} ${count(i, 0)},
][..],
)* )* )*
$( $(
&[
${ignore(i)} ${count(i, 0)},
${ignore(i)} ${count(i, 1)},
][..],
)* )*
$(
&[
${ignore(i)} ${count(i, 0)},
${ignore(i)} ${count(i, 1)},
${ignore(i)} ${count(i, 2)},
][..],
)*
&[
${count(i, 0)},
${count(i, 1)},
${count(i, 2)},
${count(i, 3)},
][..]
][..]
}
}
assert_eq!(
three_nested_count!(
{
[ (a b c) (d e f) ]
[ (g h) (i j k l m) ]
[ (n) ]
}
{
[ (o) (p q) (r s) ]
[ (t u v w x y z) ]
}
),
&[
// a b c
&[3][..],
// d e f
&[3][..],
// g h
&[2][..],
// i j k l m
&[5][..],
// n
&[1][..],
// o
&[1][..],
// p q
&[2][..],
// r s
&[2][..],
// t u v w x y z
&[7][..],
// (a b c) (d e f)
&[2, 6][..],
// (g h) (i j k l m)
&[2, 7][..],
// (n)
&[1, 1][..],
// (o) (p q) (r s)
&[3, 5][..],
// (t u v w x y z)
&[1, 7][..],
// [ (a b c) (d e f) ]
// [ (g h) (i j k l m) ]
// [ (n) ]
&[3, 5, 14][..],
// [ (o) (p q) (r s) ]
// [ (t u v w x y z) ]
&[2, 4, 12][..],
// {
// [ (a b c) (d e f) ]
// [ (g h) (i j k l m) ]
// [ (n) ]
// }
// {
// [ (o) (p q) (r s) ]
// [ (t u v w x y z) ]
// }
&[2, 5, 9, 26][..]
][..]
);
// Grouped from the outer-most to the inner-most
macro_rules! three_nested_length {
( $( { $( [ $( ( $( $i:ident )* ) )* ] )* } )* ) => {
&[
$( $( $( $(
&[
${ignore(i)} ${length(3)},
${ignore(i)} ${length(2)},
${ignore(i)} ${length(1)},
${ignore(i)} ${length(0)},
][..],
)* )* )* )*
$( $( $(
&[
${ignore(i)} ${length(2)},
${ignore(i)} ${length(1)},
${ignore(i)} ${length(0)},
][..],
)* )* )*
$( $(
&[
${ignore(i)} ${length(1)},
${ignore(i)} ${length(0)},
][..],
)* )*
$(
&[
${ignore(i)} ${length(0)},
][..],
)*
][..]
}
}
assert_eq!(
three_nested_length!(
{
[ (a b c) (d e f) ]
[ (g h) (i j k l m) ]
[ (n) ]
}
{
[ (o) (p q) (r s) ]
[ (t u v w x y z) ]
}
),
&[
// a b c
&[2, 3, 2, 3][..], &[2, 3, 2, 3][..], &[2, 3, 2, 3][..],
// d e f
&[2, 3, 2, 3][..], &[2, 3, 2, 3][..], &[2, 3, 2, 3][..],
// g h
&[2, 3, 2, 2][..], &[2, 3, 2, 2][..],
// i j k l m
&[2, 3, 2, 5][..], &[2, 3, 2, 5][..], &[2, 3, 2, 5][..], &[2, 3, 2, 5][..],
&[2, 3, 2, 5][..],
// n
&[2, 3, 1, 1][..],
// o
&[2, 2, 3, 1][..],
// p q
&[2, 2, 3, 2][..], &[2, 2, 3, 2][..],
// r s
&[2, 2, 3, 2][..], &[2, 2, 3, 2][..],
// t u v w x y z
&[2, 2, 1, 7][..], &[2, 2, 1, 7][..], &[2, 2, 1, 7][..], &[2, 2, 1, 7][..],
&[2, 2, 1, 7][..], &[2, 2, 1, 7][..], &[2, 2, 1, 7][..],
// (a b c) (d e f)
&[2, 3, 2][..], &[2, 3, 2][..],
// (g h) (i j k l m)
&[2, 3, 2][..], &[2, 3, 2][..],
// (n)
&[2, 3, 1][..],
// (o) (p q) (r s)
&[2, 2, 3][..], &[2, 2, 3][..], &[2, 2, 3][..],
// (t u v w x y z)
&[2, 2, 1][..],
// [ (a b c) (d e f) ]
// [ (g h) (i j k l m) ]
// [ (n) ]
&[2, 3][..], &[2, 3][..], &[2, 3,][..],
// [ (o) (p q) (r s) ]
// [ (t u v w x y z) ]
&[2, 2][..], &[2, 2][..],
// {
// [ (a b c) (d e f) ]
// [ (g h) (i j k l m) ]
// [ (n) ]
// }
// {
// [ (o) (p q) (r s) ]
// [ (t u v w x y z) ]
// }
&[2][..], &[2][..]
][..]
);
// It is possible to say, to some degree, that count is an "amalgamation" of length (see
// each length line result and compare them with the count results)
}