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// run-pass
#![allow(unused_mut)]
// Check that when `?` is followed by what looks like a Kleene operator (?, +, and *)
// then that `?` is not interpreted as a separator. In other words, `$(pat)?+` matches `pat +`
// or `+` but does not match `pat` or `pat ? pat`.
// edition:2018
macro_rules! foo {
// Check for `?`.
($($a:ident)? ? $num:expr) => {
foo!($($a)? ; $num);
};
// Check for `+`.
($($a:ident)? + $num:expr) => {
foo!($($a)? ; $num);
};
// Check for `*`.
($($a:ident)? * $num:expr) => {
foo!($($a)? ; $num);
};
// Check for `;`, not a kleene operator.
($($a:ident)? ; $num:expr) => {
let mut x = 0;
$(
x += $a;
)?
assert_eq!(x, $num);
};
}
pub fn main() {
let a = 1;
// Accept 0 repetitions.
foo!( ; 0);
foo!( + 0);
foo!( * 0);
foo!( ? 0);
// Accept 1 repetition.
foo!(a ; 1);
foo!(a + 1);
foo!(a * 1);
foo!(a ? 1);
}
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