51 lines
999 B
Rust
51 lines
999 B
Rust
// 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, `$(pat)?+` matches `pat +`
|
|
// or `+` but does not match `pat` or `pat ? pat`.
|
|
|
|
// edition:2015
|
|
|
|
macro_rules! foo {
|
|
// Check for `?`.
|
|
($($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);
|
|
}
|