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51 lines
999 B
Rust
51 lines
999 B
Rust
// run-pass
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#![allow(unused_mut)]
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// Check that when `?` is followed by what looks like a Kleene operator (?, +, and *)
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// then that `?` is not interpreted as a separator. In other words, `$(pat)?+` matches `pat +`
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// or `+` but does not match `pat` or `pat ? pat`.
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// edition:2015
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macro_rules! foo {
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// Check for `?`.
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($($a:ident)? ? $num:expr) => {
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foo!($($a)? ; $num);
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};
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// Check for `+`.
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($($a:ident)? + $num:expr) => {
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foo!($($a)? ; $num);
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};
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// Check for `*`.
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($($a:ident)? * $num:expr) => {
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foo!($($a)? ; $num);
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};
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// Check for `;`, not a kleene operator.
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($($a:ident)? ; $num:expr) => {
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let mut x = 0;
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$(
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x += $a;
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)?
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assert_eq!(x, $num);
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};
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}
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pub fn main() {
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let a = 1;
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// Accept 0 repetitions.
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foo!( ; 0);
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foo!( + 0);
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foo!( * 0);
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foo!( ? 0);
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// Accept 1 repetition.
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foo!(a ; 1);
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foo!(a + 1);
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foo!(a * 1);
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foo!(a ? 1);
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}
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