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https://github.com/rust-lang/rust
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26 lines
498 B
Rust
26 lines
498 B
Rust
//@ run-pass
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macro_rules! enum_number {
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($name:ident { $($variant:ident = $value:expr, )* }) => {
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enum $name {
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$($variant = $value,)*
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}
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fn foo(value: i32) -> Option<$name> {
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match value {
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$( $value => Some($name::$variant), )*
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_ => None
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}
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}
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}
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}
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enum_number!(Change {
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Down = -1,
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None = 0,
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Up = 1,
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});
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fn main() {
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if let Some(Change::Down) = foo(-1) {} else { panic!() }
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}
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