55 lines
1.4 KiB
Rust
55 lines
1.4 KiB
Rust
fn id<T>(x: T) -> T { x }
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struct StateMachineIter<'a> {
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statefn: &'a StateMachineFunc<'a>
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}
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type StateMachineFunc<'a> = fn(&mut StateMachineIter<'a>) -> Option<&'static str>;
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impl<'a> Iterator for StateMachineIter<'a> {
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type Item = &'static str;
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fn next(&mut self) -> Option<&'static str> {
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return (*self.statefn)(self);
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}
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}
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fn state1(self_: &mut StateMachineIter) -> Option<&'static str> {
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self_.statefn = &id(state2 as StateMachineFunc);
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//~^ ERROR temporary value dropped while borrowed
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return Some("state1");
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}
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fn state2(self_: &mut StateMachineIter) -> Option<(&'static str)> {
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self_.statefn = &id(state3 as StateMachineFunc);
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//~^ ERROR temporary value dropped while borrowed
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return Some("state2");
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}
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fn state3(self_: &mut StateMachineIter) -> Option<(&'static str)> {
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self_.statefn = &id(finished as StateMachineFunc);
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//~^ ERROR temporary value dropped while borrowed
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return Some("state3");
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}
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fn finished(_: &mut StateMachineIter) -> Option<(&'static str)> {
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return None;
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}
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fn state_iter() -> StateMachineIter<'static> {
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StateMachineIter {
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//~^ ERROR cannot return value referencing temporary value
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statefn: &id(state1 as StateMachineFunc)
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}
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}
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fn main() {
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let mut it = state_iter();
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println!("{:?}",it.next());
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println!("{:?}",it.next());
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println!("{:?}",it.next());
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println!("{:?}",it.next());
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println!("{:?}",it.next());
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}
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