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use std::ops;
pub trait AnyRange<Index> {
fn start(&self) -> Option<Index>;
fn end(&self) -> Option<Index>;
fn to_range(&self, start: Index, end: Index) -> ops::Range<Index> {
ops::Range {
start: self.start().unwrap_or(start),
end: self.end().unwrap_or(end),
}
}
}
impl<I: Clone> AnyRange<I> for ops::Range<I> {
fn start(&self) -> Option<I> { Some(self.start.clone()) }
fn end(&self) -> Option<I> { Some(self.end.clone()) }
fn to_range(&self, _: I, _: I) -> ops::Range<I> { self.clone() }
}
impl<I: Clone> AnyRange<I> for ops::RangeFrom<I> {
fn start(&self) -> Option<I> { Some(self.start.clone()) }
fn end(&self) -> Option<I> { None }
}
impl<I: Clone> AnyRange<I> for ops::RangeTo<I> {
fn start(&self) -> Option<I> { None }
fn end(&self) -> Option<I> { Some(self.end.clone()) }
}
impl<I> AnyRange<I> for ops::RangeFull {
fn start(&self) -> Option<I> { None }
fn end(&self) -> Option<I> { None }
fn to_range(&self, start: I, end: I) -> ops::Range<I> {
ops::Range { start: start, end: end }
}
}
#[test]
fn it_works() {
assert!( (10..20).to_range(0,100) == (10.. 20) );
assert!( (10.. ).to_range(0,100) == (10..100) );
assert!( ( ..20).to_range(0,100) == ( 0.. 20) );
assert!( ( .. ).to_range(0,100) == ( 0..100) );
}