48 lines
1.2 KiB
Rust
48 lines
1.2 KiB
Rust
//@ run-pass
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#![allow(non_camel_case_types)]
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// Tests that type assignability is used to search for instances when
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// making method calls, but only if there aren't any matches without
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// it.
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trait iterable<A> {
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fn iterate<F>(&self, blk: F) -> bool where F: FnMut(&A) -> bool;
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}
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impl<'a,A> iterable<A> for &'a [A] {
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fn iterate<F>(&self, f: F) -> bool where F: FnMut(&A) -> bool {
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self.iter().all(f)
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}
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}
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impl<A> iterable<A> for Vec<A> {
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fn iterate<F>(&self, f: F) -> bool where F: FnMut(&A) -> bool {
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self.iter().all(f)
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}
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}
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fn length<A, T: iterable<A>>(x: T) -> usize {
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let mut len = 0;
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x.iterate(|_y| {
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len += 1;
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true
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});
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return len;
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}
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pub fn main() {
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let x: Vec<isize> = vec![0,1,2,3];
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// Call a method
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x.iterate(|y| { assert_eq!(x[*y as usize], *y); true });
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// Call a parameterized function
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assert_eq!(length(x.clone()), x.len());
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// Call a parameterized function, with type arguments that require
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// a borrow
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assert_eq!(length::<isize, &[isize]>(&*x), x.len());
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// Now try it with a type that *needs* to be borrowed
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let z = [0,1,2,3];
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// Call a parameterized function
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assert_eq!(length::<isize, &[isize]>(&z), z.len());
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}
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