71 lines
1.4 KiB
Rust
71 lines
1.4 KiB
Rust
//! Operations on tuples
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trait tuple_ops<T,U> {
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pure fn first() -> T;
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pure fn second() -> U;
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pure fn swap() -> (U, T);
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}
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impl extensions <T:copy, U:copy> of tuple_ops<T,U> for (T, U) {
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/// Return the first element of self
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pure fn first() -> T {
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let (t, _) = self;
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ret t;
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}
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/// Return the second element of self
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pure fn second() -> U {
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let (_, u) = self;
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ret u;
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}
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/// Return the results of swapping the two elements of self
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pure fn swap() -> (U, T) {
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let (t, u) = self;
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ret (u, t);
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}
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}
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trait extended_tuple_ops<A,B> {
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fn zip() -> ~[(A, B)];
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fn map<C>(f: fn(A, B) -> C) -> ~[C];
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}
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impl extensions<A: copy, B: copy> of extended_tuple_ops<A,B>
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for (&[A], &[B]) {
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fn zip() -> ~[(A, B)] {
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let (a, b) = self;
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vec::zip(a, b)
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}
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fn map<C>(f: fn(A, B) -> C) -> ~[C] {
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let (a, b) = self;
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vec::map2(a, b, f)
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}
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}
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impl extensions<A: copy, B: copy> of extended_tuple_ops<A,B>
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for (~[A], ~[B]) {
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fn zip() -> ~[(A, B)] {
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let (a, b) = self;
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vec::zip(a, b)
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}
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fn map<C>(f: fn(A, B) -> C) -> ~[C] {
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let (a, b) = self;
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vec::map2(a, b, f)
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}
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}
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#[test]
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fn test_tuple() {
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assert (948, 4039.48).first() == 948;
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assert (34.5, ~"foo").second() == ~"foo";
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assert ('a', 2).swap() == (2, 'a');
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}
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