rust/src/libcore/tuple.rs

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// NB: transitionary, de-mode-ing.
#[forbid(deprecated_mode)];
#[forbid(deprecated_pattern)];
//! Operations on tuples
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use cmp::{Eq, Ord};
trait TupleOps<T,U> {
pure fn first() -> T;
pure fn second() -> U;
pure fn swap() -> (U, T);
}
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impl<T: copy, U: copy> (T, U): TupleOps<T,U> {
/// Return the first element of self
pure fn first() -> T {
let (t, _) = self;
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return t;
}
/// Return the second element of self
pure fn second() -> U {
let (_, u) = self;
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return u;
}
/// Return the results of swapping the two elements of self
pure fn swap() -> (U, T) {
let (t, u) = self;
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return (u, t);
}
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}
trait ExtendedTupleOps<A,B> {
fn zip() -> ~[(A, B)];
fn map<C>(f: fn(A, B) -> C) -> ~[C];
}
impl<A: copy, B: copy> (&[A], &[B]): ExtendedTupleOps<A,B> {
fn zip() -> ~[(A, B)] {
let (a, b) = self;
vec::zip_slice(a, b)
}
fn map<C>(f: fn(A, B) -> C) -> ~[C] {
let (a, b) = self;
vec::map2(a, b, f)
}
}
impl<A: copy, B: copy> (~[A], ~[B]): ExtendedTupleOps<A,B> {
fn zip() -> ~[(A, B)] {
let (a, b) = self;
vec::zip(a, b)
}
fn map<C>(f: fn(A, B) -> C) -> ~[C] {
let (a, b) = self;
vec::map2(a, b, f)
}
}
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impl<A: Eq, B: Eq> (A, B): Eq {
pure fn eq(&&other: (A, B)) -> bool {
// XXX: This would be a lot less wordy with ref bindings, but I don't
// trust that they work yet.
match self {
(self_a, self_b) => {
match other {
(other_a, other_b) => {
self_a.eq(other_a) && self_b.eq(other_b)
}
}
}
}
}
}
impl<A: Ord, B: Ord> (A, B): Ord {
pure fn lt(&&other: (A, B)) -> bool {
match self {
(self_a, self_b) => {
match other {
(other_a, other_b) => {
if self_a.lt(other_a) { return true; }
if other_a.lt(self_a) { return false; }
if self_b.lt(other_b) { return true; }
return false;
}
}
}
}
}
pure fn le(&&other: (A, B)) -> bool {
match self {
(self_a, self_b) => {
match other {
(other_a, other_b) => {
if self_a.lt(other_a) { return true; }
if other_a.lt(self_a) { return false; }
if self_b.le(other_b) { return true; }
return false;
}
}
}
}
}
pure fn ge(&&other: (A, B)) -> bool { !other.lt(self) }
pure fn gt(&&other: (A, B)) -> bool { !other.ge(self) }
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}
impl<A: Eq, B: Eq, C: Eq> (A, B, C): Eq {
pure fn eq(&&other: (A, B, C)) -> bool {
// XXX: This would be a lot less wordy with ref bindings, but I don't
// trust that they work yet.
match self {
(self_a, self_b, self_c) => {
match other {
(other_a, other_b, other_c) => {
self_a.eq(other_a) &&
self_b.eq(other_b) &&
self_c.eq(other_c)
}
}
}
}
}
}
impl<A: Ord, B: Ord, C: Ord> (A, B, C): Ord {
pure fn lt(&&other: (A, B, C)) -> bool {
match self {
(self_a, self_b, self_c) => {
match other {
(other_a, other_b, other_c) => {
if self_a.lt(other_a) { return true; }
if other_a.lt(self_a) { return false; }
if self_b.lt(other_b) { return true; }
if other_b.lt(self_b) { return false; }
if self_c.lt(other_c) { return true; }
return false;
}
}
}
}
}
pure fn le(&&other: (A, B, C)) -> bool {
match self {
(self_a, self_b, self_c) => {
match other {
(other_a, other_b, other_c) => {
if self_a.lt(other_a) { return true; }
if other_a.lt(self_a) { return false; }
if self_b.lt(other_b) { return true; }
if other_b.lt(self_b) { return false; }
if self_c.le(other_c) { return true; }
return false;
}
}
}
}
}
pure fn ge(&&other: (A, B, C)) -> bool { !other.lt(self) }
pure fn gt(&&other: (A, B, C)) -> bool { !other.ge(self) }
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}
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#[test]
fn test_tuple() {
assert (948, 4039.48).first() == 948;
assert (34.5, ~"foo").second() == ~"foo";
assert ('a', 2).swap() == (2, 'a');
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}