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expand on double-ended iterators in the tutorial

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This commit is contained in:
Daniel Micay 2013-07-23 14:37:06 -04:00
parent 626bb5a866
commit 8c02272512
1 changed files with 22 additions and 6 deletions
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28
doc/tutorial-container.md
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@ -192,7 +192,7 @@ let mut it = xs.iter().zip(ys.iter());
// print out the pairs of elements up to (&3, &"baz")
for it.advance |(x, y)| {
println(fmt!("%d %s", *x, *y));
printfln!("%d %s", *x, *y);
if *x == 3 {
break;
@ -200,7 +200,7 @@ for it.advance |(x, y)| {
}
// yield and print the last pair from the iterator
println(fmt!("last: %?", it.next()));
printfln!("last: %?", it.next());
// the iterator is now fully consumed
assert!(it.next().is_none());
@ -294,15 +294,31 @@ another `DoubleEndedIterator` with `next` and `next_back` exchanged.
~~~
let xs = [1, 2, 3, 4, 5, 6];
let mut it = xs.iter();
println(fmt!("%?", it.next())); // prints `Some(&1)`
println(fmt!("%?", it.next())); // prints `Some(&2)`
println(fmt!("%?", it.next_back())); // prints `Some(&6)`
printfln!("%?", it.next()); // prints `Some(&1)`
printfln!("%?", it.next()); // prints `Some(&2)`
printfln!("%?", it.next_back()); // prints `Some(&6)`
// prints `5`, `4` and `3`
for it.invert().advance |&x| {
println(fmt!("%?", x))
printfln!("%?", x)
}
~~~
The `rev_iter` and `mut_rev_iter` methods on vectors just return an inverted
version of the standard immutable and mutable vector iterators.
The `chain_`, `transform`, `filter`, `filter_map` and `peek` adaptors are
`DoubleEndedIterator` implementations if the underlying iterators are.
~~~
let xs = [1, 2, 3, 4];
let ys = [5, 6, 7, 8];
let mut it = xs.iter().chain_(ys.iter()).transform(|&x| x * 2);
printfln!("%?", it.next()); // prints `Some(2)`
// prints `16`, `14`, `12`, `10`, `8`, `6`, `4`
for it.invert().advance |x| {
printfln!("%?", x);
}
~~~