iterator: add a FromIterator trait
This is able to take advantage of the lower bound from the size hint.
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2 changed files with 20 additions and 2 deletions
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@ -27,6 +27,12 @@ use ops::{Add, Mul};
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use cmp::Ord;
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use clone::Clone;
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/// Conversion from an `Iterator`
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pub trait FromIterator<A, T: Iterator<A>> {
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/// Build a container with elements from an external iterator.
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pub fn from_iterator(iterator: &mut T) -> Self;
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}
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/// An interface for dealing with "external iterators". These types of iterators
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/// can be resumed at any time as all state is stored internally as opposed to
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/// being located on the call stack.
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@ -931,7 +937,7 @@ mod tests {
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#[test]
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fn test_counter_from_iter() {
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let mut it = Counter::new(0, 5).take_(10);
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let xs: ~[int] = iter::FromIter::from_iter::<int, ~[int]>(|f| it.advance(f));
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let xs: ~[int] = FromIterator::from_iterator(&mut it);
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assert_eq!(xs, ~[0, 5, 10, 15, 20, 25, 30, 35, 40, 45]);
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}
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@ -19,7 +19,7 @@ use cmp::{Eq, Ord, TotalEq, TotalOrd, Ordering, Less, Equal, Greater};
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use clone::Clone;
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use old_iter::BaseIter;
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use old_iter;
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use iterator::{Iterator, IteratorUtil};
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use iterator::{FromIterator, Iterator, IteratorUtil};
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use iter::FromIter;
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use kinds::Copy;
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use libc;
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@ -2511,6 +2511,18 @@ impl<T> FromIter<T> for ~[T]{
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}
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}
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#[cfg(not(stage0))]
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impl<A, T: Iterator<A>> FromIterator<A, T> for ~[A] {
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pub fn from_iterator(iterator: &mut T) -> ~[A] {
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let (lower, _) = iterator.size_hint();
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let mut xs = with_capacity(lower.get_or_zero());
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for iterator.advance |x| {
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xs.push(x);
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}
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xs
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}
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}
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#[cfg(test)]
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mod tests {
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use option::{None, Option, Some};
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