diff --git a/src/libstd/iterator.rs b/src/libstd/iterator.rs index e65904a68992e..a505c55235986 100644 --- a/src/libstd/iterator.rs +++ b/src/libstd/iterator.rs @@ -308,6 +308,12 @@ pub trait IteratorUtil { /// assert!(!it.any_(|&x| *x == 3)); /// ~~~ fn any_(&mut self, f: &fn(A) -> bool) -> bool; + + /// Return the first element satisfying the specified predicate + fn find_(&mut self, predicate: &fn(&A) -> bool) -> Option; + + /// Return the index of the first element satisfying the specified predicate + fn position_(&mut self, predicate: &fn(A) -> bool) -> Option; } /// Iterator adaptors provided for every `Iterator` implementation. The adaptor objects are also @@ -421,7 +427,7 @@ impl> IteratorUtil for T { None => { break; } } } - return accum; + accum } /// Count the number of items yielded by an iterator @@ -431,13 +437,35 @@ impl> IteratorUtil for T { #[inline(always)] fn all(&mut self, f: &fn(A) -> bool) -> bool { for self.advance |x| { if !f(x) { return false; } } - return true; + true } #[inline(always)] fn any_(&mut self, f: &fn(A) -> bool) -> bool { for self.advance |x| { if f(x) { return true; } } - return false; + false + } + + /// Return the first element satisfying the specified predicate + #[inline(always)] + fn find_(&mut self, predicate: &fn(&A) -> bool) -> Option { + for self.advance |x| { + if predicate(&x) { return Some(x) } + } + None + } + + /// Return the index of the first element satisfying the specified predicate + #[inline] + fn position_(&mut self, predicate: &fn(A) -> bool) -> Option { + let mut i = 0; + for self.advance |x| { + if predicate(x) { + return Some(i); + } + i += 1; + } + None } } @@ -1055,4 +1083,20 @@ mod tests { assert!(!v.iter().any_(|&x| x > 100)); assert!(!v.slice(0, 0).iter().any_(|_| fail!())); } + + #[test] + fn test_find() { + let v = &[1, 3, 9, 27, 103, 14, 11]; + assert_eq!(*v.iter().find_(|x| *x & 1 == 0).unwrap(), 14); + assert_eq!(*v.iter().find_(|x| *x % 3 == 0).unwrap(), 3); + assert!(v.iter().find_(|x| *x % 12 == 0).is_none()); + } + + #[test] + fn test_position() { + let v = &[1, 3, 9, 27, 103, 14, 11]; + assert_eq!(v.iter().position_(|x| *x & 1 == 0).unwrap(), 5); + assert_eq!(v.iter().position_(|x| *x % 3 == 0).unwrap(), 1); + assert!(v.iter().position_(|x| *x % 12 == 0).is_none()); + } }