auto merge of #7474 : Seldaek/rust/clean-iter, r=thestinger

I think it's WIP - but I wanted to ask for feedback (/cc @thestinger)

I had to move the impl of FromIter for vec into extra::iter because I don't think std can depend on extra, but that's a bit messed up. Similarly some FromIter uses are gone now, not sure if this is fixable or if I made a complete mess here..

3 files changed, 6 insertions, 313 deletions

diff --git a/src/libstd/iter.rs b/src/libstd/iter.rs
index 4e598a4aa1c..2092ae588d0 100644
--- a/src/libstd/iter.rs
+++ b/src/libstd/iter.rs
@@ -8,316 +8,19 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-/*! Composable internal iterators
-
-Internal iterators are functions implementing the protocol used by the `for` loop.
-
-An internal iterator takes `fn(...) -> bool` as a parameter, with returning `false` used to signal
-breaking out of iteration. The adaptors in the module work with any such iterator, not just ones
-tied to specific traits. For example:
+/*! Times trait
 
 ~~~ {.rust}
-println(iter::to_vec(|f| uint::range(0, 20, f)).to_str());
+use iter::Times;
+let ten = 10 as uint;
+let mut accum = 0;
+for ten.times { accum += 1; }
 ~~~
 
-An external iterator object implementing the interface in the `iterator` module can be used as an
-internal iterator by calling the `advance` method. For example:
-
-~~~ {.rust}
-let xs = [0u, 1, 2, 3, 4, 5];
-let ys = [30, 40, 50, 60];
-let mut it = xs.iter().chain(ys.iter());
-for it.advance |&x: &uint| {
-    println(x.to_str());
-}
-~~~
-
-Internal iterators provide a subset of the functionality of an external iterator. It's not possible
-to interleave them to implement algorithms like `zip`, `union` and `merge`. However, they're often
-much easier to implement.
-
 */
 
-use cmp::Ord;
-use option::{Option, Some, None};
-use num::{One, Zero};
-use ops::{Add, Mul};
-
 #[allow(missing_doc)]
 pub trait Times {
     fn times(&self, it: &fn() -> bool) -> bool;
 }
 
-#[allow(missing_doc)]
-pub trait FromIter<T> {
-    /// Build a container with elements from an internal iterator.
-    ///
-    /// # Example:
-    ///
-    /// ~~~ {.rust}
-    /// let xs = ~[1, 2, 3];
-    /// let ys: ~[int] = do FromIter::from_iter |f| { xs.iter().advance(|x| f(*x)) };
-    /// assert_eq!(xs, ys);
-    /// ~~~
-    pub fn from_iter(iter: &fn(f: &fn(T) -> bool) -> bool) -> Self;
-}
-
-/**
- * Return true if `predicate` is true for any values yielded by an internal iterator.
- *
- * Example:
- *
- * ~~~ {.rust}
- * let xs = ~[1u, 2, 3, 4, 5];
- * assert!(any(|&x: &uint| x > 2, |f| xs.iter().advance(f)));
- * assert!(!any(|&x: &uint| x > 5, |f| xs.iter().advance(f)));
- * ~~~
- */
-#[inline]
-pub fn any<T>(predicate: &fn(T) -> bool,
-              iter: &fn(f: &fn(T) -> bool) -> bool) -> bool {
-    for iter |x| {
-        if predicate(x) {
-            return true;
-        }
-    }
-    return false;
-}
-
-/**
- * Return true if `predicate` is true for all values yielded by an internal iterator.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * assert!(all(|&x: &uint| x < 6, |f| uint::range(1, 6, f)));
- * assert!(!all(|&x: &uint| x < 5, |f| uint::range(1, 6, f)));
- * ~~~
- */
-#[inline]
-pub fn all<T>(predicate: &fn(T) -> bool,
-              iter: &fn(f: &fn(T) -> bool) -> bool) -> bool {
-    // If we ever break, iter will return false, so this will only return true
-    // if predicate returns true for everything.
-    iter(|x| predicate(x))
-}
-
-/**
- * Return the first element where `predicate` returns `true`. Return `None` if no element is found.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * let xs = ~[1u, 2, 3, 4, 5, 6];
- * assert_eq!(*find(|& &x: & &uint| x > 3, |f| xs.iter().advance(f)).unwrap(), 4);
- * ~~~
- */
-#[inline]
-pub fn find<T>(predicate: &fn(&T) -> bool,
-               iter: &fn(f: &fn(T) -> bool) -> bool) -> Option<T> {
-    for iter |x| {
-        if predicate(&x) {
-            return Some(x);
-        }
-    }
-    None
-}
-
-/**
- * Return the largest item yielded by an iterator. Return `None` if the iterator is empty.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
- * assert_eq!(max(|f| xs.iter().advance(f)).unwrap(), &15);
- * ~~~
- */
-#[inline]
-pub fn max<T: Ord>(iter: &fn(f: &fn(T) -> bool) -> bool) -> Option<T> {
-    let mut result = None;
-    for iter |x| {
-        match result {
-            Some(ref mut y) => {
-                if x > *y {
-                    *y = x;
-                }
-            }
-            None => result = Some(x)
-        }
-    }
-    result
-}
-
-/**
- * Return the smallest item yielded by an iterator. Return `None` if the iterator is empty.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
- * assert_eq!(max(|f| xs.iter().advance(f)).unwrap(), &-5);
- * ~~~
- */
-#[inline]
-pub fn min<T: Ord>(iter: &fn(f: &fn(T) -> bool) -> bool) -> Option<T> {
-    let mut result = None;
-    for iter |x| {
-        match result {
-            Some(ref mut y) => {
-                if x < *y {
-                    *y = x;
-                }
-            }
-            None => result = Some(x)
-        }
-    }
-    result
-}
-
-/**
- * Reduce an iterator to an accumulated value.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * assert_eq!(fold(0i, |f| int::range(1, 5, f), |a, x| *a += x), 10);
- * ~~~
- */
-#[inline]
-pub fn fold<T, U>(start: T, iter: &fn(f: &fn(U) -> bool) -> bool, f: &fn(&mut T, U)) -> T {
-    let mut result = start;
-    for iter |x| {
-        f(&mut result, x);
-    }
-    result
-}
-
-/**
- * Reduce an iterator to an accumulated value.
- *
- * `fold_ref` is usable in some generic functions where `fold` is too lenient to type-check, but it
- * forces the iterator to yield borrowed pointers.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * fn product<T: One + Mul<T, T>>(iter: &fn(f: &fn(&T) -> bool) -> bool) -> T {
- *     fold_ref(One::one::<T>(), iter, |a, x| *a = a.mul(x))
- * }
- * ~~~
- */
-#[inline]
-pub fn fold_ref<T, U>(start: T, iter: &fn(f: &fn(&U) -> bool) -> bool, f: &fn(&mut T, &U)) -> T {
-    let mut result = start;
-    for iter |x| {
-        f(&mut result, x);
-    }
-    result
-}
-
-/**
- * Return the sum of the items yielding by an iterator.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * let xs: ~[int] = ~[1, 2, 3, 4];
- * assert_eq!(do sum |f| { xs.iter().advance(f) }, 10);
- * ~~~
- */
-#[inline]
-pub fn sum<T: Zero + Add<T, T>>(iter: &fn(f: &fn(&T) -> bool) -> bool) -> T {
-    fold_ref(Zero::zero::<T>(), iter, |a, x| *a = a.add(x))
-}
-
-/**
- * Return the product of the items yielded by an iterator.
- *
- * # Example:
- *
- * ~~~ {.rust}
- * let xs: ~[int] = ~[1, 2, 3, 4];
- * assert_eq!(do product |f| { xs.iter().advance(f) }, 24);
- * ~~~
- */
-#[inline]
-pub fn product<T: One + Mul<T, T>>(iter: &fn(f: &fn(&T) -> bool) -> bool) -> T {
-    fold_ref(One::one::<T>(), iter, |a, x| *a = a.mul(x))
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use prelude::*;
-
-    use int;
-    use uint;
-
-    #[test]
-    fn test_from_iter() {
-        let xs = ~[1, 2, 3];
-        let ys: ~[int] = do FromIter::from_iter |f| { xs.iter().advance(|x| f(*x)) };
-        assert_eq!(xs, ys);
-    }
-
-    #[test]
-    fn test_any() {
-        let xs = ~[1u, 2, 3, 4, 5];
-        assert!(any(|&x: &uint| x > 2, |f| xs.iter().advance(f)));
-        assert!(!any(|&x: &uint| x > 5, |f| xs.iter().advance(f)));
-    }
-
-    #[test]
-    fn test_all() {
-        assert!(all(|x: uint| x < 6, |f| uint::range(1, 6, f)));
-        assert!(!all(|x: uint| x < 5, |f| uint::range(1, 6, f)));
-    }
-
-    #[test]
-    fn test_find() {
-        let xs = ~[1u, 2, 3, 4, 5, 6];
-        assert_eq!(*find(|& &x: & &uint| x > 3, |f| xs.iter().advance(f)).unwrap(), 4);
-    }
-
-    #[test]
-    fn test_max() {
-        let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
-        assert_eq!(max(|f| xs.iter().advance(f)).unwrap(), &15);
-    }
-
-    #[test]
-    fn test_min() {
-        let xs = ~[8, 2, 3, 1, -5, 9, 11, 15];
-        assert_eq!(min(|f| xs.iter().advance(f)).unwrap(), &-5);
-    }
-
-    #[test]
-    fn test_fold() {
-        assert_eq!(fold(0i, |f| int::range(1, 5, f), |a, x| *a += x), 10);
-    }
-
-    #[test]
-    fn test_sum() {
-        let xs: ~[int] = ~[1, 2, 3, 4];
-        assert_eq!(do sum |f| { xs.iter().advance(f) }, 10);
-    }
-
-    #[test]
-    fn test_empty_sum() {
-        let xs: ~[int] = ~[];
-        assert_eq!(do sum |f| { xs.iter().advance(f) }, 0);
-    }
-
-    #[test]
-    fn test_product() {
-        let xs: ~[int] = ~[1, 2, 3, 4];
-        assert_eq!(do product |f| { xs.iter().advance(f) }, 24);
-    }
-
-    #[test]
-    fn test_empty_product() {
-        let xs: ~[int] = ~[];
-        assert_eq!(do product |f| { xs.iter().advance(f) }, 1);
-    }
-}
diff --git a/src/libstd/prelude.rs b/src/libstd/prelude.rs
index d560ce621ea..9d505209960 100644
--- a/src/libstd/prelude.rs
+++ b/src/libstd/prelude.rs
@@ -47,7 +47,7 @@ pub use cmp::{Eq, ApproxEq, Ord, TotalEq, TotalOrd, Ordering, Less, Equal, Great
 pub use char::Char;
 pub use container::{Container, Mutable, Map, Set};
 pub use hash::Hash;
-pub use iter::{Times, FromIter};
+pub use iter::{Times};
 pub use iterator::{Iterator, IteratorUtil, OrdIterator};
 pub use num::{Num, NumCast};
 pub use num::{Orderable, Signed, Unsigned, Round};
diff --git a/src/libstd/vec.rs b/src/libstd/vec.rs
index 02eadaed5e8..28532bd54e3 100644
--- a/src/libstd/vec.rs
+++ b/src/libstd/vec.rs
@@ -19,7 +19,6 @@ use cmp;
 use cmp::{Eq, Ord, TotalEq, TotalOrd, Ordering, Less, Equal, Greater};
 use clone::Clone;
 use iterator::{FromIterator, Iterator, IteratorUtil};
-use iter::FromIter;
 use kinds::Copy;
 use libc;
 use libc::c_void;
@@ -2168,15 +2167,6 @@ pub struct VecMutRevIterator<'self, T> {
 }
 iterator!{impl VecMutRevIterator -> &'self mut T, -1}
 
-impl<T> FromIter<T> for ~[T]{
-    #[inline]
-    pub fn from_iter(iter: &fn(f: &fn(T) -> bool) -> bool) -> ~[T] {
-        let mut v = ~[];
-        for iter |x| { v.push(x) }
-        v
-    }
-}
-
 #[cfg(stage0)]
 impl<A, T: Iterator<A>> FromIterator<A, T> for ~[A] {
     pub fn from_iterator(iterator: &mut T) -> ~[A] {