Assorted iterator fixes in libstd

src/libextra/bitv.rs

@@ -13,7 +13,7 @@
 
 use std::cmp;
 use std::iterator::RandomAccessIterator;
-use std::iterator::{Invert, Enumerate};
+use std::iterator::{Invert, Enumerate, Repeat, Map, Zip};
 use std::num;
 use std::ops;
 use std::uint;
@@ -206,14 +206,13 @@ impl BigBitv {
     #[inline]
     pub fn equals(&self, b: &BigBitv, nbits: uint) -> bool {
         let len = b.storage.len();
-        do uint::iterate(0, len) |i| {
+        for i in range(0, len) {
             let mask = big_mask(nbits, i);
             if mask & self.storage[i] != mask & b.storage[i] {
-                false
-            } else {
-                true
+                return false;
             }
         }
+        true
     }
 }
 
@@ -864,13 +863,12 @@ impl BitvSet {
     /// w1, w2) where the bit location is the number of bits offset so far,
     /// and w1/w2 are the words coming from the two vectors self, other.
     fn common_iter<'a>(&'a self, other: &'a BitvSet)
-        -> MapE<(uint,&uint),(uint,uint,uint), &'a ~[uint],Enumerate<vec::VecIterator<'a,uint>>> {
-        let min = num::min(self.bitv.storage.len(),
-                            other.bitv.storage.len());
-        MapE{iter: self.bitv.storage.slice(0, min).iter().enumerate(),
-             env: &other.bitv.storage,
-             f: |(i, &w): (uint, &uint), o_store| (i * uint::bits, w, o_store[i])
-        }
+        -> Map<'static, ((uint, &'a uint), &'a ~[uint]), (uint, uint, uint),
+               Zip<Enumerate<vec::VecIterator<'a, uint>>, Repeat<&'a ~[uint]>>> {
+        let min = num::min(self.bitv.storage.len(), other.bitv.storage.len());
+        self.bitv.storage.slice(0, min).iter().enumerate()
+            .zip(Repeat::new(&other.bitv.storage))
+            .transform(|((i, &w), o_store)| (i * uint::bits, w, o_store[i]))
     }
 
     /// Visits each word in self or other that extends beyond the other. This
@@ -881,45 +879,21 @@ impl BitvSet {
     /// is true if the word comes from 'self', and false if it comes from
     /// 'other'.
     fn outlier_iter<'a>(&'a self, other: &'a BitvSet)
-        -> MapE<(uint, &uint),(bool, uint, uint), uint, Enumerate<vec::VecIterator<'a, uint>>> {
-        let len1 = self.bitv.storage.len();
-        let len2 = other.bitv.storage.len();
-        let min = num::min(len1, len2);
-
-        if min < len1 {
-            MapE{iter: self.bitv.storage.slice(min, len1).iter().enumerate(),
-                 env: min,
-                 f: |(i, &w): (uint, &uint), min| (true, (i + min) * uint::bits, w)
-            }
+        -> Map<'static, ((uint, &'a uint), uint), (bool, uint, uint),
+               Zip<Enumerate<vec::VecIterator<'a, uint>>, Repeat<uint>>> {
+        let slen = self.bitv.storage.len();
+        let olen = other.bitv.storage.len();
+
+        if olen < slen {
+            self.bitv.storage.slice_from(olen).iter().enumerate()
+                .zip(Repeat::new(olen))
+                .transform(|((i, &w), min)| (true, (i + min) * uint::bits, w))
         } else {
-            MapE{iter: other.bitv.storage.slice(min, len2).iter().enumerate(),
-                 env: min,
-                 f: |(i, &w): (uint, &uint), min| (false, (i + min) * uint::bits, w)
-            }
-        }
-    }
-}
-
-/// Like iterator::Map with explicit env capture
-struct MapE<A, B, Env, I> {
-    priv env: Env,
-    priv f: &'static fn(A, Env) -> B,
-    priv iter: I,
-}
-
-impl<'self, A, B, Env: Clone, I: Iterator<A>> Iterator<B> for MapE<A, B, Env, I> {
-    #[inline]
-    fn next(&mut self) -> Option<B> {
-        match self.iter.next() {
-            Some(elt) => Some((self.f)(elt, self.env.clone())),
-            None => None
+            other.bitv.storage.slice_from(slen).iter().enumerate()
+                .zip(Repeat::new(slen))
+                .transform(|((i, &w), min)| (false, (i + min) * uint::bits, w))
         }
     }
-
-    #[inline]
-    fn size_hint(&self) -> (uint, Option<uint>) {
-        self.iter.size_hint()
-    }
 }
 
 pub struct BitvSetIterator<'self> {

src/libstd/hashmap.rs

@@ -19,7 +19,8 @@ use container::{Container, Mutable, Map, MutableMap, Set, MutableSet};
 use clone::Clone;
 use cmp::{Eq, Equiv};
 use hash::Hash;
-use iterator::{Iterator, IteratorUtil, FromIterator, Extendable, Chain, range};
+use iterator::{Iterator, IteratorUtil, FromIterator, Extendable, range};
+use iterator::{FilterMap, Chain, Repeat, Zip};
 use num;
 use option::{None, Option, Some};
 use rand::RngUtil;
@@ -712,10 +713,12 @@ impl<T:Hash + Eq> HashSet<T> {
     }
 
     /// Visit the values representing the difference
-    pub fn difference_iter<'a>(&'a self, other: &'a HashSet<T>)
-        -> SetAlgebraIter<'a, T> {
-        EnvFilterIterator{iter: self.iter(), env: other,
-                          filter: |elt, other| !other.contains(elt) }
+    pub fn difference_iter<'a>(&'a self, other: &'a HashSet<T>) -> SetAlgebraIter<'a, T> {
+        Repeat::new(other)
+            .zip(self.iter())
+            .filter_map(|(other, elt)| {
+                if !other.contains(elt) { Some(elt) } else { None }
+            })
     }
 
     /// Visit the values representing the symmetric difference
@@ -727,8 +730,11 @@ impl<T:Hash + Eq> HashSet<T> {
     /// Visit the values representing the intersection
     pub fn intersection_iter<'a>(&'a self, other: &'a HashSet<T>)
         -> SetAlgebraIter<'a, T> {
-        EnvFilterIterator{iter: self.iter(), env: other,
-                          filter: |elt, other| other.contains(elt) }
+        Repeat::new(other)
+            .zip(self.iter())
+            .filter_map(|(other, elt)| {
+                if other.contains(elt) { Some(elt) } else { None }
+            })
     }
 
     /// Visit the values representing the union
@@ -756,38 +762,12 @@ impl<K: Eq + Hash, T: Iterator<K>> Extendable<K, T> for HashSet<K> {
     }
 }
 
-// FIXME #7814: use std::iterator::FilterIterator
-/// Building block for Set operation iterators
-pub struct EnvFilterIterator<A, Env, I> {
-    priv env: Env,
-    priv filter: &'static fn(&A, Env) -> bool,
-    priv iter: I,
-}
-
-impl<'self, A, Env: Clone, I: Iterator<&'self A>> Iterator<&'self A>
-        for EnvFilterIterator<A, Env, I> {
-    #[inline]
-    fn next(&mut self) -> Option<&'self A> {
-        loop {
-            match self.iter.next() {
-                Some(elt) => if (self.filter)(elt, self.env.clone()) {
-                    return Some(elt)
-                },
-                None => return None,
-            }
-        }
-    }
-
-    #[inline]
-    fn size_hint(&self) -> (uint, Option<uint>) {
-        let (_, upper) = self.iter.size_hint();
-        (0, upper)
-    }
-}
-
+// `Repeat` is used to feed the filter closure an explicit capture
+// of a reference to the other set
 /// Set operations iterator
 pub type SetAlgebraIter<'self, T> =
-    EnvFilterIterator<T, &'self HashSet<T>, HashSetIterator<'self, T>>;
+    FilterMap<'static,(&'self HashSet<T>, &'self T), &'self T,
+              Zip<Repeat<&'self HashSet<T>>,HashSetIterator<'self,T>>>;
 
 
 #[cfg(test)]

src/libstd/iterator.rs

@@ -82,6 +82,17 @@ pub trait DoubleEndedIteratorUtil {
 /// In the future these will be default methods instead of a utility trait.
 impl<A, T: DoubleEndedIterator<A>> DoubleEndedIteratorUtil for T {
     /// Flip the direction of the iterator
+    ///
+    /// The inverted iterator flips the ends on an iterator that can already
+    /// be iterated from the front and from the back.
+    ///
+    ///
+    /// If the iterator also implements RandomAccessIterator, the inverted
+    /// iterator is also random access, with the indices starting at the back
+    /// of the original iterator.
+    ///
+    /// Note: Random access with inverted indices still only applies to the first
+    /// `uint::max_value` elements of the original iterator.
     #[inline]
     fn invert(self) -> Invert<T> {
         Invert{iter: self}
@@ -106,6 +117,16 @@ impl<A, T: DoubleEndedIterator<A>> DoubleEndedIterator<A> for Invert<T> {
     fn next_back(&mut self) -> Option<A> { self.iter.next() }
 }
 
+impl<A, T: DoubleEndedIterator<A> + RandomAccessIterator<A>> RandomAccessIterator<A>
+    for Invert<T> {
+    #[inline]
+    fn indexable(&self) -> uint { self.iter.indexable() }
+    #[inline]
+    fn idx(&self, index: uint) -> Option<A> {
+        self.iter.idx(self.indexable() - index - 1)
+    }
+}
+
 /// Iterator adaptors provided for every `Iterator` implementation. The adaptor objects are also
 /// implementations of the `Iterator` trait.
 ///
@@ -1555,6 +1576,39 @@ impl<A: Add<A, A> + Clone> Iterator<A> for Counter<A> {
     }
 }
 
+/// An iterator that repeats an element endlessly
+#[deriving(Clone, DeepClone)]
+pub struct Repeat<A> {
+    priv element: A
+}
+
+impl<A: Clone> Repeat<A> {
+    /// Create a new `Repeat` that enlessly repeats the element `elt`.
+    #[inline]
+    pub fn new(elt: A) -> Repeat<A> {
+        Repeat{element: elt}
+    }
+}
+
+impl<A: Clone> Iterator<A> for Repeat<A> {
+    #[inline]
+    fn next(&mut self) -> Option<A> { self.idx(0) }
+    #[inline]
+    fn size_hint(&self) -> (uint, Option<uint>) { (uint::max_value, None) }
+}
+
+impl<A: Clone> DoubleEndedIterator<A> for Repeat<A> {
+    #[inline]
+    fn next_back(&mut self) -> Option<A> { self.idx(0) }
+}
+
+impl<A: Clone> RandomAccessIterator<A> for Repeat<A> {
+    #[inline]
+    fn indexable(&self) -> uint { uint::max_value }
+    #[inline]
+    fn idx(&self, _: uint) -> Option<A> { Some(self.element.clone()) }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -2017,6 +2071,17 @@ mod tests {
         check_randacc_iter(xs.iter().enumerate(), xs.len());
     }
 
+    #[test]
+    fn test_random_access_invert() {
+        let xs = [1, 2, 3, 4, 5];
+        check_randacc_iter(xs.iter().invert(), xs.len());
+        let mut it = xs.iter().invert();
+        it.next();
+        it.next_back();
+        it.next();
+        check_randacc_iter(it, xs.len() - 3);
+    }
+
     #[test]
     fn test_random_access_zip() {
         let xs = [1, 2, 3, 4, 5];

src/libstd/num/uint.rs

@@ -70,30 +70,6 @@ pub fn div_round(x: uint, y: uint) -> uint {
 ///
 pub fn div_floor(x: uint, y: uint) -> uint { return x / y; }
 
-///
-/// Iterate over the range [`lo`..`hi`), or stop when requested
-///
-/// # Arguments
-///
-/// * lo - The integer at which to start the loop (included)
-/// * hi - The integer at which to stop the loop (excluded)
-/// * it - A block to execute with each consecutive integer of the range.
-///        Return `true` to continue, `false` to stop.
-///
-/// # Return value
-///
-/// `true` If execution proceeded correctly, `false` if it was interrupted,
-/// that is if `it` returned `false` at any point.
-///
-pub fn iterate(lo: uint, hi: uint, it: &fn(uint) -> bool) -> bool {
-    let mut i = lo;
-    while i < hi {
-        if (!it(i)) { return false; }
-        i += 1u;
-    }
-    return true;
-}
-
 impl iter::Times for uint {
     #[inline]
     ///

src/libstd/option.rs

@@ -116,7 +116,7 @@ impl<T: ToStr> ToStr for Option<T> {
 impl<T> Option<T> {
     /// Return an iterator over the possibly contained value
     #[inline]
-    pub fn iter<'r>(&'r self) -> OptionIterator<'r, T> {
+    pub fn iter<'r>(&'r self) -> OptionIterator<&'r T> {
         match *self {
             Some(ref x) => OptionIterator{opt: Some(x)},
             None => OptionIterator{opt: None}
@@ -125,13 +125,19 @@ impl<T> Option<T> {
 
     /// Return a mutable iterator over the possibly contained value
     #[inline]
-    pub fn mut_iter<'r>(&'r mut self) -> OptionMutIterator<'r, T> {
+    pub fn mut_iter<'r>(&'r mut self) -> OptionIterator<&'r mut T> {
         match *self {
-            Some(ref mut x) => OptionMutIterator{opt: Some(x)},
-            None => OptionMutIterator{opt: None}
+            Some(ref mut x) => OptionIterator{opt: Some(x)},
+            None => OptionIterator{opt: None}
         }
     }
 
+    /// Return a consuming iterator over the possibly contained value
+    #[inline]
+    pub fn consume(self) -> OptionIterator<T> {
+        OptionIterator{opt: self}
+    }
+
     /// Returns true if the option equals `None`
     #[inline]
     pub fn is_none(&self) -> bool {
@@ -404,34 +410,18 @@ impl<T> Zero for Option<T> {
     fn is_zero(&self) -> bool { self.is_none() }
 }
 
-/// Immutable iterator over an `Option<A>`
-pub struct OptionIterator<'self, A> {
-    priv opt: Option<&'self A>
-}
-
-impl<'self, A> Iterator<&'self A> for OptionIterator<'self, A> {
-    fn next(&mut self) -> Option<&'self A> {
-        util::replace(&mut self.opt, None)
-    }
-
-    fn size_hint(&self) -> (uint, Option<uint>) {
-        match self.opt {
-            Some(_) => (1, Some(1)),
-            None => (0, Some(0)),
-        }
-    }
-}
-
-/// Mutable iterator over an `Option<A>`
-pub struct OptionMutIterator<'self, A> {
-    priv opt: Option<&'self mut A>
+/// An iterator that yields either one or zero elements
+pub struct OptionIterator<A> {
+    priv opt: Option<A>
 }
 
-impl<'self, A> Iterator<&'self mut A> for OptionMutIterator<'self, A> {
-    fn next(&mut self) -> Option<&'self mut A> {
-        util::replace(&mut self.opt, None)
+impl<A> Iterator<A> for OptionIterator<A> {
+    #[inline]
+    fn next(&mut self) -> Option<A> {
+        self.opt.take()
     }
 
+    #[inline]
     fn size_hint(&self) -> (uint, Option<uint>) {
         match self.opt {
             Some(_) => (1, Some(1)),