extra: Use external iterators in bitv implementation

Convert some internally used functions to use a external iterators.

Change all uses of remaining internal iterators to use `do` expr

src/libextra/bitv.rs

@@ -12,7 +12,8 @@
 
 
 use std::cmp;
-use std::iterator::{DoubleEndedIterator, RandomAccessIterator, Invert};
+use std::iterator::RandomAccessIterator;
+use std::iterator::{Invert, Enumerate};
 use std::num;
 use std::ops;
 use std::uint;
@@ -164,7 +165,7 @@ pub fn each_storage(&mut self, op: &fn(v: &mut uint) -> bool) -> bool {
     }
 
     #[inline]
-    pub fn negate(&mut self) { for self.each_storage |w| { *w = !*w } }
+    pub fn negate(&mut self) { do self.each_storage |w| { *w = !*w; true }; }
 
     #[inline]
     pub fn union(&mut self, b: &BigBitv, nbits: uint) -> bool {
@@ -723,12 +724,12 @@ fn eq(&self, other: &BitvSet) -> bool {
         if self.size != other.size {
             return false;
         }
-        for self.each_common(other) |_, w1, w2| {
+        for self.common_iter(other).advance |(_, w1, w2)| {
             if w1 != w2 {
                 return false;
             }
         }
-        for self.each_outlier(other) |_, _, w| {
+        for self.outlier_iter(other).advance |(_, _, w)| {
             if w != 0 {
                 return false;
             }
@@ -746,7 +747,7 @@ fn len(&self) -> uint { self.size }
 
 impl Mutable for BitvSet {
     fn clear(&mut self) {
-        for self.bitv.each_storage |w| { *w = 0; }
+        do self.bitv.each_storage |w| { *w = 0; true };
         self.size = 0;
     }
 }
@@ -757,14 +758,13 @@ fn contains(&self, value: &uint) -> bool {
     }
 
     fn is_disjoint(&self, other: &BitvSet) -> bool {
-        for self.intersection(other) |_| {
-            return false;
+        do self.intersection(other) |_| {
+            false
         }
-        return true;
     }
 
     fn is_subset(&self, other: &BitvSet) -> bool {
-        for self.each_common(other) |_, w1, w2| {
+        for self.common_iter(other).advance |(_, w1, w2)| {
             if w1 & w2 != w1 {
                 return false;
             }
@@ -772,7 +772,7 @@ fn is_subset(&self, other: &BitvSet) -> bool {
         /* If anything is not ours, then everything is not ours so we're
            definitely a subset in that case. Otherwise if there's any stray
            ones that 'other' doesn't have, we're not a subset. */
-        for self.each_outlier(other) |mine, _, w| {
+        for self.outlier_iter(other).advance |(mine, _, w)| {
             if !mine {
                 return true;
             } else if w != 0 {
@@ -787,38 +787,38 @@ fn is_superset(&self, other: &BitvSet) -> bool {
     }
 
     fn difference(&self, other: &BitvSet, f: &fn(&uint) -> bool) -> bool {
-        for self.each_common(other) |i, w1, w2| {
+        for self.common_iter(other).advance |(i, w1, w2)| {
             if !iterate_bits(i, w1 & !w2, |b| f(&b)) {
                 return false;
             }
         }
         /* everything we have that they don't also shows up */
-        self.each_outlier(other, |mine, i, w|
+        self.outlier_iter(other).advance(|(mine, i, w)|
             !mine || iterate_bits(i, w, |b| f(&b))
         )
     }
 
     fn symmetric_difference(&self, other: &BitvSet,
                             f: &fn(&uint) -> bool) -> bool {
-        for self.each_common(other) |i, w1, w2| {
+        for self.common_iter(other).advance |(i, w1, w2)| {
             if !iterate_bits(i, w1 ^ w2, |b| f(&b)) {
                 return false;
             }
         }
-        self.each_outlier(other, |_, i, w| iterate_bits(i, w, |b| f(&b)))
+        self.outlier_iter(other).advance(|(_, i, w)| iterate_bits(i, w, |b| f(&b)))
     }
 
     fn intersection(&self, other: &BitvSet, f: &fn(&uint) -> bool) -> bool {
-        self.each_common(other, |i, w1, w2| iterate_bits(i, w1 & w2, |b| f(&b)))
+        self.common_iter(other).advance(|(i, w1, w2)| iterate_bits(i, w1 & w2, |b| f(&b)))
     }
 
     fn union(&self, other: &BitvSet, f: &fn(&uint) -> bool) -> bool {
-        for self.each_common(other) |i, w1, w2| {
+        for self.common_iter(other).advance |(i, w1, w2)| {
             if !iterate_bits(i, w1 | w2, |b| f(&b)) {
                 return false;
             }
         }
-        self.each_outlier(other, |_, i, w| iterate_bits(i, w, |b| f(&b)))
+        self.outlier_iter(other).advance(|(_, i, w)| iterate_bits(i, w, |b| f(&b)))
     }
 }
 
@@ -861,13 +861,14 @@ impl BitvSet {
     /// both have in common. The three yielded arguments are (bit location,
     /// 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 each_common(&self, other: &BitvSet,
-                   f: &fn(uint, uint, uint) -> bool) -> bool {
+    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());
-        self.bitv.storage.slice(0, min).iter().enumerate().advance(|(i, &w)| {
-            f(i * uint::bits, w, other.bitv.storage[i])
-        })
+        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])
+        }
     }
 
     /// Visits each word in self or other that extends beyond the other. This
@@ -877,24 +878,45 @@ fn each_common(&self, other: &BitvSet,
     /// The yielded arguments are a bool, the bit offset, and a word. The bool
     /// is true if the word comes from 'self', and false if it comes from
     /// 'other'.
-    fn each_outlier(&self, other: &BitvSet,
-                    f: &fn(bool, uint, uint) -> bool) -> bool {
+    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);
 
-        /* only one of these loops will execute and that's the point */
-        foreach (i, &w) in self.bitv.storage.slice(min, len1).iter().enumerate() {
-            if !f(true, (i + min) * uint::bits, w) {
-                return false;
+        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)
             }
-        }
-        foreach (i, &w) in other.bitv.storage.slice(min, len2).iter().enumerate() {
-            if !f(false, (i + min) * uint::bits, w) {
-                return false;
+        } 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)
             }
         }
-        return true;
+    }
+}
+
+/// 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
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        self.iter.size_hint()
     }
 }