Small performance boost.

src/lib.rs

@@ -76,10 +76,12 @@ impl BitSet {
         }
     }
 
+    #[inline]
     pub fn len(&self) -> usize {
         self.nbits
     }
 
+    #[inline]
     pub fn is_empty(&self) -> bool {
         self.nbits == 0
     }
@@ -89,6 +91,7 @@ impl BitSet {
         self.nbits = 0;
     }
 
+    #[inline]
     pub fn contains(&self, value: &u64) -> bool {
         let (block, bit) = block_bit(value, &BITS);
 
@@ -98,6 +101,7 @@ impl BitSet {
         }
     }
 
+    #[inline]
     pub fn is_subset(&self, other: &BitSet) -> bool {
         if self.nbits > other.nbits {
             false
@@ -116,6 +120,7 @@ impl BitSet {
         other.is_subset(self)
     }
 
+    #[inline]
     pub fn insert(&mut self, value: u64) -> bool {
         let (block, bit) = block_bit(&value, &BITS);
         let block = self.blocks.entry(block).or_insert(0);
@@ -132,6 +137,7 @@ impl BitSet {
         }
     }
 
+    #[inline]
     pub fn remove(&mut self, value: &u64) -> bool {
         let (block, bit) = block_bit(value, &BITS);
         let block = self.blocks.entry(block).or_insert(0);
@@ -148,15 +154,17 @@ impl BitSet {
         }
     }
 
+    #[inline]
     pub fn union_with(&mut self, other: &Self) {
         for (key, value) in &other.blocks {
-            *self.blocks.entry(*key).or_insert(0) |= value;
-        }
+            let block = self.blocks.entry(*key).or_insert(0);
 
-        self.nbits = self.blocks
-            .values()
-            .map(|block| block.count_ones() as usize)
-            .sum();
+            let n = block.count_ones();
+
+            *block |= value;
+
+            self.nbits += (block.count_ones() - n) as usize;
+        }
     }
 }
 
@@ -206,13 +214,14 @@ impl ops::BitOr for BitSet {
     #[inline]
     fn bitor(mut self, rhs: Self) -> Self {
         for (key, value) in &rhs.blocks {
-            *self.blocks.entry(*key).or_insert(0) |= value;
-        }
+            let block = self.blocks.entry(*key).or_insert(0);
 
-        self.nbits = self.blocks
-            .values()
-            .map(|block| block.count_ones() as usize)
-            .sum();
+            let n = block.count_ones();
+
+            *block |= value;
+
+            self.nbits += (block.count_ones() - n) as usize;
+        }
 
         self
     }
@@ -224,13 +233,14 @@ impl<'a> ops::BitOr<&'a Self> for BitSet {
     #[inline]
     fn bitor(mut self, rhs: &'a Self) -> Self {
         for (key, value) in &rhs.blocks {
-            *self.blocks.entry(*key).or_insert(0) |= value;
-        }
+            let block = self.blocks.entry(*key).or_insert(0);
 
-        self.nbits = self.blocks
-            .values()
-            .map(|block| block.count_ones() as usize)
-            .sum();
+            let n = block.count_ones();
+
+            *block |= value;
+
+            self.nbits += (block.count_ones() - n) as usize;
+        }
 
         self
     }