Add compatibility with bitvec's BitSlice trait

Cargo.toml

@@ -13,8 +13,12 @@ categories = ["data-structures"]
 
 [features]
 std = []
+bitvec-asbits = ["bitvec"]
 default = ["std"]
 
 [package.metadata.release]
 no-dev-version = true
 tag-name = "{{version}}"
+
+[dependencies]
+bitvec = { version = "^0.17", optional = true }

src/asbits.rs

@@ -0,0 +1,66 @@
+use std::ops;
+
+use bitvec::slice::{BitSlice, AsBits};
+use bitvec::order::{BitOrder, Lsb0};
+
+use super::FixedBitSet;
+use crate::range::IndexRange;
+
+impl AsBits for FixedBitSet {
+	type Store = u32;
+
+	fn bits<O: BitOrder>(&self) -> &BitSlice<O, Self::Store> {
+		BitSlice::from_slice(self.as_slice())
+	}
+
+	fn bits_mut<O: BitOrder>(&mut self) -> &mut BitSlice<O, Self::Store> {
+		BitSlice::from_slice_mut(self.as_mut_slice())
+	}
+}
+
+impl ops::Deref for FixedBitSet {
+	type Target = BitSlice<Lsb0, u32>;
+	fn deref(&self) -> &Self::Target {
+		self.bits()
+	}
+}
+
+impl ops::DerefMut for FixedBitSet {
+	fn deref_mut(&mut self) -> &mut Self::Target {
+		self.bits_mut()
+	}
+}
+
+impl<R: IndexRange> ops::Index<R> for FixedBitSet {
+	type Output = BitSlice<Lsb0, u32>;
+	fn index(&self, range: R) -> &Self::Output {
+		let start = range.start().unwrap_or(0);
+		let end = range.end().unwrap_or(self.len());
+		&self.bits()[start..end]
+	}
+}
+
+impl<R: IndexRange> ops::IndexMut<R> for FixedBitSet {
+	fn index_mut(&mut self, range: R) -> &mut Self::Output {
+		let start = range.start().unwrap_or(0);
+		let end = range.end().unwrap_or(self.len());
+		&mut self.bits_mut()[start..end]
+	}
+}
+
+#[test]
+fn test_asbits() {
+	let mut fb = FixedBitSet::with_capacity(50);
+    fb.set(11, true);
+    fb.set(12, true);
+    fb.set(7, true);
+    fb.set(35, true);
+    fb.set(40, true);
+
+	assert_eq!(fb.get(5), Some(&false));
+	assert_eq!(fb[10..].get(1), Some(&true));
+	fb[10..].set(2, false);
+	assert_eq!(fb.get(12), Some(&false));
+
+	assert_eq!(fb.count_ones(..), 4);
+}

src/lib.rs

@@ -28,6 +28,11 @@ use core as std;
 
 mod range;
 
+#[cfg(feature = "bitvec-asbits")]
+extern crate bitvec;
+#[cfg(feature = "bitvec-asbits")]
+mod asbits;
+
 use std::fmt::Write;
 use std::fmt::{Display, Error, Formatter, Binary};