diff options
Diffstat (limited to 'src/library/scala/collection/immutable/BitSet.scala')
| -rw-r--r-- | src/library/scala/collection/immutable/BitSet.scala | 41 |
1 files changed, 36 insertions, 5 deletions
diff --git a/src/library/scala/collection/immutable/BitSet.scala b/src/library/scala/collection/immutable/BitSet.scala index 70543aa3a6..ecf3326c7f 100644 --- a/src/library/scala/collection/immutable/BitSet.scala +++ b/src/library/scala/collection/immutable/BitSet.scala @@ -14,7 +14,7 @@ package immutable import generic._ import BitSetLike.{LogWL, updateArray} -import mutable.{ Builder, SetBuilder } +import mutable.Builder /** A class for immutable bitsets. * $bitsetinfo @@ -68,6 +68,8 @@ object BitSet extends BitSetFactory[BitSet] { /** The empty bitset */ val empty: BitSet = new BitSet1(0L) + private def createSmall(a: Long, b: Long): BitSet = if (b == 0L) new BitSet1(a) else new BitSet2(a, b) + /** A builder that takes advantage of mutable BitSets. */ def newBuilder: Builder[Int, BitSet] = new Builder[Int, BitSet] { private[this] val b = new mutable.BitSet @@ -84,7 +86,7 @@ object BitSet extends BitSetFactory[BitSet] { val len = elems.length if (len == 0) empty else if (len == 1) new BitSet1(elems(0)) - else if (len == 2) new BitSet2(elems(0), elems(1)) + else if (len == 2) createSmall(elems(0), elems(1)) else { val a = new Array[Long](len) Array.copy(elems, 0, a, 0, len) @@ -99,17 +101,24 @@ object BitSet extends BitSetFactory[BitSet] { val len = elems.length if (len == 0) empty else if (len == 1) new BitSet1(elems(0)) - else if (len == 2) new BitSet2(elems(0), elems(1)) + else if (len == 2) createSmall(elems(0), elems(1)) else new BitSetN(elems) } + @SerialVersionUID(2260107458435649300L) class BitSet1(val elems: Long) extends BitSet { protected def nwords = 1 protected def word(idx: Int) = if (idx == 0) elems else 0L protected def updateWord(idx: Int, w: Long): BitSet = if (idx == 0) new BitSet1(w) - else if (idx == 1) new BitSet2(elems, w) + else if (idx == 1) createSmall(elems, w) else fromBitMaskNoCopy(updateArray(Array(elems), idx, w)) + override def head: Int = + if (elems == 0L) throw new NoSuchElementException("Empty BitSet") + else java.lang.Long.numberOfTrailingZeros(elems) + override def tail: BitSet = + if (elems == 0L) throw new NoSuchElementException("Empty BitSet") + else new BitSet1(elems - java.lang.Long.lowestOneBit(elems)) } class BitSet2(val elems0: Long, elems1: Long) extends BitSet { @@ -117,8 +126,20 @@ object BitSet extends BitSetFactory[BitSet] { protected def word(idx: Int) = if (idx == 0) elems0 else if (idx == 1) elems1 else 0L protected def updateWord(idx: Int, w: Long): BitSet = if (idx == 0) new BitSet2(w, elems1) - else if (idx == 1) new BitSet2(elems0, w) + else if (idx == 1) createSmall(elems0, w) else fromBitMaskNoCopy(updateArray(Array(elems0, elems1), idx, w)) + override def head: Int = + if (elems0 == 0L) { + if (elems1 == 0) throw new NoSuchElementException("Empty BitSet") + 64 + java.lang.Long.numberOfTrailingZeros(elems1) + } + else java.lang.Long.numberOfTrailingZeros(elems0) + override def tail: BitSet = + if (elems0 == 0L) { + if (elems1 == 0L) throw new NoSuchElementException("Empty BitSet") + createSmall(elems0, elems1 - java.lang.Long.lowestOneBit(elems1)) + } + else new BitSet2(elems0 - java.lang.Long.lowestOneBit(elems0), elems1) } /** The implementing class for bit sets with elements >= 128 (exceeding @@ -131,5 +152,15 @@ object BitSet extends BitSetFactory[BitSet] { protected def nwords = elems.length protected def word(idx: Int) = if (idx < nwords) elems(idx) else 0L protected def updateWord(idx: Int, w: Long): BitSet = fromBitMaskNoCopy(updateArray(elems, idx, w)) + override def tail: BitSet = { + val n = nwords + var i = 0 + while (i < n) { + val wi = word(i) + if (wi != 0L) return fromBitMaskNoCopy(updateArray(elems, i, wi - java.lang.Long.lowestOneBit(wi))) + i += 1 + } + throw new NoSuchElementException("Empty BitSet") + } } } |