From 90962407e72d88f8f3249ade0f6bd60ff15af5ce Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 6 Dec 2012 14:06:00 +0100
Subject: Initial commit

---
 src/dotty/tools/dotc/util/HashSet.scala | 108 ++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 src/dotty/tools/dotc/util/HashSet.scala

(limited to 'src/dotty/tools/dotc/util/HashSet.scala')

diff --git a/src/dotty/tools/dotc/util/HashSet.scala b/src/dotty/tools/dotc/util/HashSet.scala
new file mode 100644
index 000000000..589cc1f41
--- /dev/null
+++ b/src/dotty/tools/dotc/util/HashSet.scala
@@ -0,0 +1,108 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2012 LAMP/EPFL
+ * @author  Martin Odersky
+ */
+
+package dotty.tools.dotc.util
+
+object HashSet {
+  def apply[T >: Null <: AnyRef](): HashSet[T] = this(16)
+  def apply[T >: Null <: AnyRef](label: String): HashSet[T] = this(label, 16)
+  def apply[T >: Null <: AnyRef](initialCapacity: Int): HashSet[T] = this("No Label", initialCapacity)
+  def apply[T >: Null <: AnyRef](label: String, initialCapacity: Int): HashSet[T] =
+    new HashSet[T](label, initialCapacity)
+}
+
+class HashSet[T >: Null <: AnyRef](val label: String, initialCapacity: Int) extends Set[T] with scala.collection.generic.Clearable {
+  private var used = 0
+  private var table = new Array[AnyRef](initialCapacity)
+  private def index(x: Int): Int = math.abs(x % table.length)
+
+  def hash(x: T): Int = x.hashCode
+
+  def size: Int = used
+  def clear() {
+    used = 0
+    table = new Array[AnyRef](initialCapacity)
+  }
+
+  def findEntryOrUpdate(x: T): T = {
+    var h = index(hash(x))
+    var entry = table(h)
+    while (entry ne null) {
+      if (x == entry)
+        return entry.asInstanceOf[T]
+
+      h = index(h + 1)
+      entry = table(h)
+    }
+    table(h) = x
+    used += 1
+    if (used > (table.length >> 2)) growTable()
+    x
+  }
+
+  def findEntry(x: T): T = {
+    var h = index(hash(x))
+    var entry = table(h)
+    while ((entry ne null) && x != entry) {
+      h = index(h + 1)
+      entry = table(h)
+    }
+    entry.asInstanceOf[T]
+  }
+
+  def addEntry(x: T) {
+    var h = index(hash(x))
+    var entry = table(h)
+    while (entry ne null) {
+      if (x == entry) return
+      h = index(h + 1)
+      entry = table(h)
+    }
+    table(h) = x
+    used += 1
+    if (used > (table.length >> 2)) growTable()
+  }
+  def addEntries(xs: TraversableOnce[T]) {
+    xs foreach addEntry
+  }
+
+  def iterator = new Iterator[T] {
+    private var i = 0
+    def hasNext: Boolean = {
+      while (i < table.length && (table(i) eq null)) i += 1
+      i < table.length
+    }
+    def next(): T =
+      if (hasNext) { i += 1; table(i - 1).asInstanceOf[T] }
+      else null
+  }
+
+  private def addOldEntry(x: T) {
+    var h = index(hash(x))
+    var entry = table(h)
+    while (entry ne null) {
+      h = index(h + 1)
+      entry = table(h)
+    }
+    table(h) = x
+  }
+
+  private def growTable() {
+    val oldtable = table
+    val growthFactor =
+      if (table.length <= initialCapacity) 8
+      else if (table.length <= (initialCapacity * 8)) 4
+      else 2
+
+    table = new Array[AnyRef](table.length * growthFactor)
+    var i = 0
+    while (i < oldtable.length) {
+      val entry = oldtable(i)
+      if (entry ne null) addOldEntry(entry.asInstanceOf[T])
+      i += 1
+    }
+  }
+  override def toString() = "HashSet %s(%d / %d)".format(label, used, table.length)
+}
-- 
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