- initial check-in.

1 files changed, 46 insertions, 0 deletions

diff --git a/sources/scala/tools/nsc/backend/WorklistAlgorithm.scala b/sources/scala/tools/nsc/backend/WorklistAlgorithm.scala
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+++ b/sources/scala/tools/nsc/backend/WorklistAlgorithm.scala
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+/* NSC -- new scala compiler
+ * Copyright 2005 LAMP/EPFL
+ * @author  Martin Odersky
+ */
+
+// $Id$
+
+package scala.tools.nsc.backend;
+
+import scala.tools.nsc.ast._;
+import scala.collection.mutable.Queue;
+
+/**
+ * Simple implementation of a worklist algorithm. A processing
+ * function is applied repeatedly to the first element in the
+ * worklist queue, as long as the queue is not empty.
+ *
+ * The client class should mix-in this trait and initialize the
+ * worklist field and define the processElement method. Then call
+ * the 'run' method providing a function that initializes the
+ * worklist.
+ *
+ * @see scala.tools.nsc.backend.icode.Linearizers
+ */
+trait WorklistAlgorithm {
+  type Elem;
+
+  val worklist: Queue[Elem];
+
+  /**
+   * Run the iterative algorithm until the worklist
+   * remains empty. The initializer is run once before
+   * the loop starts and should initialize the worklist.
+   */
+  def run(initWorklist: => Unit) = {
+    initWorklist;
+
+    while (!worklist.isEmpty)
+      processElement(worklist.dequeue);
+  }
+
+  /**
+   * Process the current element from the worklist.
+   */
+  def processElement(e: Elem): Unit;
+}