Homework B (benchmarks)

src/cd/util/DepthFirstSearchPreOrder.java

@@ -0,0 +1,60 @@
+package cd.util;
+
+import cd.ir.BasicBlock;
+import cd.ir.ControlFlowGraph;
+
+import java.util.*;
+
+/**
+ * A potentially handy iterator which yields the blocks in a control-flow
+ * graph.  The order is pre-order, depth-first.  Pre-order means that a
+ * node is visited before its successors.
+ */
+public class DepthFirstSearchPreOrder implements Iterable<BasicBlock> {
+
+	public final ControlFlowGraph cfg;
+
+	public DepthFirstSearchPreOrder(ControlFlowGraph cfg) {
+		this.cfg = cfg;
+	}
+
+	public Iterator<BasicBlock> iterator() {
+		return new Iterator<BasicBlock>() {
+
+			/** Blocks we still need to visit */
+			private final Stack<BasicBlock> stack = new Stack<BasicBlock>();
+
+			/** Blocks we pushed thus far */
+			private final Set<BasicBlock> pushed = new HashSet<BasicBlock>();
+
+			{
+				stack.add(cfg.start);
+				pushed.add(cfg.start);
+			}
+
+			public boolean hasNext() {
+				return !stack.isEmpty();
+			}
+
+			public BasicBlock next() {
+				if (stack.isEmpty())
+					throw new NoSuchElementException();
+
+				BasicBlock res = stack.pop();
+				for (BasicBlock s : res.successors)
+					if (!pushed.contains(s)) {
+						pushed.add(s);
+						stack.add(s);
+					}
+
+				return res;
+			}
+
+			public void remove() {
+				throw new UnsupportedOperationException();
+			}
+
+		};
+	}
+
+}