1 files changed, 45 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/yolean/trace/TraceVisitor.java b/vespajlib/src/main/java/com/yahoo/yolean/trace/TraceVisitor.java
new file mode 100644
index 00000000000..1b3507777b7
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/yolean/trace/TraceVisitor.java
@@ -0,0 +1,45 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.yolean.trace;
+
+/**
+ * <p>This class is an abstract visitor of {@link TraceNode}. See {@link TraceNode#accept(TraceVisitor)}.</p>
+ *
+ * @author bratseth
+ * @since 5.1.15
+ */
+public abstract class TraceVisitor {
+
+    /**
+     * <p>Visits a {@link TraceNode}. Called by {@link TraceNode#accept(TraceVisitor)}, before visiting its
+     * children.</p>
+     *
+     * @param node the <code>TraceNode</code> being visited
+     * @see TraceNode#accept(TraceVisitor)
+     */
+    public abstract void visit(TraceNode node);
+
+    /**
+     * <p>Enters a {@link TraceNode}. This method is called after {@link #visit(TraceNode)}, but before visiting its
+     * children. Note that this method is NOT called if a <code>TraceNode</code> has zero children.</p>
+     * <p>The default implementation of this method does nothing.</p>
+     *
+     * @param node the <code>TraceNode</code> being entered
+     * @see #leaving(TraceNode)
+     */
+    @SuppressWarnings("UnusedParameters")
+    public void entering(TraceNode node) {
+        // empty
+    }
+
+    /**
+     * <p>Leaves a {@link TraceNode}. This method is called after {@link #entering(TraceNode)}, and after visiting its
+     * children. Note that this method is NOT called if a <code>TraceNode</code> has zero children.</p>
+     * <p>The default implementation of this method does nothing.</p>
+     *
+     * @param node the <code>TraceNode</code> being left
+     */
+    @SuppressWarnings("UnusedParameters")
+    public void leaving(TraceNode node) {
+        // empty
+    }
+}