new: persistent ptree (-write-ptree) and klee-ptree

Introduce three different kinds of process trees:
1. Noop: does nothing (e.g. no allocations for DFS)
2. InMemory: same behaviour as before (e.g. RandomPathSearcher)
3. Persistent: similar to InMemory but writes nodes to ptree.db
     and tracks information such as branch type, termination
     type or source location (asm) in nodes. Enabled with
     -write-ptree

ptree.db files can be analysed/plotted with the new "klee-ptree"
tool.

1 files changed, 31 insertions, 0 deletions

diff --git a/tools/klee-ptree/DFSVisitor.h b/tools/klee-ptree/DFSVisitor.h
new file mode 100644
index 00000000..60d7b3bd
--- /dev/null
+++ b/tools/klee-ptree/DFSVisitor.h
@@ -0,0 +1,31 @@
+//===-- DFSVisitor.h --------------------------------------------*- C++ -*-===//
+//
+//                     The KLEE Symbolic Virtual Machine
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#pragma once
+
+#include "Tree.h"
+
+#include <functional>
+
+/// @brief Traverses a process tree and calls registered callbacks for
+/// intermediate and leaf nodes (not the classical Visitor pattern).
+class DFSVisitor {
+  // void _(node ID, node, depth)
+  using callbackT = std::function<void(std::uint32_t, Node, std::uint32_t)>;
+
+  const Tree &tree;
+  callbackT cb_intermediate;
+  callbackT cb_leaf;
+  void run() const noexcept;
+
+public:
+  DFSVisitor(const Tree &tree, callbackT cb_intermediate,
+             callbackT cb_leaf) noexcept;
+  ~DFSVisitor() = default;
+};