AU: Some graph types and a couple utility functions
These will be used by the delta diff generator.
Review URL: http://codereview.chromium.org/578009
diff --git a/graph_types.h b/graph_types.h
new file mode 100644
index 0000000..afb7f64
--- /dev/null
+++ b/graph_types.h
@@ -0,0 +1,53 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_TYPES_H__
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_TYPES_H__
+
+#include <map>
+#include <set>
+#include <utility>
+#include <vector>
+#include "base/basictypes.h"
+#include "update_engine/update_metadata.pb.h"
+
+// A few classes that help in generating delta images use these types
+// for the graph work.
+
+namespace chromeos_update_engine {
+
+struct EdgeProperties {
+ std::vector<Extent> extents; // filesystem extents represented
+};
+
+struct Vertex {
+ Vertex() : index(-1), lowlink(-1), op(NULL) {}
+ typedef std::map<std::vector<Vertex>::size_type, EdgeProperties> EdgeMap;
+ EdgeMap out_edges;
+
+ // We sometimes wish to consider a subgraph of a graph. A subgraph would have
+ // a subset of the vertices from the graph and a subset of the edges.
+ // When considering this vertex within a subgraph, subgraph_edges stores
+ // the out-edges.
+ typedef std::set<std::vector<Vertex>::size_type> SubgraphEdgeMap;
+ SubgraphEdgeMap subgraph_edges;
+
+ // For Tarjan's algorithm:
+ std::vector<Vertex>::size_type index;
+ std::vector<Vertex>::size_type lowlink;
+
+ // Other Vertex properties:
+ DeltaArchiveManifest_InstallOperation* op;
+
+ typedef std::vector<Vertex>::size_type Index;
+ static const Vertex::Index kInvalidIndex = -1;
+};
+
+typedef std::vector<Vertex> Graph;
+
+typedef std::pair<Vertex::Index, Vertex::Index> Edge;
+
+} // namespace chromeos_update_engine
+
+#endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_TYPES_H__