- Allow printing generic LLVM graphs to 'dot' files, so they can be
    visualized easily.

llvm-svn: 4061
diff --git a/llvm/include/Support/DOTGraphTraits.h b/llvm/include/Support/DOTGraphTraits.h
new file mode 100644
index 0000000..28cf365
--- /dev/null
+++ b/llvm/include/Support/DOTGraphTraits.h
@@ -0,0 +1,65 @@
+//===-- Support/DotGraphTraits.h - Customize .dot output -------*- C++ -*--===//
+//
+// This file defines a template class that can be used to customize dot output
+// graphs generated by the GraphWriter.h file.  The default implementation of
+// this file will produce a simple, but not very polished graph.  By
+// specializing this template, lots of customization opportunities are possible.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUPPORT_DOTGRAPHTRAITS_H
+#define SUPPORT_DOTGRAPHTRAITS_H
+
+#include <string>
+
+/// DefaultDOTGraphTraits - This class provides the default implementations of
+/// all of the DOTGraphTraits methods.  If a specialization does not need to
+/// override all methods here it should inherit so that it can get the default
+/// implementations.
+///
+struct DefaultDOTGraphTraits {
+  /// getGraphName - Return the label for the graph as a whole.  Printed at the
+  /// top of the graph.
+  ///
+  static std::string getGraphName(void *Graph) { return ""; }
+
+  /// getNodeLabel - Given a node and a pointer to the top level graph, return
+  /// the label to print in the node.
+  static std::string getNodeLabel(void *Node, void *Graph) { return ""; }
+
+  /// If you want to specify custom node attributes, this is the place to do so
+  ///
+  static std::string getNodeAttributes(void *Node) { return ""; }
+
+  /// If you want to override the dot attributes printed for a particular edge,
+  /// override this method.
+  template<typename EdgeIter>
+  static std::string getEdgeAttributes(void *Node, EdgeIter EI) { return ""; }
+
+  /// getEdgeSourceLabel - If you want to label the edge source itself,
+  /// implement this method.
+  template<typename EdgeIter>
+  static std::string getEdgeSourceLabel(void *Node, EdgeIter I) { return ""; }
+
+  /// edgeTargetsEdgeSource - This method returns true if this outgoing edge
+  /// should actually target another edge source, not a node.  If this method is
+  /// implemented, getEdgeTarget should be implemented.
+  template<typename EdgeIter>
+  static bool edgeTargetsEdgeSource(void *Node, EdgeIter I) { return false; }
+
+  /// getEdgeTarget - If edgeTargetsEdgeSource returns true, this method is
+  /// called to determine which outgoing edge of Node is the target of this
+  /// edge.
+  template<typename EdgeIter>
+  static EdgeIter getEdgeTarget(void *Node, EdgeIter I) { return I; }
+};
+
+
+/// DOTGraphTraits - Template class that can be specialized to customize how
+/// graphs are converted to 'dot' graphs.  When specializing, you may inherit
+/// from DefaultDOTGraphTraits if you don't need to override everything.
+///
+template <typename Ty>
+class DOTGraphTraits : public DefaultDOTGraphTraits {};
+
+#endif