1 //===-- llvm/ADT/GraphTraits.h - Graph traits template ----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the little GraphTraits<X> template class that should be
11 // specialized by classes that want to be iteratable by generic graph iterators.
13 // This file also defines the marker class Inverse that is used to iterate over
14 // graphs in a graph defined, inverse ordering...
16 //===----------------------------------------------------------------------===//
18 #ifndef LLVM_ADT_GRAPHTRAITS_H
19 #define LLVM_ADT_GRAPHTRAITS_H
23 // GraphTraits - This class should be specialized by different graph types...
24 // which is why the default version is empty.
26 template<class GraphType>
28 // Elements to provide:
30 // typedef NodeRef - Type of Node token in the graph, which should
32 // typedef ChildIteratorType - Type used to iterate over children in graph,
33 // dereference to a NodeRef.
35 // static NodeRef getEntryNode(const GraphType &)
36 // Return the entry node of the graph
38 // static ChildIteratorType child_begin(NodeRef)
39 // static ChildIteratorType child_end (NodeRef)
40 // Return iterators that point to the beginning and ending of the child
41 // node list for the specified node.
44 // typedef ...iterator nodes_iterator; - dereference to a NodeRef
45 // static nodes_iterator nodes_begin(GraphType *G)
46 // static nodes_iterator nodes_end (GraphType *G)
47 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
49 // static unsigned size (GraphType *G)
50 // Return total number of nodes in the graph
54 // If anyone tries to use this class without having an appropriate
55 // specialization, make an error. If you get this error, it's because you
56 // need to include the appropriate specialization of GraphTraits<> for your
57 // graph, or you need to define it for a new graph type. Either that or
58 // your argument to XXX_begin(...) is unknown or needs to have the proper .h
61 typedef typename GraphType::UnknownGraphTypeError NodeRef;
65 // Inverse - This class is used as a little marker class to tell the graph
66 // iterator to iterate over the graph in a graph defined "Inverse" ordering.
67 // Not all graphs define an inverse ordering, and if they do, it depends on
68 // the graph exactly what that is. Here's an example of usage with the
71 // idf_iterator<Method*> I = idf_begin(M), E = idf_end(M);
72 // for (; I != E; ++I) { ... }
74 // Which is equivalent to:
75 // df_iterator<Inverse<Method*> > I = idf_begin(M), E = idf_end(M);
76 // for (; I != E; ++I) { ... }
78 template <class GraphType>
80 const GraphType &Graph;
82 inline Inverse(const GraphType &G) : Graph(G) {}
85 // Provide a partial specialization of GraphTraits so that the inverse of an
86 // inverse falls back to the original graph.
87 template <class T> struct GraphTraits<Inverse<Inverse<T>>> : GraphTraits<T> {};
89 } // End llvm namespace