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GraphTraits.h
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1 //===- llvm/ADT/GraphTraits.h - Graph traits template -----------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
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.
12 //
13 // This file also defines the marker class Inverse that is used to iterate over
14 // graphs in a graph defined, inverse ordering...
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #ifndef LLVM_ADT_GRAPHTRAITS_H
19 #define LLVM_ADT_GRAPHTRAITS_H
20 
22 
23 namespace llvm {
24 
25 // GraphTraits - This class should be specialized by different graph types...
26 // which is why the default version is empty.
27 //
28 template<class GraphType>
29 struct GraphTraits {
30  // Elements to provide:
31 
32  // typedef NodeRef - Type of Node token in the graph, which should
33  // be cheap to copy.
34  // typedef ChildIteratorType - Type used to iterate over children in graph,
35  // dereference to a NodeRef.
36 
37  // static NodeRef getEntryNode(const GraphType &)
38  // Return the entry node of the graph
39 
40  // static ChildIteratorType child_begin(NodeRef)
41  // static ChildIteratorType child_end (NodeRef)
42  // Return iterators that point to the beginning and ending of the child
43  // node list for the specified node.
44 
45  // typedef ...iterator nodes_iterator; - dereference to a NodeRef
46  // static nodes_iterator nodes_begin(GraphType *G)
47  // static nodes_iterator nodes_end (GraphType *G)
48  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
49 
50  // static unsigned size (GraphType *G)
51  // Return total number of nodes in the graph
52 
53  // If anyone tries to use this class without having an appropriate
54  // specialization, make an error. If you get this error, it's because you
55  // need to include the appropriate specialization of GraphTraits<> for your
56  // graph, or you need to define it for a new graph type. Either that or
57  // your argument to XXX_begin(...) is unknown or needs to have the proper .h
58  // file #include'd.
59  using NodeRef = typename GraphType::UnknownGraphTypeError;
60 };
61 
62 // Inverse - This class is used as a little marker class to tell the graph
63 // iterator to iterate over the graph in a graph defined "Inverse" ordering.
64 // Not all graphs define an inverse ordering, and if they do, it depends on
65 // the graph exactly what that is. Here's an example of usage with the
66 // df_iterator:
67 //
68 // idf_iterator<Method*> I = idf_begin(M), E = idf_end(M);
69 // for (; I != E; ++I) { ... }
70 //
71 // Which is equivalent to:
72 // df_iterator<Inverse<Method*>> I = idf_begin(M), E = idf_end(M);
73 // for (; I != E; ++I) { ... }
74 //
75 template <class GraphType>
76 struct Inverse {
77  const GraphType &Graph;
78 
79  inline Inverse(const GraphType &G) : Graph(G) {}
80 };
81 
82 // Provide a partial specialization of GraphTraits so that the inverse of an
83 // inverse falls back to the original graph.
84 template <class T> struct GraphTraits<Inverse<Inverse<T>>> : GraphTraits<T> {};
85 
86 // Provide iterator ranges for the graph traits nodes and children
87 template <class GraphType>
89 nodes(const GraphType &G) {
92 }
93 template <class GraphType>
95 inverse_nodes(const GraphType &G) {
96  return make_range(GraphTraits<Inverse<GraphType>>::nodes_begin(G),
97  GraphTraits<Inverse<GraphType>>::nodes_end(G));
98 }
99 
100 template <class GraphType>
105 }
106 
107 template <class GraphType>
110  return make_range(GraphTraits<Inverse<GraphType>>::child_begin(G),
111  GraphTraits<Inverse<GraphType>>::child_end(G));
112 }
113 
114 } // end namespace llvm
115 
116 #endif // LLVM_ADT_GRAPHTRAITS_H
iterator_range< typename GraphTraits< GraphType >::ChildIteratorType > children(const typename GraphTraits< GraphType >::NodeRef &G)
Definition: GraphTraits.h:102
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
iterator_range< typename GraphTraits< Inverse< GraphType > >::ChildIteratorType > inverse_children(const typename GraphTraits< GraphType >::NodeRef &G)
Definition: GraphTraits.h:109
typename SDNode *::UnknownGraphTypeError NodeRef
Definition: GraphTraits.h:59
iterator_range< typename GraphTraits< Inverse< GraphType > >::nodes_iterator > inverse_nodes(const GraphType &G)
Definition: GraphTraits.h:95
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
const GraphType & Graph
Definition: GraphTraits.h:77
const DataFlowGraph & G
Definition: RDFGraph.cpp:211
A range adaptor for a pair of iterators.
iterator_range< typename GraphTraits< GraphType >::nodes_iterator > nodes(const GraphType &G)
Definition: GraphTraits.h:89
Inverse(const GraphType &G)
Definition: GraphTraits.h:79