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 21 #include "llvm/ADT/iterator_range.h" 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> 88 iterator_range<typename GraphTraits<GraphType>::nodes_iterator> 89 nodes(const GraphType &G) { 90 return make_range(GraphTraits<GraphType>::nodes_begin(G), 91 GraphTraits<GraphType>::nodes_end(G)); 92 } 93 template <class GraphType> 94 iterator_range<typename GraphTraits<Inverse<GraphType>>::nodes_iterator> 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> 101 iterator_range<typename GraphTraits<GraphType>::ChildIteratorType> 102 children(const typename GraphTraits<GraphType>::NodeRef &G) { 103 return make_range(GraphTraits<GraphType>::child_begin(G), 104 GraphTraits<GraphType>::child_end(G)); 105 } 106 107 template <class GraphType> 108 iterator_range<typename GraphTraits<Inverse<GraphType>>::ChildIteratorType> 109 inverse_children(const typename GraphTraits<GraphType>::NodeRef &G) { 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 117
