GraphTraits.h revision e602f473062a91e6ac9aa17097de8b5cd75b0852
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 21namespace llvm { 22 23// GraphTraits - This class should be specialized by different graph types... 24// which is why the default version is empty. 25// 26template<class GraphType> 27struct GraphTraits { 28 // Elements to provide: 29 30 // typedef NodeType - Type of Node in the graph 31 // typedef ChildIteratorType - Type used to iterate over children in graph 32 33 // static NodeType *getEntryNode(const GraphType &) 34 // Return the entry node of the graph 35 36 // static ChildIteratorType child_begin(NodeType *) 37 // static ChildIteratorType child_end (NodeType *) 38 // Return iterators that point to the beginning and ending of the child 39 // node list for the specified node. 40 // 41 42 43 // typedef ...iterator nodes_iterator; 44 // static nodes_iterator nodes_begin(GraphType *G) 45 // static nodes_iterator nodes_end (GraphType *G) 46 // 47 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 48 49 50 // If anyone tries to use this class without having an appropriate 51 // specialization, make an error. If you get this error, it's because you 52 // need to include the appropriate specialization of GraphTraits<> for your 53 // graph, or you need to define it for a new graph type. Either that or 54 // your argument to XXX_begin(...) is unknown or needs to have the proper .h 55 // file #include'd. 56 // 57 typedef typename GraphType::UnknownGraphTypeError NodeType; 58}; 59 60 61// Inverse - This class is used as a little marker class to tell the graph 62// iterator to iterate over the graph in a graph defined "Inverse" ordering. 63// Not all graphs define an inverse ordering, and if they do, it depends on 64// the graph exactly what that is. Here's an example of usage with the 65// df_iterator: 66// 67// idf_iterator<Method*> I = idf_begin(M), E = idf_end(M); 68// for (; I != E; ++I) { ... } 69// 70// Which is equivalent to: 71// df_iterator<Inverse<Method*> > I = idf_begin(M), E = idf_end(M); 72// for (; I != E; ++I) { ... } 73// 74template <class GraphType> 75struct Inverse { 76 const GraphType &Graph; 77 78 inline Inverse(const GraphType &G) : Graph(G) {} 79}; 80 81// Provide a partial specialization of GraphTraits so that the inverse of an 82// inverse falls back to the original graph. 83template<class T> 84struct GraphTraits<Inverse<Inverse<T> > > { 85 typedef typename GraphTraits<T>::NodeType NodeType; 86 typedef typename GraphTraits<T>::ChildIteratorType ChildIteratorType; 87 88 static NodeType *getEntryNode(Inverse<Inverse<T> > *G) { 89 return GraphTraits<T>::getEntryNode(G->Graph.Graph); 90 } 91 92 static ChildIteratorType child_begin(NodeType* N) { 93 return GraphTraits<T>::child_begin(N); 94 } 95 96 static ChildIteratorType child_end(NodeType* N) { 97 return GraphTraits<T>::child_end(N); 98 } 99}; 100 101} // End llvm namespace 102 103#endif 104