1 //===- llvm/ADT/GraphTraits.h - Graph traits template -----------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines the little GraphTraits<X> template class that should be 10 // specialized by classes that want to be iteratable by generic graph iterators. 11 // 12 // This file also defines the marker class Inverse that is used to iterate over 13 // graphs in a graph defined, inverse ordering... 14 // 15 //===----------------------------------------------------------------------===// 16 17 #ifndef LLVM_ADT_GRAPHTRAITS_H 18 #define LLVM_ADT_GRAPHTRAITS_H 19 20 #include "llvm/ADT/iterator_range.h" 21 22 namespace llvm { 23 24 // GraphTraits - This class should be specialized by different graph types... 25 // which is why the default version is empty. 26 // 27 // This template evolved from supporting `BasicBlock` to also later supporting 28 // more complex types (e.g. CFG and DomTree). 29 // 30 // GraphTraits can be used to create a view over a graph interpreting it 31 // differently without requiring a copy of the original graph. This could 32 // be achieved by carrying more data in NodeRef. See LoopBodyTraits for one 33 // example. 34 template<class GraphType> 35 struct GraphTraits { 36 // Elements to provide: 37 38 // typedef NodeRef - Type of Node token in the graph, which should 39 // be cheap to copy. 40 // typedef ChildIteratorType - Type used to iterate over children in graph, 41 // dereference to a NodeRef. 42 43 // static NodeRef getEntryNode(const GraphType &) 44 // Return the entry node of the graph 45 46 // static ChildIteratorType child_begin(NodeRef) 47 // static ChildIteratorType child_end (NodeRef) 48 // Return iterators that point to the beginning and ending of the child 49 // node list for the specified node. 50 51 // typedef ...iterator nodes_iterator; - dereference to a NodeRef 52 // static nodes_iterator nodes_begin(GraphType *G) 53 // static nodes_iterator nodes_end (GraphType *G) 54 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 55 56 // typedef EdgeRef - Type of Edge token in the graph, which should 57 // be cheap to copy. 58 // typedef ChildEdgeIteratorType - Type used to iterate over children edges in 59 // graph, dereference to a EdgeRef. 60 61 // static ChildEdgeIteratorType child_edge_begin(NodeRef) 62 // static ChildEdgeIteratorType child_edge_end(NodeRef) 63 // Return iterators that point to the beginning and ending of the 64 // edge list for the given callgraph node. 65 // 66 // static NodeRef edge_dest(EdgeRef) 67 // Return the destination node of an edge. 68 69 // static unsigned size (GraphType *G) 70 // Return total number of nodes in the graph 71 72 // If anyone tries to use this class without having an appropriate 73 // specialization, make an error. If you get this error, it's because you 74 // need to include the appropriate specialization of GraphTraits<> for your 75 // graph, or you need to define it for a new graph type. Either that or 76 // your argument to XXX_begin(...) is unknown or needs to have the proper .h 77 // file #include'd. 78 using NodeRef = typename GraphType::UnknownGraphTypeError; 79 }; 80 81 // Inverse - This class is used as a little marker class to tell the graph 82 // iterator to iterate over the graph in a graph defined "Inverse" ordering. 83 // Not all graphs define an inverse ordering, and if they do, it depends on 84 // the graph exactly what that is. Here's an example of usage with the 85 // df_iterator: 86 // 87 // idf_iterator<Method*> I = idf_begin(M), E = idf_end(M); 88 // for (; I != E; ++I) { ... } 89 // 90 // Which is equivalent to: 91 // df_iterator<Inverse<Method*>> I = idf_begin(M), E = idf_end(M); 92 // for (; I != E; ++I) { ... } 93 // 94 template <class GraphType> 95 struct Inverse { 96 const GraphType &Graph; 97 98 inline Inverse(const GraphType &G) : Graph(G) {} 99 }; 100 101 // Provide a partial specialization of GraphTraits so that the inverse of an 102 // inverse falls back to the original graph. 103 template <class T> struct GraphTraits<Inverse<Inverse<T>>> : GraphTraits<T> {}; 104 105 // Provide iterator ranges for the graph traits nodes and children 106 template <class GraphType> 107 iterator_range<typename GraphTraits<GraphType>::nodes_iterator> 108 nodes(const GraphType &G) { 109 return make_range(GraphTraits<GraphType>::nodes_begin(G), 110 GraphTraits<GraphType>::nodes_end(G)); 111 } 112 template <class GraphType> 113 iterator_range<typename GraphTraits<Inverse<GraphType>>::nodes_iterator> 114 inverse_nodes(const GraphType &G) { 115 return make_range(GraphTraits<Inverse<GraphType>>::nodes_begin(G), 116 GraphTraits<Inverse<GraphType>>::nodes_end(G)); 117 } 118 119 template <class GraphType> 120 iterator_range<typename GraphTraits<GraphType>::ChildIteratorType> 121 children(const typename GraphTraits<GraphType>::NodeRef &G) { 122 return make_range(GraphTraits<GraphType>::child_begin(G), 123 GraphTraits<GraphType>::child_end(G)); 124 } 125 126 template <class GraphType> 127 iterator_range<typename GraphTraits<Inverse<GraphType>>::ChildIteratorType> 128 inverse_children(const typename GraphTraits<GraphType>::NodeRef &G) { 129 return make_range(GraphTraits<Inverse<GraphType>>::child_begin(G), 130 GraphTraits<Inverse<GraphType>>::child_end(G)); 131 } 132 133 template <class GraphType> 134 iterator_range<typename GraphTraits<GraphType>::ChildEdgeIteratorType> 135 children_edges(const typename GraphTraits<GraphType>::NodeRef &G) { 136 return make_range(GraphTraits<GraphType>::child_edge_begin(G), 137 GraphTraits<GraphType>::child_edge_end(G)); 138 } 139 140 } // end namespace llvm 141 142 #endif // LLVM_ADT_GRAPHTRAITS_H 143