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
21 #include "llvm/ADT/iterator_range.h"
25 // GraphTraits - This class should be specialized by different graph types...
26 // which is why the default version is empty.
28 template<class GraphType>
30 // Elements to provide:
32 // typedef NodeRef - Type of Node token in the graph, which should
34 // typedef ChildIteratorType - Type used to iterate over children in graph,
35 // dereference to a NodeRef.
37 // static NodeRef getEntryNode(const GraphType &)
38 // Return the entry node of the graph
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.
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
50 // static unsigned size (GraphType *G)
51 // Return total number of nodes in the graph
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
59 using NodeRef = typename GraphType::UnknownGraphTypeError;
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
68 // idf_iterator<Method*> I = idf_begin(M), E = idf_end(M);
69 // for (; I != E; ++I) { ... }
71 // Which is equivalent to:
72 // df_iterator<Inverse<Method*>> I = idf_begin(M), E = idf_end(M);
73 // for (; I != E; ++I) { ... }
75 template <class GraphType>
77 const GraphType &Graph;
79 inline Inverse(const GraphType &G) : Graph(G) {}
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> {};
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));
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));
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));
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));
114 } // end namespace llvm
116 #endif // LLVM_ADT_GRAPHTRAITS_H