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.
46 // typedef ...iterator nodes_iterator; - dereference to a NodeRef
47 // static nodes_iterator nodes_begin(GraphType *G)
48 // static nodes_iterator nodes_end (GraphType *G)
49 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
51 // static unsigned size (GraphType *G)
52 // Return total number of nodes in the graph
56 // If anyone tries to use this class without having an appropriate
57 // specialization, make an error. If you get this error, it's because you
58 // need to include the appropriate specialization of GraphTraits<> for your
59 // graph, or you need to define it for a new graph type. Either that or
60 // your argument to XXX_begin(...) is unknown or needs to have the proper .h
63 typedef typename GraphType::UnknownGraphTypeError NodeRef;
67 // Inverse - This class is used as a little marker class to tell the graph
68 // iterator to iterate over the graph in a graph defined "Inverse" ordering.
69 // Not all graphs define an inverse ordering, and if they do, it depends on
70 // the graph exactly what that is. Here's an example of usage with the
73 // idf_iterator<Method*> I = idf_begin(M), E = idf_end(M);
74 // for (; I != E; ++I) { ... }
76 // Which is equivalent to:
77 // df_iterator<Inverse<Method*> > I = idf_begin(M), E = idf_end(M);
78 // for (; I != E; ++I) { ... }
80 template <class GraphType>
82 const GraphType &Graph;
84 inline Inverse(const GraphType &G) : Graph(G) {}
87 // Provide a partial specialization of GraphTraits so that the inverse of an
88 // inverse falls back to the original graph.
89 template <class T> struct GraphTraits<Inverse<Inverse<T>>> : GraphTraits<T> {};
91 // Provide iterator ranges for the graph traits nodes and children
92 template <class GraphType>
93 iterator_range<typename GraphTraits<GraphType>::nodes_iterator>
94 nodes(const GraphType &G) {
95 return make_range(GraphTraits<GraphType>::nodes_begin(G),
96 GraphTraits<GraphType>::nodes_end(G));
98 template <class GraphType>
99 iterator_range<typename GraphTraits<Inverse<GraphType>>::nodes_iterator>
100 inverse_nodes(const GraphType &G) {
101 return make_range(GraphTraits<Inverse<GraphType>>::nodes_begin(G),
102 GraphTraits<Inverse<GraphType>>::nodes_end(G));
105 template <class GraphType>
106 iterator_range<typename GraphTraits<GraphType>::ChildIteratorType>
107 children(const typename GraphTraits<GraphType>::NodeRef &G) {
108 return make_range(GraphTraits<GraphType>::child_begin(G),
109 GraphTraits<GraphType>::child_end(G));
112 template <class GraphType>
113 iterator_range<typename GraphTraits<Inverse<GraphType>>::ChildIteratorType>
114 inverse_children(const typename GraphTraits<GraphType>::NodeRef &G) {
115 return make_range(GraphTraits<Inverse<GraphType>>::child_begin(G),
116 GraphTraits<Inverse<GraphType>>::child_end(G));
118 } // End llvm namespace