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 // This template evolved from supporting `BasicBlock` to also later supporting
29 // more complex types (e.g. CFG and DomTree).
31 // GraphTraits can be used to create a view over a graph interpreting it
32 // differently without requiring a copy of the original graph. This could
33 // be achieved by carrying more data in NodeRef. See LoopBodyTraits for one
35 template<class GraphType>
37 // Elements to provide:
39 // typedef NodeRef - Type of Node token in the graph, which should
41 // typedef ChildIteratorType - Type used to iterate over children in graph,
42 // dereference to a NodeRef.
44 // static NodeRef getEntryNode(const GraphType &)
45 // Return the entry node of the graph
47 // static ChildIteratorType child_begin(NodeRef)
48 // static ChildIteratorType child_end (NodeRef)
49 // Return iterators that point to the beginning and ending of the child
50 // node list for the specified node.
52 // typedef ...iterator nodes_iterator; - dereference to a NodeRef
53 // static nodes_iterator nodes_begin(GraphType *G)
54 // static nodes_iterator nodes_end (GraphType *G)
55 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
57 // typedef EdgeRef - Type of Edge token in the graph, which should
59 // typedef ChildEdgeIteratorType - Type used to iterate over children edges in
60 // graph, dereference to a EdgeRef.
62 // static ChildEdgeIteratorType child_edge_begin(NodeRef)
63 // static ChildEdgeIteratorType child_edge_end(NodeRef)
64 // Return iterators that point to the beginning and ending of the
65 // edge list for the given callgraph node.
67 // static NodeRef edge_dest(EdgeRef)
68 // Return the destination node of an edge.
70 // static unsigned size (GraphType *G)
71 // Return total number of nodes in the graph
73 // If anyone tries to use this class without having an appropriate
74 // specialization, make an error. If you get this error, it's because you
75 // need to include the appropriate specialization of GraphTraits<> for your
76 // graph, or you need to define it for a new graph type. Either that or
77 // your argument to XXX_begin(...) is unknown or needs to have the proper .h
79 using NodeRef = typename GraphType::UnknownGraphTypeError;
82 // Inverse - This class is used as a little marker class to tell the graph
83 // iterator to iterate over the graph in a graph defined "Inverse" ordering.
84 // Not all graphs define an inverse ordering, and if they do, it depends on
85 // the graph exactly what that is. Here's an example of usage with the
88 // idf_iterator<Method*> I = idf_begin(M), E = idf_end(M);
89 // for (; I != E; ++I) { ... }
91 // Which is equivalent to:
92 // df_iterator<Inverse<Method*>> I = idf_begin(M), E = idf_end(M);
93 // for (; I != E; ++I) { ... }
95 template <class GraphType>
97 const GraphType &Graph;
99 inline Inverse(const GraphType &G) : Graph(G) {}
102 // Provide a partial specialization of GraphTraits so that the inverse of an
103 // inverse falls back to the original graph.
104 template <class T> struct GraphTraits<Inverse<Inverse<T>>> : GraphTraits<T> {};
106 // Provide iterator ranges for the graph traits nodes and children
107 template <class GraphType>
108 iterator_range<typename GraphTraits<GraphType>::nodes_iterator>
109 nodes(const GraphType &G) {
110 return make_range(GraphTraits<GraphType>::nodes_begin(G),
111 GraphTraits<GraphType>::nodes_end(G));
113 template <class GraphType>
114 iterator_range<typename GraphTraits<Inverse<GraphType>>::nodes_iterator>
115 inverse_nodes(const GraphType &G) {
116 return make_range(GraphTraits<Inverse<GraphType>>::nodes_begin(G),
117 GraphTraits<Inverse<GraphType>>::nodes_end(G));
120 template <class GraphType>
121 iterator_range<typename GraphTraits<GraphType>::ChildIteratorType>
122 children(const typename GraphTraits<GraphType>::NodeRef &G) {
123 return make_range(GraphTraits<GraphType>::child_begin(G),
124 GraphTraits<GraphType>::child_end(G));
127 template <class GraphType>
128 iterator_range<typename GraphTraits<Inverse<GraphType>>::ChildIteratorType>
129 inverse_children(const typename GraphTraits<GraphType>::NodeRef &G) {
130 return make_range(GraphTraits<Inverse<GraphType>>::child_begin(G),
131 GraphTraits<Inverse<GraphType>>::child_end(G));
134 template <class GraphType>
135 iterator_range<typename GraphTraits<GraphType>::ChildEdgeIteratorType>
136 children_edges(const typename GraphTraits<GraphType>::NodeRef &G) {
137 return make_range(GraphTraits<GraphType>::child_edge_begin(G),
138 GraphTraits<GraphType>::child_edge_end(G));
141 } // end namespace llvm
143 #endif // LLVM_ADT_GRAPHTRAITS_H