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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 :
21 : #include "llvm/ADT/iterator_range.h"
22 :
23 : namespace llvm {
24 :
25 : // GraphTraits - This class should be specialized by different graph types...
26 : // which is why the default version is empty.
27 : //
28 : // This template evolved from supporting `BasicBlock` to also later supporting
29 : // more complex types (e.g. CFG and DomTree).
30 : //
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
34 : // example.
35 : template<class GraphType>
36 : struct GraphTraits {
37 : // Elements to provide:
38 :
39 : // typedef NodeRef - Type of Node token in the graph, which should
40 : // be cheap to copy.
41 : // typedef ChildIteratorType - Type used to iterate over children in graph,
42 : // dereference to a NodeRef.
43 :
44 : // static NodeRef getEntryNode(const GraphType &)
45 : // Return the entry node of the graph
46 :
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.
51 :
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
56 :
57 : // typedef EdgeRef - Type of Edge token in the graph, which should
58 : // be cheap to copy.
59 : // typedef ChildEdgeIteratorType - Type used to iterate over children edges in
60 : // graph, dereference to a EdgeRef.
61 :
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.
66 : //
67 : // static NodeRef edge_dest(EdgeRef)
68 : // Return the destination node of an edge.
69 :
70 : // static unsigned size (GraphType *G)
71 : // Return total number of nodes in the graph
72 :
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
78 : // file #include'd.
79 : using NodeRef = typename GraphType::UnknownGraphTypeError;
80 : };
81 :
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
86 : // df_iterator:
87 : //
88 : // idf_iterator<Method*> I = idf_begin(M), E = idf_end(M);
89 : // for (; I != E; ++I) { ... }
90 : //
91 : // Which is equivalent to:
92 : // df_iterator<Inverse<Method*>> I = idf_begin(M), E = idf_end(M);
93 : // for (; I != E; ++I) { ... }
94 : //
95 : template <class GraphType>
96 : struct Inverse {
97 : const GraphType &Graph;
98 :
99 0 : inline Inverse(const GraphType &G) : Graph(G) {}
100 : };
101 :
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> {};
105 :
106 : // Provide iterator ranges for the graph traits nodes and children
107 : template <class GraphType>
108 : iterator_range<typename GraphTraits<GraphType>::nodes_iterator>
109 2 : nodes(const GraphType &G) {
110 0 : return make_range(GraphTraits<GraphType>::nodes_begin(G),
111 2 : GraphTraits<GraphType>::nodes_end(G));
112 : }
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));
118 : }
119 :
120 : template <class GraphType>
121 : iterator_range<typename GraphTraits<GraphType>::ChildIteratorType>
122 21438538 : children(const typename GraphTraits<GraphType>::NodeRef &G) {
123 21438538 : return make_range(GraphTraits<GraphType>::child_begin(G),
124 21438538 : GraphTraits<GraphType>::child_end(G));
125 : }
126 20842032 :
127 20842032 : template <class GraphType>
128 20842032 : iterator_range<typename GraphTraits<Inverse<GraphType>>::ChildIteratorType>
129 0 : inverse_children(const typename GraphTraits<GraphType>::NodeRef &G) {
130 0 : return make_range(GraphTraits<Inverse<GraphType>>::child_begin(G),
131 0 : GraphTraits<Inverse<GraphType>>::child_end(G));
132 0 : }
133 :
134 0 : template <class GraphType>
135 0 : iterator_range<typename GraphTraits<GraphType>::ChildEdgeIteratorType>
136 0 : children_edges(const typename GraphTraits<GraphType>::NodeRef &G) {
137 0 : return make_range(GraphTraits<GraphType>::child_edge_begin(G),
138 0 : GraphTraits<GraphType>::child_edge_end(G));
139 0 : }
140 :
141 0 : } // end namespace llvm
142 0 :
143 0 : #endif // LLVM_ADT_GRAPHTRAITS_H
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