1 //===- llvm/ADT/DepthFirstIterator.h - Depth First iterator -----*- 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 builds on the ADT/GraphTraits.h file to build generic depth
11 // first graph iterator. This file exposes the following functions/types:
13 // df_begin/df_end/df_iterator
14 // * Normal depth-first iteration - visit a node and then all of its children.
16 // idf_begin/idf_end/idf_iterator
17 // * Depth-first iteration on the 'inverse' graph.
19 // df_ext_begin/df_ext_end/df_ext_iterator
20 // * Normal depth-first iteration - visit a node and then all of its children.
21 // This iterator stores the 'visited' set in an external set, which allows
22 // it to be more efficient, and allows external clients to use the set for
25 // idf_ext_begin/idf_ext_end/idf_ext_iterator
26 // * Depth-first iteration on the 'inverse' graph.
27 // This iterator stores the 'visited' set in an external set, which allows
28 // it to be more efficient, and allows external clients to use the set for
31 //===----------------------------------------------------------------------===//
33 #ifndef LLVM_ADT_DEPTHFIRSTITERATOR_H
34 #define LLVM_ADT_DEPTHFIRSTITERATOR_H
36 #include "llvm/ADT/GraphTraits.h"
37 #include "llvm/ADT/iterator.h"
38 #include "llvm/ADT/SmallPtrSet.h"
44 // df_iterator_storage - A private class which is used to figure out where to
45 // store the visited set.
46 template<class SetType, bool External> // Non-external set
47 class df_iterator_storage {
52 template<class SetType>
53 class df_iterator_storage<SetType, true> {
55 df_iterator_storage(SetType &VSet) : Visited(VSet) {}
56 df_iterator_storage(const df_iterator_storage &S) : Visited(S.Visited) {}
61 // Generic Depth First Iterator
62 template<class GraphT,
63 class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>,
64 bool ExtStorage = false, class GT = GraphTraits<GraphT> >
65 class df_iterator : public forward_iterator<typename GT::NodeType, ptrdiff_t>,
66 public df_iterator_storage<SetType, ExtStorage> {
67 typedef forward_iterator<typename GT::NodeType, ptrdiff_t> super;
69 typedef typename GT::NodeType NodeType;
70 typedef typename GT::ChildIteratorType ChildItTy;
72 // VisitStack - Used to maintain the ordering. Top = current block
73 // First element is node pointer, second is the 'next child' to visit
74 std::vector<std::pair<NodeType *, ChildItTy> > VisitStack;
76 inline df_iterator(NodeType *Node) {
77 this->Visited.insert(Node);
78 VisitStack.push_back(std::make_pair(Node, GT::child_begin(Node)));
80 inline df_iterator() { /* End is when stack is empty */ }
82 inline df_iterator(NodeType *Node, SetType &S)
83 : df_iterator_storage<SetType, ExtStorage>(S) {
85 this->Visited.insert(Node);
86 VisitStack.push_back(std::make_pair(Node, GT::child_begin(Node)));
89 inline df_iterator(SetType &S)
90 : df_iterator_storage<SetType, ExtStorage>(S) {
91 // End is when stack is empty
95 typedef typename super::pointer pointer;
96 typedef df_iterator<GraphT, SetType, ExtStorage, GT> _Self;
98 // Provide static begin and end methods as our public "constructors"
99 static inline _Self begin(const GraphT& G) {
100 return _Self(GT::getEntryNode(G));
102 static inline _Self end(const GraphT& G) { return _Self(); }
104 // Static begin and end methods as our public ctors for external iterators
105 static inline _Self begin(const GraphT& G, SetType &S) {
106 return _Self(GT::getEntryNode(G), S);
108 static inline _Self end(const GraphT& G, SetType &S) { return _Self(S); }
110 inline bool operator==(const _Self& x) const {
111 return VisitStack.size() == x.VisitStack.size() &&
112 VisitStack == x.VisitStack;
114 inline bool operator!=(const _Self& x) const { return !operator==(x); }
116 inline pointer operator*() const {
117 return VisitStack.back().first;
120 // This is a nonstandard operator-> that dereferences the pointer an extra
121 // time... so that you can actually call methods ON the Node, because
122 // the contained type is a pointer. This allows BBIt->getTerminator() f.e.
124 inline NodeType *operator->() const { return operator*(); }
126 inline _Self& operator++() { // Preincrement
128 std::pair<NodeType *, ChildItTy> &Top = VisitStack.back();
129 NodeType *Node = Top.first;
130 ChildItTy &It = Top.second;
132 while (It != GT::child_end(Node)) {
133 NodeType *Next = *It++;
134 if (!this->Visited.count(Next)) { // Has our next sibling been visited?
136 this->Visited.insert(Next);
137 VisitStack.push_back(std::make_pair(Next, GT::child_begin(Next)));
142 // Oops, ran out of successors... go up a level on the stack.
143 VisitStack.pop_back();
144 } while (!VisitStack.empty());
148 inline _Self operator++(int) { // Postincrement
149 _Self tmp = *this; ++*this; return tmp;
152 // nodeVisited - return true if this iterator has already visited the
153 // specified node. This is public, and will probably be used to iterate over
154 // nodes that a depth first iteration did not find: ie unreachable nodes.
156 inline bool nodeVisited(NodeType *Node) const {
157 return this->Visited.count(Node) != 0;
162 // Provide global constructors that automatically figure out correct types...
165 df_iterator<T> df_begin(const T& G) {
166 return df_iterator<T>::begin(G);
170 df_iterator<T> df_end(const T& G) {
171 return df_iterator<T>::end(G);
174 // Provide global definitions of external depth first iterators...
175 template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> >
176 struct df_ext_iterator : public df_iterator<T, SetTy, true> {
177 df_ext_iterator(const df_iterator<T, SetTy, true> &V)
178 : df_iterator<T, SetTy, true>(V) {}
181 template <class T, class SetTy>
182 df_ext_iterator<T, SetTy> df_ext_begin(const T& G, SetTy &S) {
183 return df_ext_iterator<T, SetTy>::begin(G, S);
186 template <class T, class SetTy>
187 df_ext_iterator<T, SetTy> df_ext_end(const T& G, SetTy &S) {
188 return df_ext_iterator<T, SetTy>::end(G, S);
192 // Provide global definitions of inverse depth first iterators...
194 class SetTy = llvm::SmallPtrSet<typename GraphTraits<T>::NodeType*, 8>,
195 bool External = false>
196 struct idf_iterator : public df_iterator<Inverse<T>, SetTy, External> {
197 idf_iterator(const df_iterator<Inverse<T>, SetTy, External> &V)
198 : df_iterator<Inverse<T>, SetTy, External>(V) {}
202 idf_iterator<T> idf_begin(const T& G) {
204 return idf_iterator<T>::begin(DummyG);
208 idf_iterator<T> idf_end(const T& G){
210 return idf_iterator<T>::end(DummyG);
213 // Provide global definitions of external inverse depth first iterators...
214 template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> >
215 struct idf_ext_iterator : public idf_iterator<T, SetTy, true> {
216 idf_ext_iterator(const idf_iterator<T, SetTy, true> &V)
217 : idf_iterator<T, SetTy, true>(V) {}
218 idf_ext_iterator(const df_iterator<Inverse<T>, SetTy, true> &V)
219 : idf_iterator<T, SetTy, true>(V) {}
222 template <class T, class SetTy>
223 idf_ext_iterator<T, SetTy> idf_ext_begin(const T& G, SetTy &S) {
224 Inverse<T> DummyG(G);
225 return idf_ext_iterator<T, SetTy>::begin(DummyG, S);
228 template <class T, class SetTy>
229 idf_ext_iterator<T, SetTy> idf_ext_end(const T& G, SetTy &S) {
230 Inverse<T> DummyG(G);
231 return idf_ext_iterator<T, SetTy>::end(DummyG, S);
234 } // End llvm namespace