1 //===- llvm/ADT/DepthFirstIterator.h - Depth First iterator -----*- 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 builds on the ADT/GraphTraits.h file to build generic depth 11 // first graph iterator. This file exposes the following functions/types: 12 // 13 // df_begin/df_end/df_iterator 14 // * Normal depth-first iteration - visit a node and then all of its children. 15 // 16 // idf_begin/idf_end/idf_iterator 17 // * Depth-first iteration on the 'inverse' graph. 18 // 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 23 // other purposes. 24 // 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 29 // other purposes. 30 // 31 //===----------------------------------------------------------------------===// 32 33 #ifndef LLVM_ADT_DEPTHFIRSTITERATOR_H 34 #define LLVM_ADT_DEPTHFIRSTITERATOR_H 35 36 #include "llvm/ADT/iterator_range.h" 37 #include "llvm/ADT/GraphTraits.h" 38 #include "llvm/ADT/PointerIntPair.h" 39 #include "llvm/ADT/SmallPtrSet.h" 40 #include <set> 41 #include <vector> 42 43 namespace llvm { 44 45 // df_iterator_storage - A private class which is used to figure out where to 46 // store the visited set. 47 template<class SetType, bool External> // Non-external set 48 class df_iterator_storage { 49 public: 50 SetType Visited; 51 }; 52 53 template<class SetType> 54 class df_iterator_storage<SetType, true> { 55 public: 56 df_iterator_storage(SetType &VSet) : Visited(VSet) {} 57 df_iterator_storage(const df_iterator_storage &S) : Visited(S.Visited) {} 58 SetType &Visited; 59 }; 60 61 62 // Generic Depth First Iterator 63 template<class GraphT, 64 class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>, 65 bool ExtStorage = false, class GT = GraphTraits<GraphT> > 66 class df_iterator : public std::iterator<std::forward_iterator_tag, 67 typename GT::NodeType, ptrdiff_t>, 68 public df_iterator_storage<SetType, ExtStorage> { 69 typedef std::iterator<std::forward_iterator_tag, 70 typename GT::NodeType, ptrdiff_t> super; 71 72 typedef typename GT::NodeType NodeType; 73 typedef typename GT::ChildIteratorType ChildItTy; 74 typedef PointerIntPair<NodeType*, 1> PointerIntTy; 75 76 // VisitStack - Used to maintain the ordering. Top = current block 77 // First element is node pointer, second is the 'next child' to visit 78 // if the int in PointerIntTy is 0, the 'next child' to visit is invalid 79 std::vector<std::pair<PointerIntTy, ChildItTy> > VisitStack; 80 private: 81 inline df_iterator(NodeType *Node) { 82 this->Visited.insert(Node); 83 VisitStack.push_back(std::make_pair(PointerIntTy(Node, 0), 84 GT::child_begin(Node))); 85 } 86 inline df_iterator() { 87 // End is when stack is empty 88 } 89 inline df_iterator(NodeType *Node, SetType &S) 90 : df_iterator_storage<SetType, ExtStorage>(S) { 91 if (!S.count(Node)) { 92 VisitStack.push_back(std::make_pair(PointerIntTy(Node, 0), 93 GT::child_begin(Node))); 94 this->Visited.insert(Node); 95 } 96 } 97 inline df_iterator(SetType &S) 98 : df_iterator_storage<SetType, ExtStorage>(S) { 99 // End is when stack is empty 100 } 101 102 inline void toNext() { 103 do { 104 std::pair<PointerIntTy, ChildItTy> &Top = VisitStack.back(); 105 NodeType *Node = Top.first.getPointer(); 106 ChildItTy &It = Top.second; 107 if (!Top.first.getInt()) { 108 // now retrieve the real begin of the children before we dive in 109 It = GT::child_begin(Node); 110 Top.first.setInt(1); 111 } 112 113 while (It != GT::child_end(Node)) { 114 NodeType *Next = *It++; 115 // Has our next sibling been visited? 116 if (Next && !this->Visited.count(Next)) { 117 // No, do it now. 118 this->Visited.insert(Next); 119 VisitStack.push_back(std::make_pair(PointerIntTy(Next, 0), 120 GT::child_begin(Next))); 121 return; 122 } 123 } 124 125 // Oops, ran out of successors... go up a level on the stack. 126 VisitStack.pop_back(); 127 } while (!VisitStack.empty()); 128 } 129 130 public: 131 typedef typename super::pointer pointer; 132 typedef df_iterator<GraphT, SetType, ExtStorage, GT> _Self; 133 134 // Provide static begin and end methods as our public "constructors" 135 static inline _Self begin(const GraphT& G) { 136 return _Self(GT::getEntryNode(G)); 137 } 138 static inline _Self end(const GraphT& G) { return _Self(); } 139 140 // Static begin and end methods as our public ctors for external iterators 141 static inline _Self begin(const GraphT& G, SetType &S) { 142 return _Self(GT::getEntryNode(G), S); 143 } 144 static inline _Self end(const GraphT& G, SetType &S) { return _Self(S); } 145 146 inline bool operator==(const _Self& x) const { 147 return VisitStack == x.VisitStack; 148 } 149 inline bool operator!=(const _Self& x) const { return !operator==(x); } 150 151 inline pointer operator*() const { 152 return VisitStack.back().first.getPointer(); 153 } 154 155 // This is a nonstandard operator-> that dereferences the pointer an extra 156 // time... so that you can actually call methods ON the Node, because 157 // the contained type is a pointer. This allows BBIt->getTerminator() f.e. 158 // 159 inline NodeType *operator->() const { return operator*(); } 160 161 inline _Self& operator++() { // Preincrement 162 toNext(); 163 return *this; 164 } 165 166 // skips all children of the current node and traverses to next node 167 // 168 inline _Self& skipChildren() { 169 VisitStack.pop_back(); 170 if (!VisitStack.empty()) 171 toNext(); 172 return *this; 173 } 174 175 inline _Self operator++(int) { // Postincrement 176 _Self tmp = *this; ++*this; return tmp; 177 } 178 179 // nodeVisited - return true if this iterator has already visited the 180 // specified node. This is public, and will probably be used to iterate over 181 // nodes that a depth first iteration did not find: ie unreachable nodes. 182 // 183 inline bool nodeVisited(NodeType *Node) const { 184 return this->Visited.count(Node) != 0; 185 } 186 187 /// getPathLength - Return the length of the path from the entry node to the 188 /// current node, counting both nodes. 189 unsigned getPathLength() const { return VisitStack.size(); } 190 191 /// getPath - Return the n'th node in the path from the entry node to the 192 /// current node. 193 NodeType *getPath(unsigned n) const { 194 return VisitStack[n].first.getPointer(); 195 } 196 }; 197 198 199 // Provide global constructors that automatically figure out correct types... 200 // 201 template <class T> 202 df_iterator<T> df_begin(const T& G) { 203 return df_iterator<T>::begin(G); 204 } 205 206 template <class T> 207 df_iterator<T> df_end(const T& G) { 208 return df_iterator<T>::end(G); 209 } 210 211 // Provide an accessor method to use them in range-based patterns. 212 template <class T> 213 iterator_range<df_iterator<T>> depth_first(const T& G) { 214 return iterator_range<df_iterator<T>>(df_begin(G), df_end(G)); 215 } 216 217 // Provide global definitions of external depth first iterators... 218 template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> > 219 struct df_ext_iterator : public df_iterator<T, SetTy, true> { 220 df_ext_iterator(const df_iterator<T, SetTy, true> &V) 221 : df_iterator<T, SetTy, true>(V) {} 222 }; 223 224 template <class T, class SetTy> 225 df_ext_iterator<T, SetTy> df_ext_begin(const T& G, SetTy &S) { 226 return df_ext_iterator<T, SetTy>::begin(G, S); 227 } 228 229 template <class T, class SetTy> 230 df_ext_iterator<T, SetTy> df_ext_end(const T& G, SetTy &S) { 231 return df_ext_iterator<T, SetTy>::end(G, S); 232 } 233 234 235 // Provide global definitions of inverse depth first iterators... 236 template <class T, 237 class SetTy = llvm::SmallPtrSet<typename GraphTraits<T>::NodeType*, 8>, 238 bool External = false> 239 struct idf_iterator : public df_iterator<Inverse<T>, SetTy, External> { 240 idf_iterator(const df_iterator<Inverse<T>, SetTy, External> &V) 241 : df_iterator<Inverse<T>, SetTy, External>(V) {} 242 }; 243 244 template <class T> 245 idf_iterator<T> idf_begin(const T& G) { 246 return idf_iterator<T>::begin(Inverse<T>(G)); 247 } 248 249 template <class T> 250 idf_iterator<T> idf_end(const T& G){ 251 return idf_iterator<T>::end(Inverse<T>(G)); 252 } 253 254 // Provide an accessor method to use them in range-based patterns. 255 template <class T> 256 iterator_range<idf_iterator<T>> inverse_depth_first(const T& G) { 257 return iterator_range<idf_iterator<T>>(idf_begin(G), idf_end(G)); 258 } 259 260 // Provide global definitions of external inverse depth first iterators... 261 template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> > 262 struct idf_ext_iterator : public idf_iterator<T, SetTy, true> { 263 idf_ext_iterator(const idf_iterator<T, SetTy, true> &V) 264 : idf_iterator<T, SetTy, true>(V) {} 265 idf_ext_iterator(const df_iterator<Inverse<T>, SetTy, true> &V) 266 : idf_iterator<T, SetTy, true>(V) {} 267 }; 268 269 template <class T, class SetTy> 270 idf_ext_iterator<T, SetTy> idf_ext_begin(const T& G, SetTy &S) { 271 return idf_ext_iterator<T, SetTy>::begin(Inverse<T>(G), S); 272 } 273 274 template <class T, class SetTy> 275 idf_ext_iterator<T, SetTy> idf_ext_end(const T& G, SetTy &S) { 276 return idf_ext_iterator<T, SetTy>::end(Inverse<T>(G), S); 277 } 278 279 } // End llvm namespace 280 281 #endif 282
