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 43namespace llvm { 44 45// df_iterator_storage - A private class which is used to figure out where to 46// store the visited set. 47template<class SetType, bool External> // Non-external set 48class df_iterator_storage { 49public: 50 SetType Visited; 51}; 52 53template<class SetType> 54class df_iterator_storage<SetType, true> { 55public: 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 63template<class GraphT, 64class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>, 65 bool ExtStorage = false, class GT = GraphTraits<GraphT> > 66class 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; 80private: 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 130public: 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// 201template <class T> 202df_iterator<T> df_begin(const T& G) { 203 return df_iterator<T>::begin(G); 204} 205 206template <class T> 207df_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. 212template <class T> 213iterator_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... 218template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> > 219struct 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 224template <class T, class SetTy> 225df_ext_iterator<T, SetTy> df_ext_begin(const T& G, SetTy &S) { 226 return df_ext_iterator<T, SetTy>::begin(G, S); 227} 228 229template <class T, class SetTy> 230df_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... 236template <class T, 237 class SetTy = llvm::SmallPtrSet<typename GraphTraits<T>::NodeType*, 8>, 238 bool External = false> 239struct 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 244template <class T> 245idf_iterator<T> idf_begin(const T& G) { 246 return idf_iterator<T>::begin(Inverse<T>(G)); 247} 248 249template <class T> 250idf_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. 255template <class T> 256iterator_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... 261template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> > 262struct 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 269template <class T, class SetTy> 270idf_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 274template <class T, class SetTy> 275idf_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