//===- Support/DepthFirstIterator.h - Depth First iterator -------*- C++ -*--=// // // This file builds on the Support/GraphTraits.h file to build generic depth // first graph iterator. // //===----------------------------------------------------------------------===// #ifndef LLVM_SUPPORT_DEPTH_FIRST_ITERATOR_H #define LLVM_SUPPORT_DEPTH_FIRST_ITERATOR_H #include "Support/GraphTraits.h" #include "Support/iterator" #include <stack> #include <set> // Generic Depth First Iterator template<class GraphT, class GT = GraphTraits<GraphT> > class df_iterator : public forward_iterator<typename GT::NodeType, ptrdiff_t> { typedef forward_iterator<typename GT::NodeType, ptrdiff_t> super; typedef typename super::pointer pointer; typedef typename GT::NodeType NodeType; typedef typename GT::ChildIteratorType ChildItTy; std::set<NodeType *> Visited; // All of the blocks visited so far... // VisitStack - Used to maintain the ordering. Top = current block // First element is node pointer, second is the 'next child' to visit std::stack<std::pair<NodeType *, ChildItTy> > VisitStack; const bool Reverse; // Iterate over children before self? private: void reverseEnterNode() { std::pair<NodeType *, ChildItTy> &Top = VisitStack.top(); NodeType *Node = Top.first; ChildItTy &It = Top.second; for (; It != GT::child_end(Node); ++It) { NodeType *Child = *It; if (!Visited.count(Child)) { Visited.insert(Child); VisitStack.push(std::make_pair(Child, GT::child_begin(Child))); reverseEnterNode(); return; } } } inline df_iterator(NodeType *Node, bool reverse) : Reverse(reverse) { Visited.insert(Node); VisitStack.push(std::make_pair(Node, GT::child_begin(Node))); if (Reverse) reverseEnterNode(); } inline df_iterator() { /* End is when stack is empty */ } public: typedef df_iterator<GraphT, GT> _Self; // Provide static begin and end methods as our public "constructors" static inline _Self begin(GraphT G, bool Reverse = false) { return _Self(GT::getEntryNode(G), Reverse); } static inline _Self end(GraphT G) { return _Self(); } inline bool operator==(const _Self& x) const { return VisitStack == x.VisitStack; } inline bool operator!=(const _Self& x) const { return !operator==(x); } inline pointer operator*() const { return VisitStack.top().first; } // This is a nonstandard operator-> that dereferences the pointer an extra // time... so that you can actually call methods ON the Node, because // the contained type is a pointer. This allows BBIt->getTerminator() f.e. // inline NodeType *operator->() const { return operator*(); } inline _Self& operator++() { // Preincrement if (Reverse) { // Reverse Depth First Iterator if (VisitStack.top().second == GT::child_end(VisitStack.top().first)) VisitStack.pop(); if (!VisitStack.empty()) reverseEnterNode(); } else { // Normal Depth First Iterator do { std::pair<NodeType *, ChildItTy> &Top = VisitStack.top(); NodeType *Node = Top.first; ChildItTy &It = Top.second; while (It != GT::child_end(Node)) { NodeType *Next = *It++; if (!Visited.count(Next)) { // Has our next sibling been visited? // No, do it now. Visited.insert(Next); VisitStack.push(std::make_pair(Next, GT::child_begin(Next))); return *this; } } // Oops, ran out of successors... go up a level on the stack. VisitStack.pop(); } while (!VisitStack.empty()); } return *this; } inline _Self operator++(int) { // Postincrement _Self tmp = *this; ++*this; return tmp; } // nodeVisited - return true if this iterator has already visited the // specified node. This is public, and will probably be used to iterate over // nodes that a depth first iteration did not find: ie unreachable nodes. // inline bool nodeVisited(NodeType *Node) const { return Visited.count(Node) != 0; } }; // Provide global constructors that automatically figure out correct types... // template <class T> df_iterator<T> df_begin(T G, bool Reverse = false) { return df_iterator<T>::begin(G, Reverse); } template <class T> df_iterator<T> df_end(T G) { return df_iterator<T>::end(G); } // Provide global definitions of inverse depth first iterators... template <class T> struct idf_iterator : public df_iterator<Inverse<T> > { idf_iterator(const df_iterator<Inverse<T> > &V) :df_iterator<Inverse<T> >(V){} }; template <class T> idf_iterator<T> idf_begin(T G, bool Reverse = false) { return idf_iterator<T>::begin(G, Reverse); } template <class T> idf_iterator<T> idf_end(T G){ return idf_iterator<T>::end(G); } #endif