1 //===- Support/DepthFirstIterator.h - Depth First iterator -------*- C++ -*--=//
3 // This file builds on the Support/GraphTraits.h file to build generic depth
4 // first graph iterator.
6 //===----------------------------------------------------------------------===//
8 #ifndef LLVM_SUPPORT_DEPTH_FIRST_ITERATOR_H
9 #define LLVM_SUPPORT_DEPTH_FIRST_ITERATOR_H
11 #include "Support/GraphTraits.h"
16 // Generic Depth First Iterator
17 template<class GraphT, class GT = GraphTraits<GraphT> >
18 class df_iterator : public std::forward_iterator<typename GT::NodeType,
20 typedef typename GT::NodeType NodeType;
21 typedef typename GT::ChildIteratorType ChildItTy;
23 std::set<NodeType *> Visited; // All of the blocks visited so far...
24 // VisitStack - Used to maintain the ordering. Top = current block
25 // First element is node pointer, second is the 'next child' to visit
26 std::stack<std::pair<NodeType *, ChildItTy> > VisitStack;
27 const bool Reverse; // Iterate over children before self?
29 void reverseEnterNode() {
30 std::pair<NodeType *, ChildItTy> &Top = VisitStack.top();
31 NodeType *Node = Top.first;
32 ChildItTy &It = Top.second;
33 for (; It != GT::child_end(Node); ++It) {
34 NodeType *Child = *It;
35 if (!Visited.count(Child)) {
36 Visited.insert(Child);
37 VisitStack.push(std::make_pair(Child, GT::child_begin(Child)));
44 inline df_iterator(NodeType *Node, bool reverse) : Reverse(reverse) {
46 VisitStack.push(std::make_pair(Node, GT::child_begin(Node)));
47 if (Reverse) reverseEnterNode();
49 inline df_iterator() { /* End is when stack is empty */ }
52 typedef df_iterator<GraphT, GT> _Self;
54 // Provide static begin and end methods as our public "constructors"
55 static inline _Self begin(GraphT G, bool Reverse = false) {
56 return _Self(GT::getEntryNode(G), Reverse);
58 static inline _Self end(GraphT G) { return _Self(); }
61 inline bool operator==(const _Self& x) const {
62 return VisitStack == x.VisitStack;
64 inline bool operator!=(const _Self& x) const { return !operator==(x); }
66 inline pointer operator*() const {
67 return VisitStack.top().first;
70 // This is a nonstandard operator-> that dereferences the pointer an extra
71 // time... so that you can actually call methods ON the Node, because
72 // the contained type is a pointer. This allows BBIt->getTerminator() f.e.
74 inline NodeType *operator->() const { return operator*(); }
76 inline _Self& operator++() { // Preincrement
77 if (Reverse) { // Reverse Depth First Iterator
78 if (VisitStack.top().second == GT::child_end(VisitStack.top().first))
80 if (!VisitStack.empty())
82 } else { // Normal Depth First Iterator
84 std::pair<NodeType *, ChildItTy> &Top = VisitStack.top();
85 NodeType *Node = Top.first;
86 ChildItTy &It = Top.second;
88 while (It != GT::child_end(Node)) {
89 NodeType *Next = *It++;
90 if (!Visited.count(Next)) { // Has our next sibling been visited?
93 VisitStack.push(std::make_pair(Next, GT::child_begin(Next)));
98 // Oops, ran out of successors... go up a level on the stack.
100 } while (!VisitStack.empty());
105 inline _Self operator++(int) { // Postincrement
106 _Self tmp = *this; ++*this; return tmp;
109 // nodeVisited - return true if this iterator has already visited the
110 // specified node. This is public, and will probably be used to iterate over
111 // nodes that a depth first iteration did not find: ie unreachable nodes.
113 inline bool nodeVisited(NodeType *Node) const {
114 return Visited.count(Node) != 0;
119 // Provide global constructors that automatically figure out correct types...
122 df_iterator<T> df_begin(T G, bool Reverse = false) {
123 return df_iterator<T>::begin(G, Reverse);
127 df_iterator<T> df_end(T G) {
128 return df_iterator<T>::end(G);
131 // Provide global definitions of inverse depth first iterators...
133 struct idf_iterator : public df_iterator<Inverse<T> > {
134 idf_iterator(const df_iterator<Inverse<T> > &V) :df_iterator<Inverse<T> >(V){}
138 idf_iterator<T> idf_begin(T G, bool Reverse = false) {
139 return idf_iterator<T>::begin(G, Reverse);
143 idf_iterator<T> idf_end(T G){
144 return idf_iterator<T>::end(G);