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