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269 lines
8.9 KiB
C++
269 lines
8.9 KiB
C++
//===- llvm/ADT/DepthFirstIterator.h - Depth First iterator -----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file builds on the ADT/GraphTraits.h file to build generic depth
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// first graph iterator. This file exposes the following functions/types:
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//
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// df_begin/df_end/df_iterator
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// * Normal depth-first iteration - visit a node and then all of its children.
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//
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// idf_begin/idf_end/idf_iterator
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// * Depth-first iteration on the 'inverse' graph.
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//
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// df_ext_begin/df_ext_end/df_ext_iterator
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// * Normal depth-first iteration - visit a node and then all of its children.
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// This iterator stores the 'visited' set in an external set, which allows
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// it to be more efficient, and allows external clients to use the set for
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// other purposes.
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//
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// idf_ext_begin/idf_ext_end/idf_ext_iterator
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// * Depth-first iteration on the 'inverse' graph.
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// This iterator stores the 'visited' set in an external set, which allows
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// it to be more efficient, and allows external clients to use the set for
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// other purposes.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_DEPTHFIRSTITERATOR_H
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#define LLVM_ADT_DEPTHFIRSTITERATOR_H
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/PointerIntPair.h"
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#include <set>
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#include <vector>
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namespace llvm {
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// df_iterator_storage - A private class which is used to figure out where to
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// store the visited set.
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template<class SetType, bool External> // Non-external set
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class df_iterator_storage {
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public:
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SetType Visited;
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};
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template<class SetType>
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class df_iterator_storage<SetType, true> {
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public:
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df_iterator_storage(SetType &VSet) : Visited(VSet) {}
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df_iterator_storage(const df_iterator_storage &S) : Visited(S.Visited) {}
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SetType &Visited;
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};
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// Generic Depth First Iterator
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template<class GraphT,
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class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>,
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bool ExtStorage = false, class GT = GraphTraits<GraphT> >
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class df_iterator : public std::iterator<std::forward_iterator_tag,
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typename GT::NodeType, ptrdiff_t>,
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public df_iterator_storage<SetType, ExtStorage> {
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typedef std::iterator<std::forward_iterator_tag,
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typename GT::NodeType, ptrdiff_t> super;
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typedef typename GT::NodeType NodeType;
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typedef typename GT::ChildIteratorType ChildItTy;
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typedef PointerIntPair<NodeType*, 1> PointerIntTy;
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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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// if the int in PointerIntTy is 0, the 'next child' to visit is invalid
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std::vector<std::pair<PointerIntTy, ChildItTy> > VisitStack;
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private:
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inline df_iterator(NodeType *Node) {
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this->Visited.insert(Node);
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VisitStack.push_back(std::make_pair(PointerIntTy(Node, 0),
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GT::child_begin(Node)));
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}
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inline df_iterator() {
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// End is when stack is empty
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}
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inline df_iterator(NodeType *Node, SetType &S)
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: df_iterator_storage<SetType, ExtStorage>(S) {
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if (!S.count(Node)) {
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VisitStack.push_back(std::make_pair(PointerIntTy(Node, 0),
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GT::child_begin(Node)));
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this->Visited.insert(Node);
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}
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}
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inline df_iterator(SetType &S)
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: df_iterator_storage<SetType, ExtStorage>(S) {
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// End is when stack is empty
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}
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inline void toNext() {
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do {
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std::pair<PointerIntTy, ChildItTy> &Top = VisitStack.back();
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NodeType *Node = Top.first.getPointer();
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ChildItTy &It = Top.second;
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if (!Top.first.getInt()) {
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// now retrieve the real begin of the children before we dive in
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It = GT::child_begin(Node);
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Top.first.setInt(1);
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}
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while (It != GT::child_end(Node)) {
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NodeType *Next = *It++;
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// Has our next sibling been visited?
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if (Next && !this->Visited.count(Next)) {
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// No, do it now.
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this->Visited.insert(Next);
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VisitStack.push_back(std::make_pair(PointerIntTy(Next, 0),
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GT::child_begin(Next)));
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return;
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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_back();
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} while (!VisitStack.empty());
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}
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public:
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typedef typename super::pointer pointer;
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typedef df_iterator<GraphT, SetType, ExtStorage, GT> _Self;
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// Provide static begin and end methods as our public "constructors"
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static inline _Self begin(const GraphT& G) {
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return _Self(GT::getEntryNode(G));
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}
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static inline _Self end(const GraphT& G) { return _Self(); }
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// Static begin and end methods as our public ctors for external iterators
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static inline _Self begin(const GraphT& G, SetType &S) {
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return _Self(GT::getEntryNode(G), S);
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}
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static inline _Self end(const GraphT& G, SetType &S) { return _Self(S); }
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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.back().first.getPointer();
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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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toNext();
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return *this;
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}
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// skips all children of the current node and traverses to next node
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//
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inline _Self& skipChildren() {
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VisitStack.pop_back();
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if (!VisitStack.empty())
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toNext();
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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 this->Visited.count(Node) != 0;
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}
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/// getPathLength - Return the length of the path from the entry node to the
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/// current node, counting both nodes.
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unsigned getPathLength() const { return VisitStack.size(); }
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/// getPath - Return the n'th node in the path from the the entry node to the
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/// current node.
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NodeType *getPath(unsigned n) const {
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return VisitStack[n].first.getPointer();
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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(const T& G) {
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return df_iterator<T>::begin(G);
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}
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template <class T>
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df_iterator<T> df_end(const T& G) {
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return df_iterator<T>::end(G);
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}
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// Provide global definitions of external depth first iterators...
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template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> >
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struct df_ext_iterator : public df_iterator<T, SetTy, true> {
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df_ext_iterator(const df_iterator<T, SetTy, true> &V)
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: df_iterator<T, SetTy, true>(V) {}
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};
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template <class T, class SetTy>
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df_ext_iterator<T, SetTy> df_ext_begin(const T& G, SetTy &S) {
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return df_ext_iterator<T, SetTy>::begin(G, S);
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}
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template <class T, class SetTy>
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df_ext_iterator<T, SetTy> df_ext_end(const T& G, SetTy &S) {
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return df_ext_iterator<T, SetTy>::end(G, S);
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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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class SetTy = llvm::SmallPtrSet<typename GraphTraits<T>::NodeType*, 8>,
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bool External = false>
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struct idf_iterator : public df_iterator<Inverse<T>, SetTy, External> {
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idf_iterator(const df_iterator<Inverse<T>, SetTy, External> &V)
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: df_iterator<Inverse<T>, SetTy, External>(V) {}
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};
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template <class T>
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idf_iterator<T> idf_begin(const T& G) {
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return idf_iterator<T>::begin(Inverse<T>(G));
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}
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template <class T>
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idf_iterator<T> idf_end(const T& G){
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return idf_iterator<T>::end(Inverse<T>(G));
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}
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// Provide global definitions of external inverse depth first iterators...
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template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> >
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struct idf_ext_iterator : public idf_iterator<T, SetTy, true> {
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idf_ext_iterator(const idf_iterator<T, SetTy, true> &V)
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: idf_iterator<T, SetTy, true>(V) {}
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idf_ext_iterator(const df_iterator<Inverse<T>, SetTy, true> &V)
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: idf_iterator<T, SetTy, true>(V) {}
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};
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template <class T, class SetTy>
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idf_ext_iterator<T, SetTy> idf_ext_begin(const T& G, SetTy &S) {
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return idf_ext_iterator<T, SetTy>::begin(Inverse<T>(G), S);
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}
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template <class T, class SetTy>
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idf_ext_iterator<T, SetTy> idf_ext_end(const T& G, SetTy &S) {
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return idf_ext_iterator<T, SetTy>::end(Inverse<T>(G), S);
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}
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} // End llvm namespace
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#endif
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