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