1
//===- llvm/ADT/DepthFirstIterator.h - Depth First iterator -----*- C++ -*-===//
3
// The LLVM Compiler Infrastructure
5
// This file is distributed under the University of Illinois Open Source
6
// License. See LICENSE.TXT for details.
8
//===----------------------------------------------------------------------===//
10
// This file builds on the ADT/GraphTraits.h file to build generic depth
11
// first graph iterator. This file exposes the following functions/types:
13
// df_begin/df_end/df_iterator
14
// * Normal depth-first iteration - visit a node and then all of its children.
16
// idf_begin/idf_end/idf_iterator
17
// * Depth-first iteration on the 'inverse' graph.
19
// df_ext_begin/df_ext_end/df_ext_iterator
20
// * Normal depth-first iteration - visit a node and then all of its children.
21
// This iterator stores the 'visited' set in an external set, which allows
22
// it to be more efficient, and allows external clients to use the set for
25
// idf_ext_begin/idf_ext_end/idf_ext_iterator
26
// * Depth-first iteration on the 'inverse' graph.
27
// This iterator stores the 'visited' set in an external set, which allows
28
// it to be more efficient, and allows external clients to use the set for
31
//===----------------------------------------------------------------------===//
33
#ifndef LLVM_ADT_DEPTHFIRSTITERATOR_H
34
#define LLVM_ADT_DEPTHFIRSTITERATOR_H
36
#include "llvm/ADT/GraphTraits.h"
37
#include "llvm/ADT/SmallPtrSet.h"
38
#include "llvm/ADT/PointerIntPair.h"
44
// df_iterator_storage - A private class which is used to figure out where to
45
// store the visited set.
46
template<class SetType, bool External> // Non-external set
47
class df_iterator_storage {
52
template<class SetType>
53
class df_iterator_storage<SetType, true> {
55
df_iterator_storage(SetType &VSet) : Visited(VSet) {}
56
df_iterator_storage(const df_iterator_storage &S) : Visited(S.Visited) {}
61
// Generic Depth First Iterator
62
template<class GraphT,
63
class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>,
64
bool ExtStorage = false, class GT = GraphTraits<GraphT> >
65
class df_iterator : public std::iterator<std::forward_iterator_tag,
66
typename GT::NodeType, ptrdiff_t>,
67
public df_iterator_storage<SetType, ExtStorage> {
68
typedef std::iterator<std::forward_iterator_tag,
69
typename GT::NodeType, ptrdiff_t> super;
71
typedef typename GT::NodeType NodeType;
72
typedef typename GT::ChildIteratorType ChildItTy;
73
typedef PointerIntPair<NodeType*, 1> PointerIntTy;
75
// VisitStack - Used to maintain the ordering. Top = current block
76
// First element is node pointer, second is the 'next child' to visit
77
// if the int in PointerIntTy is 0, the 'next child' to visit is invalid
78
std::vector<std::pair<PointerIntTy, ChildItTy> > VisitStack;
80
inline df_iterator(NodeType *Node) {
81
this->Visited.insert(Node);
82
VisitStack.push_back(std::make_pair(PointerIntTy(Node, 0),
83
GT::child_begin(Node)));
85
inline df_iterator() {
86
// End is when stack is empty
88
inline df_iterator(NodeType *Node, SetType &S)
89
: df_iterator_storage<SetType, ExtStorage>(S) {
91
VisitStack.push_back(std::make_pair(PointerIntTy(Node, 0),
92
GT::child_begin(Node)));
93
this->Visited.insert(Node);
96
inline df_iterator(SetType &S)
97
: df_iterator_storage<SetType, ExtStorage>(S) {
98
// End is when stack is empty
101
inline void toNext() {
103
std::pair<PointerIntTy, ChildItTy> &Top = VisitStack.back();
104
NodeType *Node = Top.first.getPointer();
105
ChildItTy &It = Top.second;
106
if (!Top.first.getInt()) {
107
// now retrieve the real begin of the children before we dive in
108
It = GT::child_begin(Node);
112
while (It != GT::child_end(Node)) {
113
NodeType *Next = *It++;
114
// Has our next sibling been visited?
115
if (Next && !this->Visited.count(Next)) {
117
this->Visited.insert(Next);
118
VisitStack.push_back(std::make_pair(PointerIntTy(Next, 0),
119
GT::child_begin(Next)));
124
// Oops, ran out of successors... go up a level on the stack.
125
VisitStack.pop_back();
126
} while (!VisitStack.empty());
130
typedef typename super::pointer pointer;
131
typedef df_iterator<GraphT, SetType, ExtStorage, GT> _Self;
133
// Provide static begin and end methods as our public "constructors"
134
static inline _Self begin(const GraphT& G) {
135
return _Self(GT::getEntryNode(G));
137
static inline _Self end(const GraphT& G) { return _Self(); }
139
// Static begin and end methods as our public ctors for external iterators
140
static inline _Self begin(const GraphT& G, SetType &S) {
141
return _Self(GT::getEntryNode(G), S);
143
static inline _Self end(const GraphT& G, SetType &S) { return _Self(S); }
145
inline bool operator==(const _Self& x) const {
146
return VisitStack.size() == x.VisitStack.size() &&
147
VisitStack == x.VisitStack;
149
inline bool operator!=(const _Self& x) const { return !operator==(x); }
151
inline pointer operator*() const {
152
return VisitStack.back().first.getPointer();
155
// This is a nonstandard operator-> that dereferences the pointer an extra
156
// time... so that you can actually call methods ON the Node, because
157
// the contained type is a pointer. This allows BBIt->getTerminator() f.e.
159
inline NodeType *operator->() const { return operator*(); }
161
inline _Self& operator++() { // Preincrement
166
// skips all children of the current node and traverses to next node
168
inline _Self& skipChildren() {
169
VisitStack.pop_back();
170
if (!VisitStack.empty())
175
inline _Self operator++(int) { // Postincrement
176
_Self tmp = *this; ++*this; return tmp;
179
// nodeVisited - return true if this iterator has already visited the
180
// specified node. This is public, and will probably be used to iterate over
181
// nodes that a depth first iteration did not find: ie unreachable nodes.
183
inline bool nodeVisited(NodeType *Node) const {
184
return this->Visited.count(Node) != 0;
187
/// getPathLength - Return the length of the path from the entry node to the
188
/// current node, counting both nodes.
189
unsigned getPathLength() const { return VisitStack.size(); }
191
/// getPath - Return the n'th node in the path from the the entry node to the
193
NodeType *getPath(unsigned n) const {
194
return VisitStack[n].first.getPointer();
199
// Provide global constructors that automatically figure out correct types...
202
df_iterator<T> df_begin(const T& G) {
203
return df_iterator<T>::begin(G);
207
df_iterator<T> df_end(const T& G) {
208
return df_iterator<T>::end(G);
211
// Provide global definitions of external depth first iterators...
212
template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> >
213
struct df_ext_iterator : public df_iterator<T, SetTy, true> {
214
df_ext_iterator(const df_iterator<T, SetTy, true> &V)
215
: df_iterator<T, SetTy, true>(V) {}
218
template <class T, class SetTy>
219
df_ext_iterator<T, SetTy> df_ext_begin(const T& G, SetTy &S) {
220
return df_ext_iterator<T, SetTy>::begin(G, S);
223
template <class T, class SetTy>
224
df_ext_iterator<T, SetTy> df_ext_end(const T& G, SetTy &S) {
225
return df_ext_iterator<T, SetTy>::end(G, S);
229
// Provide global definitions of inverse depth first iterators...
231
class SetTy = llvm::SmallPtrSet<typename GraphTraits<T>::NodeType*, 8>,
232
bool External = false>
233
struct idf_iterator : public df_iterator<Inverse<T>, SetTy, External> {
234
idf_iterator(const df_iterator<Inverse<T>, SetTy, External> &V)
235
: df_iterator<Inverse<T>, SetTy, External>(V) {}
239
idf_iterator<T> idf_begin(const T& G) {
240
return idf_iterator<T>::begin(Inverse<T>(G));
244
idf_iterator<T> idf_end(const T& G){
245
return idf_iterator<T>::end(Inverse<T>(G));
248
// Provide global definitions of external inverse depth first iterators...
249
template <class T, class SetTy = std::set<typename GraphTraits<T>::NodeType*> >
250
struct idf_ext_iterator : public idf_iterator<T, SetTy, true> {
251
idf_ext_iterator(const idf_iterator<T, SetTy, true> &V)
252
: idf_iterator<T, SetTy, true>(V) {}
253
idf_ext_iterator(const df_iterator<Inverse<T>, SetTy, true> &V)
254
: idf_iterator<T, SetTy, true>(V) {}
257
template <class T, class SetTy>
258
idf_ext_iterator<T, SetTy> idf_ext_begin(const T& G, SetTy &S) {
259
return idf_ext_iterator<T, SetTy>::begin(Inverse<T>(G), S);
262
template <class T, class SetTy>
263
idf_ext_iterator<T, SetTy> idf_ext_end(const T& G, SetTy &S) {
264
return idf_ext_iterator<T, SetTy>::end(Inverse<T>(G), S);
267
} // End llvm namespace