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llvm-mirror/include/llvm/ADT/Trie.h
2009-11-30 13:14:13 +00:00

337 lines
9.0 KiB
C++

//===- llvm/ADT/Trie.h ---- Generic trie structure --------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This class defines a generic trie structure. The trie structure
// is immutable after creation, but the payload contained within it is not.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_TRIE_H
#define LLVM_ADT_TRIE_H
#include "llvm/ADT/GraphTraits.h"
#include "llvm/Support/DOTGraphTraits.h"
#include <cassert>
#include <vector>
namespace llvm {
// FIXME:
// - Labels are usually small, maybe it's better to use SmallString
// - Should we use char* during construction?
// - Should we templatize Empty with traits-like interface?
template<class Payload>
class Trie {
friend class GraphTraits<Trie<Payload> >;
friend class DOTGraphTraits<Trie<Payload> >;
public:
class Node {
friend class Trie;
public:
typedef std::vector<Node*> NodeVectorType;
typedef typename NodeVectorType::iterator iterator;
typedef typename NodeVectorType::const_iterator const_iterator;
private:
enum QueryResult {
Same = -3,
StringIsPrefix = -2,
LabelIsPrefix = -1,
DontMatch = 0,
HaveCommonPart
};
struct NodeCmp {
bool operator() (Node* N1, Node* N2) {
return (N1->Label[0] < N2->Label[0]);
}
bool operator() (Node* N, char Id) {
return (N->Label[0] < Id);
}
};
std::string Label;
Payload Data;
NodeVectorType Children;
// Do not implement
Node(const Node&);
Node& operator=(const Node&);
inline void addEdge(Node* N) {
if (Children.empty())
Children.push_back(N);
else {
iterator I = std::lower_bound(Children.begin(), Children.end(),
N, NodeCmp());
// FIXME: no dups are allowed
Children.insert(I, N);
}
}
inline void setEdge(Node* N) {
char Id = N->Label[0];
iterator I = std::lower_bound(Children.begin(), Children.end(),
Id, NodeCmp());
assert(I != Children.end() && "Node does not exists!");
*I = N;
}
QueryResult query(const std::string& s) const {
unsigned i, l;
unsigned l1 = s.length();
unsigned l2 = Label.length();
// Find the length of common part
l = std::min(l1, l2);
i = 0;
while ((i < l) && (s[i] == Label[i]))
++i;
if (i == l) { // One is prefix of another, find who is who
if (l1 == l2)
return Same;
else if (i == l1)
return StringIsPrefix;
else
return LabelIsPrefix;
} else // s and Label have common (possible empty) part, return its length
return (QueryResult)i;
}
public:
inline explicit Node(const Payload& data, const std::string& label = ""):
Label(label), Data(data) { }
inline const Payload& data() const { return Data; }
inline void setData(const Payload& data) { Data = data; }
inline const std::string& label() const { return Label; }
#if 0
inline void dump() {
llvm::cerr << "Node: " << this << "\n"
<< "Label: " << Label << "\n"
<< "Children:\n";
for (iterator I = Children.begin(), E = Children.end(); I != E; ++I)
llvm::cerr << (*I)->Label << "\n";
}
#endif
inline Node* getEdge(char Id) {
Node* fNode = NULL;
iterator I = std::lower_bound(Children.begin(), Children.end(),
Id, NodeCmp());
if (I != Children.end() && (*I)->Label[0] == Id)
fNode = *I;
return fNode;
}
inline iterator begin() { return Children.begin(); }
inline const_iterator begin() const { return Children.begin(); }
inline iterator end () { return Children.end(); }
inline const_iterator end () const { return Children.end(); }
inline size_t size () const { return Children.size(); }
inline bool empty() const { return Children.empty(); }
inline const Node* &front() const { return Children.front(); }
inline Node* &front() { return Children.front(); }
inline const Node* &back() const { return Children.back(); }
inline Node* &back() { return Children.back(); }
};
private:
std::vector<Node*> Nodes;
Payload Empty;
inline Node* addNode(const Payload& data, const std::string label = "") {
Node* N = new Node(data, label);
Nodes.push_back(N);
return N;
}
inline Node* splitEdge(Node* N, char Id, size_t index) {
Node* eNode = N->getEdge(Id);
assert(eNode && "Node doesn't exist");
const std::string &l = eNode->Label;
assert(index > 0 && index < l.length() && "Trying to split too far!");
std::string l1 = l.substr(0, index);
std::string l2 = l.substr(index);
Node* nNode = addNode(Empty, l1);
N->setEdge(nNode);
eNode->Label = l2;
nNode->addEdge(eNode);
return nNode;
}
// Do not implement
Trie(const Trie&);
Trie& operator=(const Trie&);
public:
inline explicit Trie(const Payload& empty):Empty(empty) {
addNode(Empty);
}
inline ~Trie() {
for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
delete Nodes[i];
}
inline Node* getRoot() const { return Nodes[0]; }
bool addString(const std::string& s, const Payload& data);
const Payload& lookup(const std::string& s) const;
};
// Define this out-of-line to dissuade the C++ compiler from inlining it.
template<class Payload>
bool Trie<Payload>::addString(const std::string& s, const Payload& data) {
Node* cNode = getRoot();
Node* tNode = NULL;
std::string s1(s);
while (tNode == NULL) {
char Id = s1[0];
if (Node* nNode = cNode->getEdge(Id)) {
typename Node::QueryResult r = nNode->query(s1);
switch (r) {
case Node::Same:
case Node::StringIsPrefix:
// Currently we don't allow to have two strings in the trie one
// being a prefix of another. This should be fixed.
assert(0 && "FIXME!");
return false;
case Node::DontMatch:
assert(0 && "Impossible!");
return false;
case Node::LabelIsPrefix:
s1 = s1.substr(nNode->label().length());
cNode = nNode;
break;
default:
nNode = splitEdge(cNode, Id, r);
tNode = addNode(data, s1.substr(r));
nNode->addEdge(tNode);
}
} else {
tNode = addNode(data, s1);
cNode->addEdge(tNode);
}
}
return true;
}
template<class Payload>
const Payload& Trie<Payload>::lookup(const std::string& s) const {
Node* cNode = getRoot();
Node* tNode = NULL;
std::string s1(s);
while (tNode == NULL) {
char Id = s1[0];
if (Node* nNode = cNode->getEdge(Id)) {
typename Node::QueryResult r = nNode->query(s1);
switch (r) {
case Node::Same:
tNode = nNode;
break;
case Node::StringIsPrefix:
return Empty;
case Node::DontMatch:
assert(0 && "Impossible!");
return Empty;
case Node::LabelIsPrefix:
s1 = s1.substr(nNode->label().length());
cNode = nNode;
break;
default:
return Empty;
}
} else
return Empty;
}
return tNode->data();
}
template<class Payload>
struct GraphTraits<Trie<Payload> > {
typedef Trie<Payload> TrieType;
typedef typename TrieType::Node NodeType;
typedef typename NodeType::iterator ChildIteratorType;
static inline NodeType *getEntryNode(const TrieType& T) {
return T.getRoot();
}
static inline ChildIteratorType child_begin(NodeType *N) {
return N->begin();
}
static inline ChildIteratorType child_end(NodeType *N) { return N->end(); }
typedef typename std::vector<NodeType*>::const_iterator nodes_iterator;
static inline nodes_iterator nodes_begin(const TrieType& G) {
return G.Nodes.begin();
}
static inline nodes_iterator nodes_end(const TrieType& G) {
return G.Nodes.end();
}
};
template<class Payload>
struct DOTGraphTraits<Trie<Payload> > : public DefaultDOTGraphTraits {
typedef typename Trie<Payload>::Node NodeType;
typedef typename GraphTraits<Trie<Payload> >::ChildIteratorType EdgeIter;
static std::string getGraphName(const Trie<Payload>& T) {
return "Trie";
}
static std::string getNodeLabel(NodeType* Node, const Trie<Payload>& T) {
if (T.getRoot() == Node)
return "<Root>";
else
return Node->label();
}
static std::string getEdgeSourceLabel(NodeType* Node, EdgeIter I) {
NodeType* N = *I;
return N->label().substr(0, 1);
}
static std::string getNodeAttributes(const NodeType* Node,
const Trie<Payload>& T) {
if (Node->data() != T.Empty)
return "color=blue";
return "";
}
};
} // end of llvm namespace
#endif // LLVM_ADT_TRIE_H