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#ifndef LUA_UNIQUE_BIN_H
#define LUA_UNIQUE_BIN_H
//
// A container that holds unique copies of a data type (with smart references).
//
// Accessing the data for any reference is always valid.
//
// Data Types that use this template must have the following properties:
//
// 1. the 'bool operator<(const T&) const' member function
//
// 2. the 'static T def' static variable that holds default values
//
#include <set>
/******************************************************************************/
/******************************************************************************/
//
// UniqueBin
//
template<typename T>
class UniqueBin
{
private:
class Data;
struct SortObj;
public:
class Ref;
typedef std::set<Data*, SortObj> DataSet;
typedef typename DataSet::const_iterator const_iterator;
const_iterator begin() const {
return dataSet.begin();
}
const_iterator end() const {
return dataSet.end();
}
unsigned int size() const {
return dataSet.size();
}
bool empty() const {
return dataSet.empty();
}
Ref GetRef(const T& t) {
Data* cmpPtr = (Data*) &t; // note the cast
const_iterator it = dataSet.find(cmpPtr);
if (it != dataSet.end()) {
return Ref(*it); // already in the set
}
Data* data = new Data(t);
dataSet.insert(data);
return Ref(data);
}
bool Exists(const T& t) const {
Data* cmpPtr = (Data*) &t; // note the cast
const_iterator it = dataSet.find(cmpPtr);
if (it != dataSet.end()) {
return true;
}
return false;
}
static UniqueBin handler;
private:
struct SortObj
{
bool operator()(const Data* a, const Data* b) {
return (*a < *b);
}
};
private:
typedef typename DataSet::iterator iterator;
private:
UniqueBin() {
defData = new Data(T::def);
defData->Ref(); // make it permanent
dataSet.insert(defData);
}
~UniqueBin() {
defData->UnRef();
for (iterator it = dataSet.begin(); it != dataSet.end(); ++it) {
delete *it;
}
}
void EraseData(Data* data) {
dataSet.erase(data);
delete data;
}
private:
Data* defData;
DataSet dataSet;
/******************************************************************************/
//
// Ref
//
public:
class Ref {
friend Ref UniqueBin::GetRef(const T& t); // for Ref(Data*) access
public:
Ref() {
dataPtr = UniqueBin::handler.defData;
}
const T& operator*() const {
return (**dataPtr);
}
const T* operator->() const {
return &(**dataPtr);
}
bool operator==(const Ref& r) const {
return dataPtr == r.dataPtr;
}
bool operator!=(const Ref& r) const {
return dataPtr != r.dataPtr;
}
void Reset() {
dataPtr->UnRef();
dataPtr = UniqueBin::handler->defData;
dataPtr->Ref();
}
~Ref() {
dataPtr->UnRef();
};
Ref(const Ref& r) {
dataPtr = r.dataPtr;
dataPtr->Ref();
}
Ref& operator=(const Ref& r) {
if (dataPtr != r.dataPtr) {
dataPtr->UnRef();
dataPtr = r.dataPtr;
dataPtr->Ref();
}
return *this;
}
private:
Ref(Data* dp) {
dataPtr = dp;
dataPtr->Ref();
}
private:
Data* dataPtr;
};
/******************************************************************************/
//
// Data
//
private:
class Data {
public:
bool operator<(const Data& d) const {
return (data < d.data);
}
const T& operator*() const {
return data;
}
void Ref() {
refCount++;
}
void UnRef() {
refCount--;
if (refCount <= 0) {
UniqueBin::handler.EraseData(this);
}
}
Data(const T& t)
: data(t), refCount(0) {}
private:
T data; // NOTE: must come first
unsigned int refCount;
};
};
/******************************************************************************/
/******************************************************************************/
template<typename T> UniqueBin<T> UniqueBin<T>::handler;
/******************************************************************************/
/******************************************************************************/
#endif // LUA_UNIQUE_BIN_H
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