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// Copyright 2008, 2009 Brady J. Garvin
// This file is part of Covering Arrays by Simulated Annealing (CASA).
// CASA is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// CASA is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with CASA. If not, see <http://www.gnu.org/licenses/>.
#ifndef LAZY_H
#define LAZY_H
#include <cassert>
#include <iostream>
template<class T>class Lazy {
protected:
T* implementation;
unsigned* referenceCount;
void destroy() {
if (referenceCount) {
assert(implementation);
if (!(--*referenceCount)) {
delete implementation;
delete referenceCount;
}
implementation = NULL;
} else {
assert(!implementation);
}
}
public:
Lazy() :
implementation(NULL),
referenceCount(NULL) {}
Lazy(T*implementation) :
implementation(implementation),
referenceCount(implementation ? new unsigned(1) : NULL) {}
Lazy(const Lazy©) :
implementation(copy.implementation),
referenceCount(copy.referenceCount) {
if (implementation) {
assert(referenceCount);
++*referenceCount;
} else {
assert(!referenceCount);
}
}
Lazy&operator =(T*implementation) {
destroy();
this->implementation = implementation;
this->referenceCount = implementation ? new unsigned(1) : NULL;
return *this;
}
Lazy&operator =(const Lazy©) {
destroy();
implementation = copy.implementation;
if (implementation) {
referenceCount = copy.referenceCount;
assert(referenceCount);
++*referenceCount;
} else {
assert(!copy.referenceCount);
referenceCount = NULL;
}
return *this;
}
virtual ~Lazy(){
destroy();
}
const T*operator ->() const {
return implementation;
}
T*operator ->() {
if (referenceCount) {
assert(implementation);
if (*referenceCount > 1) {
T*copy = new T(*implementation);
destroy();
implementation = copy;
referenceCount = new unsigned(1);
}
} else {
assert(!implementation);
}
return implementation;
}
operator const T*() const {
return operator ->();
}
operator T*() {
return operator ->();
}
};
#endif
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