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/* Set.h
Copyright (c) 2014 by Michael Zahniser
Endless Sky 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.
Endless Sky 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
this program. If not, see <https://www.gnu.org/licenses/>.
*/
#pragma once
#include <map>
#include <string>
// Template representing a set of named objects of a given type, where you can
// query it for a pointer to any object and it will return one, whether or not that
// object has been loaded yet. (This allows cyclic pointers.)
template<class Type>
class Set {
public:
// Allow non-const access to the owner of this set; it can hand off only
// const references to avoid anyone else modifying the objects.
Type *Get(const std::string &name) { return &data[name]; }
const Type *Get(const std::string &name) const { return &data[name]; }
// If an item already exists in this set, get it. Otherwise, return a null
// pointer rather than creating the item.
const Type *Find(const std::string &name) const;
bool Has(const std::string &name) const { return data.contains(name); }
typename std::map<std::string, Type>::iterator begin() { return data.begin(); }
typename std::map<std::string, Type>::const_iterator begin() const { return data.begin(); }
typename std::map<std::string, Type>::const_iterator find(const std::string &key) const { return data.find(key); }
typename std::map<std::string, Type>::iterator end() { return data.end(); }
typename std::map<std::string, Type>::const_iterator end() const { return data.end(); }
int size() const { return data.size(); }
bool empty() const { return data.empty(); }
// Remove any objects in this set that are not in the given set, and for
// those that are in the given set, revert to their contents.
void Revert(const Set<Type> &other);
private:
mutable std::map<std::string, Type> data;
};
template<class Type>
const Type *Set<Type>::Find(const std::string &name) const
{
auto it = data.find(name);
return (it == data.end() ? nullptr : &it->second);
}
template<class Type>
void Set<Type>::Revert(const Set<Type> &other)
{
auto it = data.begin();
auto oit = other.data.begin();
while(it != data.end())
{
if(oit == other.data.end() || it->first < oit->first)
it = data.erase(it);
else if(it->first == oit->first)
{
// If this is an entry that is in the set we are reverting to, copy
// the state we are reverting to.
it->second = oit->second;
++it;
++oit;
}
// There should never be a case when an entry in the set we are
// reverting to has a name that is not also in this set.
}
}
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