NameFactory.h

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/* Frobby: Software for monomial ideal computations.
   Copyright (C) 2007 Bjarke Hammersholt Roune (www.broune.com)
 
   This program 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 2 of the License, or
   (at your option) any later version.
 
   This program 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 http://www.gnu.org/licenses/.
*/
#ifndef NAME_FACTORY_GUARD
#define NAME_FACTORY_GUARD
 
#include "error.h"
#include <vector>
#include <string>
#include <algorithm>
 
template<class AbstractProduct>
class NameFactory {
 public:
  NameFactory(const char* abstractName): _abstractName(abstractName) {}
 
  typedef auto_ptr<AbstractProduct> (*FactoryFunction)();
  void registerProduct(const string& name, FactoryFunction function);
 
  auto_ptr<AbstractProduct> createNoThrow(const string& name) const;
 
  auto_ptr<AbstractProduct> create(const string& name) const;
 
  void getNamesWithPrefix(const string& prefix, vector<string>& names) const;
 
  bool empty() const;
 
  string getAbstractProductName() const;
 
 private:
  typedef pair<string, FactoryFunction> Pair;
  typedef typename vector<Pair>::const_iterator const_iterator;
  vector<Pair> _pairs;
  const string _abstractName;
};
 
template<class ConcreteProduct, class AbstractProduct>
void nameFactoryRegister(NameFactory<AbstractProduct>& factory);
 
template<class AbstractProduct>
auto_ptr<AbstractProduct> createWithPrefix
(const NameFactory<AbstractProduct>& factory, const string& prefix);
 
template<class AbstractProduct>
string getUniqueNameWithPrefix
(const NameFactory<AbstractProduct>& factory, const string& prefix);
 
 
// **************************************************************
// These are implementations that have to be included here due
// to being templates.
 
template<class AbstractProduct>
auto_ptr<AbstractProduct> NameFactory<AbstractProduct>::
createNoThrow(const string& name) const {
  for (const_iterator it = _pairs.begin(); it != _pairs.end(); ++it)
    if (it->first == name)
      return it->second();
  return auto_ptr<AbstractProduct>();
}
 
template<class AbstractProduct>
auto_ptr<AbstractProduct> NameFactory<AbstractProduct>::
create(const string& name) const {
  auto_ptr<AbstractProduct> product = createNoThrow(name);
  if (product.get() == 0)
    throwError<UnknownNameException>(
      "Unknown " + getAbstractProductName() + " \"" + name + "\".");
  return product;
}
 
template<class AbstractProduct>
void NameFactory<AbstractProduct>::
registerProduct(const string& name, FactoryFunction function) {
  _pairs.push_back(Pair(name, function));
}
 
template<class AbstractProduct>
void NameFactory<AbstractProduct>::
getNamesWithPrefix(const string& prefix, vector<string>& names) const {
  for (const_iterator it = _pairs.begin(); it != _pairs.end(); ++it)
    if (it->first.compare(0, prefix.size(), prefix) == 0)
      names.push_back(it->first);
  sort(names.begin(), names.end());
}
 
template<class AbstractProduct>
bool NameFactory<AbstractProduct>::empty() const {
  return _pairs.empty();
}
 
template<class AbstractProduct>
string NameFactory<AbstractProduct>::getAbstractProductName() const {
  return _abstractName;
}
 
template<class ConcreteProduct, class AbstractProduct>
void nameFactoryRegister(NameFactory<AbstractProduct>& factory) {
  struct HoldsFunction {
    static auto_ptr<AbstractProduct> createConcreteProduct() {
      return auto_ptr<AbstractProduct>(new ConcreteProduct());
    }
  };
  factory.registerProduct(ConcreteProduct::staticGetName(),
                          HoldsFunction::createConcreteProduct);
}
 
template<class AbstractProduct>
auto_ptr<AbstractProduct> createWithPrefix
(const NameFactory<AbstractProduct>& factory, const string& prefix) {
  return factory.createNoThrow(getUniqueNameWithPrefix(factory, prefix));
}
 
template<class AbstractProduct>
string getUniqueNameWithPrefix
(const NameFactory<AbstractProduct>& factory, const string& prefix) {
  vector<string> names;
  factory.getNamesWithPrefix(prefix, names);
 
  if (find(names.begin(), names.end(), prefix) != names.end()) {
    names.clear();
    names.push_back(prefix);
  }
 
  if (names.empty()) {
    throwError<UnknownNameException>
      ("No " + factory.getAbstractProductName() +
       " has the prefix \"" + prefix + "\".");
  }
 
  if (names.size() >= 2) {
    string errorMsg = "More than one " + factory.getAbstractProductName() +
      " has prefix \"" + prefix + "\":\n ";
    for (size_t name = 0; name < names.size(); ++name)
      errorMsg += ' ' + names[name];
    throwError<AmbiguousNameException>(errorMsg);
  }
 
  ASSERT(names.size() == 1);
  return names.back();
}
 
#endif