Factory.h

//-*-C++-*-
/***************************************************************************
 *
 *   Copyright (C) 2004 by Willem van Straten
 *   Licensed under the Academic Free License version 2.1
 *
 ***************************************************************************/
 
// psrchive/Util/units/Factory.h
 
#ifndef __MEAL_Factory_H
#define __MEAL_Factory_H
 
#include "Functor.h"
#include "stringtok.h"
 
#include <fstream>
 
namespace Factory {
 
  template< class T >
  T* load (const std::string& filename,
           Functor< T*(std::string) >& constructor,
           bool verbose = false)
  {
    std::ifstream input (filename.c_str());
    if (!input)
      throw Error (FailedSys, "Factory::load", "ifstream (" + filename + ")");
 
    std::string line;
 
    T* instance = 0;
 
    while (input)
    {
      std::getline (input, line);
      line = stringtok (line, "#\n", false);  // get rid of comments
 
      if (!line.length())
        continue;
 
      if (!instance)
      {
        // the first key loaded should be the name of the instance
        std::string key = stringtok (line, WHITESPACE);
 
        if (verbose)
          std::cerr << "Factory::load construct new " << key << std::endl;
 
        instance = constructor (key);
        
        if (!line.length())
          continue;
      }
 
      if (verbose)
        std::cerr << "Factory::load parse line '" << line << "'" << std::endl;
      
      instance->parse (line);
 
    }
 
    if (!instance)
      throw Error (InvalidParam, "Factory::load", "nothing constructed from '" + filename + "'");
 
    return instance;
 
  }
 
}
 
#endif