option.h

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#ifndef option_HEADER
#define option_HEADER

/***************************************************************************
 * Benoit Hudson (C) 2007.
 ***************************************************************************/

#include <assert.h>
#include <boost/scoped_ptr.hpp>

namespace hudson {
using namespace boost;

template <class T>
struct option {
  option() { }
  option(const T& t) : t_(new T(t)) { }
  option(const option& other) { copy(other.t_); }
  option& operator=(const option& other) {
    copy(other.t_);
    return *this;
  }

  bool isSome() const { return t_.get() != NULL; }
  bool isNone() const { return t_.get() == NULL; }
  const T& valOf() const {
    assert(isSome());
    return *t_;
  }
  const T& operator*() const {
    return valOf();
  }

  private:
  void copy(const scoped_ptr<T>& other) {
    if (other.get()) {
      t_.reset(new T(*other));
    } else {
      t_.reset(0);
    }
  }
  scoped_ptr<T> t_;
};

} // namespace hudson
#endif

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