Alignment/Geners/interface/ClassId.hh - master - githubmirror/cmssw

Alignment/Geners/interface/ClassId.hh
746 строк31 KB
Vassil Vassilev
shared_ptr has arrived to the standard. NFC
29 июл 2019, 05:52
29 июл 2019, 05:52521a053
//=========================================================================
// ClassId.hh
//
// Class identifier for I/O operations. Contains class name and version
// number. For templates, it should also contain version numbers of all
// template parameter classes.
//
// I. Volobouev
// September 2010
//=========================================================================

#ifndef GENERS_CLASSID_HH_
#define GENERS_CLASSID_HH_

#include <iostream>
#include <string>
#include <vector>

namespace gs {
  class ClassId {
  public:
    // Generic constructor using a prefix (which is usually
    // a class name) and a version number
    inline ClassId(const char *prefix, const unsigned version, const bool isPtr = false) {
      initialize(prefix, version, isPtr);
    }

    // Generic constructor using a prefix (which is usually
    // a class name) and a version number
    inline ClassId(const std::string &prefix, const unsigned version, const bool isPtr = false) {
      initialize(prefix.c_str(), version, isPtr);
    }

    // Use the following constructor in the "classId()" methods
    // of user-developed classes.
    //
    // Implementation note: it is possible to "specialize"
    // this constructor by delegating the actual job to the
    // "ClassIdSpecialization". Then we would be able to create
    // class ids for built-in and user types in a unified
    // way. This, however, would incur a performance hit
    // due to the necessity of making another ClassId and
    // copying the result into the internals of the new object.
    // This performance hit was deemed significant. If you
    // need a universal way to create class ids at some
    // point in your code, use the "itemId" method instead
    // (this may or may not incur a performance hit, depending
    // on what exactly the compiler does).
    template <class T>
    inline ClassId(const T &) {
      initialize(T::classname(), T::version(), false);
    }

    // Constructor from the class id represented by a string
    explicit ClassId(const std::string &id);

    // Use the following constructor in "read" functions.
    // Dummy argument "reading" is needed in order to generate
    // a distinct function signature (otherwise the templated
    // constructor can win).
    ClassId(std::istream &in, int reading);

    // Use the following pseudo-constructor in static "read"
    // methods in case a type check is desired. It has to be
    // made static because constructor without any arguments
    // can not be a template. Also, this is the way to construct
    // class ids for built-in types (there is no way to specialize
    // member methods).
    template <class T>
    static ClassId makeId();

    // "Universal" item id which also works for built-in types
    template <class T>
    static ClassId itemId(const T &);

    // Inspectors for the class name and version number
    inline const std::string &name() const { return name_; }
    inline unsigned version() const { return version_; }

    // Is this class a pointer for I/O purposes?
    inline bool isPointer() const { return isPtr_; }

    // The following function should return a unique class id string
    // which takes version number into account
    inline const std::string &id() const { return id_; }

    // The following checks if the class name corresponds to
    // a template (using the standard manner of class name forming)
    bool isTemplate() const;

    // The following function fills the vector with class template
    // parameters (if the class is not a template, the vector is
    // cleared). Due to the manner in which things are used in this
    // package, the result is actually a vector of (vectors of size 1).
    void templateParameters(std::vector<std::vector<ClassId>> *p) const;

    // Function to write this object out. Returns "true" on success.
    bool write(std::ostream &of) const;

    // Comparison operators
    inline bool operator==(const ClassId &r) const { return id_ == r.id_; }
    inline bool operator!=(const ClassId &r) const { return !(*this == r); }
    inline bool operator<(const ClassId &r) const { return id_ < r.id_; }
    inline bool operator>(const ClassId &r) const { return id_ > r.id_; }

    // Modify the version number
    void setVersion(unsigned newVersion);

    // The following methods verify that the id/classname/version
    // of this object are equal to those of the argument and throw
    // "gs::IOInvalidArgument" exception if this is not so
    void ensureSameId(const ClassId &id) const;
    void ensureSameName(const ClassId &id) const;
    void ensureSameVersion(const ClassId &id) const;

    // The following method ensures that the version number of this
    // class id is within certain range [min, max], with both limits
    // allowed. "gs::IOInvalidArgument" exception is thrown if this
    // is not so.
    void ensureVersionInRange(unsigned min, unsigned max) const;

    // Sometimes one really needs to make a placeholder class id...
    // This is a dangerous function: the code using ClassId class
    // will normally assume that a ClassId object is always in a valid
    // state. Invalid class ids can be distinguished by their empty
    // class names (i.e., name().empty() returns "true").
    static ClassId invalidId();

  private:
    ClassId();

    void initialize(const char *prefix, unsigned version, bool isPtr);
    bool makeName();
    bool makeVersion();

    std::string name_;
    std::string id_;
    unsigned version_;
    bool isPtr_;

    // Return "true" if the prefix is valid
    static bool validatePrefix(const char *prefix);
  };

  // Simple class id compatibility checkers for use as policy classes
  // in templated code
  struct SameClassId {
    inline static bool compatible(const ClassId &id1, const ClassId &id2) { return id1.name() == id2.name(); }
  };

  struct SameClassName {
    inline static bool compatible(const ClassId &id1, const ClassId &id2) { return id1 == id2; }
  };

  // Specialize the following template in order to be able to construct
  // ClassId for classes which do not implement static functions
  // "classname()" and "version()".
  template <class T>
  struct ClassIdSpecialization {
    inline static ClassId classId(const bool isPtr = false) { return ClassId(T::classname(), T::version(), isPtr); }
  };

  // Utility functions for naming template classes. The "nInclude"
  // argument tells us how many template parameters to include into
  // the generated template name. For example, use of
  //
  // template_class_name<X,Y>("myTemplate",1)
  //
  // will generate a class name which looks like myTemplate<X>, with
  // second template parameter omitted. While the result is equivalent
  // to invoking "template_class_name<X>("myTemplate")", having an
  // explicit limit is convenient for use from certain higher-level
  // functions. Note, however, that in the call with two template
  // parameters the class id specialization for Y must be available,
  // even though it is not used.
  //
  // This feature is sometimes helpful when certain template parameters
  // specify aspects of template behavior which have nothing to do
  // with object data contents and I/O. Typical example of such
  // a parameter is std::allocator of STL -- changing this to a custom
  // allocator will not affect serialized representation of an STL
  // container.
  //
  template <class T>
  std::string template_class_name(const char *templateName, unsigned nInclude = 1);
  template <class T>
  std::string template_class_name(const std::string &templateName, unsigned nInclude = 1);
  template <class T1, class T2>
  std::string template_class_name(const char *templateName, unsigned nInclude = 2);
  template <class T1, class T2>
  std::string template_class_name(const std::string &templateName, unsigned nInclude = 2);
  template <class T1, class T2, class T3>
  std::string template_class_name(const char *templateName, unsigned nInclude = 3);
  template <class T1, class T2, class T3>
  std::string template_class_name(const std::string &templateName, unsigned nInclude = 3);
  template <class T1, class T2, class T3, class T4>
  std::string template_class_name(const char *templateName, unsigned nInclude = 4);
  template <class T1, class T2, class T3, class T4>
  std::string template_class_name(const std::string &templateName, unsigned nInclude = 4);
  template <class T1, class T2, class T3, class T4, class T5>
  std::string template_class_name(const char *templateName, unsigned nInclude = 5);
  template <class T1, class T2, class T3, class T4, class T5>
  std::string template_class_name(const std::string &templateName, unsigned nInclude = 5);
  template <class T1, class T2, class T3, class T4, class T5, class T6>
  std::string template_class_name(const char *templateName, unsigned nInclude = 6);
  template <class T1, class T2, class T3, class T4, class T5, class T6>
  std::string template_class_name(const std::string &templateName, unsigned nInclude = 6);

  // Utility functions for naming stack-based containers such as std::array
  template <class T, std::size_t N>
  std::string stack_container_name(const char *templateName);

  template <class T, std::size_t N>
  std::string stack_container_name(const std::string &templateName);
}  // namespace gs

#include <cassert>
#include <sstream>
#include <utility>
#include <vector>

#include "Alignment/Geners/interface/IOIsAnyPtr.hh"
#include "Alignment/Geners/interface/IOIsClassType.hh"

#ifdef GENERS_EMPTY_TYPE_QUALIFYER_
#undef GENERS_EMPTY_TYPE_QUALIFYER_
#endif

#define GENERS_EMPTY_TYPE_QUALIFYER_

// Specializations of "ClassIdSpecialization" for built-in classes.
// They all look the same, so we want to use a macro
#define gs_specialize_class_helper(qualifyer, name, version) /**/                                      \
  template <>                                                                                          \
  struct ClassIdSpecialization<qualifyer name> {                                                       \
    inline static ClassId classId(const bool isPtr = false) { return ClassId(#name, version, isPtr); } \
  };

#define gs_specialize_class_id(name, version) /**/                                                           \
  namespace gs {                                                                                             \
    gs_specialize_class_helper(GENERS_EMPTY_TYPE_QUALIFYER_, name, version)                                  \
        gs_specialize_class_helper(const, name, version) gs_specialize_class_helper(volatile, name, version) \
            gs_specialize_class_helper(const volatile, name, version)                                        \
  }

// Specializations of "ClassIdSpecialization" for single-argument templates
#define gs_specialize_template_help_T(qualifyer, name, version, MAX) /**/ \
  template <class T>                                                      \
  struct ClassIdSpecialization<qualifyer name<T>> {                       \
    inline static ClassId classId(const bool isPtr = false) {             \
      return ClassId(template_class_name<T>(#name, MAX), version, isPtr); \
    }                                                                     \
  };

#define gs_specialize_template_id_T(name, version, MAX) /**/                        \
  namespace gs {                                                                    \
    gs_specialize_template_help_T(GENERS_EMPTY_TYPE_QUALIFYER_, name, version, MAX) \
        gs_specialize_template_help_T(const, name, version, MAX)                    \
            gs_specialize_template_help_T(volatile, name, version, MAX)             \
                gs_specialize_template_help_T(const volatile, name, version, MAX)   \
  }

// Specializations of "ClassIdSpecialization" for two-argument templates
#define gs_specialize_template_help_TT(qualifyer, name, version, MAX) /**/   \
  template <class T, class U>                                                \
  struct ClassIdSpecialization<qualifyer name<T, U>> {                       \
    inline static ClassId classId(const bool isPtr = false) {                \
      return ClassId(template_class_name<T, U>(#name, MAX), version, isPtr); \
    }                                                                        \
  };

#define gs_specialize_template_id_TT(name, version, MAX) /**/                        \
  namespace gs {                                                                     \
    gs_specialize_template_help_TT(GENERS_EMPTY_TYPE_QUALIFYER_, name, version, MAX) \
        gs_specialize_template_help_TT(const, name, version, MAX)                    \
            gs_specialize_template_help_TT(volatile, name, version, MAX)             \
                gs_specialize_template_help_TT(const volatile, name, version, MAX)   \
  }

// Specializations of "ClassIdSpecialization" for three-argument templates
#define gs_specialize_template_help_TTT(qualifyer, name, version, MAX) /**/     \
  template <class T, class U, class V>                                          \
  struct ClassIdSpecialization<qualifyer name<T, U, V>> {                       \
    inline static ClassId classId(const bool isPtr = false) {                   \
      return ClassId(template_class_name<T, U, V>(#name, MAX), version, isPtr); \
    }                                                                           \
  };

#define gs_specialize_template_id_TTT(name, version, MAX) /**/                        \
  namespace gs {                                                                      \
    gs_specialize_template_help_TTT(GENERS_EMPTY_TYPE_QUALIFYER_, name, version, MAX) \
        gs_specialize_template_help_TTT(const, name, version, MAX)                    \
            gs_specialize_template_help_TTT(volatile, name, version, MAX)             \
                gs_specialize_template_help_TTT(const volatile, name, version, MAX)   \
  }

// Specializations of "ClassIdSpecialization" for four-argument templates
#define gs_specialize_template_help_TTTT(qualifyer, name, version, MAX) /**/       \
  template <class T, class U, class V, class X>                                    \
  struct ClassIdSpecialization<qualifyer name<T, U, V, X>> {                       \
    inline static ClassId classId(const bool isPtr = false) {                      \
      return ClassId(template_class_name<T, U, V, X>(#name, MAX), version, isPtr); \
    }                                                                              \
  };

#define gs_specialize_template_id_TTTT(name, version, MAX) /**/                        \
  namespace gs {                                                                       \
    gs_specialize_template_help_TTTT(GENERS_EMPTY_TYPE_QUALIFYER_, name, version, MAX) \
        gs_specialize_template_help_TTTT(const, name, version, MAX)                    \
            gs_specialize_template_help_TTTT(volatile, name, version, MAX)             \
                gs_specialize_template_help_TTTT(const volatile, name, version, MAX)   \
  }

// Specializations of "ClassIdSpecialization" for five-argument templates
#define gs_specialize_template_hlp_TTTTT(qualifyer, name, version, MAX) /**/          \
  template <class T, class U, class V, class X, class Y>                              \
  struct ClassIdSpecialization<qualifyer name<T, U, V, X, Y>> {                       \
    inline static ClassId classId(const bool isPtr = false) {                         \
      return ClassId(template_class_name<T, U, V, X, Y>(#name, MAX), version, isPtr); \
    }                                                                                 \
  };

#define gs_specialize_template_id_TTTTT(name, version, MAX) /**/                       \
  namespace gs {                                                                       \
    gs_specialize_template_hlp_TTTTT(GENERS_EMPTY_TYPE_QUALIFYER_, name, version, MAX) \
        gs_specialize_template_hlp_TTTTT(const, name, version, MAX)                    \
            gs_specialize_template_hlp_TTTTT(volatile, name, version, MAX)             \
                gs_specialize_template_hlp_TTTTT(const volatile, name, version, MAX)   \
  }

// Specializations of "ClassIdSpecialization" for six-argument templates
#define gs_specialize_template_h_TTTTTT(qualifyer, name, version, MAX) /**/              \
  template <class T, class U, class V, class X, class Y, class Z>                        \
  struct ClassIdSpecialization<qualifyer name<T, U, V, X, Y, Z>> {                       \
    inline static ClassId classId(const bool isPtr = false) {                            \
      return ClassId(template_class_name<T, U, V, X, Y, Z>(#name, MAX), version, isPtr); \
    }                                                                                    \
  };

#define gs_specialize_template_id_TTTTTT(name, version, MAX) /**/                     \
  namespace gs {                                                                      \
    gs_specialize_template_h_TTTTTT(GENERS_EMPTY_TYPE_QUALIFYER_, name, version, MAX) \
        gs_specialize_template_h_TTTTTT(const, name, version, MAX)                    \
            gs_specialize_template_h_TTTTTT(volatile, name, version, MAX)             \
                gs_specialize_template_h_TTTTTT(const volatile, name, version, MAX)   \
  }

// Specializations of "ClassIdSpecialization" for two-argument templates
// which include an integer as a second argument (like std::array)
#define gs_specialize_template_help_TN(qualifyer, name, version, MAX) /**/    \
  template <class T, std::size_t N>                                           \
  struct ClassIdSpecialization<qualifyer name<T, N>> {                        \
    inline static ClassId classId(const bool isPtr = false) {                 \
      return ClassId(stack_container_name<T, N>(#name, MAX), version, isPtr); \
    }                                                                         \
  };

#define gs_specialize_template_id_TN(name, version, MAX) /**/                        \
  namespace gs {                                                                     \
    gs_specialize_template_help_TN(GENERS_EMPTY_TYPE_QUALIFYER_, name, version, MAX) \
        gs_specialize_template_help_TN(const, name, version, MAX)                    \
            gs_specialize_template_help_TN(volatile, name, version, MAX)             \
                gs_specialize_template_help_TN(const volatile, name, version, MAX)   \
  }

namespace gs {
  // "template_class_name" implementations
  template <class T>
  std::string template_class_name(const char *templateName, const unsigned nInclude) {
    assert(templateName);
    std::string name(templateName);
    if (nInclude) {
      name += '<';
      const ClassId &id(ClassIdSpecialization<T>::classId());
      name += id.id();
      name += '>';
    }
    return name;
  }

  template <class T>
  inline std::string template_class_name(const std::string &templateName, const unsigned nInclude) {
    return template_class_name<T>(templateName.c_str(), nInclude);
  }

  template <class T1, class T2>
  std::string template_class_name(const char *templateName, const unsigned nInclude) {
    assert(templateName);
    std::string name(templateName);
    if (nInclude) {
      name += '<';
      const ClassId &id1(ClassIdSpecialization<T1>::classId());
      name += id1.id();
      if (nInclude > 1) {
        name += ',';
        const ClassId &id2(ClassIdSpecialization<T2>::classId());
        name += id2.id();
      }
      name += '>';
    }
    return name;
  }

  template <class T1, class T2>
  inline std::string template_class_name(const std::string &templateName, const unsigned nInclude) {
    return template_class_name<T1, T2>(templateName.c_str(), nInclude);
  }

  template <class T1, class T2, class T3>
  std::string template_class_name(const char *templateName, const unsigned nInclude) {
    assert(templateName);
    std::string name(templateName);
    if (nInclude) {
      name += '<';
      const ClassId &id1(ClassIdSpecialization<T1>::classId());
      name += id1.id();
      if (nInclude > 1) {
        name += ',';
        const ClassId &id2(ClassIdSpecialization<T2>::classId());
        name += id2.id();
      }
      if (nInclude > 2) {
        name += ',';
        const ClassId &id3(ClassIdSpecialization<T3>::classId());
        name += id3.id();
      }
      name += '>';
    }
    return name;
  }

  template <class T1, class T2, class T3>
  inline std::string template_class_name(const std::string &templateName, const unsigned nInclude) {
    return template_class_name<T1, T2, T3>(templateName.c_str(), nInclude);
  }

  template <class T1, class T2, class T3, class T4>
  std::string template_class_name(const char *templateName, const unsigned nInclude) {
    assert(templateName);
    std::string name(templateName);
    if (nInclude) {
      name += '<';
      const ClassId &id1(ClassIdSpecialization<T1>::classId());
      name += id1.id();
      if (nInclude > 1) {
        name += ',';
        const ClassId &id2(ClassIdSpecialization<T2>::classId());
        name += id2.id();
      }
      if (nInclude > 2) {
        name += ',';
        const ClassId &id3(ClassIdSpecialization<T3>::classId());
        name += id3.id();
      }
      if (nInclude > 3) {
        name += ',';
        const ClassId &id4(ClassIdSpecialization<T4>::classId());
        name += id4.id();
      }
      name += '>';
    }
    return name;
  }

  template <class T1, class T2, class T3, class T4>
  inline std::string template_class_name(const std::string &templateName, const unsigned n) {
    return template_class_name<T1, T2, T3, T4>(templateName.c_str(), n);
  }

  template <class T1, class T2, class T3, class T4, class T5>
  std::string template_class_name(const char *templateName, const unsigned nInclude) {
    assert(templateName);
    std::string name(templateName);
    if (nInclude) {
      name += '<';
      const ClassId &id1(ClassIdSpecialization<T1>::classId());
      name += id1.id();
      if (nInclude > 1) {
        name += ',';
        const ClassId &id2(ClassIdSpecialization<T2>::classId());
        name += id2.id();
      }
      if (nInclude > 2) {
        name += ',';
        const ClassId &id3(ClassIdSpecialization<T3>::classId());
        name += id3.id();
      }
      if (nInclude > 3) {
        name += ',';
        const ClassId &id4(ClassIdSpecialization<T4>::classId());
        name += id4.id();
      }
      if (nInclude > 4) {
        name += ',';
        const ClassId &id5(ClassIdSpecialization<T5>::classId());
        name += id5.id();
      }
      name += '>';
    }
    return name;
  }

  template <class T1, class T2, class T3, class T4, class T5>
  inline std::string template_class_name(const std::string &templateName, const unsigned n) {
    return template_class_name<T1, T2, T3, T4, T5>(templateName.c_str(), n);
  }

  template <class T1, class T2, class T3, class T4, class T5, class T6>
  std::string template_class_name(const char *templateName, const unsigned nInclude) {
    assert(templateName);
    std::string name(templateName);
    if (nInclude) {
      name += '<';
      const ClassId &id1(ClassIdSpecialization<T1>::classId());
      name += id1.id();
      if (nInclude > 1) {
        name += ',';
        const ClassId &id2(ClassIdSpecialization<T2>::classId());
        name += id2.id();
      }
      if (nInclude > 2) {
        name += ',';
        const ClassId &id3(ClassIdSpecialization<T3>::classId());
        name += id3.id();
      }
      if (nInclude > 3) {
        name += ',';
        const ClassId &id4(ClassIdSpecialization<T4>::classId());
        name += id4.id();
      }
      if (nInclude > 4) {
        name += ',';
        const ClassId &id5(ClassIdSpecialization<T5>::classId());
        name += id5.id();
      }
      if (nInclude > 5) {
        name += ',';
        const ClassId &id6(ClassIdSpecialization<T6>::classId());
        name += id6.id();
      }
      name += '>';
    }
    return name;
  }

  template <class T1, class T2, class T3, class T4, class T5, class T6>
  inline std::string template_class_name(const std::string &templateName, const unsigned n) {
    return template_class_name<T1, T2, T3, T4, T5, T6>(templateName.c_str(), n);
  }

  template <class T, std::size_t N>
  std::string stack_container_name(const char *templateName) {
    assert(templateName);
    const ClassId &id1(ClassIdSpecialization<T>::classId());
    std::ostringstream os;
    os << templateName << '<' << id1.id() << ',' << N << "(0)>";
    return os.str();
  }

  template <class T, std::size_t N>
  std::string stack_container_name(const std::string &templateName) {
    return stack_container_name<T, N>(templateName.c_str());
  }

  // Skip references in class ids
  template <class T>
  struct ClassIdSpecialization<T &> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  // Skip pointers in class ids
  template <class T>
  struct ClassIdSpecialization<T *> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  template <class T>
  struct ClassIdSpecialization<T *const> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  template <class T>
  struct ClassIdSpecialization<T *volatile> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  template <class T>
  struct ClassIdSpecialization<T *const volatile> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  // Skip shared pointers in class ids
  template <class T>
  struct ClassIdSpecialization<std::shared_ptr<T>> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  template <class T>
  struct ClassIdSpecialization<const std::shared_ptr<T>> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  template <class T>
  struct ClassIdSpecialization<volatile std::shared_ptr<T>> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  template <class T>
  struct ClassIdSpecialization<const volatile std::shared_ptr<T>> {
    inline static ClassId classId(const bool /* isPtr */ = false) { return ClassIdSpecialization<T>::classId(true); }
  };

  // Skip IOPtr in class ids and do not turn on the pointer flag
  template <class T>
  struct ClassIdSpecialization<IOPtr<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  template <class T>
  struct ClassIdSpecialization<const IOPtr<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  template <class T>
  struct ClassIdSpecialization<volatile IOPtr<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  template <class T>
  struct ClassIdSpecialization<const volatile IOPtr<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  // Same thing for IOProxy
  template <class T>
  struct ClassIdSpecialization<IOProxy<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  template <class T>
  struct ClassIdSpecialization<const IOProxy<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  template <class T>
  struct ClassIdSpecialization<volatile IOProxy<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  template <class T>
  struct ClassIdSpecialization<const volatile IOProxy<T>> {
    inline static ClassId classId(const bool isPtr = false) { return ClassIdSpecialization<T>::classId(isPtr); }
  };

  // The remaining ClassId static functions
  template <class T>
  inline ClassId ClassId::makeId() {
    return ClassIdSpecialization<T>::classId();
  }

  namespace Private {
    template <bool, class T>
    struct CallClassId {
      static inline ClassId get(const T &) { return ClassIdSpecialization<T>::classId(); }
    };

    template <class T>
    struct CallClassId<true, T> {
      static inline ClassId get(const T &obj) { return obj.classId(); }
    };

    // The following class will check for the existence of two
    // possible signatures of the "classId" method:
    // "const ClassId& classId() const" and "ClassId classId() const".
    template <class Tp>
    class TypeHasClassIdHelper {
      template <typename T, T>
      struct TypeCheck;
      template <typename T>
      struct FcnType1 {
        typedef ClassId (T::*fptr)() const;
      };
      template <typename T>
      struct FcnType2 {
        typedef const ClassId &(T::*fptr)() const;
      };

      typedef char Yes;
      typedef struct {
        char a[2];
      } No;

      template <typename T>
      static Yes Has1(TypeCheck<typename FcnType1<T>::fptr, &T::classId> *);
      template <typename T>
      static No Has1(...);

      template <typename T>
      static Yes Has2(TypeCheck<typename FcnType2<T>::fptr, &T::classId> *);
      template <typename T>
      static No Has2(...);

    public:
      static const bool value = ((sizeof(Has1<Tp>(0)) == sizeof(Yes)) || (sizeof(Has2<Tp>(0)) == sizeof(Yes)));
    };

    template <class T, bool b = IOIsClassType<T>::value>
    struct TypeHasClassId {
      static const bool value = false;
    };

    template <typename T>
    struct TypeHasClassId<T, true> {
      static const bool value = TypeHasClassIdHelper<T>::value;
    };
  }  // namespace Private

  template <class T>
  inline ClassId ClassId::itemId(const T &item) {
    // Make sure that item is not a pointer.
    static_assert((!IOIsAnyPtr<T>::value), "can not use pointers with this method");

    // If the classId() function is avalable for this item, call it
    // (it could be virtual). Otherwise, call the generic method.
    return Private::CallClassId<Private::TypeHasClassId<T>::value, T>::get(item);
  }
}  // namespace gs

// Class ids for standard types
gs_specialize_class_id(float, 0) gs_specialize_class_id(double, 0) gs_specialize_class_id(long double, 0)
    gs_specialize_class_id(int, 0) gs_specialize_class_id(unsigned, 0) gs_specialize_class_id(long, 0)
        gs_specialize_class_id(long long, 0) gs_specialize_class_id(unsigned long, 0)
            gs_specialize_class_id(unsigned long long, 0) gs_specialize_class_id(short, 0)
                gs_specialize_class_id(unsigned short, 0) gs_specialize_class_id(bool, 0)
                    gs_specialize_class_id(char, 0) gs_specialize_class_id(unsigned char, 0)
                        gs_specialize_class_id(signed char, 0) gs_specialize_class_id(void, 0)
                            gs_specialize_class_id(std::string, 0)

    // Class ids for some standard library templates
    // used by this I/O package
    gs_specialize_template_id_T(std::less, 0, 1) gs_specialize_template_id_T(std::equal_to, 0, 1)
        gs_specialize_template_id_T(std::allocator, 0, 1) gs_specialize_template_id_T(std::char_traits, 0, 1)
            gs_specialize_template_id_TT(std::vector, 0, 1) gs_specialize_template_id_TT(std::pair, 0, 2)
                gs_specialize_template_id_TTT(std::basic_string, 0, 2)

#endif  // GENERS_CLASSID_HH_