deskflow/src/lib/base/XBase.h

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2012-2016 Symless Ltd.
 * Copyright (C) 2002 Chris Schoeneman
 *
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file LICENSE that should have accompanied this file.
 *
 * This package 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/>.
 */

#pragma once

#include "base/String.h"
#include "common/stdexcept.h"

//! Exception base class
/*!
This is the base class of most exception types.
*/
class XBase : public std::runtime_error {
public:
  //! Use getWhat() as the result of what()
  XBase();
  //! Use \c msg as the result of what()
  XBase(const String &msg);
  virtual ~XBase() _NOEXCEPT;

  //! Reason for exception
  virtual const char *what() const _NOEXCEPT;

protected:
  //! Get a human readable string describing the exception
  virtual String getWhat() const throw() { return ""; }

  //! Format a string
  /*!
  Looks up a message format using \c id, using \c defaultFormat if
  no format can be found, then replaces positional parameters in
  the format string and returns the result.
  */
  virtual String format(const char *id, const char *defaultFormat, ...) const
      throw();

private:
  mutable String m_what;
};

/*!
\def XBASE_SUBCLASS
Convenience macro to subclass from XBase (or a subclass of it),
providing the c'tor taking a const String&.  getWhat() is not
declared.
*/
#define XBASE_SUBCLASS(name_, super_)                                          \
  class name_ : public super_ {                                                \
  public:                                                                      \
    name_() : super_() {}                                                      \
    name_(const String &msg) : super_(msg) {}                                  \
    virtual ~name_() _NOEXCEPT {}                                              \
  }

/*!
\def XBASE_SUBCLASS
Convenience macro to subclass from XBase (or a subclass of it),
providing the c'tor taking a const String&.  getWhat() must be
implemented.
*/
#define XBASE_SUBCLASS_WHAT(name_, super_)                                     \
  class name_ : public super_ {                                                \
  public:                                                                      \
    name_() : super_() {}                                                      \
    name_(const String &msg) : super_(msg) {}                                  \
    virtual ~name_() _NOEXCEPT {}                                              \
                                                                               \
  protected:                                                                   \
    virtual String getWhat() const throw();                                    \
  }

/*!
\def XBASE_SUBCLASS_FORMAT
Convenience macro to subclass from XBase (or a subclass of it),
providing the c'tor taking a const String&.  what() is overridden
to call getWhat() when first called;  getWhat() can format the
error message and can call what() to get the message passed to the
c'tor.
*/
#define XBASE_SUBCLASS_FORMAT(name_, super_)                                   \
  class name_ : public super_ {                                                \
  private:                                                                     \
    enum EState { kFirst, kFormat, kDone };                                    \
                                                                               \
  public:                                                                      \
    name_() : super_(), m_state(kDone) {}                                      \
    name_(const String &msg) : super_(msg), m_state(kFirst) {}                 \
    virtual ~name_() _NOEXCEPT {}                                              \
                                                                               \
    virtual const char *what() const _NOEXCEPT {                               \
      if (m_state == kFirst) {                                                 \
        m_state = kFormat;                                                     \
        m_formatted = getWhat();                                               \
        m_state = kDone;                                                       \
      }                                                                        \
      if (m_state == kDone) {                                                  \
        return m_formatted.c_str();                                            \
      } else {                                                                 \
        return super_::what();                                                 \
      }                                                                        \
    }                                                                          \
                                                                               \
  protected:                                                                   \
    virtual String getWhat() const throw();                                    \
                                                                               \
  private:                                                                     \
    mutable EState m_state;                                                    \
    mutable std::string m_formatted;                                           \
  }