barrier/src/lib/base/XBase.h

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2012 Bolton Software 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 COPYING 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 CString& msg);
	virtual ~XBase() _NOEXCEPT;

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

protected:
	//! Get a human readable string describing the exception
	virtual CString		getWhat() const throw() = 0;

	//! 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 CString		format(const char* id,
							const char* defaultFormat, ...) const throw();
private:
	mutable CString		m_what;
};

/*!
\def XBASE_SUBCLASS
Convenience macro to subclass from XBase (or a subclass of it),
providing the c'tor taking a const CString&.  getWhat() is not
declared.
*/
#define XBASE_SUBCLASS(name_, super_)									\
class name_ : public super_ {											\
public:																	\
	name_() : super_() { }												\
	name_(const CString& 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 CString&.  getWhat() must be
implemented.
*/
#define XBASE_SUBCLASS_WHAT(name_, super_)								\
class name_ : public super_ {											\
public:																	\
	name_() : super_() { }												\
	name_(const CString& msg) : super_(msg) { }							\
	virtual ~name_() _NOEXCEPT { }										\
																		\
protected:																\
	virtual CString		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 CString&.  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 CString& 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 CString		getWhat() const throw();						\
																		\
private:																\
	mutable EState				m_state;								\
	mutable std::string			m_formatted;							\
}