gexception.h

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//
// Copyright (C) 2017 Graeme Walker
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program 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/>.
// ===
///
/// \file gexception.h
///

#ifndef G_EXCEPTION_H
#define G_EXCEPTION_H

#include "gdef.h"
#include <string>
#include <iostream>

namespace G
{
    class Exception ;
}

/// \class G::Exception
/// A general-purpose exception class derived from std::exception and containing 
/// a std::string. Provides constructors that simplify the assembly of multi-part
/// error messages.
/// 
/// Usage:
/// \code
/// throw G::Exception( "initialisation error" , "no such file" , path ) ;
/// \endcode
/// 
class G::Exception : public std::exception
{
protected:
    std::string m_what ;

public:
    explicit Exception( const char * what ) ;
        ///< Constructor.

    explicit Exception( const std::string & what ) ;
        ///< Constructor.

    Exception( const char * what , const std::string & more ) ;
        ///< Constructor.

    Exception( const std::string & what , const std::string & more ) ;
        ///< Constructor.

    Exception( const std::string & what , const std::string & more1 , const std::string & more2 ) ;
        ///< Constructor.

    Exception( const std::string & what , const std::string & more1 , const std::string & more2 , const std::string & more3 ) ;
        ///< Constructor.

    virtual ~Exception() g__noexcept ;
        ///< Destructor.

    virtual const char * what() const g__noexcept override ;
        ///< Override from std::exception.

    void prepend( const char * context ) ;
        ///< Prepends context to the what string.
        ///< Inserts a separator as needed.

    void append( const char * more ) ;
        ///< Appends 'more' to the what string.
        ///< Inserts a separator as needed.

    void append( const std::string & more ) ;
        ///< Appends 'more' to the what string.
        ///< Inserts a separator as needed.
} ;

#define G_EXCEPTION_CLASS( class_name , description ) class class_name : public G::Exception { public: class_name() : G::Exception(description) {} explicit class_name(const char *more) : G::Exception(description,more) {} explicit class_name(const std::string &more) : G::Exception(description,more) {} class_name(const std::string &more1,const std::string &more2) : G::Exception(description,more1,more2) {} class_name(const std::string &more1,const std::string &more2,const std::string &more3) : G::Exception(description,more1,more2,more3) {} }

#ifndef G_EXCEPTION
#define G_EXCEPTION( class_name , description ) G_EXCEPTION_CLASS( class_name , description )
#endif

#endif