/* -*- C++ -*-

  *

  * This file is a part of LEMON, a generic C++ optimization library

  *

  * Copyright (C) 2003-2008

  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Research Group on Combinatorial Optimization, EGRES).

  *

  * Permission to use, modify and distribute this software is granted

  * provided that this copyright notice appears in all copies. For

  * precise terms see the accompanying LICENSE file.

  *

  * This software is provided "AS IS" with no warranty of any kind,

  * express or implied, and with no claim as to its suitability for any

  * purpose.

  *

  */

 #ifndef LEMON_ERROR_H

 #define LEMON_ERROR_H

 /// \ingroup exceptions

 /// \file

 /// \brief Basic exception classes and error handling.

 #include <exception>

 #include <string>

 #include <sstream>

 #include <iostream>

 #include <cstdlib>

 #include <memory>

 namespace lemon {

   /// \addtogroup exceptions

   /// @{

   /// \brief Exception safe wrapper class.

   ///

   /// Exception safe wrapper class to implement the members of exceptions.

   template <typename _Type>

   class ExceptionMember {

   public:

     typedef _Type Type;

     ExceptionMember() throw() {

       try {

 	ptr.reset(new Type());

       } catch (...) {}

     }

     ExceptionMember(const Type& type) throw() {

       try {

 	ptr.reset(new Type());

 	if (ptr.get() == 0) return;

 	*ptr = type;

       } catch (...) {}

     }

     ExceptionMember(const ExceptionMember& copy) throw() {

       try {

 	if (!copy.valid()) return;

 	ptr.reset(new Type());

 	if (ptr.get() == 0) return;

 	*ptr = copy.get();

       } catch (...) {}

     }

     ExceptionMember& operator=(const ExceptionMember& copy) throw() {

       if (ptr.get() == 0) return;

       try {

 	if (!copy.valid()) return;

  	*ptr = copy.get();

       } catch (...) {}

     }

     void set(const Type& type) throw() {

       if (ptr.get() == 0) return;

       try {

 	*ptr = type;

       } catch (...) {}

     }

     const Type& get() const {

       return *ptr;

     }

     bool valid() const throw() {

       return ptr.get() != 0;

     }

   private:

     std::auto_ptr<_Type> ptr;

   };

   /// Exception-safe convenient error message builder class.

   /// Helper class which provides a convenient ostream-like (operator <<

   /// based) interface to create a string message. Mostly useful in

   /// exception classes (therefore the name).

   class ErrorMessage {

   protected:

     ///\e

     ///\todo The good solution is boost::shared_ptr...

     ///

     mutable std::auto_ptr<std::ostringstream> buf;

     ///\e

     bool init() throw() {

       try {

 	buf.reset(new std::ostringstream);

       }

       catch(...) {

 	buf.reset();

       }

       return buf.get();

     }

   public:

     ///\e

     ErrorMessage() throw() { init(); }

     ErrorMessage(const ErrorMessage& em) throw() : buf(em.buf) { }

     ///\e

     ErrorMessage(const char *msg) throw() {

       init();

       *this << msg;

     }

     ///\e

     ErrorMessage(const std::string &msg) throw() {

       init();

       *this << msg;

     }

     ///\e

     template <typename T>

     ErrorMessage& operator<<(const T &t) throw() {

       if( ! buf.get() ) return *this;

       try {

 	*buf << t;

       }

       catch(...) {

 	buf.reset();

       }

       return *this;

     }

     ///\e

     const char* message() throw() {

       if( ! buf.get() ) return 0;

       const char* mes = 0;

       try {

 	mes = buf->str().c_str();

       }

       catch(...) {}

       return mes;

     }

   };

   /// Generic exception class.

   /// Base class for exceptions used in LEMON.

   ///

   class Exception : public std::exception {

   public:

     ///\e

     Exception() {}

     ///\e

     virtual ~Exception() throw() {}

     ///\e

     virtual const char* what() const throw() {

       return "lemon::Exception";

     }

   };

   /// One of the two main subclasses of \ref Exception.

   /// Logic errors represent problems in the internal logic of a program;

   /// in theory, these are preventable, and even detectable before the

   /// program runs (e.g. violations of class invariants).

   ///

   /// A typical example for this is \ref UninitializedParameter.

   class LogicError : public Exception {

   public:

     virtual const char* what() const throw() {

       return "lemon::LogicError";

     }

   };

   /// \ref Exception for uninitialized parameters.

   /// This error represents problems in the initialization

   /// of the parameters of the algorithms.

   class UninitializedParameter : public LogicError {

   public:

     virtual const char* what() const throw() {

       return "lemon::UninitializedParameter";

     }

   };

   /// One of the two main subclasses of \ref Exception.

   /// Runtime errors represent problems outside the scope of a program;

   /// they cannot be easily predicted and can generally only be caught

   /// as the program executes.

   class RuntimeError : public Exception {

   public:

     virtual const char* what() const throw() {

       return "lemon::RuntimeError";

     }

   };

   ///\e

   class RangeError : public RuntimeError {

   public:

     virtual const char* what() const throw() {

       return "lemon::RangeError";

     }

   };

   ///\e

   class IoError : public RuntimeError {

   public:

     virtual const char* what() const throw() {

       return "lemon::IoError";

     }

   };

   ///\e

   class DataFormatError : public IoError {

   protected:

     ExceptionMember<std::string> _message;

     ExceptionMember<std::string> _file;

     int _line;

     mutable ExceptionMember<std::string> _message_holder;

   public:

     DataFormatError(const DataFormatError &dfe) :

       IoError(dfe), _message(dfe._message), _file(dfe._file),

       _line(dfe._line) {}

     ///\e

     explicit DataFormatError(const char *the_message)

       : _message(the_message), _line(0) {}

     ///\e

     DataFormatError(const std::string &file_name, int line_num,

 		    const char *the_message)

       : _message(the_message), _line(line_num) { file(file_name); }

     ///\e

     void line(int ln) { _line = ln; }

     ///\e

     void message(const std::string& msg) { _message.set(msg); }

     ///\e

     void file(const std::string &fl) { _file.set(fl); }

     ///\e

     int line() const { return _line; }

     ///\e

     const char* message() const {

       if (_message.valid() && !_message.get().empty()) {

 	return _message.get().c_str();

       } else {

 	return 0;

       }

     }

     /// \brief Returns the filename.

     ///

     /// Returns \e null if the filename was not specified.

     const char* file() const {

       if (_file.valid() && !_file.get().empty()) {

 	return _file.get().c_str();

       } else {

 	return 0;

       }

     }

     ///\e

     virtual const char* what() const throw() {

       try {

 	std::ostringstream ostr;

 	ostr << "lemon:DataFormatError" << ": ";

 	if (message()) ostr << message();

 	if( file() || line() != 0 ) {

 	  ostr << " (";

 	  if( file() ) ostr << "in file '" << file() << "'";

 	  if( file() && line() != 0 ) ostr << " ";

 	  if( line() != 0 ) ostr << "at line " << line();

 	  ostr << ")";

 	}

 	_message_holder.set(ostr.str());

       }

       catch (...) {}

       if( _message_holder.valid()) return _message_holder.get().c_str();

       return "lemon:DataFormatError";

     }

     virtual ~DataFormatError() throw() {}

   };

   ///\e

   class FileOpenError : public IoError {

   protected:

     ExceptionMember<std::string> _file;

     mutable ExceptionMember<std::string> _message_holder;

   public:

     FileOpenError(const FileOpenError &foe) :

       IoError(foe), _file(foe._file) {}

     ///\e

     explicit FileOpenError(const std::string& fl)

       : _file(fl) {}

     ///\e

     void file(const std::string &fl) { _file.set(fl); }

     /// \brief Returns the filename.

     ///

     /// Returns \e null if the filename was not specified.

     const char* file() const {

       if (_file.valid() && !_file.get().empty()) {

 	return _file.get().c_str();

       } else {

 	return 0;

       }

     }

     ///\e

     virtual const char* what() const throw() {

       try {

 	std::ostringstream ostr;

 	ostr << "lemon::FileOpenError" << ": ";

 	ostr << "Cannot open file - " << file();

 	_message_holder.set(ostr.str());

       }

       catch (...) {}

       if( _message_holder.valid()) return _message_holder.get().c_str();

       return "lemon::FileOpenError";

     }

     virtual ~FileOpenError() throw() {}

   };

   class IoParameterError : public IoError {

   protected:

     ExceptionMember<std::string> _message;

     ExceptionMember<std::string> _file;

     mutable ExceptionMember<std::string> _message_holder;

   public:

     IoParameterError(const IoParameterError &ile) :

       IoError(ile), _message(ile._message), _file(ile._file) {}

     ///\e

     explicit IoParameterError(const char *the_message)

       : _message(the_message) {}

     ///\e

     IoParameterError(const char *file_name, const char *the_message)

       : _message(the_message), _file(file_name) {}

      ///\e

     void message(const std::string& msg) { _message.set(msg); }

     ///\e

     void file(const std::string &fl) { _file.set(fl); }

      ///\e

     const char* message() const {

       if (_message.valid()) {

 	return _message.get().c_str();

       } else {

 	return 0;

       }

     }

     /// \brief Returns the filename.

     ///

     /// Returns \c 0 if the filename was not specified.

     const char* file() const {

       if (_file.valid()) {

 	return _file.get().c_str();

       } else {

 	return 0;

       }

     }

     ///\e

     virtual const char* what() const throw() {

       try {

 	std::ostringstream ostr;

 	if (message()) ostr << message();

 	if (file()) ostr << "(when reading file '" << file() << "')";

 	_message_holder.set(ostr.str());

       }

       catch (...) {}

       if( _message_holder.valid() ) return _message_holder.get().c_str();

       return "lemon:IoParameterError";

     }

     virtual ~IoParameterError() throw() {}

   };

   /// @}

 }

 #endif // LEMON_ERROR_H