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/*               Copyright 1998-2002 by Ullrich Koethe                  */
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/*    This file is part of the VIGRA computer vision library.           */
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#ifndef VIGRA_ERROR_HXX
#define VIGRA_ERROR_HXX

#include <stdexcept>
#include <sstream>
#include <string>
#include "config.hxx"

/** \page ErrorReporting Error Reporting
    Exceptions and assertions provided by VIGRA

    <b>\#include</b> \<vigra/error.hxx\>

    VIGRA defines the following exception classes:

    \code
    namespace vigra {
        class ContractViolation : public std::exception;
        class PreconditionViolation : public ContractViolation;
        class PostconditionViolation : public ContractViolation;
        class InvariantViolation : public ContractViolation;
    }
    \endcode

    The following associated macros throw the corresponding exception if
    their PREDICATE evaluates to '<TT>false</TT>':

    \code
    vigra_precondition(PREDICATE, MESSAGE);
    vigra_postcondition(PREDICATE, MESSAGE);
    vigra_invariant(PREDICATE, MESSAGE);
    \endcode

    The MESSAGE is passed to the exception and can be retrieved via
    the overloaded member function '<TT>exception.what()</TT>'. If the compiler
    flag '<TT>NDEBUG</TT>' is <em>not</em> defined, the file name and line number of
    the error are automatically included in the message. The macro

    \code
    vigra_assert(PREDICATE, MESSAGE);
    \endcode

    is identical to <tt>vigra_precondition()</tt> except that it is completely removed
    when '<TT>NDEBUG</TT>' is defined. This is useful for test that are only needed during
    debugging, such as array index bound checking. The following macro

    \code
    vigra_fail(MESSAGE);
    \endcode

    unconditionally throws a '<TT>std::runtime_error</TT>' constructed from the message
    (along with file name and line number, if NDEBUG is not set).

    <b> Usage:</b>

    Include-File:
    \<vigra/error.hxx\>
    <p>
    Namespace: vigra (except for the macros, of course)

    \code
    int main(int argc, char ** argv)
    {
        try
        {
            const char* input_file_name = argv[1];

            // read input image
            vigra::ImageImportInfo info(input_file_name);

            // fail if input image is not grayscale
            vigra_precondition(info.isGrayscale(), "Input image must be grayscale");

            ...// process image
        }
        catch (std::exception & e)
        {
            std::cerr << e.what() << std::endl; // print message
            return 1;
        }

        return 0;
    }
    \endcode
**/

namespace vigra {

class ContractViolation : public StdException
{
  public:
    ContractViolation()
    {}

    ContractViolation(char const * prefix, char const * message,
                      char const * file, int line)
    {
        (*this) << "\n" << prefix << "\n" << message << "\n("
                 << file << ":" << line << ")\n";
    }

    ContractViolation(char const * prefix, char const * message)
    {
        (*this) << "\n" << prefix << "\n" << message << "\n";
    }

    ~ContractViolation() throw()
    {}

    template<class T>
    ContractViolation & operator<<(T const & data)
    {
        std::ostringstream what;
        what << data;
        what_ += what.str();
        return *this;
    }

    virtual const char * what() const throw()
    {
        try
        {
            return what_.c_str();
        }
        catch(...)
        {
            return "vigra::ContractViolation: error message was lost, sorry.";
        }
    }

  private:
    std::string what_;
};

class PreconditionViolation : public ContractViolation
{
  public:
    PreconditionViolation(char const * message, const char * file, int line)
    : ContractViolation("Precondition violation!", message, file, line)
    {}

    PreconditionViolation(char const * message)
    : ContractViolation("Precondition violation!", message)
    {}
};

class PostconditionViolation : public ContractViolation
{
  public:
    PostconditionViolation(char const * message, const char * file, int line)
    : ContractViolation("Postcondition violation!", message, file, line)
    {}

    PostconditionViolation(char const * message)
    : ContractViolation("Postcondition violation!", message)
    {}
};

class InvariantViolation : public ContractViolation
{
  public:
    InvariantViolation(char const * message, const char * file, int line)
    : ContractViolation("Invariant violation!", message, file, line)
    {}

    InvariantViolation(char const * message)
    : ContractViolation("Invariant violation!", message)
    {}
};

inline
void throw_invariant_error(bool predicate, char const * message, char const * file, int line)
{
    if(!predicate)
       throw vigra::InvariantViolation(message, file, line);
}

inline
void throw_invariant_error(bool predicate, std::string message, char const * file, int line)
{
    if(!predicate)
       throw vigra::InvariantViolation(message.c_str(), file, line);
}

inline
void throw_precondition_error(bool predicate, char const * message, char const * file, int line)
{
    if(!predicate)
       throw vigra::PreconditionViolation(message, file, line);
}

inline
void throw_precondition_error(bool predicate, std::string message, char const * file, int line)
{
    if(!predicate)
       throw vigra::PreconditionViolation(message.c_str(), file, line);
}

inline
void throw_postcondition_error(bool predicate, char const * message, char const * file, int line)
{
    if(!predicate)
       throw vigra::PostconditionViolation(message, file, line);
}

inline
void throw_postcondition_error(bool predicate, std::string message, char const * file, int line)
{
    if(!predicate)
       throw vigra::PostconditionViolation(message.c_str(), file, line);
}

inline
void throw_runtime_error(char const * message, char const * file, int line)
{
    std::ostringstream what;
    what << "\n" << message << "\n(" << file << ":" << line << ")\n";
    throw std::runtime_error(what.str());
}

inline
void throw_runtime_error(std::string message, char const * file, int line)
{
    std::ostringstream what;
    what << "\n" << message << "\n(" << file << ":" << line << ")\n";
    throw std::runtime_error(what.str());
}

#define vigra_precondition(PREDICATE, MESSAGE) vigra::throw_precondition_error((PREDICATE), MESSAGE, __FILE__, __LINE__)

// Compile assertions only in debug mode
#ifdef NDEBUG
    #define vigra_assert(PREDICATE, MESSAGE)
#else
    #define vigra_assert(PREDICATE, MESSAGE) vigra_precondition(PREDICATE, MESSAGE)
#endif

#define vigra_postcondition(PREDICATE, MESSAGE) vigra::throw_postcondition_error((PREDICATE), MESSAGE, __FILE__, __LINE__)

#define vigra_invariant(PREDICATE, MESSAGE) vigra::throw_invariant_error((PREDICATE), MESSAGE, __FILE__, __LINE__)

#define vigra_fail(MESSAGE) vigra::throw_runtime_error(MESSAGE, __FILE__, __LINE__)

} // namespace vigra

#endif // VIGRA_ERROR_HXX
