SymEngine Exceptions

SymEngine uses SymEngineException as the base type for exceptions arising from various SymEngine functions.

All exceptions derived from SymEngineException must contain symengine_exceptions_t error_code() which returns one of the error codes from the enum symengine_exceptions_t.

In the symengine_exceptions_t enum, 0 means no exception and 1 means a generic SymEngineException. Add other exception values as necessary.

In the C wrappers, all methods will return a CWRAPPER_OUTPUT_TYPE (which is the same as symengine_exceptions_t) and the functional code should be sandwiched between the macros CWRAPPER_BEGIN and CWRAPPER_END to accommodate exception handling.

In the other language wrappers, proper exception handling should be performed according to the language by examining the error code returned by the C wrapper. For an example, in the Ruby wrapper, the void raise_exception(symengine_exceptions_t error_code) is called with the returned error code.