stack trace exception.cpp

class StackTraceException : public std::exception {
protected:
        static constexpr int STACK_POINTER_COUNT = 100;
        void * stack_pointers[STACK_POINTER_COUNT];
        std::size_t stack_pointers_filled = 0;
        mutable std::string stacktrace;
public:
       	StackTraceException();
        ~StackTraceException();

        virtual const char *what() const noexcept override;


};



constexpr int StackTraceException::STACK_POINTER_COUNT;
StackTraceException::StackTraceException() {
        stack_pointers_filled = backtrace(stack_pointers, STACK_POINTER_COUNT);
}


StackTraceException::~StackTraceException() { }

const char* StackTraceException::what() const noexcept {
        // this is quite expensive, so only do it on demand                                                                                              
        if (stacktrace == "") {
		char **symbols = nullptr;
		symbols = backtrace_symbols(stack_pointers, stack_pointers_filled);

                std::stringstream stream;
                for (int i = 0; i < stack_pointers_filled; i++) {
                        stream << symbols[i] << std::endl;
                }
                stacktrace = stream.str();
                free(symbols);
        }

        return stacktrace.c_str();
}