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/*
* File: format_string.cpp
*
* Copyright (c) Freescale Semiconductor, Inc. All rights reserved.
* See included license file for license details.
*/
#include "format_string.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdexcept>
#include <string.h>
#include <stdlib.h>
//! Size of the temporary buffer to hold the formatted output string.
#define WIN32_FMT_BUF_LEN (512)
/*!
* \brief Simple template class to free a pointer.
*/
template <typename T>
class free_ptr
{
public:
//! \brief Constructor.
free_ptr(T ptr)
: m_p(ptr)
{
}
//! \brief Destructor.
~free_ptr()
{
if (m_p)
{
free(m_p);
}
}
protected:
T m_p; //!< The value to free.
};
//! The purpose of this function to provide a convenient way of generating formatted
//! STL strings inline. This is especially useful when throwing exceptions that take
//! a std::string for a message. The length of the formatted output string is limited
//! only by memory. Memory temporarily allocated for the output string is disposed of
//! before returning.
//!
//! Example usage:
//! \code
//! throw std::runtime_error(format_string("error on line %d", line));
//! \endcode
//!
//! \param fmt Format string using printf-style format markers.
//! \return An STL string object of the formatted output.
std::string format_string(const char * fmt, ...)
{
char * buf = 0;
va_list vargs;
va_start(vargs, fmt);
int result = -1;
#if WIN32
buf = (char *)malloc(WIN32_FMT_BUF_LEN);
if (buf)
{
result = _vsnprintf(buf, WIN32_FMT_BUF_LEN, fmt, vargs);
}
#else // WIN32
result = vasprintf(&buf, fmt, vargs);
#endif // WIN32
va_end(vargs);
if (result != -1 && buf)
{
free_ptr<char *> freebuf(buf);
return std::string(buf);
}
return "";
}
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