to_string.hpp

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/*
    Copyright 2012 Adobe Systems Incorporated
    Distributed under the Boost Software License - Version 1.0 (see the accompanying file LICENSE
    or a copy at https://stlab.github.io/adobe_source_libraries/licenses.html)
*/
 
/**************************************************************************************************/
 
#ifndef ADOBE_STRING_TO_STRING_HPP
#define ADOBE_STRING_TO_STRING_HPP
 
#include <algorithm>
#include <cfloat>
#include <cstdio>
#include <string>
 
#include <adobe/cassert.hpp>
 
/**************************************************************************************************/
 
namespace adobe {
 
/**************************************************************************************************/

 
template <typename O> // O models output iterator accepting type char
O to_string(double x, O out, bool precise = false) {
    ADOBE_ASSERT((-DBL_MAX <= x && x <= DBL_MAX) &&
                 "WARNING (sparent) : to_string() only supports finite values.");
 
    /*
        longest possible string result is:
             1 "-"
             1 digit (will not be 0)
             1 "."
            16 digits (precise, 14 digits otherwise).
             2 "e+" or "e-"
             3 digit exponent
             1 null
          -------------------
          = 25 characters
        Use 32 as the next power-of-two for some safety with no overhead.
    */
    char buf[32];
 
#if defined(_MSC_VER)
    int size = _snprintf_s(&buf[0], sizeof(buf), sizeof(buf), "%.*g", precise ? 17 : 15, x);
#else
    int size = std::snprintf(&buf[0], sizeof(buf), "%.*g", precise ? 17 : 15, x);
    ADOBE_ASSERT(size < static_cast<int>(sizeof(buf)) && "WARNING (sparent) : snprintf truncated.");
#endif
    ADOBE_ASSERT(size < (precise ? 25 : 23) &&
                 "WARNING (sparent) : to_string() result larger than expected.");
    ADOBE_ASSERT(0 < size && "FATAL (sparent) : snprintf failed in to_string().");
 
    return std::copy(&buf[0], &buf[0] + size, out);
}
 
/**************************************************************************************************/
std::string to_string(double x);
 
/**************************************************************************************************/
 
} // namespace adobe
 
/**************************************************************************************************/
 
#endif
 
/**************************************************************************************************/