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// Copyright (c) 2009-2016 Vladimir Batov.
// Use, modification and distribution are subject to the Boost Software License,
// Version 1.0. See http://www.boost.org/LICENSE_1_0.txt.
#ifndef BOOST_CONVERT_STRTOL_CONVERTER_HPP
#define BOOST_CONVERT_STRTOL_CONVERTER_HPP
#include <boost/convert/base.hpp>
#include <boost/type_traits/make_unsigned.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/math/special_functions/round.hpp>
#include <limits>
#include <cmath>
#include <cstdlib>
#include <climits>
#if __GNUC__ == 4 && __GNUC_MINOR__ <= 2
namespace std
{
using ::strtold; // Tests indicated that gcc-4.2.1 does not have 'std::strtold'
}
#endif
namespace boost { namespace cnv
{
struct strtol;
}}
/// @brief std::strtol-based extended converter
/// @details The converter offers a fairly decent overall performance and moderate formatting facilities.
struct boost::cnv::strtol : public boost::cnv::cnvbase<boost::cnv::strtol>
{
typedef boost::cnv::strtol this_type;
typedef boost::cnv::cnvbase<this_type> base_type;
using base_type::operator();
private:
friend struct boost::cnv::cnvbase<this_type>;
template<typename string_type> void str_to(cnv::range<string_type> v, optional< int_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< sint_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< lint_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< llint_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< uint_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< usint_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< ulint_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional<ullint_type>& r) const { str_to_i (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< flt_type>& r) const { str_to_d (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< dbl_type>& r) const { str_to_d (v, r); }
template<typename string_type> void str_to(cnv::range<string_type> v, optional< ldbl_type>& r) const { str_to_d (v, r); }
template <typename char_type> cnv::range<char_type*> to_str ( int_type v, char_type* buf) const { return i_to_str(v, buf); }
template <typename char_type> cnv::range<char_type*> to_str ( uint_type v, char_type* buf) const { return i_to_str(v, buf); }
template <typename char_type> cnv::range<char_type*> to_str ( lint_type v, char_type* buf) const { return i_to_str(v, buf); }
template <typename char_type> cnv::range<char_type*> to_str ( ulint_type v, char_type* buf) const { return i_to_str(v, buf); }
template <typename char_type> cnv::range<char_type*> to_str ( llint_type v, char_type* buf) const { return i_to_str(v, buf); }
template <typename char_type> cnv::range<char_type*> to_str (ullint_type v, char_type* buf) const { return i_to_str(v, buf); }
template <typename char_type> cnv::range<char_type*> to_str ( dbl_type v, char_type* buf) const;
template<typename char_type, typename in_type> cnv::range<char_type*> i_to_str (in_type, char_type*) const;
template<typename string_type, typename out_type> void str_to_i (cnv::range<string_type>, optional<out_type>&) const;
template<typename string_type, typename out_type> void str_to_d (cnv::range<string_type>, optional<out_type>&) const;
static double adjust_fraction (double, int);
static int get_char (int v) { return (v < 10) ? (v += '0') : (v += 'A' - 10); }
};
template<typename char_type, typename Type>
boost::cnv::range<char_type*>
boost::cnv::strtol::i_to_str(Type in_value, char_type* buf) const
{
// C1. Base=10 optimization improves performance 10%
typedef typename boost::make_unsigned<Type>::type unsigned_type;
char_type* beg = buf + bufsize_ / 2;
char_type* end = beg;
bool const is_neg = std::is_signed<Type>::value && in_value < 0;
unsigned_type value = static_cast<unsigned_type>(is_neg ? -in_value : in_value);
if (base_ == 10) for (; value; *(--beg) = int(value % 10) + '0', value /= 10); //C1
else for (; value; *(--beg) = get_char(value % base_), value /= base_);
if (beg == end) *(--beg) = '0';
if (is_neg) *(--beg) = '-';
return cnv::range<char_type*>(beg, end);
}
inline
double
boost::cnv::strtol::adjust_fraction(double fraction, int precision)
{
// C1. Bring forward the fraction coming right after precision digits.
// That is, say, fraction=0.234567, precision=2. Then brought forward=23.4567
// C3. INT_MAX(4bytes)=2,147,483,647. So, 10^8 seems appropriate. If not, drop it down to 4.
// C4. ::round() returns the integral value that is nearest to x,
// with halfway cases rounded away from zero. Therefore,
// round( 0.4) = 0
// round( 0.5) = 1
// round( 0.6) = 1
// round(-0.4) = 0
// round(-0.5) = -1
// round(-0.6) = -1
int const tens[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000 };
for (int k = precision / 8; k; --k) fraction *= 100000000; //C3.
fraction *= tens[precision % 8]; //C1
// return ::rint(fraction); //C4
return boost::math::round(fraction); //C4
}
template <typename char_type>
inline
boost::cnv::range<char_type*>
boost::cnv::strtol::to_str(double value, char_type* buf) const
{
char_type* beg = buf + bufsize_ / 2;
char_type* end = beg;
char_type* ipos = end - 1;
bool const is_negative = (value < 0) ? (value = -value, true) : false;
double ipart = std::floor(value);
double fpart = adjust_fraction(value - ipart, precision_);
int precision = precision_;
int const base = 10;
for (; 1 <= ipart; ipart /= base)
*(--beg) = get_char(int(ipart - std::floor(ipart / base) * base));
if (beg == end) *(--beg) = '0';
if (precision) *(end++) = '.';
for (char_type* fpos = end += precision; precision; --precision, fpart /= base)
*(--fpos) = get_char(int(fpart - std::floor(fpart / base) * base));
if (1 <= fpart)
{
for (; beg <= ipos; --ipos)
if (*ipos == '9') *ipos = '0';
else { ++*ipos; break; }
if (ipos < beg)
*(beg = ipos) = '1';
}
if (is_negative) *(--beg) = '-';
return cnv::range<char_type*>(beg, end);
}
template<typename string_type, typename out_type>
void
boost::cnv::strtol::str_to_i(cnv::range<string_type> range, boost::optional<out_type>& result_out) const
{
typedef typename boost::make_unsigned<out_type>::type unsigned_type;
typedef cnv::range<string_type> range_type;
typedef typename range_type::iterator iterator;
iterator s = range.begin();
unsigned int ch = *s;
bool const is_negative = ch == '-' ? (ch = *++s, true) : ch == '+' ? (ch = *++s, false) : false;
bool const is_unsigned = boost::is_same<out_type, unsigned_type>::value;
unsigned int base = base_;
/**/ if (is_negative && is_unsigned) return;
else if ((base == 0 || base == 16) && ch == '0' && (*++s == 'x' || *s == 'X')) ++s, base = 16;
else if (base == 0) base = ch == '0' ? (++s, 8) : 10;
unsigned_type const max = (std::numeric_limits<out_type>::max)() + (is_negative ? 1 : 0);
unsigned_type const cutoff = max / base;
unsigned int const cutlim = max % base;
unsigned_type result = 0;
for (; s != range.sentry(); ++s)
{
ch = *s;
/**/ if (std::isdigit(ch)) ch -= '0';
else if (std::isalpha(ch)) ch -= (std::isupper(ch) ? 'A' : 'a') - 10;
else return;
if (base <= ch || cutoff < result || (result == cutoff && cutlim < ch))
return;
result *= base;
result += ch;
}
result_out = is_negative ? -out_type(result) : out_type(result);
}
template<typename string_type, typename out_type>
void
boost::cnv::strtol::str_to_d(cnv::range<string_type> range, optional<out_type>& result_out) const
{
// C1. Because of strtold() currently only works with 'char'
// C2. strtold() does not work with ranges.
// Consequently, we have to copy the supplied range into a string for strtold().
// C3. Check if the end-of-string was reached -- *cnv_end == 0.
typedef cnv::range<string_type> range_type;
typedef typename range_type::value_type ch_type;
size_t const sz = 128;
ch_type str[sz] = {0}; std::strncpy(str, &*range.begin(), std::min(sz - 1, range.size()));
char* cnv_end = 0;
ldbl_type result = strtold(str, &cnv_end);
bool good = result != -HUGE_VALL && result != HUGE_VALL && *cnv_end == 0; //C3
out_type max = (std::numeric_limits<out_type>::max)();
if (good && -max <= result && result <= max)
result_out = out_type(result);
}
#endif // BOOST_CONVERT_STRTOL_CONVERTER_HPP
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