1 // Copyright (c) 2009-2020 Vladimir Batov. 2 // Use, modification and distribution are subject to the Boost Software License, 3 // Version 1.0. See http://www.boost.org/LICENSE_1_0.txt. 4 5 #ifndef BOOST_CONVERT_PRINTF_HPP 6 #define BOOST_CONVERT_PRINTF_HPP 7 8 #include <boost/convert/base.hpp> 9 #include <boost/make_default.hpp> 10 #include <boost/mpl/vector.hpp> 11 #include <boost/mpl/find.hpp> 12 #include <string> 13 #include <cstdio> 14 15 namespace boost { namespace cnv 16 { 17 struct printf; 18 }} 19 20 struct boost::cnv::printf : boost::cnv::cnvbase<boost::cnv::printf> 21 { 22 using this_type = boost::cnv::printf; 23 using base_type = boost::cnv::cnvbase<this_type>; 24 25 using base_type::operator(); 26 27 template<typename in_type> 28 cnv::range<char*> to_strboost::cnv::printf29 to_str(in_type value_in, char* buf) const 30 { 31 char const* fmt = pformat(pos<in_type>()); 32 int const num_chars = snprintf(buf, bufsize_, fmt, precision_, value_in); 33 bool const success = num_chars < bufsize_; 34 35 return cnv::range<char*>(buf, success ? (buf + num_chars) : buf); 36 } 37 template<typename string_type, typename out_type> 38 void str_toboost::cnv::printf39 str_to(cnv::range<string_type> range, optional<out_type>& result_out) const 40 { 41 out_type result = boost::make_default<out_type>(); 42 int const num_read = sscanf(&*range.begin(), format(pos<out_type>()), &result); 43 44 if (num_read == 1) 45 result_out = result; 46 } 47 48 private: 49 posboost::cnv::printf50 template<typename Type> int pos() const 51 { 52 using managed_types = boost::mpl::vector<double, float, 53 int, unsigned int, 54 short int, unsigned short int, 55 long int, unsigned long int>; 56 using type_iterator = typename boost::mpl::find<managed_types, Type>::type; 57 using type_pos = typename type_iterator::pos; 58 59 return type_pos::value; 60 } 61 pformatboost::cnv::printf62 char const* pformat(int pos) const 63 { 64 static char const* d_fmt[] = { "%.*f", "%.*f", "%.*d", "%.*u", "%.*hd", "%.*hu", "%.*ld", "%.*lu" }; // Must match managed_types 65 static char const* x_fmt[] = { "%.*f", "%.*f", "%.*x", "%.*x", "%.*hx", "%.*hx", "%.*lx", "%.*lx" }; // Must match managed_types 66 static char const* o_fmt[] = { "%.*f", "%.*f", "%.*o", "%.*o", "%.*ho", "%.*ho", "%.*lo", "%.*lo" }; // Must match managed_types 67 char const* fmt = base_ == boost::cnv::base::dec ? d_fmt[pos] 68 : base_ == boost::cnv::base::hex ? x_fmt[pos] 69 : base_ == boost::cnv::base::oct ? o_fmt[pos] 70 : (BOOST_ASSERT(0), nullptr); 71 return fmt; 72 } formatboost::cnv::printf73 char const* format(int pos) const 74 { 75 static char const* d_fmt[] = { "%f", "%f", "%d", "%u", "%hd", "%hu", "%ld", "%lu" }; // Must match managed_types 76 static char const* x_fmt[] = { "%f", "%f", "%x", "%x", "%hx", "%hx", "%lx", "%lx" }; // Must match managed_types 77 static char const* o_fmt[] = { "%f", "%f", "%o", "%o", "%ho", "%ho", "%lo", "%lo" }; // Must match managed_types 78 char const* fmt = base_ == boost::cnv::base::dec ? d_fmt[pos] 79 : base_ == boost::cnv::base::hex ? x_fmt[pos] 80 : base_ == boost::cnv::base::oct ? o_fmt[pos] 81 : (BOOST_ASSERT(0), nullptr); 82 return fmt; 83 } 84 }; 85 86 #endif // BOOST_CONVERT_PRINTF_HPP 87