1 // ---------------------------------------------------------------------------- 2 // internals.hpp : internal structs : stream_format_state, format_item. 3 // included by format.hpp 4 // ---------------------------------------------------------------------------- 5 6 // Copyright Samuel Krempp 2003. Use, modification, and distribution are 7 // subject to the Boost Software License, Version 1.0. (See accompanying 8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 9 10 // See http://www.boost.org/libs/format for library home page 11 12 // ---------------------------------------------------------------------------- 13 14 #ifndef BOOST_FORMAT_INTERNALS_HPP 15 #define BOOST_FORMAT_INTERNALS_HPP 16 17 18 #include <string> 19 #include <boost/assert.hpp> 20 #include <boost/core/ignore_unused.hpp> 21 #include <boost/optional.hpp> 22 #include <boost/limits.hpp> 23 #include <boost/format/detail/compat_workarounds.hpp> 24 #include <boost/format/alt_sstream.hpp> // used as a dummy stream 25 26 namespace boost { 27 namespace io { 28 namespace detail { 29 30 31 //---- stream_format_state --------------------------------------------------// 32 33 // set of params that define the format state of a stream 34 template<class Ch, class Tr> 35 struct stream_format_state 36 { 37 typedef BOOST_IO_STD basic_ios<Ch, Tr> basic_ios; 38 stream_format_stateboost::io::detail::stream_format_state39 stream_format_state(Ch fill) { reset(fill); } 40 // stream_format_state(const basic_ios& os) { set_by_stream(os); } 41 42 void reset(Ch fill); //- sets to default state. 43 void set_by_stream(const basic_ios& os); //- sets to os's state. 44 void apply_on(basic_ios & os, //- applies format_state to the stream 45 boost::io::detail::locale_t * loc_default = 0) const; 46 template<class T> apply_manipboost::io::detail::stream_format_state47 void apply_manip(T manipulator) //- modifies state by applying manipulator 48 { apply_manip_body<Ch, Tr, T>( *this, manipulator) ; } 49 50 // --- data --- 51 std::streamsize width_; 52 std::streamsize precision_; 53 Ch fill_; 54 std::ios_base::fmtflags flags_; 55 std::ios_base::iostate rdstate_; 56 std::ios_base::iostate exceptions_; 57 boost::optional<boost::io::detail::locale_t> loc_; 58 }; 59 60 61 //---- format_item ---------------------------------------------------------// 62 63 // stores all parameters that can be specified in format strings 64 template<class Ch, class Tr, class Alloc> 65 struct format_item 66 { 67 enum pad_values { zeropad = 1, spacepad =2, centered=4, tabulation = 8 }; 68 // 1. if zeropad is set, all other bits are not, 69 // 2. if tabulation is set, all others are not. 70 // centered and spacepad can be mixed freely. 71 enum arg_values { argN_no_posit = -1, // non-positional directive. will set argN later 72 argN_tabulation = -2, // tabulation directive. (no argument read) 73 argN_ignored = -3 // ignored directive. (no argument read) 74 }; 75 typedef BOOST_IO_STD basic_ios<Ch, Tr> basic_ios; 76 typedef detail::stream_format_state<Ch, Tr> stream_format_state; 77 typedef ::std::basic_string<Ch, Tr, Alloc> string_type; 78 format_itemboost::io::detail::format_item79 format_item(Ch fill) :argN_(argN_no_posit), fmtstate_(fill), 80 truncate_(max_streamsize()), pad_scheme_(0) {} 81 void reset(Ch fill); 82 void compute_states(); // sets states according to truncate and pad_scheme. 83 max_streamsizeboost::io::detail::format_item84 static std::streamsize max_streamsize() { 85 return (std::numeric_limits<std::streamsize>::max)(); 86 } 87 88 // --- data --- 89 int argN_; //- argument number (starts at 0, eg : %1 => argN=0) 90 // negative values for items that don't process an argument 91 string_type res_; //- result of the formatting of this item 92 string_type appendix_; //- piece of string between this item and the next 93 94 stream_format_state fmtstate_;// set by parsing, is only affected by modify_item 95 96 std::streamsize truncate_;//- is set for directives like %.5s that ask truncation 97 unsigned int pad_scheme_;//- several possible padding schemes can mix. see pad_values 98 }; 99 100 101 102 //--- Definitions ------------------------------------------------------------ 103 104 // - stream_format_state:: ------------------------------------------------- 105 template<class Ch, class Tr> apply_on(basic_ios & os,boost::io::detail::locale_t * loc_default) const106 void stream_format_state<Ch,Tr>:: apply_on (basic_ios & os, 107 boost::io::detail::locale_t * loc_default) const { 108 // If a locale is available, set it first. "os.fill(fill_);" may chrash otherwise. 109 #if !defined(BOOST_NO_STD_LOCALE) 110 if(loc_) 111 os.imbue(loc_.get()); 112 else if(loc_default) 113 os.imbue(*loc_default); 114 #else 115 ignore_unused(loc_default); 116 #endif 117 // set the state of this stream according to our params 118 if(width_ != -1) 119 os.width(width_); 120 if(precision_ != -1) 121 os.precision(precision_); 122 if(fill_ != 0) 123 os.fill(fill_); 124 os.flags(flags_); 125 os.clear(rdstate_); 126 os.exceptions(exceptions_); 127 } 128 129 template<class Ch, class Tr> set_by_stream(const basic_ios & os)130 void stream_format_state<Ch,Tr>:: set_by_stream(const basic_ios& os) { 131 // set our params according to the state of this stream 132 flags_ = os.flags(); 133 width_ = os.width(); 134 precision_ = os.precision(); 135 fill_ = os.fill(); 136 rdstate_ = os.rdstate(); 137 exceptions_ = os.exceptions(); 138 } 139 140 141 template<class Ch, class Tr, class T> apply_manip_body(stream_format_state<Ch,Tr> & self,T manipulator)142 void apply_manip_body( stream_format_state<Ch, Tr>& self, 143 T manipulator) { 144 // modify our params according to the manipulator 145 basic_oaltstringstream<Ch, Tr> ss; 146 self.apply_on( ss ); 147 ss << manipulator; 148 self.set_by_stream( ss ); 149 } 150 151 template<class Ch, class Tr> inline reset(Ch fill)152 void stream_format_state<Ch,Tr>:: reset(Ch fill) { 153 // set our params to standard's default state. cf 27.4.4.1 of the C++ norm 154 width_=0; precision_=6; 155 fill_=fill; // default is widen(' '), but we cant compute it without the locale 156 flags_ = std::ios_base::dec | std::ios_base::skipws; 157 // the adjust_field part is left equal to 0, which means right. 158 exceptions_ = std::ios_base::goodbit; 159 rdstate_ = std::ios_base::goodbit; 160 } 161 162 163 // --- format_item:: -------------------------------------------------------- 164 165 template<class Ch, class Tr, class Alloc> 166 void format_item<Ch, Tr, Alloc>:: reset(Ch fill)167 reset (Ch fill) { 168 argN_=argN_no_posit; truncate_ = max_streamsize(); pad_scheme_ =0; 169 res_.resize(0); appendix_.resize(0); 170 fmtstate_.reset(fill); 171 } 172 173 template<class Ch, class Tr, class Alloc> 174 void format_item<Ch, Tr, Alloc>:: compute_states()175 compute_states() { 176 // reflect pad_scheme_ on fmt_state_ 177 // because some pad_schemes has complex consequences on several state params. 178 if(pad_scheme_ & zeropad) { 179 // ignore zeropad in left alignment : 180 if(fmtstate_.flags_ & std::ios_base::left) { 181 BOOST_ASSERT(!(fmtstate_.flags_ &(std::ios_base::adjustfield ^std::ios_base::left))); 182 // only left bit might be set. (not right, nor internal) 183 pad_scheme_ = pad_scheme_ & (~zeropad); 184 } 185 else { 186 pad_scheme_ &= ~spacepad; // printf ignores spacepad when zeropadding 187 fmtstate_.fill_='0'; 188 fmtstate_.flags_ = (fmtstate_.flags_ & ~std::ios_base::adjustfield) 189 | std::ios_base::internal; 190 // removes all adjustfield bits, and adds internal. 191 } 192 } 193 if(pad_scheme_ & spacepad) { 194 if(fmtstate_.flags_ & std::ios_base::showpos) 195 pad_scheme_ &= ~spacepad; 196 } 197 } 198 199 200 } } } // namespaces boost :: io :: detail 201 202 203 #endif // BOOST_FORMAT_INTERNALS_HPP 204