boost/format/internals.hpp
// ---------------------------------------------------------------------------- // internals.hpp : internal structs : stream_format_state, format_item. // included by format.hpp // ---------------------------------------------------------------------------- // Copyright Samuel Krempp 2003. Use, modification, and distribution are // subject to the Boost Software License, Version 1.0. (See accompanying // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // See http://www.boost.org/libs/format for library home page // ---------------------------------------------------------------------------- #ifndef BOOST_FORMAT_INTERNALS_HPP #define BOOST_FORMAT_INTERNALS_HPP #include <string> #include <boost/assert.hpp> #include <boost/optional.hpp> #include <boost/limits.hpp> #include <boost/format/detail/compat_workarounds.hpp> #include <boost/format/alt_sstream.hpp> // used as a dummy stream namespace boost { namespace io { namespace detail { //---- stream_format_state --------------------------------------------------// // set of params that define the format state of a stream template<class Ch, class Tr> struct stream_format_state { typedef BOOST_IO_STD basic_ios<Ch, Tr> basic_ios; stream_format_state(Ch fill) { reset(fill); } // stream_format_state(const basic_ios& os) { set_by_stream(os); } void reset(Ch fill); //- sets to default state. void set_by_stream(const basic_ios& os); //- sets to os's state. void apply_on(basic_ios & os, //- applies format_state to the stream boost::io::detail::locale_t * loc_default = 0) const; template<class T> void apply_manip(T manipulator) //- modifies state by applying manipulator { apply_manip_body<Ch, Tr, T>( *this, manipulator) ; } // --- data --- std::streamsize width_; std::streamsize precision_; Ch fill_; std::ios_base::fmtflags flags_; std::ios_base::iostate rdstate_; std::ios_base::iostate exceptions_; boost::optional<boost::io::detail::locale_t> loc_; }; //---- format_item ---------------------------------------------------------// // stores all parameters that can be specified in format strings template<class Ch, class Tr, class Alloc> struct format_item { enum pad_values { zeropad = 1, spacepad =2, centered=4, tabulation = 8 }; // 1. if zeropad is set, all other bits are not, // 2. if tabulation is set, all others are not. // centered and spacepad can be mixed freely. enum arg_values { argN_no_posit = -1, // non-positional directive. will set argN later argN_tabulation = -2, // tabulation directive. (no argument read) argN_ignored = -3 // ignored directive. (no argument read) }; typedef BOOST_IO_STD basic_ios<Ch, Tr> basic_ios; typedef detail::stream_format_state<Ch, Tr> stream_format_state; typedef ::std::basic_string<Ch, Tr, Alloc> string_type; format_item(Ch fill) :argN_(argN_no_posit), fmtstate_(fill), truncate_(max_streamsize()), pad_scheme_(0) {} void reset(Ch fill); void compute_states(); // sets states according to truncate and pad_scheme. static std::streamsize max_streamsize() { return (std::numeric_limits<std::streamsize>::max)(); } // --- data --- int argN_; //- argument number (starts at 0, eg : %1 => argN=0) // negative values for items that don't process an argument string_type res_; //- result of the formatting of this item string_type appendix_; //- piece of string between this item and the next stream_format_state fmtstate_;// set by parsing, is only affected by modify_item std::streamsize truncate_;//- is set for directives like %.5s that ask truncation unsigned int pad_scheme_;//- several possible padding schemes can mix. see pad_values }; //--- Definitions ------------------------------------------------------------ // - stream_format_state:: ------------------------------------------------- template<class Ch, class Tr> void stream_format_state<Ch,Tr>:: apply_on (basic_ios & os, boost::io::detail::locale_t * loc_default) const { // If a locale is available, set it first. "os.fill(fill_);" may chrash otherwise. #if !defined(BOOST_NO_STD_LOCALE) if(loc_) os.imbue(loc_.get()); else if(loc_default) os.imbue(*loc_default); #else (void) loc_default; // keep compiler quiet if we don't support locales #endif // set the state of this stream according to our params if(width_ != -1) os.width(width_); if(precision_ != -1) os.precision(precision_); if(fill_ != 0) os.fill(fill_); os.flags(flags_); os.clear(rdstate_); os.exceptions(exceptions_); } template<class Ch, class Tr> void stream_format_state<Ch,Tr>:: set_by_stream(const basic_ios& os) { // set our params according to the state of this stream flags_ = os.flags(); width_ = os.width(); precision_ = os.precision(); fill_ = os.fill(); rdstate_ = os.rdstate(); exceptions_ = os.exceptions(); } template<class Ch, class Tr, class T> void apply_manip_body( stream_format_state<Ch, Tr>& self, T manipulator) { // modify our params according to the manipulator basic_oaltstringstream<Ch, Tr> ss; self.apply_on( ss ); ss << manipulator; self.set_by_stream( ss ); } template<class Ch, class Tr> inline void stream_format_state<Ch,Tr>:: reset(Ch fill) { // set our params to standard's default state. cf 27.4.4.1 of the C++ norm width_=0; precision_=6; fill_=fill; // default is widen(' '), but we cant compute it without the locale flags_ = std::ios_base::dec | std::ios_base::skipws; // the adjust_field part is left equal to 0, which means right. exceptions_ = std::ios_base::goodbit; rdstate_ = std::ios_base::goodbit; } // --- format_item:: -------------------------------------------------------- template<class Ch, class Tr, class Alloc> void format_item<Ch, Tr, Alloc>:: reset (Ch fill) { argN_=argN_no_posit; truncate_ = max_streamsize(); pad_scheme_ =0; res_.resize(0); appendix_.resize(0); fmtstate_.reset(fill); } template<class Ch, class Tr, class Alloc> void format_item<Ch, Tr, Alloc>:: compute_states() { // reflect pad_scheme_ on fmt_state_ // because some pad_schemes has complex consequences on several state params. if(pad_scheme_ & zeropad) { // ignore zeropad in left alignment : if(fmtstate_.flags_ & std::ios_base::left) { BOOST_ASSERT(!(fmtstate_.flags_ &(std::ios_base::adjustfield ^std::ios_base::left))); // only left bit might be set. (not right, nor internal) pad_scheme_ = pad_scheme_ & (~zeropad); } else { pad_scheme_ &= ~spacepad; // printf ignores spacepad when zeropadding fmtstate_.fill_='0'; fmtstate_.flags_ = (fmtstate_.flags_ & ~std::ios_base::adjustfield) | std::ios_base::internal; // removes all adjustfield bits, and adds internal. } } if(pad_scheme_ & spacepad) { if(fmtstate_.flags_ & std::ios_base::showpos) pad_scheme_ &= ~spacepad; } } } } } // namespaces boost :: io :: detail #endif // BOOST_FORMAT_INTERNALS_HPP