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Diffstat (limited to 'boost/format/internals.hpp')
| -rw-r--r-- | boost/format/internals.hpp | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/boost/format/internals.hpp b/boost/format/internals.hpp new file mode 100644 index 000000000000..52448b731c2f --- /dev/null +++ b/boost/format/internals.hpp @@ -0,0 +1,169 @@ +// -*- C++ -*- +// Boost general library 'format' --------------------------- +// See http://www.boost.org for updates, documentation, and revision history. + +// (C) Samuel Krempp 2001 +// krempp@crans.ens-cachan.fr +// Permission to copy, use, modify, sell and +// distribute this software is granted provided this copyright notice appears +// in all copies. This software is provided "as is" without express or implied +// warranty, and with no claim as to its suitability for any purpose. + +// ideas taken from Rüdiger Loos's format class +// and Karl Nelson's ofstream + +// ---------------------------------------------------------------------------- +// internals.hpp : internal structs. included by format.hpp +// stream_format_state, and format_item +// ---------------------------------------------------------------------------- + + +#ifndef BOOST_FORMAT_INTERNALS_HPP +#define BOOST_FORMAT_INTERNALS_HPP + + +#include <string> +#include <sstream> + +namespace boost { +namespace io { +namespace detail { + + +// -------------- +// 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; + + std::streamsize width_; + std::streamsize precision_; + Ch fill_; + std::ios_base::fmtflags flags_; + + stream_format_state() : width_(-1), precision_(-1), fill_(0), flags_(std::ios_base::dec) {} + stream_format_state(basic_ios& os) {set_by_stream(os); } + + void apply_on(basic_ios & os) const; //- applies format_state to the stream + template<class T> void apply_manip(T manipulator) //- modifies state by applying manipulator. + { apply_manip_body<Ch, Tr, T>( *this, manipulator) ; } + void reset(); //- sets to default state. + void set_by_stream(const basic_ios& os); //- sets to os's state. +}; + + + +// -------------- +// format_item : stores all parameters that can be defined by directives in the format-string + +template<class Ch, class Tr> +struct format_item +{ + enum pad_values { zeropad = 1, spacepad =2, centered=4, tabulation = 8 }; + + enum arg_values { argN_no_posit = -1, // non-positional directive. argN will be set 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> string_t; + typedef BOOST_IO_STD basic_ostringstream<Ch, Tr> internal_stream_t; + + + int argN_; //- argument number (starts at 0, eg : %1 => argN=0) + // negative values are used for items that don't process + // an argument + string_t res_; //- result of the formatting of this item + string_t appendix_; //- piece of string between this item and the next + + stream_format_state ref_state_;// set by parsing the format_string, is only affected by modify_item + stream_format_state state_; // always same as ref_state, _unless_ modified by manipulators 'group(..)' + + // non-stream format-state parameters + signed int truncate_; //- is >=0 for directives like %.5s (take 5 chars from the string) + unsigned int pad_scheme_; //- several possible padding schemes can mix. see pad_values + + format_item() : argN_(argN_no_posit), truncate_(-1), pad_scheme_(0) {} + + void compute_states(); // sets states according to truncate and pad_scheme. +}; + + + +// ----------------------------------------------------------- +// Definitions +// ----------------------------------------------------------- + +// --- stream_format_state:: ------------------------------------------- +template<class Ch, class Tr> inline +void stream_format_state<Ch,Tr> ::apply_on(basic_ios & os) const + // 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_); +} + +template<class Ch, class Tr> inline +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(); +} + +template<class Ch, class Tr, class T> inline +void apply_manip_body( stream_format_state<Ch, Tr>& self, + T manipulator) + // modify our params according to the manipulator +{ + BOOST_IO_STD basic_stringstream<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() + // set our params to standard's default state +{ + width_=-1; precision_=-1; fill_=0; + flags_ = std::ios_base::dec; +} + + +// --- format_items:: ------------------------------------------- +template<class Ch, class Tr> inline +void format_item<Ch, Tr> ::compute_states() + // reflect pad_scheme_ on state_ and ref_state_ + // because some pad_schemes has complex consequences on several state params. +{ + if(pad_scheme_ & zeropad) + { + if(ref_state_.flags_ & std::ios_base::left) + { + pad_scheme_ = pad_scheme_ & (~zeropad); // ignore zeropad in left alignment + } + else + { + ref_state_.fill_='0'; + ref_state_.flags_ |= std::ios_base::internal; + } + } + state_ = ref_state_; +} + + +} } } // namespaces boost :: io :: detail + + +#endif // BOOST_FORMAT_INTERNALS_HPP |