168 lines
5.3 KiB
C++
168 lines
5.3 KiB
C++
// -*- C++ -*-
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// Boost general library 'format' ---------------------------
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// See http://www.boost.org for updates, documentation, and revision history.
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// (C) Samuel Krempp 2001
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// krempp@crans.ens-cachan.fr
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// Permission to copy, use, modify, sell and
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// distribute this software is granted provided this copyright notice appears
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// in all copies. This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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// ideas taken from Rüdiger Loos's format class
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// and Karl Nelson's ofstream
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// ----------------------------------------------------------------------------
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// internals.hpp : internal structs. included by format.hpp
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// stream_format_state, and format_item
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// ----------------------------------------------------------------------------
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#ifndef BOOST_FORMAT_INTERNALS_HPP
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#define BOOST_FORMAT_INTERNALS_HPP
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#include <string>
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#include <sstream>
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namespace boost {
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namespace io {
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namespace detail {
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// --------------
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// set of params that define the format state of a stream
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struct stream_format_state
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{
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typedef std::ios basic_ios;
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std::streamsize width_;
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std::streamsize precision_;
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char fill_;
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std::ios::fmtflags flags_;
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stream_format_state() : width_(-1), precision_(-1), fill_(0), flags_(std::ios::dec) {}
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stream_format_state(basic_ios& os) {set_by_stream(os); }
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void apply_on(basic_ios & os) const; //- applies format_state to the stream
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template<class T> void apply_manip(T manipulator) //- modifies state by applying manipulator.
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{ apply_manip_body<T>( *this, manipulator) ; }
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void reset(); //- sets to default state.
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void set_by_stream(const basic_ios& os); //- sets to os's state.
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};
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// --------------
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// format_item : stores all parameters that can be defined by directives in the format-string
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struct format_item
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{
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enum pad_values { zeropad = 1, spacepad =2, centered=4, tabulation = 8 };
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enum arg_values { argN_no_posit = -1, // non-positional directive. argN will be set later.
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argN_tabulation = -2, // tabulation directive. (no argument read)
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argN_ignored = -3 // ignored directive. (no argument read)
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};
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typedef BOOST_IO_STD ios basic_ios;
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typedef detail::stream_format_state stream_format_state;
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typedef std::string string_t;
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typedef BOOST_IO_STD ostringstream internal_stream_t;
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int argN_; //- argument number (starts at 0, eg : %1 => argN=0)
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// negative values are used for items that don't process
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// an argument
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string_t res_; //- result of the formatting of this item
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string_t appendix_; //- piece of string between this item and the next
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stream_format_state ref_state_;// set by parsing the format_string, is only affected by modify_item
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stream_format_state state_; // always same as ref_state, _unless_ modified by manipulators 'group(..)'
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// non-stream format-state parameters
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signed int truncate_; //- is >=0 for directives like %.5s (take 5 chars from the string)
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unsigned int pad_scheme_; //- several possible padding schemes can mix. see pad_values
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format_item() : argN_(argN_no_posit), truncate_(-1), pad_scheme_(0) {}
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void compute_states(); // sets states according to truncate and pad_scheme.
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};
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// -----------------------------------------------------------
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// Definitions
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// -----------------------------------------------------------
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// --- stream_format_state:: -------------------------------------------
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inline
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void stream_format_state::apply_on(basic_ios & os) const
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// set the state of this stream according to our params
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{
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if(width_ != -1)
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os.width(width_);
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if(precision_ != -1)
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os.precision(precision_);
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if(fill_ != 0)
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os.fill(fill_);
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os.flags(flags_);
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}
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inline
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void stream_format_state::set_by_stream(const basic_ios& os)
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// set our params according to the state of this stream
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{
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flags_ = os.flags();
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width_ = os.width();
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precision_ = os.precision();
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fill_ = os.fill();
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}
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template<class T> inline
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void apply_manip_body( stream_format_state& self,
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T manipulator)
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// modify our params according to the manipulator
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{
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BOOST_IO_STD stringstream ss;
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self.apply_on( ss );
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ss << manipulator;
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self.set_by_stream( ss );
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}
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inline
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void stream_format_state::reset()
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// set our params to standard's default state
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{
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width_=-1; precision_=-1; fill_=0;
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flags_ = std::ios::dec;
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}
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// --- format_items:: -------------------------------------------
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inline
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void format_item::compute_states()
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// reflect pad_scheme_ on state_ and ref_state_
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// because some pad_schemes has complex consequences on several state params.
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{
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if(pad_scheme_ & zeropad)
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{
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if(ref_state_.flags_ & std::ios::left)
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{
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pad_scheme_ = pad_scheme_ & (~zeropad); // ignore zeropad in left alignment
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}
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else
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{
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ref_state_.fill_='0';
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ref_state_.flags_ |= std::ios::internal;
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}
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}
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state_ = ref_state_;
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}
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} } } // namespaces boost :: io :: detail
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#endif // BOOST_FORMAT_INTERNALS_HPP
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