boost/locale/util.hpp
// // Copyright (c) 2009-2011 Artyom Beilis (Tonkikh) // // Distributed under 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) // #ifndef BOOST_LOCALE_UTIL_HPP #define BOOST_LOCALE_UTIL_HPP #include <locale> #include <typeinfo> #include <boost/cstdint.hpp> #include <boost/locale/utf.hpp> #include <boost/locale/generator.hpp> #include <boost/assert.hpp> #include <vector> namespace boost { namespace locale { /// /// \brief This namespace provides various utility function useful for Boost.Locale backends /// implementations /// namespace util { /// /// \brief Return default system locale name in POSIX format. /// /// This function tries to detect the locale using, LC_CTYPE, LC_ALL and LANG environment /// variables in this order and if all of them unset, in POSIX platforms it returns "C" /// /// On Windows additionally to check the above environment variables, this function /// tries to creates locale name from ISO-339 and ISO-3199 country codes defined /// for user default locale. /// If \a use_utf8_on_windows is true it sets the encoding to UTF-8, otherwise, if system /// locale supports ANSI code-page it defines the ANSI encoding like windows-1252, otherwise it fall-backs /// to UTF-8 encoding if ANSI code-page is not available. /// BOOST_LOCALE_DECL std::string get_system_locale(bool use_utf8_on_windows = false); /// /// \brief Installs information facet to locale in based on locale name \a name /// /// This function installs boost::locale::info facet into the locale \a in and returns /// newly created locale. /// /// Note: all information is based only on parsing of string \a name; /// /// The name has following format: language[_COUNTRY][.encoding][\@variant] /// Where language is ISO-639 language code like "en" or "ru", COUNTRY is ISO-3166 /// country identifier like "US" or "RU". the Encoding is a charracter set name /// like UTF-8 or ISO-8859-1. Variant is backend specific variant like \c euro or /// calendar=hebrew. /// /// If some parameters are missing they are specified as blanks, default encoding /// is assumed to be US-ASCII and missing language is assumed to be "C" /// BOOST_LOCALE_DECL std::locale create_info(std::locale const &in,std::string const &name); /// /// \brief This class represent a simple stateless converter from UCS-4 and to UCS-4 for /// each single code point /// /// This class is used for creation of std::codecvt facet for converting utf-16/utf-32 encoding /// to encoding supported by this converter /// /// Please note, this converter should be fully stateless. Fully stateless means it should /// never assume that it is called in any specific order on the text. Even if the /// encoding itself seems to be stateless like windows-1255 or shift-jis, some /// encoders (most notably iconv) can actually compose several code-point into one or /// decompose them in case composite characters are found. So be very careful when implementing /// these converters for certain character set. /// class base_converter { public: /// /// This value should be returned when an illegal input sequence or code-point is observed: /// For example if a UCS-32 code-point is in the range reserved for UTF-16 surrogates /// or an invalid UTF-8 sequence is found /// static const uint32_t illegal=utf::illegal; /// /// This value is returned in following cases: The of incomplete input sequence was found or /// insufficient output buffer was provided so complete output could not be written. /// static const uint32_t incomplete=utf::incomplete; virtual ~base_converter() { } /// /// Return the maximal length that one Unicode code-point can be converted to, for example /// for UTF-8 it is 4, for Shift-JIS it is 2 and ISO-8859-1 is 1 /// virtual int max_len() const { return 1; } /// /// Returns true if calling the functions from_unicode, to_unicode, and max_len is thread safe. /// /// Rule of thumb: if this class' implementation uses simple tables that are unchanged /// or is purely algorithmic like UTF-8 - so it does not share any mutable bit for /// independent to_unicode, from_unicode calls, you may set it to true, otherwise, /// for example if you use iconv_t descriptor or UConverter as conversion object return false, /// and this object will be cloned for each use. /// virtual bool is_thread_safe() const { return false; } /// /// Create a polymorphic copy of this object, usually called only if is_thread_safe() return false /// virtual base_converter *clone() const { BOOST_ASSERT(typeid(*this)==typeid(base_converter)); return new base_converter(); } /// /// Convert a single character starting at begin and ending at most at end to Unicode code-point. /// /// if valid input sequence found in [\a begin,\a code_point_end) such as \a begin < \a code_point_end && \a code_point_end <= \a end /// it is converted to its Unicode code point equivalent, \a begin is set to \a code_point_end /// /// if incomplete input sequence found in [\a begin,\a end), i.e. there my be such \a code_point_end that \a code_point_end > \a end /// and [\a begin, \a code_point_end) would be valid input sequence, then \a incomplete is returned begin stays unchanged, for example /// for UTF-8 conversion a *begin = 0xc2, \a begin +1 = \a end is such situation. /// /// if invalid input sequence found, i.e. there there is a sequence [\a begin, \a code_point_end) such as \a code_point_end <= \a end /// that is illegal for this encoding, \a illegal is returned and begin stays unchanged. For example if *begin = 0xFF and begin < end /// for UTF-8, then \a illegal is returned. /// /// virtual uint32_t to_unicode(char const *&begin,char const *end) { if(begin == end) return incomplete; unsigned char cp = *begin; if(cp <= 0x7F) { begin++; return cp; } return illegal; } /// /// Convert a single code-point \a u into encoding and store it in [begin,end) range. /// /// If u is invalid Unicode code-point, or it can not be mapped correctly to represented character set, /// \a illegal should be returned /// /// If u can be converted to a sequence of bytes c1, ... , cN (1<= N <= max_len() ) then /// /// -# If end - begin >= N, c1, ... cN are written starting at begin and N is returned /// -# If end - begin < N, incomplete is returned, it is unspecified what would be /// stored in bytes in range [begin,end) virtual uint32_t from_unicode(uint32_t u,char *begin,char const *end) { if(begin==end) return incomplete; if(u >= 0x80) return illegal; *begin = static_cast<char>(u); return 1; } }; /// /// This function creates a \a base_converter that can be used for conversion between UTF-8 and /// unicode code points /// BOOST_LOCALE_DECL std::auto_ptr<base_converter> create_utf8_converter(); /// /// This function creates a \a base_converter that can be used for conversion between single byte /// character encodings like ISO-8859-1, koi8-r, windows-1255 and Unicode code points, /// /// If \a encoding is not supported, empty pointer is returned. You should check if /// std::auto_ptr<base_converter>::get() != 0 /// BOOST_LOCALE_DECL std::auto_ptr<base_converter> create_simple_converter(std::string const &encoding); /// /// Install codecvt facet into locale \a in and return new locale that is based on \a in and uses new /// facet. /// /// codecvt facet would convert between narrow and wide/char16_t/char32_t encodings using \a cvt converter. /// If \a cvt is null pointer, always failure conversion would be used that fails on every first input or output. /// /// Note: the codecvt facet handles both UTF-16 and UTF-32 wide encodings, it knows to break and join /// Unicode code-points above 0xFFFF to and from surrogate pairs correctly. \a cvt should be unaware /// of wide encoding type /// BOOST_LOCALE_DECL std::locale create_codecvt(std::locale const &in,std::auto_ptr<base_converter> cvt,character_facet_type type); } // util } // locale } // boost #endif // vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4