gnu_gettext.hpp
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//
// Copyright (c) 2009-2011 Artyom Beilis (Tonkikh)
//
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#ifndef BOOST_LOCLAE_GNU_GETTEXT_HPP
#define BOOST_LOCLAE_GNU_GETTEXT_HPP
#include <boost/locale/message.hpp>
#include <functional>
#include <stdexcept>
#include <vector>
namespace boost { namespace locale {
/// \addtogroup message
/// @{
/// \brief This namespace holds classes that provide GNU Gettext message catalogs support.
namespace gnu_gettext {
/// \brief This structure holds all information required for creating gnu-gettext message catalogs,
///
/// The user is expected to set its parameters to load these catalogs correctly. This structure
/// also allows providing functions for charset conversion. Note, you need to provide them,
/// so this structure is not useful for wide characters without subclassing and it will also
/// ignore gettext catalogs that use a charset different from \a encoding.
struct messages_info {
messages_info() : language("C"), locale_category("LC_MESSAGES") {}
std::string language; ///< The language we load the catalog for, like "ru", "en", "de"
std::string country; ///< The country we load the catalog for, like "US", "IL"
std::string variant; ///< Language variant, like "euro" so it would look for catalog like de_DE\@euro
std::string encoding; ///< Required target charset encoding. Ignored for wide characters.
///< For narrow, should specify the correct encoding required for this catalog
std::string locale_category; ///< Locale category, is set by default to LC_MESSAGES, but may be changed
///
/// \brief This type represents GNU Gettext domain name for the messages.
///
/// It consists of two parameters:
///
/// - name - the name of the domain - used for opening the file name
/// - encoding - the encoding of the keys in the sources, default - UTF-8
///
struct domain {
std::string name; ///< The name of the domain
std::string encoding; ///< The character encoding for the domain
domain() = default;
/// Create a domain object from the name that can hold an encoding after symbol "/"
/// such that if n is "hello/cp1255" then the name would be "hello" and "encoding" would
/// be "cp1255" and if n is "hello" then the name would be the same but encoding would be
/// "UTF-8"
domain(const std::string& n)
{
size_t pos = n.find('/');
if(pos == std::string::npos) {
name = n;
encoding = "UTF-8";
} else {
name = n.substr(0, pos);
encoding = n.substr(pos + 1);
}
}
/// Check whether two objects are equivalent, only names are compared, encoding is ignored
bool operator==(const domain& other) const { return name == other.name; }
/// Check whether two objects are distinct, only names are compared, encoding is ignored
bool operator!=(const domain& other) const { return !(*this == other); }
};
typedef std::vector<domain> domains_type; ///< Type that defines a list of domains that are loaded
///< The first one is the default one
domains_type domains; ///< Message domains - application name, like my_app. So files named my_app.mo
///< would be loaded
std::vector<std::string> paths; ///< Paths to search files in. Under MS Windows it uses encoding
///< parameter to convert them to wide OS specific paths.
/// The callback for custom file system support. This callback should read the file named \a file_name
/// encoded in \a encoding character set into std::vector<char> and return it.
///
/// - If the file does not exist, it should return an empty vector.
/// - If a error occurs during file read it should throw a error.
///
/// \note The user should support only the encodings the locales are created for. So if the user
/// uses only one encoding or the file system is encoding agnostic, he may ignore the \a encoding parameter.
typedef std::function<std::vector<char>(const std::string& file_name, const std::string& encoding)>
callback_type;
/// The callback for handling custom file systems, if it is empty, the real OS file-system
/// is being used.
callback_type callback;
};
/// Create a message_format facet using GNU Gettext catalogs. It uses \a info structure to get
/// information about where to read them from and uses it for character set conversion (if needed)
template<typename CharType>
message_format<CharType>* create_messages_facet(const messages_info& info);
/// \cond INTERNAL
template<>
BOOST_LOCALE_DECL message_format<char>* create_messages_facet(const messages_info& info);
template<>
BOOST_LOCALE_DECL message_format<wchar_t>* create_messages_facet(const messages_info& info);
#ifdef BOOST_LOCALE_ENABLE_CHAR16_T
template<>
BOOST_LOCALE_DECL message_format<char16_t>* create_messages_facet(const messages_info& info);
#endif
#ifdef BOOST_LOCALE_ENABLE_CHAR32_T
template<>
BOOST_LOCALE_DECL message_format<char32_t>* create_messages_facet(const messages_info& info);
#endif
/// \endcond
} // namespace gnu_gettext
/// @}
}} // namespace boost::locale
#endif