lyx_mirror/src/support/unicode.h
Jean-Marc Lasgouttes 22f599250e Remove support for gcc 4.6
This was kept so long because of Ubuntu 12.04 LTS, but having a
not-really-c++11 compiler is not nice.
2019-06-12 15:03:18 +02:00

126 lines
3.9 KiB
C++

// -*- C++ -*-
/**
* \file unicode.h
* This file is part of LyX, the document processor.
* Licence details can be found in the file COPYING.
*
* \author Lars Gullik Bjønnes
*
* Full author contact details are available in file CREDITS.
*
* A collection of unicode conversion functions, using iconv.
*/
#ifndef LYX_SUPPORT_UNICODE_H
#define LYX_SUPPORT_UNICODE_H
#include "support/strfwd.h"
#include "support/unique_ptr.h"
#include <cstddef>
#include <string>
#include <vector>
namespace lyx {
/**
* Wrapper for iconv(3).
*
* According to the POSIX standard, all specified functions are thread-safe,
* with some exceptions. The iconv() function is not listed as an exception:
* http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xsh_chap02.html#tag_22_02_09_09
* http://man7.org/linux/man-pages/man7/pthreads.7.html
*
* Therefore, you can use as many instances of this class in parallel as you
* like. However, you need to ensure that each instance is only used by one
* thread at any given time. If this condition is not met you get nasty
* mixtures of different thread data as in bug 7240.
*
* From a performance point of view it is best to use one static instance
* per thread for each in/out encoding pair. This can e.g. be achieved by
* using helpers for thread-local storage such as QThreadStorage or
* boost::thread_specific_ptr. A single static instance protected by a mutex
* would work as well, and might be preferrable for exotic encoding pairs.
* Creating local IconvProcessor instances should be avoided because of the
* overhead in iconv_open().
*/
class IconvProcessor
{
/// open iconv.
/// \return true if the processor is ready to use.
bool init();
std::string const tocode_;
std::string const fromcode_;
struct Handler;
unique_ptr<Handler> h_;
public:
IconvProcessor(std::string tocode, std::string fromcode);
/// convert any data from \c fromcode to \c tocode unicode format.
/// \return the number of bytes of the converted output buffer.
int convert(char const * in_buffer, size_t in_size,
char * out_buffer, size_t max_out_size);
/// target encoding
std::string to() const { return tocode_; }
// required by g++ 4.7
IconvProcessor(IconvProcessor &&) = default;
};
/// Get the global IconvProcessor instance of the current thread for
/// utf8->ucs4 conversions
IconvProcessor & utf8ToUcs4();
// A single codepoint conversion for utf8_to_ucs4 does not make
// sense, so that function is left out.
std::vector<char_type> utf8_to_ucs4(std::vector<char> const & utf8str);
std::vector<char_type> utf8_to_ucs4(char const * utf8str, size_t ls);
// utf16_to_ucs4
std::vector<char_type> utf16_to_ucs4(unsigned short const * s, size_t ls);
// ucs4_to_utf16
std::vector<unsigned short> ucs4_to_utf16(char_type const * s, size_t ls);
/// Get the global IconvProcessor instance of the current thread for
/// ucs4->utf8 conversions
IconvProcessor & ucs4ToUtf8();
// ucs4_to_utf8
std::vector<char> ucs4_to_utf8(char_type c);
std::vector<char> ucs4_to_utf8(std::vector<char_type> const & ucs4str);
std::vector<char> ucs4_to_utf8(char_type const * ucs4str, size_t ls);
/// convert \p s from encoding \p encoding to ucs4.
/// \p encoding must be a valid iconv 8bit encoding
std::vector<char_type>
eightbit_to_ucs4(char const * s, size_t ls, std::string const & encoding);
/// convert \p s from ucs4 to encoding \p encoding.
/// \p encoding must be a valid iconv 8bit encoding
std::vector<char> ucs4_to_eightbit(char_type const * ucs4str,
size_t ls, std::string const & encoding);
/// convert ucs4 character \p c to encoding \p encoding.
/// \p encoding must be a valid iconv 8bit encoding
char ucs4_to_eightbit(char_type c, std::string const & encoding);
///
void ucs4_to_multibytes(char_type ucs4, std::vector<char> & out,
std::string const & encoding);
extern char const * ucs4_codeset;
/// How many bytes does one UCS4 code point use at most in encoding \p encoding?
int max_encoded_bytes(std::string const & encoding);
} // namespace lyx
#endif