    // Copyright (C) 2007  Davis E. King (davis@dlib.net), and Nils Labugt
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_UNICODe_H_
    #define DLIB_UNICODe_H_

    #include "../uintn.h"
    #include "../algs.h"
    #include "unicode_abstract.h"
    #include <string>
    #include <cstring>

    #include <fstream>

    namespace dlib
    {

    // ----------------------------------------------------------------------------------------

        typedef uint32 unichar;

    #if defined(__GNUC__) && __GNUC__ < 4 && __GNUC_MINOR__ < 4
        struct unichar_traits
        {
            typedef dlib::unichar    char_type;
            typedef dlib::unichar    int_type;
            typedef std::streamoff   off_type;
            typedef std::streampos   pos_type;
            typedef std::mbstate_t   state_type;

            static void assign(char_type& c1, const char_type& c2) { c1 = c2; }
            static bool eq(const char_type& c1, const char_type& c2) { return c1 == c2; }
            static bool lt(const char_type& c1, const char_type& c2) { return c1 < c2; }
            static int compare(const char_type* s1, const char_type* s2, size_t n)
            {
                for (size_t i = 0; i < n; ++i)
                {
                    if (s1[i] < s2[i])
                        return -1;
                    else if (s1[i] > s2[i])
                        return 1;
                }
                return 0;
            }

            static size_t length(const char_type* s)
            {
                size_t i = 0;
                while (s[i] != 0)
                    ++i;
                return i;
            }

            static const char_type* find(const char_type* s, size_t n,
                                         const char_type& a)
            {
                for (size_t i = 0; i < n; ++i)
                {
                    if (s[i] == a)
                    {
                        return s+i;
                    }
                }
                return 0;
            }

            static char_type* move(char_type* s1, const char_type* s2, size_t n)
            {
                return static_cast<char_type*>(std::memmove(s1, s2, sizeof(char_type)*n));
            }

            static char_type* copy(char_type* s1, const char_type* s2, size_t n)
            {
                for (size_t i = 0; i < n; ++i)
                    s1[i] = s2[i];

                return s1;
            }

            static char_type* assign(char_type* s, size_t n, char_type a)
            {
                for (size_t i = 0; i < n; ++i)
                    s[i] = a;

                return s;
            }

            static int_type not_eof(const int_type& c)
            {
                if (!eq_int_type(c,eof()))
                    return to_int_type(c);
                else
                    return 0;
            }

            static char_type to_char_type(const int_type& c) { return static_cast<char_type>(c); }
            static int_type to_int_type(const char_type& c) { return zero_extend_cast<int_type>(c); }

            static bool eq_int_type(const int_type& c1, const int_type& c2) { return c1 == c2; }

            static int_type eof() { return static_cast<int_type>(EOF); }
        };

        typedef std::basic_string<unichar, unichar_traits> ustring;
    #else
        typedef std::basic_string<unichar> ustring;
    #endif

    // ----------------------------------------------------------------------------------------

        namespace unicode_helpers
        {

            template <
                typename charT
                >
            int u8_to_u32(
                charT& result,
                std::istream& in
            )
            /*!
                ensures
                    - if (there just wasn't any more data and we hit EOF) then
                        - returns 0
                    - else if (we decoded another character without error) then
                        - #result == the decoded character
                        - returns the number of bytes consumed to make this character
                    - else
                        - some error occurred
                        - returns -1
            !*/
            {
                int val = in.get();
                if (val == EOF)
                    return 0;

                unichar ch[4];
                ch[0] = zero_extend_cast<unichar>(val);
                if ( ch[0] < 0x80 )
                {
                    result = static_cast<charT>(ch[0]);
                    return 1;
                }
                if ( ( ch[0] & ~0x3F ) == 0x80 )
                {
                    // invalid leading byte
                    return -1;
                }
                if ( ( ch[0] & ~0x1F ) == 0xC0 )
                {
                    val = in.get();
                    if ( val == EOF )
                        return -1;

                    ch[1] = zero_extend_cast<unichar>(val);
                    if ( ( ch[1] & ~0x3F ) != 0x80 )
                        return -1; // invalid tail
                    if ( ( ch[0] & ~0x01 ) == 0xC0 )
                        return -1; // overlong form
                    ch[0] &= 0x1F;
                    ch[1] &= 0x3F;
                    result = static_cast<charT>(( ch[0] << 6 ) | ch[1]);
                    return 2;
                }
                if ( ( ch[0] & ~0x0F ) == 0xE0 )
                {
                    for ( unsigned n = 1;n < 3;n++ )
                    {
                        val = in.get();
                        if ( val == EOF )
                            return -1;
                        ch[n] = zero_extend_cast<unichar>(val);
                        if ( ( ch[n] & ~0x3F ) != 0x80 )
                            return -1; // invalid tail
                        ch[n] &= 0x3F;
                    }
                    ch[0] &= 0x0F;
                    result = static_cast<charT>(( ch[0] << 12 ) | ( ch[1] << 6 ) | ch[2]);
                    if ( result < 0x0800 )
                        return -1; // overlong form
                    if ( result >= 0xD800 && result < 0xE000 )
                        return -1; // invalid character (UTF-16 surrogate pairs)
                    if ( result >= 0xFDD0 && result <= 0xFDEF )
                        return -1; // noncharacter
                    if ( result >= 0xFFFE )
                        return -1; // noncharacter
                    return 3;
                }
                if ( ( ch[0] & ~0x07 ) == 0xF0 )
                {
                    for ( unsigned n = 1;n < 4;n++ )
                    {
                        val = in.get();
                        if ( val == EOF )
                            return -1;
                        ch[n] = zero_extend_cast<unichar>(val);
                        if ( ( ch[n] & ~0x3F ) != 0x80 )
                            return -1; // invalid tail
                        ch[n] &= 0x3F;
                    }
                    if ( ( ch[0] ^ 0xF6 ) < 4 )
                        return -1;
                    ch[0] &= 0x07;
                    result  = static_cast<charT>(( ch[0] << 18 ) | ( ch[1] << 12 ) | ( ch[2] << 6 ) | ch[3]);
                    if ( result < 0x10000 )
                        return -1; // overlong form
                    if ( (result & 0xFFFF) >= 0xFFFE )
                        return -1; // noncharacter
                    return 4;
                }
                return -1;
            }

        // ------------------------------------------------------------------------------------

            template <typename charT>
            class basic_utf8_streambuf : public std::basic_streambuf<charT>
            {
            public:
                basic_utf8_streambuf (
                    std::ifstream& fin_
                ) :
                    fin(fin_)
                {
                    this->setg(in_buffer+max_putback,
                         in_buffer+max_putback,
                         in_buffer+max_putback);
                }

            protected:

                typedef typename std::basic_streambuf<charT>::int_type int_type;

                // input functions
                int_type underflow(
                )
                {
                    if (this->gptr() < this->egptr())
                    {
                        return zero_extend_cast<int_type>(*this->gptr());
                    }

                    int num_put_back = static_cast<int>(this->gptr() - this->eback());
                    if (num_put_back > max_putback)
                    {
                        num_put_back = max_putback;
                    }

                    // copy the putback characters into the putback end of the in_buffer
                    std::memmove(in_buffer+(max_putback-num_put_back), this->gptr()-num_put_back, num_put_back);

                    // fill the buffer with characters
                    int n = in_buffer_size-max_putback;
                    int i;
                    for (i = 0; i < n; ++i)
                    {
                        charT ch;
                        if (unicode_helpers::u8_to_u32(ch,fin) > 0)
                        {
                            (in_buffer+max_putback)[i] = ch;
                        }
                        else
                        {
                            break;
                        }
                    }

                    if (i == 0)
                    {
                        // an error occurred or we hit EOF
                        return EOF;
                    }

                    // reset in_buffer pointers
                    this->setg (in_buffer+(max_putback-num_put_back),
                          in_buffer+max_putback,
                          in_buffer+max_putback+i);

                    return zero_extend_cast<int_type>(*this->gptr());
                }

            private:
                std::ifstream& fin;
                static const int max_putback = 4;
                static const int in_buffer_size = 10;
                charT in_buffer[in_buffer_size];
            };
        }

    // ----------------------------------------------------------------------------------------

        template <typename T>
        bool is_combining_char(
            const T ch_
        )
        {
            const unichar ch = zero_extend_cast<unichar>(ch_);
            if ( ch < 0x300 ) return false;
            if ( ch < 0x370 ) return true;

            if ( ch < 0x800 )
            {
                if ( ch < 0x483 )return false;if ( ch < 0x48A )return true;

                if ( ch < 0x591 )return false;if ( ch < 0x5D0 )
                {
                    if ( ch == 0x5C0 )return false;
                    if ( ch == 0x5C3 )return false;
                    if ( ch == 0x5C6 )return false;
                    return true;
                }
                if ( ch < 0x610 )return false;if ( ch < 0x616 )return true;
                if ( ch < 0x64B )return false;if ( ch < 0x660 )return true;

                if ( ch == 0x670 )return true;

                if ( ch < 0x6D6 )return false;if ( ch < 0x6EE )
                {
                    if ( ch == 0x6DD )return false;
                    if ( ch == 0x6E5 )return false;
                    if ( ch == 0x6E6 )return false;
                    if ( ch == 0x6E9 )return false;
                    return true;
                }
                if ( ch == 0x711 )return true;

                if ( ch < 0x730 )return false;if ( ch < 0x74B )return true;
                if ( ch < 0x7A6 )return false;if ( ch < 0x7B1 )return true;
                if ( ch < 0x7EB )return false;if ( ch < 0x7F4 )return true;
                return false;
            }
            if ( ch < 0xA00 )
            {
                if ( ch < 0x901 )return false;if ( ch < 0x904 )return true;
                if ( ch < 0x93C )return false;if ( ch < 0x955 )
                {
                    if ( ch == 0x93D )return false;
                    if ( ch == 0x950 )return false;
                    return true;
                }
                if ( ch < 0x962 )return false;if ( ch < 0x964 )return true;
                if ( ch < 0x981 )return false;if ( ch < 0x984 )return true;
                if ( ch < 0x9BC )return false;if ( ch < 0x9D8 )
                {
                    if ( ch == 0x9BD )return false;
                    if ( ch == 0x9CE )return false;
                    return true;
                }
                if ( ch < 0x9E2 )return false;if ( ch < 0x9E4 )return true;
                return false;
            }
            if ( ch < 0xC00 )
            {
                if ( ch < 0xA01 )return false;if ( ch < 0xA04 )return true;
                if ( ch < 0xA3C )return false;if ( ch < 0xA4E )return true;
                if ( ch < 0xA70 )return false;if ( ch < 0xA72 )return true;
                if ( ch < 0xA81 )return false;if ( ch < 0xA84 )return true;
                if ( ch < 0xABC )return false;if ( ch < 0xACE )
                {
                    if ( ch == 0xABD )return false;
                    return true;
                }
                if ( ch < 0xAE2 )return false;if ( ch < 0xAE4 )return true;
                if ( ch < 0xB01 )return false;if ( ch < 0xB04 )return true;
                if ( ch < 0xB3C )return false;if ( ch < 0xB58 )
                {
                    if ( ch == 0xB3D )return false;
                    return true;
                }
                if ( ch == 0xB82 )return true;

                if ( ch < 0xBBE )return false;if ( ch < 0xBD8 )return true;

                if ( ch == 0xBF4 )return true;
                if ( ch == 0xBF8 )return true;
                return false;
            }
            if(ch < 0xE00)
            {
                if ( ch < 0xC01 )return false;if ( ch < 0xC04 )return true;
                if ( ch < 0xC3E )return false;if ( ch < 0xC57 )return true;
                if ( ch < 0xC82 )return false;if ( ch < 0xC84 )return true;
                if ( ch < 0xCBC )return false;if ( ch < 0xCD7 )
                {
                    if ( ch == 0xCBD )return false;
                    return true;
                }
                if ( ch < 0xCE2 )return false;if ( ch < 0xCE4 )return true;
                if ( ch < 0xD02 )return false;if ( ch < 0xD04 )return true;
                if ( ch < 0xD3E )return false;if ( ch < 0xD58 )return true;
                if ( ch < 0xD82 )return false;if ( ch < 0xD84 )return true;
                if ( ch < 0xDCA )return false;if ( ch < 0xDF4 )return true;
                return false;
            }
            if(ch < 0x1000)
            {
                if ( ch == 0xE31 )return true;

                if ( ch < 0xE34 )return false;if ( ch < 0xE3B )return true;
                if ( ch < 0xE47 )return false;if ( ch < 0xE4F )return true;

                if ( ch == 0xEB1 )return true;

                if ( ch < 0xEB4 )return false;if ( ch < 0xEBD )return true;
                if ( ch < 0xEC8 )return false;if ( ch < 0xECE )return true;
                if ( ch < 0xF18 )return false;if ( ch < 0xF1A )return true;

                if ( ch == 0xF35 )return true;
                if ( ch == 0xF37 )return true;
                if ( ch == 0xF39 )return true;

                if ( ch < 0xF3E )return false;if ( ch < 0xF40 )return true;
                if ( ch < 0xF71 )return false;if ( ch < 0xF88 )
                {
                    if ( ch == 0xF85 )return false;
                    return true;
                }
                if ( ch < 0xF90 )return false;if ( ch < 0xFBD )return true;

                if ( ch == 0xFC6 )return true;
                return false;
            }
            if ( ch < 0x1800 )
            {
                if ( ch < 0x102C )return false;if ( ch < 0x1040 )return true;
                if ( ch < 0x1056 )return false;if ( ch < 0x105A )return true;

                if ( ch == 0x135F )return true;

                if ( ch < 0x1712 )return false;if ( ch < 0x1715 )return true;
                if ( ch < 0x1732 )return false;if ( ch < 0x1735 )return true;
                if ( ch < 0x1752 )return false;if ( ch < 0x1754 )return true;
                if ( ch < 0x1772 )return false;if ( ch < 0x1774 )return true;
                if ( ch < 0x17B6 )return false;if ( ch < 0x17D4 )return true;

                if ( ch == 0x17DD )return true;
                return false;
            }
            if(ch < 0x2000)
            {
                if ( ch < 0x180B )return false;if ( ch < 0x180E )return true;

                if ( ch == 0x18A9 )return true;

                if ( ch < 0x1920 )return false;if ( ch < 0x193C )return true;
                if ( ch < 0x19B0 )return false;if ( ch < 0x19C1 )return true;
                if ( ch < 0x19C8 )return false;if ( ch < 0x19CA )return true;
                if ( ch < 0x1A17 )return false;if ( ch < 0x1A1C )return true;
                if ( ch < 0x1B00 )return false;if ( ch < 0x1B05 )return true;
                if ( ch < 0x1B34 )return false;if ( ch < 0x1B45 )return true;
                if ( ch < 0x1B6B )return false;if ( ch < 0x1B74 )return true;
                if ( ch < 0x1DC0 )return false;if ( ch < 0x1E00 )return true;
                return false;
            }
            if ( ch < 0x20D0 )return false;if ( ch < 0x2100 )return true;
            if ( ch < 0x302A )return false;if ( ch < 0x3030 )return true;
            if ( ch < 0x3099 )return false;if ( ch < 0x309B )return true;

            if ( ch == 0xA802 )return true;
            if ( ch == 0xA806 )return true;
            if ( ch == 0xA80B )return true;

            if ( ch < 0xA823 )return false;if ( ch < 0xA828 )return true;

            if ( ch == 0xFB1E )return true;

            if ( ch < 0xFE00 )return false;if ( ch < 0xFE10 )return true;
            if ( ch < 0xFE20 )return false;if ( ch < 0xFE30 )return true;
            if ( ch < 0x10A01 )return false;if ( ch < 0x10A10 )return true;
            if ( ch < 0x10A38 )return false;if ( ch < 0x10A40 )return true;
            if ( ch < 0x1D165 )return false;if ( ch < 0x1D16A )return true;
            if ( ch < 0x1D16D )return false;if ( ch < 0x1D173 )return true;
            if ( ch < 0x1D17B )return false;if ( ch < 0x1D183 )return true;
            if ( ch < 0x1D185 )return false;if ( ch < 0x1D18C )return true;
            if ( ch < 0x1D1AA )return false;if ( ch < 0x1D1AE )return true;
            if ( ch < 0x1D242 )return false;if ( ch < 0x1D245 )return true;
            if ( ch < 0xE0100 )return false;if ( ch < 0xE01F0 )return true;
            return false;
        }

    // ----------------------------------------------------------------------------------------

        class invalid_utf8_error : public error
        {
        public:
            invalid_utf8_error():error(EUTF8_TO_UTF32) {}
        };

        inline const ustring convert_utf8_to_utf32 (
            const std::string& str
        )
        {
            using namespace unicode_helpers;
            ustring temp;
            std::istringstream sin(str);

            temp.reserve(str.size());

            int status;
            unichar ch;
            while ( (status = u8_to_u32(ch,sin)) > 0)
                temp.push_back(ch);

            if (status < 0)
                throw invalid_utf8_error();

            return temp;
        }

    // ----------------------------------------------------------------------------------------

        bool is_surrogate(unichar ch);

        unichar surrogate_pair_to_unichar(unichar first, unichar second);

        void unichar_to_surrogate_pair(unichar unicode, unichar &first, unichar &second);

        const ustring convert_wstring_to_utf32 (
            const std::wstring &wstr
        );

        const std::wstring convert_utf32_to_wstring (
            const ustring &src
        );

        const std::wstring convert_mbstring_to_wstring (
            const std::string &src
        );

        const std::string convert_wstring_to_mbstring(
            const std::wstring &src
        );

    // ----------------------------------------------------------------------------------------

        template <typename charT>
        class basic_utf8_ifstream : public std::basic_istream<charT>
        {
        public:

            basic_utf8_ifstream (
            ) : std::basic_istream<charT>(&buf), buf(fin) {}

            basic_utf8_ifstream (
                const char* file_name,
                std::ios_base::openmode mode = std::ios::in
            ) :
                std::basic_istream<charT>(&buf),
                buf(fin)
            {
                fin.open(file_name,mode);
                // make this have the same error state as fin
                this->clear(fin.rdstate());
            }

            basic_utf8_ifstream (
                const std::string& file_name,
                std::ios_base::openmode mode = std::ios::in
            ) :
                std::basic_istream<charT>(&buf),
                buf(fin)
            {
                fin.open(file_name.c_str(),mode);
                // make this have the same error state as fin
                this->clear(fin.rdstate());
            }

            void open(
                const std::string& file_name,
                std::ios_base::openmode mode = std::ios::in
            )
            {
                open(file_name.c_str(),mode);
            }

            void open (
                const char* file_name,
                std::ios_base::openmode mode = std::ios::in
            )
            {
                fin.close();
                fin.clear();
                fin.open(file_name,mode);
                // make this have the same error state as fin
                this->clear(fin.rdstate());
            }

            void close (
            )
            {
                fin.close();
                // make this have the same error state as fin
                this->clear(fin.rdstate());
            }

        private:

            std::ifstream fin;
            unicode_helpers::basic_utf8_streambuf<charT> buf;
        };

        typedef basic_utf8_ifstream<unichar> utf8_uifstream;
        typedef basic_utf8_ifstream<wchar_t> utf8_wifstream;

    // ----------------------------------------------------------------------------------------

    }

    #ifdef NO_MAKEFILE
    #include "unicode.cpp"
    #endif

    #endif // DLIB_UNICODe_H_