Update ClockTAI and RemoteControl

8 files changed, 771 insertions, 215 deletions

diff --git a/lib/charset/README b/lib/charset/README
index b20f76b..3217b87 100644
--- a/lib/charset/README
+++ b/lib/charset/README
@@ -1,2 +1,2 @@
 This UTF-8 to EBU charset (defined in ETSI TS 101 756v1.8.1) was copied from
-ODR-PadEnc.
+ODR-PadEnc, with utf8 library v4.0.5 from https://github.com/nemtrif/utfcpp/tree/master/source/utf8
diff --git a/lib/charset/utf8.h b/lib/charset/utf8.h
index 4e44514..b513530 100644
--- a/lib/charset/utf8.h
+++ b/lib/charset/utf8.h
@@ -1,34 +1,46 @@
-// Copyright 2006 Nemanja Trifunovic

-

-/*

-Permission is hereby granted, free of charge, to any person or organization

-obtaining a copy of the software and accompanying documentation covered by

-this license (the "Software") to use, reproduce, display, distribute,

-execute, and transmit the Software, and to prepare derivative works of the

-Software, and to permit third-parties to whom the Software is furnished to

-do so, all subject to the following:

-

-The copyright notices in the Software and this entire statement, including

-the above license grant, this restriction and the following disclaimer,

-must be included in all copies of the Software, in whole or in part, and

-all derivative works of the Software, unless such copies or derivative

-works are solely in the form of machine-executable object code generated by

-a source language processor.

-

-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

-FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT

-SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE

-FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,

-ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

-DEALINGS IN THE SOFTWARE.

-*/

-

-

-#ifndef UTF8_FOR_CPP_2675DCD0_9480_4c0c_B92A_CC14C027B731

-#define UTF8_FOR_CPP_2675DCD0_9480_4c0c_B92A_CC14C027B731

-

-#include "utf8/checked.h"

-#include "utf8/unchecked.h"

-

-#endif // header guard

+// Copyright 2006 Nemanja Trifunovic
+
+/*
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+#ifndef UTF8_FOR_CPP_2675DCD0_9480_4c0c_B92A_CC14C027B731
+#define UTF8_FOR_CPP_2675DCD0_9480_4c0c_B92A_CC14C027B731
+
+/*
+To control the C++ language version used by the library, you can define UTF_CPP_CPLUSPLUS macro
+and set it to one of the values used by the __cplusplus predefined macro.
+
+For instance,
+    #define UTF_CPP_CPLUSPLUS 199711L
+will cause the UTF-8 CPP library to use only types and language features available in the C++ 98 standard.
+Some library features will be disabled.
+
+If you leave UTF_CPP_CPLUSPLUS undefined, it will be internally assigned to __cplusplus.
+*/
+
+#include "utf8/checked.h"
+#include "utf8/unchecked.h"
+
+#endif // header guard
diff --git a/lib/charset/utf8/checked.h b/lib/charset/utf8/checked.h
index 1331155..98949f8 100644
--- a/lib/charset/utf8/checked.h
+++ b/lib/charset/utf8/checked.h
@@ -1,4 +1,4 @@
-// Copyright 2006 Nemanja Trifunovic
+// Copyright 2006-2016 Nemanja Trifunovic
 
 /*
 Permission is hereby granted, free of charge, to any person or organization
@@ -39,64 +39,62 @@ namespace utf8
 
     // Exceptions that may be thrown from the library functions.
     class invalid_code_point : public exception {
-        uint32_t cp;
+        utfchar32_t cp;
     public:
-        invalid_code_point(uint32_t cp) : cp(cp) {}
-        virtual const char* what() const throw() { return "Invalid code point"; }
-        uint32_t code_point() const {return cp;}
+        invalid_code_point(utfchar32_t codepoint) : cp(codepoint) {}
+        virtual const char* what() const UTF_CPP_NOEXCEPT UTF_CPP_OVERRIDE { return "Invalid code point"; }
+        utfchar32_t code_point() const {return cp;}
     };
 
     class invalid_utf8 : public exception {
-        uint8_t u8;
+        utfchar8_t u8;
     public:
-        invalid_utf8 (uint8_t u) : u8(u) {}
-        virtual const char* what() const throw() { return "Invalid UTF-8"; }
-        uint8_t utf8_octet() const {return u8;}
+        invalid_utf8 (utfchar8_t u) : u8(u) {}
+        invalid_utf8 (char c) : u8(static_cast<utfchar8_t>(c)) {}
+        virtual const char* what() const UTF_CPP_NOEXCEPT UTF_CPP_OVERRIDE { return "Invalid UTF-8"; }
+        utfchar8_t utf8_octet() const {return u8;}
     };
 
     class invalid_utf16 : public exception {
-        uint16_t u16;
+        utfchar16_t u16;
     public:
-        invalid_utf16 (uint16_t u) : u16(u) {}
-        virtual const char* what() const throw() { return "Invalid UTF-16"; }
-        uint16_t utf16_word() const {return u16;}
+        invalid_utf16 (utfchar16_t u) : u16(u) {}
+        virtual const char* what() const UTF_CPP_NOEXCEPT UTF_CPP_OVERRIDE { return "Invalid UTF-16"; }
+        utfchar16_t utf16_word() const {return u16;}
     };
 
     class not_enough_room : public exception {
     public:
-        virtual const char* what() const throw() { return "Not enough space"; }
+        virtual const char* what() const UTF_CPP_NOEXCEPT UTF_CPP_OVERRIDE { return "Not enough space"; }
     };
 
     /// The library API - functions intended to be called by the users
 
     template <typename octet_iterator>
-    octet_iterator append(uint32_t cp, octet_iterator result)
+    octet_iterator append(utfchar32_t cp, octet_iterator result)
     {
         if (!utf8::internal::is_code_point_valid(cp))
             throw invalid_code_point(cp);
 
-        if (cp < 0x80)                        // one octet
-            *(result++) = static_cast<uint8_t>(cp);
-        else if (cp < 0x800) {                // two octets
-            *(result++) = static_cast<uint8_t>((cp >> 6)            | 0xc0);
-            *(result++) = static_cast<uint8_t>((cp & 0x3f)          | 0x80);
-        }
-        else if (cp < 0x10000) {              // three octets
-            *(result++) = static_cast<uint8_t>((cp >> 12)           | 0xe0);
-            *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f)   | 0x80);
-            *(result++) = static_cast<uint8_t>((cp & 0x3f)          | 0x80);
-        }
-        else {                                // four octets
-            *(result++) = static_cast<uint8_t>((cp >> 18)           | 0xf0);
-            *(result++) = static_cast<uint8_t>(((cp >> 12) & 0x3f)  | 0x80);
-            *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f)   | 0x80);
-            *(result++) = static_cast<uint8_t>((cp & 0x3f)          | 0x80);
-        }
-        return result;
+        return internal::append(cp, result);
+    }
+
+    inline void append(utfchar32_t cp, std::string& s)
+    {
+        append(cp, std::back_inserter(s));
+    }
+
+    template <typename word_iterator>
+    word_iterator append16(utfchar32_t cp, word_iterator result)
+    {
+        if (!utf8::internal::is_code_point_valid(cp))
+            throw invalid_code_point(cp);
+
+        return internal::append16(cp, result);
     }
 
     template <typename octet_iterator, typename output_iterator>
-    output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out, uint32_t replacement)
+    output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out, utfchar32_t replacement)
     {
         while (start != end) {
             octet_iterator sequence_start = start;
@@ -107,7 +105,9 @@ namespace utf8
                         *out++ = *it;
                     break;
                 case internal::NOT_ENOUGH_ROOM:
-                    throw not_enough_room();
+                    out = utf8::append (replacement, out);
+                    start = end;
+                    break;
                 case internal::INVALID_LEAD:
                     out = utf8::append (replacement, out);
                     ++start;
@@ -129,14 +129,28 @@ namespace utf8
     template <typename octet_iterator, typename output_iterator>
     inline output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out)
     {
-        static const uint32_t replacement_marker = utf8::internal::mask16(0xfffd);
+        static const utfchar32_t replacement_marker = utf8::internal::mask16(0xfffd);
         return utf8::replace_invalid(start, end, out, replacement_marker);
     }
 
+    inline std::string replace_invalid(const std::string& s, utfchar32_t replacement)
+    {
+        std::string result;
+        replace_invalid(s.begin(), s.end(), std::back_inserter(result), replacement);
+        return result;
+    }
+
+    inline std::string replace_invalid(const std::string& s)
+    {
+        std::string result;
+        replace_invalid(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
     template <typename octet_iterator>
-    uint32_t next(octet_iterator& it, octet_iterator end)
+    utfchar32_t next(octet_iterator& it, octet_iterator end)
     {
-        uint32_t cp = 0;
+        utfchar32_t cp = 0;
         internal::utf_error err_code = utf8::internal::validate_next(it, end, cp);
         switch (err_code) {
             case internal::UTF8_OK :
@@ -146,21 +160,31 @@ namespace utf8
             case internal::INVALID_LEAD :
             case internal::INCOMPLETE_SEQUENCE :
             case internal::OVERLONG_SEQUENCE :
-                throw invalid_utf8(*it);
+                throw invalid_utf8(static_cast<utfchar8_t>(*it));
             case internal::INVALID_CODE_POINT :
                 throw invalid_code_point(cp);
         }
         return cp;
     }
 
+    template <typename word_iterator>
+    utfchar32_t next16(word_iterator& it, word_iterator end)
+    {
+        utfchar32_t cp = 0;
+        internal::utf_error err_code = utf8::internal::validate_next16(it, end, cp);
+        if (err_code == internal::NOT_ENOUGH_ROOM)
+            throw not_enough_room();
+        return cp;
+    }
+
     template <typename octet_iterator>
-    uint32_t peek_next(octet_iterator it, octet_iterator end)
+    utfchar32_t peek_next(octet_iterator it, octet_iterator end)
     {
         return utf8::next(it, end);
     }
 
     template <typename octet_iterator>
-    uint32_t prior(octet_iterator& it, octet_iterator start)
+    utfchar32_t prior(octet_iterator& it, octet_iterator start)
     {
         // can't do much if it == start
         if (it == start)
@@ -174,23 +198,19 @@ namespace utf8
         return utf8::peek_next(it, end);
     }
 
-    /// Deprecated in versions that include "prior"
-    template <typename octet_iterator>
-    uint32_t previous(octet_iterator& it, octet_iterator pass_start)
-    {
-        octet_iterator end = it;
-        while (utf8::internal::is_trail(*(--it)))
-            if (it == pass_start)
-                throw invalid_utf8(*it); // error - no lead byte in the sequence
-        octet_iterator temp = it;
-        return utf8::next(temp, end);
-    }
-
     template <typename octet_iterator, typename distance_type>
     void advance (octet_iterator& it, distance_type n, octet_iterator end)
     {
-        for (distance_type i = 0; i < n; ++i)
-            utf8::next(it, end);
+        const distance_type zero(0);
+        if (n < zero) {
+            // backward
+            for (distance_type i = n; i < zero; ++i)
+                utf8::prior(it, end);
+        } else {
+            // forward
+            for (distance_type i = zero; i < n; ++i)
+                utf8::next(it, end);
+        }
     }
 
     template <typename octet_iterator>
@@ -207,23 +227,23 @@ namespace utf8
     octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result)
     {
         while (start != end) {
-            uint32_t cp = utf8::internal::mask16(*start++);
+            utfchar32_t cp = utf8::internal::mask16(*start++);
             // Take care of surrogate pairs first
             if (utf8::internal::is_lead_surrogate(cp)) {
                 if (start != end) {
-                    uint32_t trail_surrogate = utf8::internal::mask16(*start++);
+                    const utfchar32_t trail_surrogate = utf8::internal::mask16(*start++);
                     if (utf8::internal::is_trail_surrogate(trail_surrogate))
                         cp = (cp << 10) + trail_surrogate + internal::SURROGATE_OFFSET;
                     else
-                        throw invalid_utf16(static_cast<uint16_t>(trail_surrogate));
+                        throw invalid_utf16(static_cast<utfchar16_t>(trail_surrogate));
                 }
                 else
-                    throw invalid_utf16(static_cast<uint16_t>(cp));
+                    throw invalid_utf16(static_cast<utfchar16_t>(cp));
 
             }
             // Lone trail surrogate
             else if (utf8::internal::is_trail_surrogate(cp))
-                throw invalid_utf16(static_cast<uint16_t>(cp));
+                throw invalid_utf16(static_cast<utfchar16_t>(cp));
 
             result = utf8::append(cp, result);
         }
@@ -233,14 +253,14 @@ namespace utf8
     template <typename u16bit_iterator, typename octet_iterator>
     u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result)
     {
-        while (start != end) {
-            uint32_t cp = utf8::next(start, end);
+        while (start < end) {
+            const utfchar32_t cp = utf8::next(start, end);
             if (cp > 0xffff) { //make a surrogate pair
-                *result++ = static_cast<uint16_t>((cp >> 10)   + internal::LEAD_OFFSET);
-                *result++ = static_cast<uint16_t>((cp & 0x3ff) + internal::TRAIL_SURROGATE_MIN);
+                *result++ = static_cast<utfchar16_t>((cp >> 10)   + internal::LEAD_OFFSET);
+                *result++ = static_cast<utfchar16_t>((cp & 0x3ff) + internal::TRAIL_SURROGATE_MIN);
             }
             else
-                *result++ = static_cast<uint16_t>(cp);
+                *result++ = static_cast<utfchar16_t>(cp);
         }
         return result;
     }
@@ -257,7 +277,7 @@ namespace utf8
     template <typename octet_iterator, typename u32bit_iterator>
     u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result)
     {
-        while (start != end)
+        while (start < end)
             (*result++) = utf8::next(start, end);
 
         return result;
@@ -265,23 +285,28 @@ namespace utf8
 
     // The iterator class
     template <typename octet_iterator>
-    class iterator : public std::iterator <std::bidirectional_iterator_tag, uint32_t> {
+    class iterator {
       octet_iterator it;
       octet_iterator range_start;
       octet_iterator range_end;
       public:
+      typedef utfchar32_t value_type;
+      typedef utfchar32_t* pointer;
+      typedef utfchar32_t& reference;
+      typedef std::ptrdiff_t difference_type;
+      typedef std::bidirectional_iterator_tag iterator_category;
       iterator () {}
       explicit iterator (const octet_iterator& octet_it,
-                         const octet_iterator& range_start,
-                         const octet_iterator& range_end) :
-               it(octet_it), range_start(range_start), range_end(range_end)
+                         const octet_iterator& rangestart,
+                         const octet_iterator& rangeend) :
+               it(octet_it), range_start(rangestart), range_end(rangeend)
       {
           if (it < range_start || it > range_end)
               throw std::out_of_range("Invalid utf-8 iterator position");
       }
       // the default "big three" are OK
       octet_iterator base () const { return it; }
-      uint32_t operator * () const
+      utfchar32_t operator * () const
       {
           octet_iterator temp = it;
           return utf8::next(temp, range_end);
@@ -322,6 +347,13 @@ namespace utf8
 
 } // namespace utf8
 
-#endif //header guard
+#if UTF_CPP_CPLUSPLUS >= 202002L // C++ 20 or later
+#include "cpp20.h"
+#elif UTF_CPP_CPLUSPLUS >= 201703L // C++ 17 or later
+#include "cpp17.h"
+#elif UTF_CPP_CPLUSPLUS >= 201103L // C++ 11 or later
+#include "cpp11.h"
+#endif // C++ 11 or later
 
+#endif //header guard
 
diff --git a/lib/charset/utf8/core.h b/lib/charset/utf8/core.h
index 693d388..4494c53 100644
--- a/lib/charset/utf8/core.h
+++ b/lib/charset/utf8/core.h
@@ -29,15 +29,42 @@ DEALINGS IN THE SOFTWARE.
 #define UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
 
 #include <iterator>
+#include <cstring>
+#include <string>
+
+// Determine the C++ standard version.
+// If the user defines UTF_CPP_CPLUSPLUS, use that.
+// Otherwise, trust the unreliable predefined macro __cplusplus
+
+#if !defined UTF_CPP_CPLUSPLUS
+    #define UTF_CPP_CPLUSPLUS __cplusplus
+#endif
+
+#if UTF_CPP_CPLUSPLUS >= 201103L // C++ 11 or later
+    #define UTF_CPP_OVERRIDE override
+    #define UTF_CPP_NOEXCEPT noexcept
+#else // C++ 98/03
+    #define UTF_CPP_OVERRIDE
+    #define UTF_CPP_NOEXCEPT throw()
+#endif // C++ 11 or later
+
 
 namespace utf8
 {
-    // The typedefs for 8-bit, 16-bit and 32-bit unsigned integers
-    // You may need to change them to match your system.
-    // These typedefs have the same names as ones from cstdint, or boost/cstdint
-    typedef unsigned char   uint8_t;
-    typedef unsigned short  uint16_t;
-    typedef unsigned int    uint32_t;
+// The typedefs for 8-bit, 16-bit and 32-bit code units
+#if UTF_CPP_CPLUSPLUS >= 201103L // C++ 11 or later
+    #if UTF_CPP_CPLUSPLUS >= 202002L // C++ 20 or later
+        typedef char8_t         utfchar8_t;
+    #else // C++ 11/14/17
+        typedef unsigned char   utfchar8_t;
+    #endif
+    typedef char16_t        utfchar16_t;
+    typedef char32_t        utfchar32_t;
+#else // C++ 98/03
+    typedef unsigned char   utfchar8_t;
+    typedef unsigned short  utfchar16_t;
+    typedef unsigned int    utfchar32_t;
+#endif // C++ 11 or later
 
 // Helper code - not intended to be directly called by the library users. May be changed at any time
 namespace internal
@@ -45,61 +72,62 @@ namespace internal
     // Unicode constants
     // Leading (high) surrogates: 0xd800 - 0xdbff
     // Trailing (low) surrogates: 0xdc00 - 0xdfff
-    const uint16_t LEAD_SURROGATE_MIN  = 0xd800u;
-    const uint16_t LEAD_SURROGATE_MAX  = 0xdbffu;
-    const uint16_t TRAIL_SURROGATE_MIN = 0xdc00u;
-    const uint16_t TRAIL_SURROGATE_MAX = 0xdfffu;
-    const uint16_t LEAD_OFFSET         = LEAD_SURROGATE_MIN - (0x10000 >> 10);
-    const uint32_t SURROGATE_OFFSET    = 0x10000u - (LEAD_SURROGATE_MIN << 10) - TRAIL_SURROGATE_MIN;
+    const utfchar16_t LEAD_SURROGATE_MIN  = 0xd800u;
+    const utfchar16_t LEAD_SURROGATE_MAX  = 0xdbffu;
+    const utfchar16_t TRAIL_SURROGATE_MIN = 0xdc00u;
+    const utfchar16_t TRAIL_SURROGATE_MAX = 0xdfffu;
+    const utfchar16_t LEAD_OFFSET         = 0xd7c0u;       // LEAD_SURROGATE_MIN - (0x10000 >> 10)
+    const utfchar32_t SURROGATE_OFFSET    = 0xfca02400u;   // 0x10000u - (LEAD_SURROGATE_MIN << 10) - TRAIL_SURROGATE_MIN
 
     // Maximum valid value for a Unicode code point
-    const uint32_t CODE_POINT_MAX      = 0x0010ffffu;
+    const utfchar32_t CODE_POINT_MAX      = 0x0010ffffu;
 
     template<typename octet_type>
-    inline uint8_t mask8(octet_type oc)
+    inline utfchar8_t mask8(octet_type oc)
     {
-        return static_cast<uint8_t>(0xff & oc);
+        return static_cast<utfchar8_t>(0xff & oc);
     }
     template<typename u16_type>
-    inline uint16_t mask16(u16_type oc)
+    inline utfchar16_t mask16(u16_type oc)
     {
-        return static_cast<uint16_t>(0xffff & oc);
+        return static_cast<utfchar16_t>(0xffff & oc);
     }
+
     template<typename octet_type>
     inline bool is_trail(octet_type oc)
     {
         return ((utf8::internal::mask8(oc) >> 6) == 0x2);
     }
 
-    template <typename u16>
-    inline bool is_lead_surrogate(u16 cp)
+    inline bool is_lead_surrogate(utfchar32_t cp)
     {
         return (cp >= LEAD_SURROGATE_MIN && cp <= LEAD_SURROGATE_MAX);
     }
 
-    template <typename u16>
-    inline bool is_trail_surrogate(u16 cp)
+    inline bool is_trail_surrogate(utfchar32_t cp)
     {
         return (cp >= TRAIL_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
     }
 
-    template <typename u16>
-    inline bool is_surrogate(u16 cp)
+    inline bool is_surrogate(utfchar32_t cp)
     {
         return (cp >= LEAD_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
     }
 
-    template <typename u32>
-    inline bool is_code_point_valid(u32 cp)
+    inline bool is_code_point_valid(utfchar32_t cp)
     {
         return (cp <= CODE_POINT_MAX && !utf8::internal::is_surrogate(cp));
     }
 
+    inline bool is_in_bmp(utfchar32_t cp)
+    {
+        return cp < utfchar32_t(0x10000);
+    }
+
     template <typename octet_iterator>
-    inline typename std::iterator_traits<octet_iterator>::difference_type
-    sequence_length(octet_iterator lead_it)
+    int sequence_length(octet_iterator lead_it)
     {
-        uint8_t lead = utf8::internal::mask8(*lead_it);
+        const utfchar8_t lead = utf8::internal::mask8(*lead_it);
         if (lead < 0x80)
             return 1;
         else if ((lead >> 5) == 0x6)
@@ -112,8 +140,7 @@ namespace internal
             return 0;
     }
 
-    template <typename octet_difference_type>
-    inline bool is_overlong_sequence(uint32_t cp, octet_difference_type length)
+    inline bool is_overlong_sequence(utfchar32_t cp, int length)
     {
         if (cp < 0x80) {
             if (length != 1) 
@@ -127,7 +154,6 @@ namespace internal
             if (length != 3) 
                 return true;
         }
-
         return false;
     }
 
@@ -135,22 +161,22 @@ namespace internal
 
     /// Helper for get_sequence_x
     template <typename octet_iterator>
-    utf_error increase_safely(octet_iterator& it, octet_iterator end)
+    utf_error increase_safely(octet_iterator& it, const octet_iterator end)
     {
         if (++it == end)
             return NOT_ENOUGH_ROOM;
 
         if (!utf8::internal::is_trail(*it))
             return INCOMPLETE_SEQUENCE;
-        
+
         return UTF8_OK;
     }
 
-    #define UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(IT, END) {utf_error ret = increase_safely(IT, END); if (ret != UTF8_OK) return ret;}    
+    #define UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(IT, END) {utf_error ret = increase_safely(IT, END); if (ret != UTF8_OK) return ret;}
 
     /// get_sequence_x functions decode utf-8 sequences of the length x
     template <typename octet_iterator>
-    utf_error get_sequence_1(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    utf_error get_sequence_1(octet_iterator& it, octet_iterator end, utfchar32_t& code_point)
     {
         if (it == end)
             return NOT_ENOUGH_ROOM;
@@ -161,11 +187,11 @@ namespace internal
     }
 
     template <typename octet_iterator>
-    utf_error get_sequence_2(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    utf_error get_sequence_2(octet_iterator& it, octet_iterator end, utfchar32_t& code_point)
     {
         if (it == end) 
             return NOT_ENOUGH_ROOM;
-        
+
         code_point = utf8::internal::mask8(*it);
 
         UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
@@ -176,7 +202,7 @@ namespace internal
     }
 
     template <typename octet_iterator>
-    utf_error get_sequence_3(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    utf_error get_sequence_3(octet_iterator& it, octet_iterator end, utfchar32_t& code_point)
     {
         if (it == end)
             return NOT_ENOUGH_ROOM;
@@ -195,7 +221,7 @@ namespace internal
     }
 
     template <typename octet_iterator>
-    utf_error get_sequence_4(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    utf_error get_sequence_4(octet_iterator& it, octet_iterator end, utfchar32_t& code_point)
     {
         if (it == end)
            return NOT_ENOUGH_ROOM;
@@ -220,21 +246,23 @@ namespace internal
     #undef UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR
 
     template <typename octet_iterator>
-    utf_error validate_next(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    utf_error validate_next(octet_iterator& it, octet_iterator end, utfchar32_t& code_point)
     {
+        if (it == end)
+            return NOT_ENOUGH_ROOM;
+
         // Save the original value of it so we can go back in case of failure
         // Of course, it does not make much sense with i.e. stream iterators
         octet_iterator original_it = it;
 
-        uint32_t cp = 0;
+        utfchar32_t cp = 0;
         // Determine the sequence length based on the lead octet
-        typedef typename std::iterator_traits<octet_iterator>::difference_type octet_difference_type;
-        const octet_difference_type length = utf8::internal::sequence_length(it);
+        const int length = utf8::internal::sequence_length(it);
 
         // Get trail octets and calculate the code point
         utf_error err = UTF8_OK;
         switch (length) {
-            case 0: 
+            case 0:
                 return INVALID_LEAD;
             case 1:
                 err = utf8::internal::get_sequence_1(it, end, cp);
@@ -273,16 +301,133 @@ namespace internal
 
     template <typename octet_iterator>
     inline utf_error validate_next(octet_iterator& it, octet_iterator end) {
-        uint32_t ignored;
+        utfchar32_t ignored;
         return utf8::internal::validate_next(it, end, ignored);
     }
 
+    template <typename word_iterator>
+    utf_error validate_next16(word_iterator& it, word_iterator end, utfchar32_t& code_point)
+    {
+        if (it == end)
+            return NOT_ENOUGH_ROOM;
+        // Save the original value of it so we can go back in case of failure
+        // Of course, it does not make much sense with i.e. stream iterators
+        word_iterator original_it = it;
+
+        utf_error err = UTF8_OK;
+
+        const utfchar16_t first_word = *it++;
+        if (!is_surrogate(first_word)) {
+            code_point = first_word;
+            return UTF8_OK;
+        }
+        else {
+            if (it == end)
+                err = NOT_ENOUGH_ROOM;
+            else if (is_lead_surrogate(first_word)) {
+                const utfchar16_t second_word = *it++;
+                if (is_trail_surrogate(second_word)) {
+                    code_point = (first_word << 10) + second_word + SURROGATE_OFFSET;
+                    return UTF8_OK;
+                } else 
+                    err = INCOMPLETE_SEQUENCE; 
+                
+            } else {
+                err = INVALID_LEAD;               
+            }
+        }
+        // error branch
+        it = original_it;
+        return err;
+    }
+
+    // Internal implementation of both checked and unchecked append() function
+    // This function will be invoked by the overloads below, as they will know
+    // the octet_type.
+    template <typename octet_iterator, typename octet_type>
+    octet_iterator append(utfchar32_t cp, octet_iterator result) {
+        if (cp < 0x80)                        // one octet
+            *(result++) = static_cast<octet_type>(cp);
+        else if (cp < 0x800) {                // two octets
+            *(result++) = static_cast<octet_type>((cp >> 6)          | 0xc0);
+            *(result++) = static_cast<octet_type>((cp & 0x3f)        | 0x80);
+        }
+        else if (cp < 0x10000) {              // three octets
+            *(result++) = static_cast<octet_type>((cp >> 12)         | 0xe0);
+            *(result++) = static_cast<octet_type>(((cp >> 6) & 0x3f) | 0x80);
+            *(result++) = static_cast<octet_type>((cp & 0x3f)        | 0x80);
+        }
+        else {                                // four octets
+            *(result++) = static_cast<octet_type>((cp >> 18)         | 0xf0);
+            *(result++) = static_cast<octet_type>(((cp >> 12) & 0x3f)| 0x80);
+            *(result++) = static_cast<octet_type>(((cp >> 6) & 0x3f) | 0x80);
+            *(result++) = static_cast<octet_type>((cp & 0x3f)        | 0x80);
+        }
+        return result;
+    }
+    
+    // One of the following overloads will be invoked from the API calls
+
+    // A simple (but dangerous) case: the caller appends byte(s) to a char array
+    inline char* append(utfchar32_t cp, char* result) {
+        return append<char*, char>(cp, result);
+    }
+
+    // Hopefully, most common case: the caller uses back_inserter
+    // i.e. append(cp, std::back_inserter(str));
+    template<typename container_type>
+    std::back_insert_iterator<container_type> append
+            (utfchar32_t cp, std::back_insert_iterator<container_type> result) {
+        return append<std::back_insert_iterator<container_type>,
+            typename container_type::value_type>(cp, result);
+    }
+
+    // The caller uses some other kind of output operator - not covered above
+    // Note that in this case we are not able to determine octet_type
+    // so we assume it's utfchar8_t; that can cause a conversion warning if we are wrong.
+    template <typename octet_iterator>
+    octet_iterator append(utfchar32_t cp, octet_iterator result) {
+        return append<octet_iterator, utfchar8_t>(cp, result);
+    }
+
+    // Internal implementation of both checked and unchecked append16() function
+    // This function will be invoked by the overloads below, as they will know
+    // the word_type.
+    template <typename word_iterator, typename word_type>
+    word_iterator append16(utfchar32_t cp, word_iterator result) {
+        if (is_in_bmp(cp))
+            *(result++) = static_cast<word_type>(cp);
+        else {
+            // Code points from the supplementary planes are encoded via surrogate pairs
+            *(result++) = static_cast<word_type>(LEAD_OFFSET + (cp >> 10));
+            *(result++) = static_cast<word_type>(TRAIL_SURROGATE_MIN + (cp & 0x3FF));
+        }
+        return result;
+    }
+
+    // Hopefully, most common case: the caller uses back_inserter
+    // i.e. append16(cp, std::back_inserter(str));
+    template<typename container_type>
+    std::back_insert_iterator<container_type> append16
+            (utfchar32_t cp, std::back_insert_iterator<container_type> result) {
+        return append16<std::back_insert_iterator<container_type>,
+            typename container_type::value_type>(cp, result);
+    }
+
+    // The caller uses some other kind of output operator - not covered above
+    // Note that in this case we are not able to determine word_type
+    // so we assume it's utfchar16_t; that can cause a conversion warning if we are wrong.
+    template <typename word_iterator>
+    word_iterator append16(utfchar32_t cp, word_iterator result) {
+        return append16<word_iterator, utfchar16_t>(cp, result);
+    }
+
 } // namespace internal
 
     /// The library API - functions intended to be called by the users
 
     // Byte order mark
-    const uint8_t bom[] = {0xef, 0xbb, 0xbf};
+    const utfchar8_t bom[] = {0xef, 0xbb, 0xbf};
 
     template <typename octet_iterator>
     octet_iterator find_invalid(octet_iterator start, octet_iterator end)
@@ -296,12 +441,36 @@ namespace internal
         return result;
     }
 
+    inline const char* find_invalid(const char* str)
+    {
+        const char* end = str + std::strlen(str);
+        return find_invalid(str, end); 
+    }
+
+    inline std::size_t find_invalid(const std::string& s)
+    {
+        std::string::const_iterator invalid = find_invalid(s.begin(), s.end());
+        return (invalid == s.end()) ? std::string::npos : static_cast<std::size_t>(invalid - s.begin());
+    }
+
     template <typename octet_iterator>
     inline bool is_valid(octet_iterator start, octet_iterator end)
     {
         return (utf8::find_invalid(start, end) == end);
     }
 
+    inline bool is_valid(const char* str)
+    {
+        return (*(utf8::find_invalid(str)) == '\0');
+    }
+
+    inline bool is_valid(const std::string& s)
+    {
+        return is_valid(s.begin(), s.end());
+    }
+
+
+
     template <typename octet_iterator>
     inline bool starts_with_bom (octet_iterator it, octet_iterator end)
     {
@@ -311,17 +480,11 @@ namespace internal
             ((it != end) && (utf8::internal::mask8(*it))   == bom[2])
            );
     }
-	
-    //Deprecated in release 2.3 
-    template <typename octet_iterator>
-    inline bool is_bom (octet_iterator it)
+
+    inline bool starts_with_bom(const std::string& s)
     {
-        return (
-            (utf8::internal::mask8(*it++)) == bom[0] &&
-            (utf8::internal::mask8(*it++)) == bom[1] &&
-            (utf8::internal::mask8(*it))   == bom[2]
-           );
-    }
+        return starts_with_bom(s.begin(), s.end());
+    } 
 } // namespace utf8
 
 #endif // header guard
diff --git a/lib/charset/utf8/cpp11.h b/lib/charset/utf8/cpp11.h
new file mode 100644
index 0000000..691633c
--- /dev/null
+++ b/lib/charset/utf8/cpp11.h
@@ -0,0 +1,70 @@
+// Copyright 2018 Nemanja Trifunovic
+
+/*
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+#ifndef UTF8_FOR_CPP_a184c22c_d012_11e8_a8d5_f2801f1b9fd1
+#define UTF8_FOR_CPP_a184c22c_d012_11e8_a8d5_f2801f1b9fd1
+
+#include "checked.h"
+
+namespace utf8
+{
+    inline void append16(utfchar32_t cp, std::u16string& s)
+    {
+        append16(cp, std::back_inserter(s));
+    }
+
+    inline std::string utf16to8(const std::u16string& s)
+    {
+        std::string result;
+        utf16to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u16string utf8to16(const std::string& s)
+    {
+        std::u16string result;
+        utf8to16(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::string utf32to8(const std::u32string& s)
+    {
+        std::string result;
+        utf32to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u32string utf8to32(const std::string& s)
+    {
+        std::u32string result;
+        utf8to32(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+} // namespace utf8
+
+#endif // header guard
+
diff --git a/lib/charset/utf8/cpp17.h b/lib/charset/utf8/cpp17.h
new file mode 100644
index 0000000..6e2fcc2
--- /dev/null
+++ b/lib/charset/utf8/cpp17.h
@@ -0,0 +1,96 @@
+// Copyright 2018 Nemanja Trifunovic
+
+/*
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+#ifndef UTF8_FOR_CPP_7e906c01_03a3_4daf_b420_ea7ea952b3c9
+#define UTF8_FOR_CPP_7e906c01_03a3_4daf_b420_ea7ea952b3c9
+
+#include "cpp11.h"
+
+namespace utf8
+{
+    inline std::string utf16to8(std::u16string_view s)
+    {
+        std::string result;
+        utf16to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u16string utf8to16(std::string_view s)
+    {
+        std::u16string result;
+        utf8to16(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::string utf32to8(std::u32string_view s)
+    {
+        std::string result;
+        utf32to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u32string utf8to32(std::string_view s)
+    {
+        std::u32string result;
+        utf8to32(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::size_t find_invalid(std::string_view s)
+    {
+        std::string_view::const_iterator invalid = find_invalid(s.begin(), s.end());
+        return (invalid == s.end()) ? std::string_view::npos : static_cast<std::size_t>(invalid - s.begin());
+    }
+
+    inline bool is_valid(std::string_view s)
+    {
+        return is_valid(s.begin(), s.end());
+    }
+
+    inline std::string replace_invalid(std::string_view s, char32_t replacement)
+    {
+        std::string result;
+        replace_invalid(s.begin(), s.end(), std::back_inserter(result), replacement);
+        return result;
+    }
+
+    inline std::string replace_invalid(std::string_view s)
+    {
+        std::string result;
+        replace_invalid(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline bool starts_with_bom(std::string_view s)
+    {
+        return starts_with_bom(s.begin(), s.end());
+    }
+ 
+} // namespace utf8
+
+#endif // header guard
+
diff --git a/lib/charset/utf8/cpp20.h b/lib/charset/utf8/cpp20.h
new file mode 100644
index 0000000..07b61d0
--- /dev/null
+++ b/lib/charset/utf8/cpp20.h
@@ -0,0 +1,124 @@
+// Copyright 2022 Nemanja Trifunovic
+
+/*
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+#ifndef UTF8_FOR_CPP_207e906c01_03a3_4daf_b420_ea7ea952b3c9
+#define UTF8_FOR_CPP_207e906c01_03a3_4daf_b420_ea7ea952b3c9
+
+#include "cpp17.h"
+
+namespace utf8
+{
+    inline std::u8string utf16tou8(const std::u16string& s)
+    {
+        std::u8string result;
+        utf16to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u8string utf16tou8(std::u16string_view s)
+    {
+        std::u8string result;
+        utf16to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u16string utf8to16(const std::u8string& s)
+    {
+        std::u16string result;
+        utf8to16(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u16string utf8to16(const std::u8string_view& s)
+    {
+        std::u16string result;
+        utf8to16(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u8string utf32tou8(const std::u32string& s)
+    {
+        std::u8string result;
+        utf32to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u8string utf32tou8(const std::u32string_view& s)
+    {
+        std::u8string result;
+        utf32to8(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u32string utf8to32(const std::u8string& s)
+    {
+        std::u32string result;
+        utf8to32(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::u32string utf8to32(const std::u8string_view& s)
+    {
+        std::u32string result;
+        utf8to32(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline std::size_t find_invalid(const std::u8string& s)
+    {
+        std::u8string::const_iterator invalid = find_invalid(s.begin(), s.end());
+        return (invalid == s.end()) ? std::string_view::npos : static_cast<std::size_t>(invalid - s.begin());
+    }
+
+    inline bool is_valid(const std::u8string& s)
+    {
+        return is_valid(s.begin(), s.end());
+    }
+
+    inline std::u8string replace_invalid(const std::u8string& s, char32_t replacement)
+    {
+        std::u8string result;
+        replace_invalid(s.begin(), s.end(), std::back_inserter(result), replacement);
+        return result;
+    }
+
+    inline std::u8string replace_invalid(const std::u8string& s)
+    {
+        std::u8string result;
+        replace_invalid(s.begin(), s.end(), std::back_inserter(result));
+        return result;
+    }
+
+    inline bool starts_with_bom(const std::u8string& s)
+    {
+        return starts_with_bom(s.begin(), s.end());
+    }
+ 
+} // namespace utf8
+
+#endif // header guard
+
diff --git a/lib/charset/utf8/unchecked.h b/lib/charset/utf8/unchecked.h
index cb24271..65d4948 100644
--- a/lib/charset/utf8/unchecked.h
+++ b/lib/charset/utf8/unchecked.h
@@ -32,37 +32,79 @@ DEALINGS IN THE SOFTWARE.
 
 namespace utf8
 {
-    namespace unchecked 
+    namespace unchecked
     {
         template <typename octet_iterator>
-        octet_iterator append(uint32_t cp, octet_iterator result)
+        octet_iterator append(utfchar32_t cp, octet_iterator result)
         {
-            if (cp < 0x80)                        // one octet
-                *(result++) = static_cast<uint8_t>(cp);  
-            else if (cp < 0x800) {                // two octets
-                *(result++) = static_cast<uint8_t>((cp >> 6)          | 0xc0);
-                *(result++) = static_cast<uint8_t>((cp & 0x3f)        | 0x80);
-            }
-            else if (cp < 0x10000) {              // three octets
-                *(result++) = static_cast<uint8_t>((cp >> 12)         | 0xe0);
-                *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f) | 0x80);
-                *(result++) = static_cast<uint8_t>((cp & 0x3f)        | 0x80);
-            }
-            else {                                // four octets
-                *(result++) = static_cast<uint8_t>((cp >> 18)         | 0xf0);
-                *(result++) = static_cast<uint8_t>(((cp >> 12) & 0x3f)| 0x80);
-                *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f) | 0x80);
-                *(result++) = static_cast<uint8_t>((cp & 0x3f)        | 0x80);
+            return internal::append(cp, result);
+        }
+
+        template <typename word_iterator>
+        word_iterator append16(utfchar32_t cp, word_iterator result)
+        {
+            return internal::append16(cp, result);
+        }
+
+        template <typename octet_iterator, typename output_iterator>
+        output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out, utfchar32_t replacement)
+        {
+            while (start != end) {
+                octet_iterator sequence_start = start;
+                internal::utf_error err_code = utf8::internal::validate_next(start, end);
+                switch (err_code) {
+                    case internal::UTF8_OK :
+                        for (octet_iterator it = sequence_start; it != start; ++it)
+                            *out++ = *it;
+                        break;
+                    case internal::NOT_ENOUGH_ROOM:
+                        out = utf8::unchecked::append(replacement, out);
+                        start = end;
+                        break;
+                    case internal::INVALID_LEAD:
+                        out = utf8::unchecked::append(replacement, out);
+                        ++start;
+                        break;
+                    case internal::INCOMPLETE_SEQUENCE:
+                    case internal::OVERLONG_SEQUENCE:
+                    case internal::INVALID_CODE_POINT:
+                        out = utf8::unchecked::append(replacement, out);
+                        ++start;
+                        // just one replacement mark for the sequence
+                        while (start != end && utf8::internal::is_trail(*start))
+                            ++start;
+                        break;
+                }
             }
+            return out;
+        }
+
+        template <typename octet_iterator, typename output_iterator>
+        inline output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out)
+        {
+            static const utfchar32_t replacement_marker = utf8::internal::mask16(0xfffd);
+            return utf8::unchecked::replace_invalid(start, end, out, replacement_marker);
+        }
+
+        inline std::string replace_invalid(const std::string& s, utfchar32_t replacement)
+        {
+            std::string result;
+            replace_invalid(s.begin(), s.end(), std::back_inserter(result), replacement);
+            return result;
+        }
+
+        inline std::string replace_invalid(const std::string& s)
+        {
+            std::string result;
+            replace_invalid(s.begin(), s.end(), std::back_inserter(result));
             return result;
         }
 
         template <typename octet_iterator>
-        uint32_t next(octet_iterator& it)
+        utfchar32_t next(octet_iterator& it)
         {
-            uint32_t cp = utf8::internal::mask8(*it);
-            typename std::iterator_traits<octet_iterator>::difference_type length = utf8::internal::sequence_length(it);
-            switch (length) {
+            utfchar32_t cp = utf8::internal::mask8(*it);
+            switch (utf8::internal::sequence_length(it)) {
                 case 1:
                     break;
                 case 2:
@@ -85,40 +127,50 @@ namespace utf8
                     break;
             }
             ++it;
-            return cp;        
+            return cp;
         }
 
         template <typename octet_iterator>
-        uint32_t peek_next(octet_iterator it)
+        utfchar32_t peek_next(octet_iterator it)
         {
-            return utf8::unchecked::next(it);    
+            return utf8::unchecked::next(it);
         }
 
-        template <typename octet_iterator>
-        uint32_t prior(octet_iterator& it)
+        template <typename word_iterator>
+        utfchar32_t next16(word_iterator& it)
         {
-            while (utf8::internal::is_trail(*(--it))) ;
-            octet_iterator temp = it;
-            return utf8::unchecked::next(temp);
+            utfchar32_t cp = utf8::internal::mask16(*it++);
+            if (utf8::internal::is_lead_surrogate(cp))
+                return (cp << 10) + *it++ + utf8::internal::SURROGATE_OFFSET;
+            return cp;
         }
 
-        // Deprecated in versions that include prior, but only for the sake of consistency (see utf8::previous)
         template <typename octet_iterator>
-        inline uint32_t previous(octet_iterator& it)
+        utfchar32_t prior(octet_iterator& it)
         {
-            return utf8::unchecked::prior(it);
+            while (utf8::internal::is_trail(*(--it))) ;
+            octet_iterator temp = it;
+            return utf8::unchecked::next(temp);
         }
 
         template <typename octet_iterator, typename distance_type>
-        void advance (octet_iterator& it, distance_type n)
+        void advance(octet_iterator& it, distance_type n)
         {
-            for (distance_type i = 0; i < n; ++i)
-                utf8::unchecked::next(it);
+            const distance_type zero(0);
+            if (n < zero) {
+                // backward
+                for (distance_type i = n; i < zero; ++i)
+                    utf8::unchecked::prior(it);
+            } else {
+                // forward
+                for (distance_type i = zero; i < n; ++i)
+                    utf8::unchecked::next(it);
+            }
         }
 
         template <typename octet_iterator>
         typename std::iterator_traits<octet_iterator>::difference_type
-        distance (octet_iterator first, octet_iterator last)
+        distance(octet_iterator first, octet_iterator last)
         {
             typename std::iterator_traits<octet_iterator>::difference_type dist;
             for (dist = 0; first < last; ++dist) 
@@ -127,37 +179,39 @@ namespace utf8
         }
 
         template <typename u16bit_iterator, typename octet_iterator>
-        octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result)
-        {       
+        octet_iterator utf16to8(u16bit_iterator start, u16bit_iterator end, octet_iterator result)
+        {
             while (start != end) {
-                uint32_t cp = utf8::internal::mask16(*start++);
-            // Take care of surrogate pairs first
+                utfchar32_t cp = utf8::internal::mask16(*start++);
+                // Take care of surrogate pairs first
                 if (utf8::internal::is_lead_surrogate(cp)) {
-                    uint32_t trail_surrogate = utf8::internal::mask16(*start++);
+                    if (start == end)
+                        return result;
+                    utfchar32_t trail_surrogate = utf8::internal::mask16(*start++);
                     cp = (cp << 10) + trail_surrogate + internal::SURROGATE_OFFSET;
                 }
                 result = utf8::unchecked::append(cp, result);
             }
-            return result;         
+            return result;
         }
 
         template <typename u16bit_iterator, typename octet_iterator>
-        u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result)
+        u16bit_iterator utf8to16(octet_iterator start, octet_iterator end, u16bit_iterator result)
         {
             while (start < end) {
-                uint32_t cp = utf8::unchecked::next(start);
+                utfchar32_t cp = utf8::unchecked::next(start);
                 if (cp > 0xffff) { //make a surrogate pair
-                    *result++ = static_cast<uint16_t>((cp >> 10)   + internal::LEAD_OFFSET);
-                    *result++ = static_cast<uint16_t>((cp & 0x3ff) + internal::TRAIL_SURROGATE_MIN);
+                    *result++ = static_cast<utfchar16_t>((cp >> 10)   + internal::LEAD_OFFSET);
+                    *result++ = static_cast<utfchar16_t>((cp & 0x3ff) + internal::TRAIL_SURROGATE_MIN);
                 }
                 else
-                    *result++ = static_cast<uint16_t>(cp);
+                    *result++ = static_cast<utfchar16_t>(cp);
             }
             return result;
         }
 
         template <typename octet_iterator, typename u32bit_iterator>
-        octet_iterator utf32to8 (u32bit_iterator start, u32bit_iterator end, octet_iterator result)
+        octet_iterator utf32to8(u32bit_iterator start, u32bit_iterator end, octet_iterator result)
         {
             while (start != end)
                 result = utf8::unchecked::append(*(start++), result);
@@ -166,7 +220,7 @@ namespace utf8
         }
 
         template <typename octet_iterator, typename u32bit_iterator>
-        u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result)
+        u32bit_iterator utf8to32(octet_iterator start, octet_iterator end, u32bit_iterator result)
         {
             while (start < end)
                 (*result++) = utf8::unchecked::next(start);
@@ -176,14 +230,19 @@ namespace utf8
 
         // The iterator class
         template <typename octet_iterator>
-          class iterator : public std::iterator <std::bidirectional_iterator_tag, uint32_t> { 
+          class iterator {
             octet_iterator it;
             public:
+            typedef utfchar32_t value_type;
+            typedef utfchar32_t* pointer;
+            typedef utfchar32_t& reference;
+            typedef std::ptrdiff_t difference_type;
+            typedef std::bidirectional_iterator_tag iterator_category;
             iterator () {}
             explicit iterator (const octet_iterator& octet_it): it(octet_it) {}
             // the default "big three" are OK
             octet_iterator base () const { return it; }
-            uint32_t operator * () const
+            utfchar32_t operator * () const
             {
                 octet_iterator temp = it;
                 return utf8::unchecked::next(temp);