Imported Upstream version 1.51.0upstream/1.51.0

3 files changed, 609 insertions, 40 deletions

diff --git a/boost/detail/container_fwd.hpp b/boost/detail/container_fwd.hpp
index 7df7ccbb94..ef17498063 100644
--- a/boost/detail/container_fwd.hpp
+++ b/boost/detail/container_fwd.hpp
@@ -21,10 +21,17 @@
 // Define BOOST_DETAIL_NO_CONTAINER_FWD if you don't want this header to      //
 // forward declare standard containers.                                       //
 //                                                                            //
+// BOOST_DETAIL_CONTAINER_FWD to make it foward declare containers even if it //
+// normally doesn't.                                                          //
+//                                                                            //
+// BOOST_DETAIL_NO_CONTAINER_FWD overrides BOOST_DETAIL_CONTAINER_FWD.        //
+//                                                                            //
 ////////////////////////////////////////////////////////////////////////////////
 
 #if !defined(BOOST_DETAIL_NO_CONTAINER_FWD)
-#  if defined(__SGI_STL_PORT) || defined(_STLPORT_VERSION)
+#  if defined(BOOST_DETAIL_CONTAINER_FWD)
+     // Force forward declarations.
+#  elif defined(__SGI_STL_PORT) || defined(_STLPORT_VERSION)
      // STLport
 #    define BOOST_DETAIL_NO_CONTAINER_FWD
 #  elif defined(__LIBCOMO__)
@@ -76,11 +83,6 @@
 #  endif
 #endif
 
-// BOOST_DETAIL_TEST_* macros are for testing only
-// and shouldn't be relied upon. But you can use
-// BOOST_DETAIL_NO_CONTAINER_FWD to prevent forward
-// declaration of containers.
-
 #if !defined(BOOST_DETAIL_TEST_CONFIG_ONLY)
 
 #if defined(BOOST_DETAIL_NO_CONTAINER_FWD) && \
@@ -118,6 +120,7 @@ namespace std
     template <class charT, class traits, class Allocator> class basic_string;
 
 #if BOOST_WORKAROUND(__GNUC__, < 3) && !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION)
+
     template <class charT> struct string_char_traits;
 #else
     template <class charT> struct char_traits;
diff --git a/boost/detail/scoped_enum_emulation.hpp b/boost/detail/scoped_enum_emulation.hpp
index e695a20857..80394cf433 100644
--- a/boost/detail/scoped_enum_emulation.hpp
+++ b/boost/detail/scoped_enum_emulation.hpp
@@ -1,56 +1,337 @@
 //  scoped_enum_emulation.hpp  ---------------------------------------------------------//
 
 //  Copyright Beman Dawes, 2009
+//  Copyright (C) 2011-2012 Vicente J. Botet Escriba
+//  Copyright (C) 2012 Anthony Williams
 
 //  Distributed under the Boost Software License, Version 1.0.
 //  See http://www.boost.org/LICENSE_1_0.txt
 
-//  Generates C++0x scoped enums if the feature is present, otherwise emulates C++0x
-//  scoped enums with C++03 namespaces and enums. The Boost.Config BOOST_NO_SCOPED_ENUMS
-//  macro is used to detect feature support.
-//
-//  See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a
-//  description of the scoped enum feature. Note that the committee changed the name
-//  from strongly typed enum to scoped enum.  
-//
-//  Caution: only the syntax is emulated; the semantics are not emulated and
-//  the syntax emulation doesn't include being able to specify the underlying
-//  representation type.
-//
-//  The emulation is via struct rather than namespace to allow use within classes.
-//  Thanks to Andrey Semashev for pointing that out.
-//
-//  Helpful comments and suggestions were also made by Kjell Elster, Phil Endecott,
-//  Joel Falcou, Mathias Gaunard, Felipe Magno de Almeida, Matt Calabrese, Vincente
-//  Botet, and Daniel James. 
-//
-//  Sample usage:
-//
-//     BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END
-//     ...
-//     BOOST_SCOPED_ENUM(algae) sample( algae::red );
-//     void foo( BOOST_SCOPED_ENUM(algae) color );
-//     ...
-//     sample = algae::green;
-//     foo( algae::cyan );
+/*
+[section:scoped_enums Scoped Enums]
+
+Generates C++0x scoped enums if the feature is present, otherwise emulates C++0x
+scoped enums with C++03 namespaces and enums. The Boost.Config BOOST_NO_SCOPED_ENUMS
+macro is used to detect feature support.
+
+See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a
+description of the scoped enum feature. Note that the committee changed the name
+from strongly typed enum to scoped enum.
+
+Some of the enumerations defined in the standard library are scoped enums.
+
+  enum class future_errc
+  {
+      broken_promise,
+      future_already_retrieved,
+      promise_already_satisfied,
+      no_state
+  };
+
+On compilers that don't support them, the library provides two emulations:
+
+[heading Strict]
+
+* Able to specify the underlying type.
+* explicit conversion to/from underlying type.
+* The wrapper is not a C++03 enum type.
+
+The user can declare  declare these types as
+
+  BOOST_SCOPED_ENUM_DECLARE_BEGIN(future_errc)
+  {
+      broken_promise,
+      future_already_retrieved,
+      promise_already_satisfied,
+      no_state
+  }
+  BOOST_SCOPED_ENUM_DECLARE_END(future_errc)
+
+These macros allows to use 'future_errc' in almost all the cases as an scoped enum.
+
+  future_errc err = future_errc::no_state;
+
+There are however some limitations:
+
+* The type is not a C++ enum, so 'is_enum<future_errc>' will be false_type.
+* The emulated scoped enum can not be used in switch nor in template arguments. For these cases the user needs to use some macros.
+
+Instead of
+
+        switch (ev)
+        {
+        case future_errc::broken_promise:
+  // ...
+
+use
+
+        switch (boost::native_value(ev))
+        {
+        case future_errc::broken_promise:
+
+And instead of
+
+    #ifdef BOOST_NO_SCOPED_ENUMS
+    template <>
+    struct BOOST_SYMBOL_VISIBLE is_error_code_enum<future_errc> : public true_type { };
+    #endif
+
+use
+
+    #ifdef BOOST_NO_SCOPED_ENUMS
+    template <>
+    struct BOOST_SYMBOL_VISIBLE is_error_code_enum<future_errc::enum_type > : public true_type { };
+    #endif
+
+
+Sample usage:
+
+     BOOST_SCOPED_ENUM_UT_DECLARE_BEGIN(algae, char) { green, red, cyan }; BOOST_SCOPED_ENUM_DECLARE_END(algae)
+     ...
+     algae sample( algae::red );
+     void foo( algae color );
+     ...
+     sample = algae::green;
+     foo( algae::cyan );
+
+ Light
+  Caution: only the syntax is emulated; the semantics are not emulated and
+  the syntax emulation doesn't include being able to specify the underlying
+  representation type.
+
+  The literal scoped emulation is via struct rather than namespace to allow use within classes.
+  Thanks to Andrey Semashev for pointing that out.
+  However the type is an real C++03 enum and so convertible implicitly to an int.
+
+  Sample usage:
+
+     BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END
+     ...
+     BOOST_SCOPED_ENUM(algae) sample( algae::red );
+     void foo( BOOST_SCOPED_ENUM(algae) color );
+     ...
+     sample = algae::green;
+     foo( algae::cyan );
+
+  Helpful comments and suggestions were also made by Kjell Elster, Phil Endecott,
+  Joel Falcou, Mathias Gaunard, Felipe Magno de Almeida, Matt Calabrese, Vicente
+  Botet, and Daniel James.
+
+[endsect]
+*/
+
 
 #ifndef BOOST_SCOPED_ENUM_EMULATION_HPP
 #define BOOST_SCOPED_ENUM_EMULATION_HPP
 
 #include <boost/config.hpp>
+#include <boost/detail/workaround.hpp>
+
+namespace boost
+{
 
 #ifdef BOOST_NO_SCOPED_ENUMS
+  /**
+   * Meta-function to get the underlying type of a scoped enum.
+   *
+   * Requires EnumType must be an enum type or the emulation of a scoped enum
+   */
+  template <typename EnumType>
+  struct underlying_type
+  {
+    /**
+     * The member typedef type names the underlying type of EnumType. It is EnumType::underlying_type when the EnumType is an emulated scoped enum,
+     * std::underlying_type<EnumType>::type when the standard library std::underlying_type is provided.
+     *
+     * The user will need to specialize it when the compiler supports scoped enums but don't provides std::underlying_type.
+     */
+    typedef typename EnumType::underlying_type type;
+  };
+
+  /**
+   * Meta-function to get the native enum type associated to an enum class or its emulation.
+   */
+  template <typename EnumType>
+  struct native_type
+  {
+    /**
+     * The member typedef type names the native enum type associated to the scoped enum,
+     * which is it self if the compiler supports scoped enums or EnumType::enum_type if it is an emulated scoped enum.
+     */
+    typedef typename EnumType::enum_type type;
+  };
+
+  /**
+   * Casts a scoped enum to its underlying type.
+   *
+   * This function is useful when working with scoped enum classes, which doens't implicitly convert to the underlying type.
+   * @param v A scoped enum.
+   * @returns The underlying type.
+   * @throws No-throws.
+   */
+  template <typename UnderlyingType, typename EnumType>
+  UnderlyingType underlying_cast(EnumType v)
+  {
+    return v.get_underlying_value_();
+  }
+
+  /**
+   * Casts a scoped enum to its native enum type.
+   *
+   * This function is useful to make programs portable when the scoped enum emulation can not be use where native enums can.
+   *
+   * EnumType the scoped enum type
+   *
+   * @param v A scoped enum.
+   * @returns The native enum value.
+   * @throws No-throws.
+   */
+  template <typename EnumType>
+  inline
+  typename EnumType::enum_type native_value(EnumType e)
+  {
+    return e.native_value_();
+  }
+
+#else  // BOOST_NO_SCOPED_ENUMS
 
-# define BOOST_SCOPED_ENUM_START(name) struct name { enum enum_type
-# define BOOST_SCOPED_ENUM_END };
-# define BOOST_SCOPED_ENUM(name) name::enum_type
+  template <typename EnumType>
+  struct underlying_type
+  {
+    //typedef typename std::underlying_type<EnumType>::type type;
+  };
+
+  template <typename EnumType>
+  struct native_type
+  {
+    typedef EnumType type;
+  };
+
+  template <typename UnderlyingType, typename EnumType>
+  UnderlyingType underlying_cast(EnumType v)
+  {
+    return static_cast<UnderlyingType>(v);
+  }
+
+  template <typename EnumType>
+  inline
+  EnumType native_value(EnumType e)
+  {
+    return e;
+ }
+
+#endif
+}
+
+
+#ifdef BOOST_NO_SCOPED_ENUMS
+
+#ifndef BOOST_NO_EXPLICIT_CONVERSION_OPERATORS
+
+#define BOOST_SCOPED_ENUM_UT_DECLARE_CONVERSION_OPERATOR \
+     explicit operator underlying_type() const { return get_underlying_value_(); }
 
 #else
 
-# define BOOST_SCOPED_ENUM_START(name) enum class name
-# define BOOST_SCOPED_ENUM_END
-# define BOOST_SCOPED_ENUM(name) name
+#define BOOST_SCOPED_ENUM_UT_DECLARE_CONVERSION_OPERATOR
 
 #endif
 
+/**
+ * Start a declaration of a scoped enum.
+ *
+ * @param EnumType The new scoped enum.
+ * @param UnderlyingType The underlying type.
+ */
+#define BOOST_SCOPED_ENUM_UT_DECLARE_BEGIN(EnumType, UnderlyingType)    \
+    struct EnumType {                                                   \
+        typedef UnderlyingType underlying_type;                         \
+        EnumType() BOOST_NOEXCEPT {}                                    \
+        explicit EnumType(underlying_type v) : v_(v) {}                 \
+        underlying_type get_underlying_value_() const { return v_; }               \
+        BOOST_SCOPED_ENUM_UT_DECLARE_CONVERSION_OPERATOR                \
+    private:                                                            \
+        underlying_type v_;                                             \
+        typedef EnumType self_type;                                     \
+    public:                                                             \
+        enum enum_type
+
+#define BOOST_SCOPED_ENUM_DECLARE_END2() \
+        enum_type get_native_value_() const BOOST_NOEXCEPT { return enum_type(v_); } \
+        operator enum_type() const BOOST_NOEXCEPT { return get_native_value_(); } \
+        friend bool operator ==(self_type lhs, self_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)==enum_type(rhs.v_); } \
+        friend bool operator ==(self_type lhs, enum_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)==rhs; } \
+        friend bool operator ==(enum_type lhs, self_type rhs) BOOST_NOEXCEPT { return lhs==enum_type(rhs.v_); } \
+        friend bool operator !=(self_type lhs, self_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)!=enum_type(rhs.v_); } \
+        friend bool operator !=(self_type lhs, enum_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)!=rhs; } \
+        friend bool operator !=(enum_type lhs, self_type rhs) BOOST_NOEXCEPT { return lhs!=enum_type(rhs.v_); } \
+        friend bool operator <(self_type lhs, self_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)<enum_type(rhs.v_); } \
+        friend bool operator <(self_type lhs, enum_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)<rhs; } \
+        friend bool operator <(enum_type lhs, self_type rhs) BOOST_NOEXCEPT { return lhs<enum_type(rhs.v_); } \
+        friend bool operator <=(self_type lhs, self_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)<=enum_type(rhs.v_); } \
+        friend bool operator <=(self_type lhs, enum_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)<=rhs; } \
+        friend bool operator <=(enum_type lhs, self_type rhs) BOOST_NOEXCEPT { return lhs<=enum_type(rhs.v_); } \
+        friend bool operator >(self_type lhs, self_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)>enum_type(rhs.v_); } \
+        friend bool operator >(self_type lhs, enum_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)>rhs; } \
+        friend bool operator >(enum_type lhs, self_type rhs) BOOST_NOEXCEPT { return lhs>enum_type(rhs.v_); } \
+        friend bool operator >=(self_type lhs, self_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)>=enum_type(rhs.v_); } \
+        friend bool operator >=(self_type lhs, enum_type rhs) BOOST_NOEXCEPT { return enum_type(lhs.v_)>=rhs; } \
+        friend bool operator >=(enum_type lhs, self_type rhs) BOOST_NOEXCEPT { return lhs>=enum_type(rhs.v_); } \
+    };
+
+#define BOOST_SCOPED_ENUM_DECLARE_END(EnumType) \
+    ; \
+    EnumType(enum_type v) BOOST_NOEXCEPT : v_(v) {}                 \
+    BOOST_SCOPED_ENUM_DECLARE_END2()
+
+/**
+ * Starts a declaration of a scoped enum with the default int underlying type.
+ *
+ * @param EnumType The new scoped enum.
+ */
+#define BOOST_SCOPED_ENUM_DECLARE_BEGIN(EnumType) \
+  BOOST_SCOPED_ENUM_UT_DECLARE_BEGIN(EnumType,int)
+
+/**
+ * Name of the native enum type.
+ *
+ * @param NT The new scoped enum.
+ */
+#define BOOST_SCOPED_ENUM_NATIVE(EnumType) EnumType::enum_type
+/**
+ * Forward declares an scoped enum.
+ *
+ * @param NT The scoped enum.
+ */
+#define BOOST_SCOPED_ENUM_FORWARD_DECLARE(EnumType) struct EnumType
+
+#else  // BOOST_NO_SCOPED_ENUMS
+
+#define BOOST_SCOPED_ENUM_UT_DECLARE_BEGIN(EnumType,UnderlyingType) enum class EnumType:UnderlyingType
+#define BOOST_SCOPED_ENUM_DECLARE_BEGIN(EnumType) enum class EnumType
+#define BOOST_SCOPED_ENUM_DECLARE_END2()
+#define BOOST_SCOPED_ENUM_DECLARE_END(EnumType) ;
+
+#define BOOST_SCOPED_ENUM_NATIVE(EnumType) EnumType
+#define BOOST_SCOPED_ENUM_FORWARD_DECLARE(EnumType) enum class EnumType
+
+#endif  // BOOST_NO_SCOPED_ENUMS
+
+#define BOOST_SCOPED_ENUM_START(name) BOOST_SCOPED_ENUM_DECLARE_BEGIN(name)
+#define BOOST_SCOPED_ENUM_END BOOST_SCOPED_ENUM_DECLARE_END2()
+#define BOOST_SCOPED_ENUM(name) BOOST_SCOPED_ENUM_NATIVE(name)
+
+//#ifdef BOOST_NO_SCOPED_ENUMS
+//
+//# define BOOST_SCOPED_ENUM_START(name) struct name { enum enum_type
+//# define BOOST_SCOPED_ENUM_END };
+//# define BOOST_SCOPED_ENUM(name) name::enum_type
+//
+//#else
+//
+//# define BOOST_SCOPED_ENUM_START(name) enum class name
+//# define BOOST_SCOPED_ENUM_END
+//# define BOOST_SCOPED_ENUM(name) name
+//
+//#endif
 #endif  // BOOST_SCOPED_ENUM_EMULATION_HPP
diff --git a/boost/detail/utf8_codecvt_facet.ipp b/boost/detail/utf8_codecvt_facet.ipp
new file mode 100644
index 0000000000..064fdaf58e
--- /dev/null
+++ b/boost/detail/utf8_codecvt_facet.ipp
@@ -0,0 +1,285 @@
+/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
+// utf8_codecvt_facet.ipp
+
+// Copyright (c) 2001 Ronald Garcia, Indiana University (garcia@osl.iu.edu)
+// Andrew Lumsdaine, Indiana University (lums@osl.iu.edu). 
+// Use, modification and distribution is subject to 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)
+
+// Please see the comments in <boost/detail/utf8_codecvt_facet.hpp> to
+// learn how this file should be used.
+
+#include <boost/detail/utf8_codecvt_facet.hpp>
+
+#include <cstdlib> // for multi-byte converson routines
+#include <cassert>
+
+#include <boost/limits.hpp>
+#include <boost/config.hpp>
+
+// If we don't have wstring, then Unicode support 
+// is not available anyway, so we don't need to even
+// compiler this file. This also fixes the problem
+// with mingw, which can compile this file, but will
+// generate link error when building DLL.
+#ifndef BOOST_NO_STD_WSTRING
+
+BOOST_UTF8_BEGIN_NAMESPACE
+
+/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
+// implementation for wchar_t
+
+// Translate incoming UTF-8 into UCS-4
+std::codecvt_base::result utf8_codecvt_facet::do_in(
+    std::mbstate_t& /*state*/, 
+    const char * from,
+    const char * from_end, 
+    const char * & from_next,
+    wchar_t * to, 
+    wchar_t * to_end, 
+    wchar_t * & to_next
+) const {
+    // Basic algorithm:  The first octet determines how many
+    // octets total make up the UCS-4 character.  The remaining
+    // "continuing octets" all begin with "10". To convert, subtract
+    // the amount that specifies the number of octets from the first
+    // octet.  Subtract 0x80 (1000 0000) from each continuing octet,
+    // then mash the whole lot together.  Note that each continuing
+    // octet only uses 6 bits as unique values, so only shift by
+    // multiples of 6 to combine.
+    while (from != from_end && to != to_end) {
+
+        // Error checking   on the first octet
+        if (invalid_leading_octet(*from)){
+            from_next = from;
+            to_next = to;
+            return std::codecvt_base::error;
+        }
+
+        // The first octet is   adjusted by a value dependent upon 
+        // the number   of "continuing octets" encoding the character
+        const   int cont_octet_count = get_cont_octet_count(*from);
+        const   wchar_t octet1_modifier_table[] =   {
+            0x00, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc
+        };
+
+        // The unsigned char conversion is necessary in case char is
+        // signed   (I learned this the hard way)
+        wchar_t ucs_result = 
+            (unsigned char)(*from++) - octet1_modifier_table[cont_octet_count];
+
+        // Invariants   : 
+        //   1) At the start of the loop,   'i' continuing characters have been
+        //    processed 
+        //   2) *from   points to the next continuing character to be processed.
+        int i   = 0;
+        while(i != cont_octet_count && from != from_end) {
+
+            // Error checking on continuing characters
+            if (invalid_continuing_octet(*from)) {
+                from_next   = from;
+                to_next =   to;
+                return std::codecvt_base::error;
+            }
+
+            ucs_result *= (1 << 6); 
+
+            // each continuing character has an extra (10xxxxxx)b attached to 
+            // it that must be removed.
+            ucs_result += (unsigned char)(*from++) - 0x80;
+            ++i;
+        }
+
+        // If   the buffer ends with an incomplete unicode character...
+        if (from == from_end && i   != cont_octet_count) {
+            // rewind "from" to before the current character translation
+            from_next = from - (i+1); 
+            to_next = to;
+            return std::codecvt_base::partial;
+        }
+        *to++   = ucs_result;
+    }
+    from_next = from;
+    to_next = to;
+
+    // Were we done converting or did we run out of destination space?
+    if(from == from_end) return std::codecvt_base::ok;
+    else return std::codecvt_base::partial;
+}
+
+std::codecvt_base::result utf8_codecvt_facet::do_out(
+    std::mbstate_t& /*state*/, 
+    const wchar_t *   from,
+    const wchar_t * from_end, 
+    const wchar_t * & from_next,
+    char * to, 
+    char * to_end, 
+    char * & to_next
+) const
+{
+    // RG - consider merging this table with the other one
+    const wchar_t octet1_modifier_table[] = {
+        0x00, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc
+    };
+
+    wchar_t max_wchar = (std::numeric_limits<wchar_t>::max)();
+    while (from != from_end && to != to_end) {
+
+        // Check for invalid UCS-4 character
+        if (*from  > max_wchar) {
+            from_next = from;
+            to_next = to;
+            return std::codecvt_base::error;
+        }
+
+        int cont_octet_count = get_cont_octet_out_count(*from);
+
+        // RG  - comment this formula better
+        int shift_exponent = (cont_octet_count) *   6;
+
+        // Process the first character
+        *to++ = static_cast<char>(octet1_modifier_table[cont_octet_count] +
+            (unsigned char)(*from / (1 << shift_exponent)));
+
+        // Process the continuation characters 
+        // Invariants: At   the start of the loop:
+        //   1) 'i' continuing octets   have been generated
+        //   2) '*to'   points to the next location to place an octet
+        //   3) shift_exponent is   6 more than needed for the next octet
+        int i   = 0;
+        while   (i != cont_octet_count && to != to_end) {
+            shift_exponent -= 6;
+            *to++ = static_cast<char>(0x80 + ((*from / (1 << shift_exponent)) % (1 << 6)));
+            ++i;
+        }
+        // If   we filled up the out buffer before encoding the character
+        if(to   == to_end && i != cont_octet_count) {
+            from_next = from;
+            to_next = to - (i+1);
+            return std::codecvt_base::partial;
+        }
+        ++from;
+    }
+    from_next = from;
+    to_next = to;
+    // Were we done or did we run out of destination space
+    if(from == from_end) return std::codecvt_base::ok;
+    else return std::codecvt_base::partial;
+}
+
+// How many char objects can I process to get <= max_limit
+// wchar_t objects?
+int utf8_codecvt_facet::do_length(
+    BOOST_CODECVT_DO_LENGTH_CONST std::mbstate_t &,
+    const char * from,
+    const char * from_end, 
+    std::size_t max_limit
+#if BOOST_WORKAROUND(__IBMCPP__, BOOST_TESTED_AT(600))
+) const throw()
+#else
+) const
+#endif
+{ 
+    // RG - this code is confusing!  I need a better way to express it.
+    // and test cases.
+
+    // Invariants:
+    // 1) last_octet_count has the size of the last measured character
+    // 2) char_count holds the number of characters shown to fit
+    // within the bounds so far (no greater than max_limit)
+    // 3) from_next points to the octet 'last_octet_count' before the
+    // last measured character.  
+    int last_octet_count=0;
+    std::size_t char_count = 0;
+    const char* from_next = from;
+    // Use "<" because the buffer may represent incomplete characters
+    while (from_next+last_octet_count <= from_end && char_count <= max_limit) {
+        from_next += last_octet_count;
+        last_octet_count = (get_octet_count(*from_next));
+        ++char_count;
+    }
+    return static_cast<int>(from_next-from_end);
+}
+
+unsigned int utf8_codecvt_facet::get_octet_count(
+    unsigned char   lead_octet
+){
+    // if the 0-bit (MSB) is 0, then 1 character
+    if (lead_octet <= 0x7f) return 1;
+
+    // Otherwise the count number of consecutive 1 bits starting at MSB
+//    assert(0xc0 <= lead_octet && lead_octet <= 0xfd);
+
+    if (0xc0 <= lead_octet && lead_octet <= 0xdf) return 2;
+    else if (0xe0 <= lead_octet && lead_octet <= 0xef) return 3;
+    else if (0xf0 <= lead_octet && lead_octet <= 0xf7) return 4;
+    else if (0xf8 <= lead_octet && lead_octet <= 0xfb) return 5;
+    else return 6;
+}
+BOOST_UTF8_END_NAMESPACE
+
+namespace {
+template<std::size_t s>
+int get_cont_octet_out_count_impl(wchar_t word){
+    if (word < 0x80) {
+        return 0;
+    }
+    if (word < 0x800) {
+        return 1;
+    }
+    return 2;
+}
+
+template<>
+int get_cont_octet_out_count_impl<4>(wchar_t word){
+    if (word < 0x80) {
+        return 0;
+    }
+    if (word < 0x800) {
+        return 1;
+    }
+
+    // Note that the following code will generate warnings on some platforms
+    // where wchar_t is defined as UCS2.  The warnings are superfluous as the
+    // specialization is never instantitiated with such compilers, but this
+    // can cause problems if warnings are being treated as errors, so we guard
+    // against that.  Including <boost/detail/utf8_codecvt_facet.hpp> as we do
+    // should be enough to get WCHAR_MAX defined.
+#if !defined(WCHAR_MAX)
+#   error WCHAR_MAX not defined!
+#endif
+    // cope with VC++ 7.1 or earlier having invalid WCHAR_MAX
+#if defined(_MSC_VER) && _MSC_VER <= 1310 // 7.1 or earlier
+    return 2;
+#elif WCHAR_MAX > 0x10000
+    
+   if (word < 0x10000) {
+        return 2;
+    }
+    if (word < 0x200000) {
+        return 3;
+    }
+    if (word < 0x4000000) {
+        return 4;
+    }
+    return 5;
+    
+#else
+    return 2;
+#endif
+}
+
+} // namespace anonymous
+
+BOOST_UTF8_BEGIN_NAMESPACE
+// How many "continuing octets" will be needed for this word
+// ==   total octets - 1.
+int utf8_codecvt_facet::get_cont_octet_out_count(
+    wchar_t word
+) const {
+    return get_cont_octet_out_count_impl<sizeof(wchar_t)>(word);
+}
+BOOST_UTF8_END_NAMESPACE
+
+#endif