Implement algorithm::hex_lower as lower-case alternative to algorithm::hex

include/boost/algorithm/hex.hpp

@@ -54,12 +54,12 @@ namespace detail {
 /// \cond DOXYGEN_HIDE
 
     template <typename T, typename OutputIterator>
-    OutputIterator encode_one ( T val, OutputIterator out ) {
+    OutputIterator encode_one ( T val, OutputIterator out, const char * hexDigits ) {
         const std::size_t num_hex_digits =  2 * sizeof ( T );
         char res [ num_hex_digits ];
         char  *p = res + num_hex_digits;
         for ( std::size_t i = 0; i < num_hex_digits; ++i, val >>= 4 )
-            *--p = "0123456789ABCDEF" [ val & 0x0F ];
+            *--p = hexDigits [ val & 0x0F ];
         return std::copy ( res, res + num_hex_digits, out );
         }
 
@@ -148,7 +148,24 @@ template <typename InputIterator, typename OutputIterator>
 typename boost::enable_if<boost::is_integral<typename detail::hex_iterator_traits<InputIterator>::value_type>, OutputIterator>::type
 hex ( InputIterator first, InputIterator last, OutputIterator out ) {
     for ( ; first != last; ++first )
-        out = detail::encode_one ( *first, out );
+        out = detail::encode_one ( *first, out, "0123456789ABCDEF" );
+    return out;
+    }
+
+
+/// \fn hex_lower ( InputIterator first, InputIterator last, OutputIterator out )
+/// \brief   Converts a sequence of integral types into a lower case hexadecimal sequence of characters.
+///
+/// \param first    The start of the input sequence
+/// \param last     One past the end of the input sequence
+/// \param out      An output iterator to the results into
+/// \return         The updated output iterator
+/// \note           Based on the MySQL function of the same name
+template <typename InputIterator, typename OutputIterator>
+typename boost::enable_if<boost::is_integral<typename detail::hex_iterator_traits<InputIterator>::value_type>, OutputIterator>::type
+hex_lower ( InputIterator first, InputIterator last, OutputIterator out ) {
+    for ( ; first != last; ++first )
+        out = detail::encode_one ( *first, out, "0123456789abcdef" );
     return out;
     }
 
@@ -164,10 +181,27 @@ template <typename T, typename OutputIterator>
 typename boost::enable_if<boost::is_integral<T>, OutputIterator>::type
 hex ( const T *ptr, OutputIterator out ) {
     while ( *ptr )
-        out = detail::encode_one ( *ptr++, out );
+        out = detail::encode_one ( *ptr++, out, "0123456789ABCDEF" );
     return out;
     }
 
+
+/// \fn hex_lower ( const T *ptr, OutputIterator out )
+/// \brief   Converts a sequence of integral types into a lower case hexadecimal sequence of characters.
+///
+/// \param ptr      A pointer to a 0-terminated sequence of data.
+/// \param out      An output iterator to the results into
+/// \return         The updated output iterator
+/// \note           Based on the MySQL function of the same name
+template <typename T, typename OutputIterator>
+typename boost::enable_if<boost::is_integral<T>, OutputIterator>::type
+hex_lower ( const T *ptr, OutputIterator out ) {
+    while ( *ptr )
+        out = detail::encode_one ( *ptr++, out, "0123456789abcdef" );
+    return out;
+    }
+
+
 /// \fn hex ( const Range &r, OutputIterator out )
 /// \brief   Converts a sequence of integral types into a hexadecimal sequence of characters.
 ///
@@ -182,6 +216,20 @@ hex ( const Range &r, OutputIterator out ) {
 }
 
 
+/// \fn hex_lower ( const Range &r, OutputIterator out )
+/// \brief   Converts a sequence of integral types into a lower case hexadecimal sequence of characters.
+///
+/// \param r        The input range
+/// \param out      An output iterator to the results into
+/// \return         The updated output iterator
+/// \note           Based on the MySQL function of the same name
+template <typename Range, typename OutputIterator>
+typename boost::enable_if<boost::is_integral<typename detail::hex_iterator_traits<typename Range::iterator>::value_type>, OutputIterator>::type
+hex_lower ( const Range &r, OutputIterator out ) {
+    return hex_lower (boost::begin(r), boost::end(r), out);
+}
+
+
 /// \fn unhex ( InputIterator first, InputIterator last, OutputIterator out )
 /// \brief   Converts a sequence of hexadecimal characters into a sequence of integers.
 ///