Merge pull request #1950 from FrancoisChabot/issues/1457

templated input adapters

include/nlohmann/detail/input/binary_reader.hpp

@@ -24,6 +24,20 @@ namespace nlohmann
 {
 namespace detail
 {
+
+/*!
+@brief determine system byte order
+
+@return true if and only if system's byte order is little endian
+
+@note from https://stackoverflow.com/a/1001328/266378
+*/
+static bool little_endianess(int num = 1) noexcept
+{
+    return *reinterpret_cast<char*>(&num) == 1;
+}
+
+
 ///////////////////
 // binary reader //
 ///////////////////
@@ -31,7 +45,7 @@ namespace detail
 /*!
 @brief deserialization of CBOR, MessagePack, and UBJSON values
 */
-template<typename BasicJsonType, typename SAX = json_sax_dom_parser<BasicJsonType>>
+template<typename BasicJsonType, typename InputAdapterType, typename SAX = json_sax_dom_parser<BasicJsonType>>
 class binary_reader
 {
     using number_integer_t = typename BasicJsonType::number_integer_t;
@@ -47,10 +61,9 @@ class binary_reader
 
     @param[in] adapter  input adapter to read from
     */
-    explicit binary_reader(input_adapter_t adapter) : ia(std::move(adapter))
+    explicit binary_reader(InputAdapterType&& adapter) : ia(std::move(adapter))
     {
         (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
-        assert(ia);
     }
 
     // make class move-only
@@ -119,18 +132,6 @@ class binary_reader
         return result;
     }
 
-    /*!
-    @brief determine system byte order
-
-    @return true if and only if system's byte order is little endian
-
-    @note from https://stackoverflow.com/a/1001328/266378
-    */
-    static constexpr bool little_endianess(int num = 1) noexcept
-    {
-        return *reinterpret_cast<char*>(&num) == 1;
-    }
-
   private:
     //////////
     // BSON //
@@ -2085,7 +2086,7 @@ class binary_reader
     int get()
     {
         ++chars_read;
-        return current = ia->get_character();
+        return current = ia.get_character();
     }
 
     /*!
@@ -2273,7 +2274,7 @@ class binary_reader
 
   private:
     /// input adapter
-    input_adapter_t ia = nullptr;
+    InputAdapterType ia;
 
     /// the current character
     int current = std::char_traits<char>::eof();

include/nlohmann/detail/input/input_adapters.hpp

@@ -27,32 +27,11 @@ enum class input_format_t { json, cbor, msgpack, ubjson, bson };
 // input adapters //
 ////////////////////
 
-/*!
-@brief abstract input adapter interface
-
-Produces a stream of std::char_traits<char>::int_type characters from a
-std::istream, a buffer, or some other input type. Accepts the return of
-exactly one non-EOF character for future input. The int_type characters
-returned consist of all valid char values as positive values (typically
-unsigned char), plus an EOF value outside that range, specified by the value
-of the function std::char_traits<char>::eof(). This value is typically -1, but
-could be any arbitrary value which is not a valid char value.
-*/
-struct input_adapter_protocol
-{
-    /// get a character [0,255] or std::char_traits<char>::eof().
-    virtual std::char_traits<char>::int_type get_character() = 0;
-    virtual ~input_adapter_protocol() = default;
-};
-
-/// a type to simplify interfaces
-using input_adapter_t = std::shared_ptr<input_adapter_protocol>;
-
 /*!
 Input adapter for stdio file access. This adapter read only 1 byte and do not use any
  buffer. This adapter is a very low level adapter.
 */
-class file_input_adapter : public input_adapter_protocol
+class file_input_adapter
 {
   public:
     JSON_HEDLEY_NON_NULL(2)
@@ -64,10 +43,9 @@ class file_input_adapter : public input_adapter_protocol
     file_input_adapter(const file_input_adapter&) = delete;
     file_input_adapter(file_input_adapter&&) = default;
     file_input_adapter& operator=(const file_input_adapter&) = delete;
-    file_input_adapter& operator=(file_input_adapter&&) = default;
+    file_input_adapter& operator=(file_input_adapter&&) = delete;
-    ~file_input_adapter() override = default;
 
-    std::char_traits<char>::int_type get_character() noexcept override
+    std::char_traits<char>::int_type get_character() noexcept
     {
         return std::fgetc(m_file);
     }
@@ -87,48 +65,56 @@ characters following those used in parsing the JSON input.  Clears the
 std::istream flags; any input errors (e.g., EOF) will be detected by the first
 subsequent call for input from the std::istream.
 */
-class input_stream_adapter : public input_adapter_protocol
+class input_stream_adapter
 {
   public:
-    ~input_stream_adapter() override
+    ~input_stream_adapter()
     {
         // clear stream flags; we use underlying streambuf I/O, do not
         // maintain ifstream flags, except eof
-        is.clear(is.rdstate() & std::ios::eofbit);
+        if (is)
+        {
+            is->clear(is->rdstate() & std::ios::eofbit);
+        }
     }
 
     explicit input_stream_adapter(std::istream& i)
-        : is(i), sb(*i.rdbuf())
+        : is(&i), sb(i.rdbuf())
     {}
 
     // delete because of pointer members
     input_stream_adapter(const input_stream_adapter&) = delete;
     input_stream_adapter& operator=(input_stream_adapter&) = delete;
-    input_stream_adapter(input_stream_adapter&&) = delete;
+    input_stream_adapter& operator=(input_stream_adapter&& rhs) = delete;
-    input_stream_adapter& operator=(input_stream_adapter&&) = delete;
+
+    input_stream_adapter(input_stream_adapter&& rhs) : is(rhs.is), sb(rhs.sb)
+    {
+        rhs.is = nullptr;
+        rhs.sb = nullptr;
+    }
 
     // std::istream/std::streambuf use std::char_traits<char>::to_int_type, to
     // ensure that std::char_traits<char>::eof() and the character 0xFF do not
     // end up as the same value, eg. 0xFFFFFFFF.
-    std::char_traits<char>::int_type get_character() override
+    std::char_traits<char>::int_type get_character()
     {
-        auto res = sb.sbumpc();
+        auto res = sb->sbumpc();
         // set eof manually, as we don't use the istream interface.
         if (res == EOF)
         {
-            is.clear(is.rdstate() | std::ios::eofbit);
+            is->clear(is->rdstate() | std::ios::eofbit);
         }
         return res;
     }
 
   private:
     /// the associated input stream
-    std::istream& is;
+    std::istream* is = nullptr;
-    std::streambuf& sb;
+    std::streambuf* sb = nullptr;
 };
 
 /// input adapter for buffer input
-class input_buffer_adapter : public input_adapter_protocol
+class input_buffer_adapter
 {
   public:
     input_buffer_adapter(const char* b, const std::size_t l) noexcept
@@ -138,11 +124,10 @@ class input_buffer_adapter : public input_adapter_protocol
     // delete because of pointer members
     input_buffer_adapter(const input_buffer_adapter&) = delete;
     input_buffer_adapter& operator=(input_buffer_adapter&) = delete;
-    input_buffer_adapter(input_buffer_adapter&&) = delete;
+    input_buffer_adapter(input_buffer_adapter&&) = default;
     input_buffer_adapter& operator=(input_buffer_adapter&&) = delete;
-    ~input_buffer_adapter() override = default;
 
-    std::char_traits<char>::int_type get_character() noexcept override
+    std::char_traits<char>::int_type get_character() noexcept
     {
         if (JSON_HEDLEY_LIKELY(cursor < limit))
         {
@@ -285,14 +270,14 @@ struct wide_string_input_helper<WideStringType, 2>
 };
 
 template<typename WideStringType>
-class wide_string_input_adapter : public input_adapter_protocol
+class wide_string_input_adapter
 {
   public:
     explicit wide_string_input_adapter(const WideStringType& w) noexcept
         : str(w)
     {}
 
-    std::char_traits<char>::int_type get_character() noexcept override
+    std::char_traits<char>::int_type get_character() noexcept
     {
         // check if buffer needs to be filled
         if (utf8_bytes_index == utf8_bytes_filled)
@@ -331,60 +316,50 @@ class wide_string_input_adapter : public input_adapter_protocol
     std::size_t utf8_bytes_filled = 0;
 };
 
-class input_adapter
+inline file_input_adapter input_adapter(std::FILE* file)
 {
-  public:
+    return file_input_adapter(file);
-    // native support
+}
-    JSON_HEDLEY_NON_NULL(2)
-    input_adapter(std::FILE* file)
-        : ia(std::make_shared<file_input_adapter>(file)) {}
-    /// input adapter for input stream
-    input_adapter(std::istream& i)
-        : ia(std::make_shared<input_stream_adapter>(i)) {}
 
-    /// input adapter for input stream
+inline input_stream_adapter input_adapter(std::istream& stream)
-    input_adapter(std::istream&& i)
+{
-        : ia(std::make_shared<input_stream_adapter>(i)) {}
+    return input_stream_adapter(stream);
+}
 
-    input_adapter(const std::wstring& ws)
+inline input_stream_adapter input_adapter(std::istream&& stream)
-        : ia(std::make_shared<wide_string_input_adapter<std::wstring>>(ws)) {}
+{
+    return input_stream_adapter(stream);
+}
 
-    input_adapter(const std::u16string& ws)
+template<typename CharT,
-        : ia(std::make_shared<wide_string_input_adapter<std::u16string>>(ws)) {}
-
-    input_adapter(const std::u32string& ws)
-        : ia(std::make_shared<wide_string_input_adapter<std::u32string>>(ws)) {}
-
-    /// input adapter for buffer
-    template<typename CharT,
          typename std::enable_if<
              std::is_pointer<CharT>::value and
              std::is_integral<typename std::remove_pointer<CharT>::type>::value and
              sizeof(typename std::remove_pointer<CharT>::type) == 1,
              int>::type = 0>
-    input_adapter(CharT b, std::size_t l)
+input_buffer_adapter input_adapter(CharT b, std::size_t l)
-        : ia(std::make_shared<input_buffer_adapter>(reinterpret_cast<const char*>(b), l)) {}
+{
+    return input_buffer_adapter(reinterpret_cast<const char*>(b), l);
+}
 
-    // derived support
+template<typename CharT,
-
-    /// input adapter for string literal
-    template<typename CharT,
          typename std::enable_if<
              std::is_pointer<CharT>::value and
              std::is_integral<typename std::remove_pointer<CharT>::type>::value and
              sizeof(typename std::remove_pointer<CharT>::type) == 1,
              int>::type = 0>
-    input_adapter(CharT b)
+input_buffer_adapter input_adapter(CharT b)
-        : input_adapter(reinterpret_cast<const char*>(b),
+{
-                        std::strlen(reinterpret_cast<const char*>(b))) {}
+    return input_adapter(reinterpret_cast<const char*>(b),
+                         std::strlen(reinterpret_cast<const char*>(b)));
+}
 
-    /// input adapter for iterator range with contiguous storage
+template<class IteratorType,
-    template<class IteratorType,
          typename std::enable_if<
              std::is_same<typename iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value,
              int>::type = 0>
-    input_adapter(IteratorType first, IteratorType last)
+input_buffer_adapter input_adapter(IteratorType first, IteratorType last)
-    {
+{
 #ifndef NDEBUG
     // assertion to check that the iterator range is indeed contiguous,
     // see https://stackoverflow.com/a/35008842/266378 for more discussion
@@ -407,36 +382,98 @@ class input_adapter
     if (JSON_HEDLEY_LIKELY(len > 0))
     {
         // there is at least one element: use the address of first
-            ia = std::make_shared<input_buffer_adapter>(reinterpret_cast<const char*>(&(*first)), len);
+        return input_buffer_adapter(reinterpret_cast<const char*>(&(*first)), len);
     }
     else
     {
         // the address of first cannot be used: use nullptr
-            ia = std::make_shared<input_buffer_adapter>(nullptr, len);
+        return input_buffer_adapter(nullptr, len);
-        }
     }
+}
+
+inline wide_string_input_adapter<std::wstring> input_adapter(const std::wstring& ws)
+{
+    return wide_string_input_adapter<std::wstring>(ws);
+}
+
+
+inline wide_string_input_adapter<std::u16string> input_adapter(const std::u16string& ws)
+{
+    return wide_string_input_adapter<std::u16string>(ws);
+}
+
+inline wide_string_input_adapter<std::u32string> input_adapter(const std::u32string& ws)
+{
+    return wide_string_input_adapter<std::u32string>(ws);
+}
+
+template<class ContiguousContainer, typename
+         std::enable_if<not std::is_pointer<ContiguousContainer>::value and
+                        std::is_base_of<std::random_access_iterator_tag, typename iterator_traits<decltype(std::begin(std::declval<ContiguousContainer const>()))>::iterator_category>::value,
+                        int>::type = 0>
+input_buffer_adapter input_adapter(const ContiguousContainer& c)
+{
+    return input_adapter(std::begin(c), std::end(c));
+}
+
+
+template<class T, std::size_t N>
+input_buffer_adapter input_adapter(T (&array)[N])
+{
+    return input_adapter(std::begin(array), std::end(array));
+}
+
+// This class only handles inputs of input_buffer_adapter type.
+// It's required so that expressions like {ptr, len} can be implicitely casted
+// to the correct adapter.
+class span_input_adapter
+{
+  public:
+    template<typename CharT,
+             typename std::enable_if<
+                 std::is_pointer<CharT>::value and
+                 std::is_integral<typename std::remove_pointer<CharT>::type>::value and
+                 sizeof(typename std::remove_pointer<CharT>::type) == 1,
+                 int>::type = 0>
+    span_input_adapter(CharT b, std::size_t l)
+        : ia(reinterpret_cast<const char*>(b), l) {}
+
+    template<typename CharT,
+             typename std::enable_if<
+                 std::is_pointer<CharT>::value and
+                 std::is_integral<typename std::remove_pointer<CharT>::type>::value and
+                 sizeof(typename std::remove_pointer<CharT>::type) == 1,
+                 int>::type = 0>
+    span_input_adapter(CharT b)
+        : span_input_adapter(reinterpret_cast<const char*>(b),
+                             std::strlen(reinterpret_cast<const char*>(b))) {}
+
+    template<class IteratorType,
+             typename std::enable_if<
+                 std::is_same<typename iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value,
+                 int>::type = 0>
+    span_input_adapter(IteratorType first, IteratorType last)
+        : ia(input_adapter(first, last)) {}
 
-    /// input adapter for array
     template<class T, std::size_t N>
-    input_adapter(T (&array)[N])
+    span_input_adapter(T (&array)[N])
-        : input_adapter(std::begin(array), std::end(array)) {}
+        : span_input_adapter(std::begin(array), std::end(array)) {}
 
     /// input adapter for contiguous container
     template<class ContiguousContainer, typename
              std::enable_if<not std::is_pointer<ContiguousContainer>::value and
                             std::is_base_of<std::random_access_iterator_tag, typename iterator_traits<decltype(std::begin(std::declval<ContiguousContainer const>()))>::iterator_category>::value,
                             int>::type = 0>
-    input_adapter(const ContiguousContainer& c)
+    span_input_adapter(const ContiguousContainer& c)
-        : input_adapter(std::begin(c), std::end(c)) {}
+        : span_input_adapter(std::begin(c), std::end(c)) {}
 
-    operator input_adapter_t()
+    input_buffer_adapter&& get()
     {
-        return ia;
+        return std::move(ia);
     }
 
   private:
-    /// the actual adapter
+    input_buffer_adapter ia;
-    input_adapter_t ia = nullptr;
 };
 }  // namespace detail
 }  // namespace nlohmann

include/nlohmann/detail/input/lexer.hpp

@@ -22,19 +22,9 @@ namespace detail
 // lexer //
 ///////////
 
-/*!
-@brief lexical analysis
-
-This class organizes the lexical analysis during JSON deserialization.
-*/
 template<typename BasicJsonType>
-class lexer
+class lexer_base
 {
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-
   public:
     /// token types for the parser
     enum class token_type
@@ -75,9 +65,9 @@ class lexer
                 return "null literal";
             case token_type::value_string:
                 return "string literal";
-            case lexer::token_type::value_unsigned:
+            case token_type::value_unsigned:
-            case lexer::token_type::value_integer:
+            case token_type::value_integer:
-            case lexer::token_type::value_float:
+            case token_type::value_float:
                 return "number literal";
             case token_type::begin_array:
                 return "'['";
@@ -103,15 +93,31 @@ class lexer
                 // LCOV_EXCL_STOP
         }
     }
+};
+/*!
+@brief lexical analysis
 
-    explicit lexer(detail::input_adapter_t&& adapter)
+This class organizes the lexical analysis during JSON deserialization.
+*/
+template<typename BasicJsonType, typename InputAdapterType>
+class lexer : public lexer_base<BasicJsonType>
+{
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+
+  public:
+    using token_type = typename lexer_base<BasicJsonType>::token_type;
+
+    explicit lexer(InputAdapterType&& adapter)
         : ia(std::move(adapter)), decimal_point_char(get_decimal_point()) {}
 
     // delete because of pointer members
     lexer(const lexer&) = delete;
-    lexer(lexer&&) = delete;
+    lexer(lexer&&) = default;
     lexer& operator=(lexer&) = delete;
-    lexer& operator=(lexer&&) = delete;
+    lexer& operator=(lexer&&) = default;
     ~lexer() = default;
 
   private:
@@ -1256,7 +1262,7 @@ scan_number_done:
         }
         else
         {
-            current = ia->get_character();
+            current = ia.get_character();
         }
 
         if (JSON_HEDLEY_LIKELY(current != std::char_traits<char>::eof()))
@@ -1480,7 +1486,7 @@ scan_number_done:
 
   private:
     /// input adapter
-    detail::input_adapter_t ia = nullptr;
+    InputAdapterType ia;
 
     /// the current character
     std::char_traits<char>::int_type current = std::char_traits<char>::eof();

include/nlohmann/detail/input/parser.hpp

@@ -24,24 +24,8 @@ namespace detail
 // parser //
 ////////////
 
-/*!
+enum class parse_event_t : uint8_t
-@brief syntax analysis
-
-This class implements a recursive descent parser.
-*/
-template<typename BasicJsonType>
-class parser
 {
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using lexer_t = lexer<BasicJsonType>;
-    using token_type = typename lexer_t::token_type;
-
-  public:
-    enum class parse_event_t : uint8_t
-    {
     /// the parser read `{` and started to process a JSON object
     object_start,
     /// the parser read `}` and finished processing a JSON object
@@ -54,14 +38,31 @@ class parser
     key,
     /// the parser finished reading a JSON value
     value
-    };
+};
 
-    using parser_callback_t =
+template<typename BasicJsonType>
+using parser_callback_t =
     std::function<bool(int depth, parse_event_t event, BasicJsonType& parsed)>;
 
+/*!
+@brief syntax analysis
+
+This class implements a recursive descent parser.
+*/
+template<typename BasicJsonType, typename InputAdapterType>
+class parser
+{
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using lexer_t = lexer<BasicJsonType, InputAdapterType>;
+    using token_type = typename lexer_t::token_type;
+
+  public:
     /// a parser reading from an input adapter
-    explicit parser(detail::input_adapter_t&& adapter,
+    explicit parser(InputAdapterType&& adapter,
-                    const parser_callback_t cb = nullptr,
+                    const parser_callback_t<BasicJsonType> cb = nullptr,
                     const bool allow_exceptions_ = true)
         : callback(cb), m_lexer(std::move(adapter)), allow_exceptions(allow_exceptions_)
     {
@@ -486,7 +487,7 @@ class parser
 
   private:
     /// callback function
-    const parser_callback_t callback = nullptr;
+    const parser_callback_t<BasicJsonType> callback = nullptr;
     /// the type of the last read token
     token_type last_token = token_type::uninitialized;
     /// the lexer

include/nlohmann/detail/output/binary_writer.hpp

@@ -1538,7 +1538,7 @@ class binary_writer
 
   private:
     /// whether we can assume little endianess
-    const bool is_little_endian = binary_reader<BasicJsonType>::little_endianess();
+    const bool is_little_endian = little_endianess();
 
     /// the output
     output_adapter_t<CharType> oa = nullptr;

include/nlohmann/json.hpp

@@ -170,13 +170,15 @@ class basic_json
   private:
     template<detail::value_t> friend struct detail::external_constructor;
     friend ::nlohmann::json_pointer<basic_json>;
-    friend ::nlohmann::detail::parser<basic_json>;
+
+    template<typename BasicJsonType, typename InputType>
+    friend class ::nlohmann::detail::parser;
     friend ::nlohmann::detail::serializer<basic_json>;
     template<typename BasicJsonType>
     friend class ::nlohmann::detail::iter_impl;
     template<typename BasicJsonType, typename CharType>
     friend class ::nlohmann::detail::binary_writer;
-    template<typename BasicJsonType, typename SAX>
+    template<typename BasicJsonType, typename InputType, typename SAX>
     friend class ::nlohmann::detail::binary_reader;
     template<typename BasicJsonType>
     friend class ::nlohmann::detail::json_sax_dom_parser;
@@ -187,8 +189,17 @@ class basic_json
     using basic_json_t = NLOHMANN_BASIC_JSON_TPL;
 
     // convenience aliases for types residing in namespace detail;
-    using lexer = ::nlohmann::detail::lexer<basic_json>;
+    using lexer = ::nlohmann::detail::lexer_base<basic_json>;
-    using parser = ::nlohmann::detail::parser<basic_json>;
+
+    template<typename InputAdapterType>
+    static ::nlohmann::detail::parser<basic_json, InputAdapterType> parser(
+        InputAdapterType adapter,
+        detail::parser_callback_t<basic_json>cb = nullptr,
+        bool allow_exceptions = true
+    )
+    {
+        return ::nlohmann::detail::parser<basic_json, InputAdapterType>(std::move(adapter), std::move(cb), allow_exceptions);
+    }
 
     using primitive_iterator_t = ::nlohmann::detail::primitive_iterator_t;
     template<typename BasicJsonType>
@@ -202,7 +213,8 @@ class basic_json
     template<typename CharType>
     using output_adapter_t = ::nlohmann::detail::output_adapter_t<CharType>;
 
-    using binary_reader = ::nlohmann::detail::binary_reader<basic_json>;
+    template<typename InputType>
+    using binary_reader = ::nlohmann::detail::binary_reader<basic_json, InputType>;
     template<typename CharType> using binary_writer = ::nlohmann::detail::binary_writer<basic_json, CharType>;
 
     using serializer = ::nlohmann::detail::serializer<basic_json>;
@@ -1254,7 +1266,7 @@ class basic_json
 
     @sa @ref parser_callback_t for more information and examples
     */
-    using parse_event_t = typename parser::parse_event_t;
+    using parse_event_t = detail::parse_event_t;
 
     /*!
     @brief per-element parser callback type
@@ -1305,7 +1317,7 @@ class basic_json
 
     @since version 1.0.0
     */
-    using parser_callback_t = typename parser::parser_callback_t;
+    using parser_callback_t = detail::parser_callback_t<basic_json>;
 
     //////////////////
     // constructors //
@@ -6694,21 +6706,39 @@ class basic_json
 
     @since version 2.0.3 (contiguous containers)
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json parse(detail::input_adapter&& i,
+    static basic_json parse(InputType&& i,
                             const parser_callback_t cb = nullptr,
                             const bool allow_exceptions = true)
     {
         basic_json result;
-        parser(i, cb, allow_exceptions).parse(true, result);
+        parser(detail::input_adapter(std::forward<InputType>(i)), cb, allow_exceptions).parse(true, result);
         return result;
     }
 
-    static bool accept(detail::input_adapter&& i)
+
+
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json parse(detail::span_input_adapter&& i,
+                            const parser_callback_t cb = nullptr,
+                            const bool allow_exceptions = true)
     {
-        return parser(i).accept(true);
+        basic_json result;
+        parser(i.get(), cb, allow_exceptions).parse(true, result);
+        return result;
     }
 
+    template<typename InputType>
+    static bool accept(InputType&& i)
+    {
+        return parser(detail::input_adapter(std::forward<InputType>(i))).accept(true);
+    }
+
+    static bool accept(detail::span_input_adapter&& i)
+    {
+        return parser(i.get()).accept(true);
+    }
     /*!
     @brief generate SAX events
 
@@ -6762,17 +6792,34 @@ class basic_json
 
     @since version 3.2.0
     */
-    template <typename SAX>
+    template <typename SAX, typename InputType>
     JSON_HEDLEY_NON_NULL(2)
-    static bool sax_parse(detail::input_adapter&& i, SAX* sax,
+    static bool sax_parse(InputType&& i, SAX* sax,
                           input_format_t format = input_format_t::json,
                           const bool strict = true)
     {
+        assert(sax);
+
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
         return format == input_format_t::json
-               ? parser(std::move(i)).sax_parse(sax, strict)
+               ? parser(std::move(ia)).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, SAX>(std::move(i)).sax_parse(format, sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia)).sax_parse(format, sax, strict);
     }
 
+    template <typename SAX>
+    JSON_HEDLEY_NON_NULL(2)
+    static bool sax_parse(detail::span_input_adapter&& i, SAX* sax,
+                          input_format_t format = input_format_t::json,
+                          const bool strict = true)
+    {
+        assert(sax);
+        auto ia = i.get();
+        return format == input_format_t::json
+               ? parser(std::move(ia)).sax_parse(sax, strict)
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia)).sax_parse(format, sax, strict);
+    }
+
+
     /*!
     @brief deserialize from an iterator range with contiguous storage
 
@@ -7484,14 +7531,16 @@ class basic_json
            @a strict parameter since 3.0.0; added @a allow_exceptions parameter
            since 3.2.0
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_cbor(detail::input_adapter&& i,
+    static basic_json from_cbor(InputType&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::cbor, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -7499,7 +7548,7 @@ class basic_json
     @copydoc from_cbor(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_cbor(A1 && a1, A2 && a2,
                                 const bool strict = true,
@@ -7507,7 +7556,18 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::cbor, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::cbor, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
+
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json from_cbor(detail::span_input_adapter&& i,
+                                const bool strict = true,
+                                const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::cbor, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -7597,14 +7657,16 @@ class basic_json
            @a strict parameter since 3.0.0; added @a allow_exceptions parameter
            since 3.2.0
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_msgpack(detail::input_adapter&& i,
+    static basic_json from_msgpack(InputType&& i,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::msgpack, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -7612,7 +7674,7 @@ class basic_json
     @copydoc from_msgpack(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_msgpack(A1 && a1, A2 && a2,
                                    const bool strict = true,
@@ -7620,10 +7682,23 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::msgpack, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::msgpack, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
+
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json from_msgpack(detail::span_input_adapter&& i,
+                                   const bool strict = true,
+                                   const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::msgpack, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
+
+
     /*!
     @brief create a JSON value from an input in UBJSON format
 
@@ -7685,14 +7760,16 @@ class basic_json
 
     @since version 3.1.0; added @a allow_exceptions parameter since 3.2.0
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_ubjson(detail::input_adapter&& i,
+    static basic_json from_ubjson(InputType&& i,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::ubjson, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -7700,7 +7777,7 @@ class basic_json
     @copydoc from_ubjson(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_ubjson(A1 && a1, A2 && a2,
                                   const bool strict = true,
@@ -7708,10 +7785,22 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::ubjson, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::ubjson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
+
+    static basic_json from_ubjson(detail::span_input_adapter&& i,
+                                  const bool strict = true,
+                                  const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::ubjson, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
+
+
     /*!
     @brief Create a JSON value from an input in BSON format
 
@@ -7772,14 +7861,16 @@ class basic_json
     @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the
         related UBJSON format
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_bson(detail::input_adapter&& i,
+    static basic_json from_bson(InputType&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::bson, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -7787,7 +7878,7 @@ class basic_json
     @copydoc from_bson(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_bson(A1 && a1, A2 && a2,
                                 const bool strict = true,
@@ -7795,12 +7886,20 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::bson, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::bson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
-
+    JSON_HEDLEY_WARN_UNUSED_RESULT
-
+    static basic_json from_bson(detail::span_input_adapter&& i,
+                                const bool strict = true,
+                                const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::bson, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
     /// @}
 
     //////////////////////////

single_include/nlohmann/json.hpp

@@ -4248,32 +4248,11 @@ enum class input_format_t { json, cbor, msgpack, ubjson, bson };
 // input adapters //
 ////////////////////
 
-/*!
-@brief abstract input adapter interface
-
-Produces a stream of std::char_traits<char>::int_type characters from a
-std::istream, a buffer, or some other input type. Accepts the return of
-exactly one non-EOF character for future input. The int_type characters
-returned consist of all valid char values as positive values (typically
-unsigned char), plus an EOF value outside that range, specified by the value
-of the function std::char_traits<char>::eof(). This value is typically -1, but
-could be any arbitrary value which is not a valid char value.
-*/
-struct input_adapter_protocol
-{
-    /// get a character [0,255] or std::char_traits<char>::eof().
-    virtual std::char_traits<char>::int_type get_character() = 0;
-    virtual ~input_adapter_protocol() = default;
-};
-
-/// a type to simplify interfaces
-using input_adapter_t = std::shared_ptr<input_adapter_protocol>;
-
 /*!
 Input adapter for stdio file access. This adapter read only 1 byte and do not use any
  buffer. This adapter is a very low level adapter.
 */
-class file_input_adapter : public input_adapter_protocol
+class file_input_adapter
 {
   public:
     JSON_HEDLEY_NON_NULL(2)
@@ -4285,10 +4264,9 @@ class file_input_adapter : public input_adapter_protocol
     file_input_adapter(const file_input_adapter&) = delete;
     file_input_adapter(file_input_adapter&&) = default;
     file_input_adapter& operator=(const file_input_adapter&) = delete;
-    file_input_adapter& operator=(file_input_adapter&&) = default;
+    file_input_adapter& operator=(file_input_adapter&&) = delete;
-    ~file_input_adapter() override = default;
 
-    std::char_traits<char>::int_type get_character() noexcept override
+    std::char_traits<char>::int_type get_character() noexcept
     {
         return std::fgetc(m_file);
     }
@@ -4308,48 +4286,56 @@ characters following those used in parsing the JSON input.  Clears the
 std::istream flags; any input errors (e.g., EOF) will be detected by the first
 subsequent call for input from the std::istream.
 */
-class input_stream_adapter : public input_adapter_protocol
+class input_stream_adapter
 {
   public:
-    ~input_stream_adapter() override
+    ~input_stream_adapter()
     {
         // clear stream flags; we use underlying streambuf I/O, do not
         // maintain ifstream flags, except eof
-        is.clear(is.rdstate() & std::ios::eofbit);
+        if (is)
+        {
+            is->clear(is->rdstate() & std::ios::eofbit);
+        }
     }
 
     explicit input_stream_adapter(std::istream& i)
-        : is(i), sb(*i.rdbuf())
+        : is(&i), sb(i.rdbuf())
     {}
 
     // delete because of pointer members
     input_stream_adapter(const input_stream_adapter&) = delete;
     input_stream_adapter& operator=(input_stream_adapter&) = delete;
-    input_stream_adapter(input_stream_adapter&&) = delete;
+    input_stream_adapter& operator=(input_stream_adapter&& rhs) = delete;
-    input_stream_adapter& operator=(input_stream_adapter&&) = delete;
+
+    input_stream_adapter(input_stream_adapter&& rhs) : is(rhs.is), sb(rhs.sb)
+    {
+        rhs.is = nullptr;
+        rhs.sb = nullptr;
+    }
 
     // std::istream/std::streambuf use std::char_traits<char>::to_int_type, to
     // ensure that std::char_traits<char>::eof() and the character 0xFF do not
     // end up as the same value, eg. 0xFFFFFFFF.
-    std::char_traits<char>::int_type get_character() override
+    std::char_traits<char>::int_type get_character()
     {
-        auto res = sb.sbumpc();
+        auto res = sb->sbumpc();
         // set eof manually, as we don't use the istream interface.
         if (res == EOF)
         {
-            is.clear(is.rdstate() | std::ios::eofbit);
+            is->clear(is->rdstate() | std::ios::eofbit);
         }
         return res;
     }
 
   private:
     /// the associated input stream
-    std::istream& is;
+    std::istream* is = nullptr;
-    std::streambuf& sb;
+    std::streambuf* sb = nullptr;
 };
 
 /// input adapter for buffer input
-class input_buffer_adapter : public input_adapter_protocol
+class input_buffer_adapter
 {
   public:
     input_buffer_adapter(const char* b, const std::size_t l) noexcept
@@ -4359,11 +4345,10 @@ class input_buffer_adapter : public input_adapter_protocol
     // delete because of pointer members
     input_buffer_adapter(const input_buffer_adapter&) = delete;
     input_buffer_adapter& operator=(input_buffer_adapter&) = delete;
-    input_buffer_adapter(input_buffer_adapter&&) = delete;
+    input_buffer_adapter(input_buffer_adapter&&) = default;
     input_buffer_adapter& operator=(input_buffer_adapter&&) = delete;
-    ~input_buffer_adapter() override = default;
 
-    std::char_traits<char>::int_type get_character() noexcept override
+    std::char_traits<char>::int_type get_character() noexcept
     {
         if (JSON_HEDLEY_LIKELY(cursor < limit))
         {
@@ -4506,14 +4491,14 @@ struct wide_string_input_helper<WideStringType, 2>
 };
 
 template<typename WideStringType>
-class wide_string_input_adapter : public input_adapter_protocol
+class wide_string_input_adapter
 {
   public:
     explicit wide_string_input_adapter(const WideStringType& w) noexcept
         : str(w)
     {}
 
-    std::char_traits<char>::int_type get_character() noexcept override
+    std::char_traits<char>::int_type get_character() noexcept
     {
         // check if buffer needs to be filled
         if (utf8_bytes_index == utf8_bytes_filled)
@@ -4552,60 +4537,50 @@ class wide_string_input_adapter : public input_adapter_protocol
     std::size_t utf8_bytes_filled = 0;
 };
 
-class input_adapter
+inline file_input_adapter input_adapter(std::FILE* file)
 {
-  public:
+    return file_input_adapter(file);
-    // native support
+}
-    JSON_HEDLEY_NON_NULL(2)
-    input_adapter(std::FILE* file)
-        : ia(std::make_shared<file_input_adapter>(file)) {}
-    /// input adapter for input stream
-    input_adapter(std::istream& i)
-        : ia(std::make_shared<input_stream_adapter>(i)) {}
 
-    /// input adapter for input stream
+inline input_stream_adapter input_adapter(std::istream& stream)
-    input_adapter(std::istream&& i)
+{
-        : ia(std::make_shared<input_stream_adapter>(i)) {}
+    return input_stream_adapter(stream);
+}
 
-    input_adapter(const std::wstring& ws)
+inline input_stream_adapter input_adapter(std::istream&& stream)
-        : ia(std::make_shared<wide_string_input_adapter<std::wstring>>(ws)) {}
+{
+    return input_stream_adapter(stream);
+}
 
-    input_adapter(const std::u16string& ws)
+template<typename CharT,
-        : ia(std::make_shared<wide_string_input_adapter<std::u16string>>(ws)) {}
-
-    input_adapter(const std::u32string& ws)
-        : ia(std::make_shared<wide_string_input_adapter<std::u32string>>(ws)) {}
-
-    /// input adapter for buffer
-    template<typename CharT,
          typename std::enable_if<
              std::is_pointer<CharT>::value and
              std::is_integral<typename std::remove_pointer<CharT>::type>::value and
              sizeof(typename std::remove_pointer<CharT>::type) == 1,
              int>::type = 0>
-    input_adapter(CharT b, std::size_t l)
+input_buffer_adapter input_adapter(CharT b, std::size_t l)
-        : ia(std::make_shared<input_buffer_adapter>(reinterpret_cast<const char*>(b), l)) {}
+{
+    return input_buffer_adapter(reinterpret_cast<const char*>(b), l);
+}
 
-    // derived support
+template<typename CharT,
-
-    /// input adapter for string literal
-    template<typename CharT,
          typename std::enable_if<
              std::is_pointer<CharT>::value and
              std::is_integral<typename std::remove_pointer<CharT>::type>::value and
              sizeof(typename std::remove_pointer<CharT>::type) == 1,
              int>::type = 0>
-    input_adapter(CharT b)
+input_buffer_adapter input_adapter(CharT b)
-        : input_adapter(reinterpret_cast<const char*>(b),
+{
-                        std::strlen(reinterpret_cast<const char*>(b))) {}
+    return input_adapter(reinterpret_cast<const char*>(b),
+                         std::strlen(reinterpret_cast<const char*>(b)));
+}
 
-    /// input adapter for iterator range with contiguous storage
+template<class IteratorType,
-    template<class IteratorType,
          typename std::enable_if<
              std::is_same<typename iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value,
              int>::type = 0>
-    input_adapter(IteratorType first, IteratorType last)
+input_buffer_adapter input_adapter(IteratorType first, IteratorType last)
-    {
+{
 #ifndef NDEBUG
     // assertion to check that the iterator range is indeed contiguous,
     // see https://stackoverflow.com/a/35008842/266378 for more discussion
@@ -4628,36 +4603,98 @@ class input_adapter
     if (JSON_HEDLEY_LIKELY(len > 0))
     {
         // there is at least one element: use the address of first
-            ia = std::make_shared<input_buffer_adapter>(reinterpret_cast<const char*>(&(*first)), len);
+        return input_buffer_adapter(reinterpret_cast<const char*>(&(*first)), len);
     }
     else
     {
         // the address of first cannot be used: use nullptr
-            ia = std::make_shared<input_buffer_adapter>(nullptr, len);
+        return input_buffer_adapter(nullptr, len);
-        }
     }
+}
+
+inline wide_string_input_adapter<std::wstring> input_adapter(const std::wstring& ws)
+{
+    return wide_string_input_adapter<std::wstring>(ws);
+}
+
+
+inline wide_string_input_adapter<std::u16string> input_adapter(const std::u16string& ws)
+{
+    return wide_string_input_adapter<std::u16string>(ws);
+}
+
+inline wide_string_input_adapter<std::u32string> input_adapter(const std::u32string& ws)
+{
+    return wide_string_input_adapter<std::u32string>(ws);
+}
+
+template<class ContiguousContainer, typename
+         std::enable_if<not std::is_pointer<ContiguousContainer>::value and
+                        std::is_base_of<std::random_access_iterator_tag, typename iterator_traits<decltype(std::begin(std::declval<ContiguousContainer const>()))>::iterator_category>::value,
+                        int>::type = 0>
+input_buffer_adapter input_adapter(const ContiguousContainer& c)
+{
+    return input_adapter(std::begin(c), std::end(c));
+}
+
+
+template<class T, std::size_t N>
+input_buffer_adapter input_adapter(T (&array)[N])
+{
+    return input_adapter(std::begin(array), std::end(array));
+}
+
+// This class only handles inputs of input_buffer_adapter type.
+// It's required so that expressions like {ptr, len} can be implicitely casted
+// to the correct adapter.
+class span_input_adapter
+{
+  public:
+    template<typename CharT,
+             typename std::enable_if<
+                 std::is_pointer<CharT>::value and
+                 std::is_integral<typename std::remove_pointer<CharT>::type>::value and
+                 sizeof(typename std::remove_pointer<CharT>::type) == 1,
+                 int>::type = 0>
+    span_input_adapter(CharT b, std::size_t l)
+        : ia(reinterpret_cast<const char*>(b), l) {}
+
+    template<typename CharT,
+             typename std::enable_if<
+                 std::is_pointer<CharT>::value and
+                 std::is_integral<typename std::remove_pointer<CharT>::type>::value and
+                 sizeof(typename std::remove_pointer<CharT>::type) == 1,
+                 int>::type = 0>
+    span_input_adapter(CharT b)
+        : span_input_adapter(reinterpret_cast<const char*>(b),
+                             std::strlen(reinterpret_cast<const char*>(b))) {}
+
+    template<class IteratorType,
+             typename std::enable_if<
+                 std::is_same<typename iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value,
+                 int>::type = 0>
+    span_input_adapter(IteratorType first, IteratorType last)
+        : ia(input_adapter(first, last)) {}
 
-    /// input adapter for array
     template<class T, std::size_t N>
-    input_adapter(T (&array)[N])
+    span_input_adapter(T (&array)[N])
-        : input_adapter(std::begin(array), std::end(array)) {}
+        : span_input_adapter(std::begin(array), std::end(array)) {}
 
     /// input adapter for contiguous container
     template<class ContiguousContainer, typename
              std::enable_if<not std::is_pointer<ContiguousContainer>::value and
                             std::is_base_of<std::random_access_iterator_tag, typename iterator_traits<decltype(std::begin(std::declval<ContiguousContainer const>()))>::iterator_category>::value,
                             int>::type = 0>
-    input_adapter(const ContiguousContainer& c)
+    span_input_adapter(const ContiguousContainer& c)
-        : input_adapter(std::begin(c), std::end(c)) {}
+        : span_input_adapter(std::begin(c), std::end(c)) {}
 
-    operator input_adapter_t()
+    input_buffer_adapter&& get()
     {
-        return ia;
+        return std::move(ia);
     }
 
   private:
-    /// the actual adapter
+    input_buffer_adapter ia;
-    input_adapter_t ia = nullptr;
 };
 }  // namespace detail
 }  // namespace nlohmann
@@ -5551,6 +5588,20 @@ namespace nlohmann
 {
 namespace detail
 {
+
+/*!
+@brief determine system byte order
+
+@return true if and only if system's byte order is little endian
+
+@note from https://stackoverflow.com/a/1001328/266378
+*/
+static bool little_endianess(int num = 1) noexcept
+{
+    return *reinterpret_cast<char*>(&num) == 1;
+}
+
+
 ///////////////////
 // binary reader //
 ///////////////////
@@ -5558,7 +5609,7 @@ namespace detail
 /*!
 @brief deserialization of CBOR, MessagePack, and UBJSON values
 */
-template<typename BasicJsonType, typename SAX = json_sax_dom_parser<BasicJsonType>>
+template<typename BasicJsonType, typename InputAdapterType, typename SAX = json_sax_dom_parser<BasicJsonType>>
 class binary_reader
 {
     using number_integer_t = typename BasicJsonType::number_integer_t;
@@ -5574,10 +5625,9 @@ class binary_reader
 
     @param[in] adapter  input adapter to read from
     */
-    explicit binary_reader(input_adapter_t adapter) : ia(std::move(adapter))
+    explicit binary_reader(InputAdapterType&& adapter) : ia(std::move(adapter))
     {
         (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
-        assert(ia);
     }
 
     // make class move-only
@@ -5646,18 +5696,6 @@ class binary_reader
         return result;
     }
 
-    /*!
-    @brief determine system byte order
-
-    @return true if and only if system's byte order is little endian
-
-    @note from https://stackoverflow.com/a/1001328/266378
-    */
-    static constexpr bool little_endianess(int num = 1) noexcept
-    {
-        return *reinterpret_cast<char*>(&num) == 1;
-    }
-
   private:
     //////////
     // BSON //
@@ -7612,7 +7650,7 @@ class binary_reader
     int get()
     {
         ++chars_read;
-        return current = ia->get_character();
+        return current = ia.get_character();
     }
 
     /*!
@@ -7800,7 +7838,7 @@ class binary_reader
 
   private:
     /// input adapter
-    input_adapter_t ia = nullptr;
+    InputAdapterType ia;
 
     /// the current character
     int current = std::char_traits<char>::eof();
@@ -7847,19 +7885,9 @@ namespace detail
 // lexer //
 ///////////
 
-/*!
-@brief lexical analysis
-
-This class organizes the lexical analysis during JSON deserialization.
-*/
 template<typename BasicJsonType>
-class lexer
+class lexer_base
 {
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-
   public:
     /// token types for the parser
     enum class token_type
@@ -7900,9 +7928,9 @@ class lexer
                 return "null literal";
             case token_type::value_string:
                 return "string literal";
-            case lexer::token_type::value_unsigned:
+            case token_type::value_unsigned:
-            case lexer::token_type::value_integer:
+            case token_type::value_integer:
-            case lexer::token_type::value_float:
+            case token_type::value_float:
                 return "number literal";
             case token_type::begin_array:
                 return "'['";
@@ -7928,15 +7956,31 @@ class lexer
                 // LCOV_EXCL_STOP
         }
     }
+};
+/*!
+@brief lexical analysis
 
-    explicit lexer(detail::input_adapter_t&& adapter)
+This class organizes the lexical analysis during JSON deserialization.
+*/
+template<typename BasicJsonType, typename InputAdapterType>
+class lexer : public lexer_base<BasicJsonType>
+{
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+
+  public:
+    using token_type = typename lexer_base<BasicJsonType>::token_type;
+
+    explicit lexer(InputAdapterType&& adapter)
         : ia(std::move(adapter)), decimal_point_char(get_decimal_point()) {}
 
     // delete because of pointer members
     lexer(const lexer&) = delete;
-    lexer(lexer&&) = delete;
+    lexer(lexer&&) = default;
     lexer& operator=(lexer&) = delete;
-    lexer& operator=(lexer&&) = delete;
+    lexer& operator=(lexer&&) = default;
     ~lexer() = default;
 
   private:
@@ -9081,7 +9125,7 @@ scan_number_done:
         }
         else
         {
-            current = ia->get_character();
+            current = ia.get_character();
         }
 
         if (JSON_HEDLEY_LIKELY(current != std::char_traits<char>::eof()))
@@ -9305,7 +9349,7 @@ scan_number_done:
 
   private:
     /// input adapter
-    detail::input_adapter_t ia = nullptr;
+    InputAdapterType ia;
 
     /// the current character
     std::char_traits<char>::int_type current = std::char_traits<char>::eof();
@@ -9370,24 +9414,8 @@ namespace detail
 // parser //
 ////////////
 
-/*!
+enum class parse_event_t : uint8_t
-@brief syntax analysis
-
-This class implements a recursive descent parser.
-*/
-template<typename BasicJsonType>
-class parser
 {
-    using number_integer_t = typename BasicJsonType::number_integer_t;
-    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-    using number_float_t = typename BasicJsonType::number_float_t;
-    using string_t = typename BasicJsonType::string_t;
-    using lexer_t = lexer<BasicJsonType>;
-    using token_type = typename lexer_t::token_type;
-
-  public:
-    enum class parse_event_t : uint8_t
-    {
     /// the parser read `{` and started to process a JSON object
     object_start,
     /// the parser read `}` and finished processing a JSON object
@@ -9400,14 +9428,31 @@ class parser
     key,
     /// the parser finished reading a JSON value
     value
-    };
+};
 
-    using parser_callback_t =
+template<typename BasicJsonType>
+using parser_callback_t =
     std::function<bool(int depth, parse_event_t event, BasicJsonType& parsed)>;
 
+/*!
+@brief syntax analysis
+
+This class implements a recursive descent parser.
+*/
+template<typename BasicJsonType, typename InputAdapterType>
+class parser
+{
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using lexer_t = lexer<BasicJsonType, InputAdapterType>;
+    using token_type = typename lexer_t::token_type;
+
+  public:
     /// a parser reading from an input adapter
-    explicit parser(detail::input_adapter_t&& adapter,
+    explicit parser(InputAdapterType&& adapter,
-                    const parser_callback_t cb = nullptr,
+                    const parser_callback_t<BasicJsonType> cb = nullptr,
                     const bool allow_exceptions_ = true)
         : callback(cb), m_lexer(std::move(adapter)), allow_exceptions(allow_exceptions_)
     {
@@ -9832,7 +9877,7 @@ class parser
 
   private:
     /// callback function
-    const parser_callback_t callback = nullptr;
+    const parser_callback_t<BasicJsonType> callback = nullptr;
     /// the type of the last read token
     token_type last_token = token_type::uninitialized;
     /// the lexer
@@ -13487,7 +13532,7 @@ class binary_writer
 
   private:
     /// whether we can assume little endianess
-    const bool is_little_endian = binary_reader<BasicJsonType>::little_endianess();
+    const bool is_little_endian = little_endianess();
 
     /// the output
     output_adapter_t<CharType> oa = nullptr;
@@ -15616,13 +15661,15 @@ class basic_json
   private:
     template<detail::value_t> friend struct detail::external_constructor;
     friend ::nlohmann::json_pointer<basic_json>;
-    friend ::nlohmann::detail::parser<basic_json>;
+
+    template<typename BasicJsonType, typename InputType>
+    friend class ::nlohmann::detail::parser;
     friend ::nlohmann::detail::serializer<basic_json>;
     template<typename BasicJsonType>
     friend class ::nlohmann::detail::iter_impl;
     template<typename BasicJsonType, typename CharType>
     friend class ::nlohmann::detail::binary_writer;
-    template<typename BasicJsonType, typename SAX>
+    template<typename BasicJsonType, typename InputType, typename SAX>
     friend class ::nlohmann::detail::binary_reader;
     template<typename BasicJsonType>
     friend class ::nlohmann::detail::json_sax_dom_parser;
@@ -15633,8 +15680,17 @@ class basic_json
     using basic_json_t = NLOHMANN_BASIC_JSON_TPL;
 
     // convenience aliases for types residing in namespace detail;
-    using lexer = ::nlohmann::detail::lexer<basic_json>;
+    using lexer = ::nlohmann::detail::lexer_base<basic_json>;
-    using parser = ::nlohmann::detail::parser<basic_json>;
+
+    template<typename InputAdapterType>
+    static ::nlohmann::detail::parser<basic_json, InputAdapterType> parser(
+        InputAdapterType adapter,
+        detail::parser_callback_t<basic_json>cb = nullptr,
+        bool allow_exceptions = true
+    )
+    {
+        return ::nlohmann::detail::parser<basic_json, InputAdapterType>(std::move(adapter), std::move(cb), allow_exceptions);
+    }
 
     using primitive_iterator_t = ::nlohmann::detail::primitive_iterator_t;
     template<typename BasicJsonType>
@@ -15648,7 +15704,8 @@ class basic_json
     template<typename CharType>
     using output_adapter_t = ::nlohmann::detail::output_adapter_t<CharType>;
 
-    using binary_reader = ::nlohmann::detail::binary_reader<basic_json>;
+    template<typename InputType>
+    using binary_reader = ::nlohmann::detail::binary_reader<basic_json, InputType>;
     template<typename CharType> using binary_writer = ::nlohmann::detail::binary_writer<basic_json, CharType>;
 
     using serializer = ::nlohmann::detail::serializer<basic_json>;
@@ -16700,7 +16757,7 @@ class basic_json
 
     @sa @ref parser_callback_t for more information and examples
     */
-    using parse_event_t = typename parser::parse_event_t;
+    using parse_event_t = detail::parse_event_t;
 
     /*!
     @brief per-element parser callback type
@@ -16751,7 +16808,7 @@ class basic_json
 
     @since version 1.0.0
     */
-    using parser_callback_t = typename parser::parser_callback_t;
+    using parser_callback_t = detail::parser_callback_t<basic_json>;
 
     //////////////////
     // constructors //
@@ -22140,21 +22197,39 @@ class basic_json
 
     @since version 2.0.3 (contiguous containers)
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json parse(detail::input_adapter&& i,
+    static basic_json parse(InputType&& i,
                             const parser_callback_t cb = nullptr,
                             const bool allow_exceptions = true)
     {
         basic_json result;
-        parser(i, cb, allow_exceptions).parse(true, result);
+        parser(detail::input_adapter(std::forward<InputType>(i)), cb, allow_exceptions).parse(true, result);
         return result;
     }
 
-    static bool accept(detail::input_adapter&& i)
+
+
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json parse(detail::span_input_adapter&& i,
+                            const parser_callback_t cb = nullptr,
+                            const bool allow_exceptions = true)
     {
-        return parser(i).accept(true);
+        basic_json result;
+        parser(i.get(), cb, allow_exceptions).parse(true, result);
+        return result;
     }
 
+    template<typename InputType>
+    static bool accept(InputType&& i)
+    {
+        return parser(detail::input_adapter(std::forward<InputType>(i))).accept(true);
+    }
+
+    static bool accept(detail::span_input_adapter&& i)
+    {
+        return parser(i.get()).accept(true);
+    }
     /*!
     @brief generate SAX events
 
@@ -22208,17 +22283,34 @@ class basic_json
 
     @since version 3.2.0
     */
-    template <typename SAX>
+    template <typename SAX, typename InputType>
     JSON_HEDLEY_NON_NULL(2)
-    static bool sax_parse(detail::input_adapter&& i, SAX* sax,
+    static bool sax_parse(InputType&& i, SAX* sax,
                           input_format_t format = input_format_t::json,
                           const bool strict = true)
     {
+        assert(sax);
+
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
         return format == input_format_t::json
-               ? parser(std::move(i)).sax_parse(sax, strict)
+               ? parser(std::move(ia)).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, SAX>(std::move(i)).sax_parse(format, sax, strict);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia)).sax_parse(format, sax, strict);
     }
 
+    template <typename SAX>
+    JSON_HEDLEY_NON_NULL(2)
+    static bool sax_parse(detail::span_input_adapter&& i, SAX* sax,
+                          input_format_t format = input_format_t::json,
+                          const bool strict = true)
+    {
+        assert(sax);
+        auto ia = i.get();
+        return format == input_format_t::json
+               ? parser(std::move(ia)).sax_parse(sax, strict)
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia)).sax_parse(format, sax, strict);
+    }
+
+
     /*!
     @brief deserialize from an iterator range with contiguous storage
 
@@ -22930,14 +23022,16 @@ class basic_json
            @a strict parameter since 3.0.0; added @a allow_exceptions parameter
            since 3.2.0
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_cbor(detail::input_adapter&& i,
+    static basic_json from_cbor(InputType&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::cbor, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -22945,7 +23039,7 @@ class basic_json
     @copydoc from_cbor(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_cbor(A1 && a1, A2 && a2,
                                 const bool strict = true,
@@ -22953,7 +23047,18 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::cbor, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::cbor, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
+
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json from_cbor(detail::span_input_adapter&& i,
+                                const bool strict = true,
+                                const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::cbor, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -23043,14 +23148,16 @@ class basic_json
            @a strict parameter since 3.0.0; added @a allow_exceptions parameter
            since 3.2.0
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_msgpack(detail::input_adapter&& i,
+    static basic_json from_msgpack(InputType&& i,
                                    const bool strict = true,
                                    const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::msgpack, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -23058,7 +23165,7 @@ class basic_json
     @copydoc from_msgpack(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_msgpack(A1 && a1, A2 && a2,
                                    const bool strict = true,
@@ -23066,10 +23173,23 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::msgpack, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::msgpack, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
+
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json from_msgpack(detail::span_input_adapter&& i,
+                                   const bool strict = true,
+                                   const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::msgpack, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
+
+
     /*!
     @brief create a JSON value from an input in UBJSON format
 
@@ -23131,14 +23251,16 @@ class basic_json
 
     @since version 3.1.0; added @a allow_exceptions parameter since 3.2.0
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_ubjson(detail::input_adapter&& i,
+    static basic_json from_ubjson(InputType&& i,
                                   const bool strict = true,
                                   const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::ubjson, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -23146,7 +23268,7 @@ class basic_json
     @copydoc from_ubjson(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_ubjson(A1 && a1, A2 && a2,
                                   const bool strict = true,
@@ -23154,10 +23276,22 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::ubjson, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::ubjson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
+
+    static basic_json from_ubjson(detail::span_input_adapter&& i,
+                                  const bool strict = true,
+                                  const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::ubjson, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
+
+
     /*!
     @brief Create a JSON value from an input in BSON format
 
@@ -23218,14 +23352,16 @@ class basic_json
     @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the
         related UBJSON format
     */
+    template<typename InputType>
     JSON_HEDLEY_WARN_UNUSED_RESULT
-    static basic_json from_bson(detail::input_adapter&& i,
+    static basic_json from_bson(InputType&& i,
                                 const bool strict = true,
                                 const bool allow_exceptions = true)
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::bson, &sdp, strict);
+        auto ia = detail::input_adapter(std::forward<InputType>(i));
+        const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
@@ -23233,7 +23369,7 @@ class basic_json
     @copydoc from_bson(detail::input_adapter&&, const bool, const bool)
     */
     template<typename A1, typename A2,
-             detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0>
+             detail::enable_if_t<std::is_constructible<detail::span_input_adapter, A1, A2>::value, int> = 0>
     JSON_HEDLEY_WARN_UNUSED_RESULT
     static basic_json from_bson(A1 && a1, A2 && a2,
                                 const bool strict = true,
@@ -23241,12 +23377,20 @@ class basic_json
     {
         basic_json result;
         detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
-        const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::bson, &sdp, strict);
+        const bool res = binary_reader<detail::input_buffer_adapter>(detail::span_input_adapter(std::forward<A1>(a1), std::forward<A2>(a2)).get()).sax_parse(input_format_t::bson, &sdp, strict);
         return res ? result : basic_json(value_t::discarded);
     }
 
-
+    JSON_HEDLEY_WARN_UNUSED_RESULT
-
+    static basic_json from_bson(detail::span_input_adapter&& i,
+                                const bool strict = true,
+                                const bool allow_exceptions = true)
+    {
+        basic_json result;
+        detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions);
+        const bool res = binary_reader<detail::input_buffer_adapter>(i.get()).sax_parse(input_format_t::bson, &sdp, strict);
+        return res ? result : basic_json(value_t::discarded);
+    }
     /// @}
 
     //////////////////////////

test/src/unit-class_lexer.cpp

@@ -40,7 +40,8 @@ namespace
 json::lexer::token_type scan_string(const char* s);
 json::lexer::token_type scan_string(const char* s)
 {
-    return json::lexer(nlohmann::detail::input_adapter(s)).scan();
+    auto ia = nlohmann::detail::input_adapter(s);
+    return nlohmann::detail::lexer<json, decltype(ia)>(std::move(ia)).scan();
 }
 }