Merge origin/develop into claude/json-view-canada-perf-99bbe3

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

single_include/nlohmann/json.hpp

@@ -15629,7 +15629,10 @@ struct diagnostic_positions
         {
             // Lexer has read the first character of the container, so
             // subtract 1 from the position to get the correct start position.
-            v.start_position = lexer->get_chars_read_total() - 1;
+            // (npos: a value without a source position, see materialize() of
+            // json_view)
+            const std::size_t read = lexer->get_chars_read_total();
+            v.start_position = read == std::string::npos ? std::string::npos : read - 1;
         }
     }
 
@@ -15644,6 +15647,12 @@ struct diagnostic_positions
         {
             // Lexer's position is past the closing brace or bracket, so set that as the end position.
             v.end_position = lexer->get_chars_read_total();
+            if (v.end_position == std::string::npos)
+            {
+                // a range has both ends or none (exception::diagnostics()
+                // prints only complete ones)
+                v.start_position = std::string::npos;
+            }
         }
     }
 
@@ -15660,6 +15669,12 @@ struct diagnostic_positions
             // The start position will be set below based on the length of the string representation
             // of the value.
             v.end_position = lexer->get_chars_read_total();
+            if (v.end_position == std::string::npos)
+            {
+                // a value without a source position
+                v.start_position = std::string::npos;
+                return;
+            }
 
             switch (v.type())
             {
@@ -15872,8 +15887,12 @@ read up to it.
 @tparam Collect  whether to collect the values of containers of unknown size on
                  a stack (only for a caller that does not use the value after a
                  parse error)
+@tparam LexerType  the type of the lexer that reports the source positions
+                   (JSON_DIAGNOSTIC_POSITIONS); only diagnostic_positions uses
+                   it, so any type with its three functions works (as
+                   materialize() of json_view uses it)
 */
-template<typename BasicJsonType, typename InputAdapterType, bool Collect = false>
+template<typename BasicJsonType, typename InputAdapterType, bool Collect = false, typename LexerType = lexer<BasicJsonType, InputAdapterType>>
 class json_sax_dom_parser : public json_sax_dom_error_state
 {
   public:
@@ -15882,7 +15901,7 @@ class json_sax_dom_parser : public json_sax_dom_error_state
     using number_float_t = typename BasicJsonType::number_float_t;
     using string_t = typename BasicJsonType::string_t;
     using binary_t = typename BasicJsonType::binary_t;
-    using lexer_t = lexer<BasicJsonType, InputAdapterType>;
+    using lexer_t = LexerType;
 
     /*!
     @param[in,out] r  reference to a JSON value that is manipulated while
@@ -22515,8 +22534,8 @@ using parser_callback_t =
 template<typename SAX>
 struct sax_ignores_number_text : std::false_type {};
 
-template<typename BasicJsonType, typename InputAdapterType, bool Collect>
-struct sax_ignores_number_text<json_sax_dom_parser<BasicJsonType, InputAdapterType, Collect>> : std::true_type {};
+template<typename BasicJsonType, typename InputAdapterType, bool Collect, typename LexerType>
+struct sax_ignores_number_text<json_sax_dom_parser<BasicJsonType, InputAdapterType, Collect, LexerType>> : std::true_type {};
 
 template<typename BasicJsonType, typename InputAdapterType>
 struct sax_ignores_number_text<json_sax_dom_callback_parser<BasicJsonType, InputAdapterType>> : std::true_type {};
@@ -24331,6 +24350,13 @@ class json_pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/operator_slasheq/
     json_pointer& operator/=(const json_pointer& ptr)
     {
+        // insert() must not be given iterators into the vector it inserts
+        // into: append a copy when a pointer is appended to itself
+        if (JSON_HEDLEY_UNLIKELY(&ptr == this))
+        {
+            return *this /= json_pointer(ptr);
+        }
+
         reference_tokens.insert(reference_tokens.end(),
                                 ptr.reference_tokens.begin(),
                                 ptr.reference_tokens.end());
@@ -36910,7 +36936,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     friend class ::nlohmann::detail::binary_writer;
     template<typename BasicJsonType, typename InputType, typename SAX>
     friend class ::nlohmann::detail::binary_reader;
-    template<typename BasicJsonType, typename InputAdapterType, bool Collect>
+    template<typename BasicJsonType, typename InputAdapterType, bool Collect, typename LexerType>
     friend class ::nlohmann::detail::json_sax_dom_parser;
     template<typename BasicJsonType, typename InputAdapterType>
     friend class ::nlohmann::detail::json_sax_dom_binary_parser;
@@ -43701,6 +43727,25 @@ public:
     /// @sa https://json.nlohmann.me/api/basic_json/patch/
     void patch_inplace(const basic_json& json_patch)
     {
+        // the operations below change *this while iterating json_patch: apply
+        // a copy when a value is applied as patch to itself or, with
+        // JSON_DIAGNOSTICS, to a value stored inside it
+        // NOLINTNEXTLINE(misc-const-correctness): only the JSON_DIAGNOSTICS build modifies it
+        bool patch_aliases_this = (&json_patch == this);
+#if JSON_DIAGNOSTICS
+        for (const basic_json* p = json_patch.m_parent; !patch_aliases_this && p != nullptr; p = p->m_parent)
+        {
+            patch_aliases_this = (p == this);
+        }
+#endif
+        if (JSON_HEDLEY_UNLIKELY(patch_aliases_this))
+        {
+            // NOLINTNEXTLINE(performance-unnecessary-copy-initialization): *this is modified below
+            const basic_json json_patch_copy = json_patch;
+            patch_inplace(json_patch_copy);
+            return;
+        }
+
         basic_json& result = *this;
         // the valid JSON Patch operations
         enum class patch_operations {add, remove, replace, move, copy, test, invalid};

single_include/nlohmann/json_view.hpp

@@ -269,7 +269,7 @@ struct node
     std::uint16_t extra; ///< numbers: integer digits (low byte) and fraction digits (high byte), 255 = "many"; objects: number of the object's key hash index (1-based, 0 = none); otherwise 0
     std::uint32_t off;   ///< source offset (string content, number token, literal, bracket); arena offset if escaped/edited; number of the element sequence if moved
     std::uint32_t len;   ///< string: decoded bytes; float: token bytes; array/object: element count
-    std::uint32_t next;  ///< array/object: number of nodes of the subtree (its extent in the enclosing sequence)
+    std::uint32_t next;  ///< array/object: number of nodes of the subtree (its extent in the enclosing sequence); escaped string: source offset of the opening quote plus one (JSON_DIAGNOSTIC_POSITIONS; 0: unknown)
 };
 static_assert(sizeof(node) == 16, "node must stay 16 bytes");
 
@@ -1185,6 +1185,32 @@ NLOHMANN_VIEW_ALWAYS_INLINE const unsigned char* skip_digits(const unsigned char
     return p;
 }
 
+/// advance over the text of a line comment (after its "//") to the line
+/// break or the end (with NulIsEnd also a null byte, which is left for the
+/// caller to see, as in parse())
+template<bool NulIsEnd = false>
+inline const unsigned char* skip_line_comment(const unsigned char* p, const unsigned char* e) noexcept
+{
+    while (p != e && *p != '\n' && *p != '\r' && !(NulIsEnd && *p == 0))
+    {
+        ++p;
+    }
+    return p;
+}
+
+/// the "*/" that ends a block comment whose text starts at p (after its "/*");
+/// if it is unterminated, the end (with NulIsEnd also a null byte), which is
+/// where the caller reports the error
+template<bool NulIsEnd = false>
+inline const unsigned char* find_block_comment_end(const unsigned char* p, const unsigned char* e) noexcept
+{
+    while (p != e && !(NulIsEnd && *p == 0) && !(*p == '*' && p + 1 != e && p[1] == '/'))
+    {
+        ++p;
+    }
+    return p;
+}
+
 /// powers of ten up to 10^19 as integers
 inline std::uint64_t int_pow10(unsigned k) noexcept
 {
@@ -1382,31 +1408,16 @@ class builder
         }
         if (p[1] == '/')
         {
-            p += 2;
-            // (as in parse(), a null byte is the end of the input, so it is
-            // left for the caller to see)
-            while (p != m_end && *p != '\n' && *p != '\r' && !(NulIsEnd && *p == 0))
-            {
-                ++p;
-            }
-            return p;
+            return skip_line_comment<NulIsEnd>(p + 2, m_end);
         }
         if (p[1] == '*')
         {
-            p += 2;
-            for (;;)
+            p = find_block_comment_end<NulIsEnd>(p + 2, m_end);
+            if (p == m_end || *p != '*')
             {
-                if (p == m_end || (NulIsEnd && *p == 0))
-                {
-                    return fail_at(error_code::comment_unterminated, p);
-                }
-                if (*p == '*' && p + 1 != m_end && p[1] == '/')
-                {
-                    p += 2;
-                    return p;
-                }
-                ++p;
+                return fail_at(error_code::comment_unterminated, p);
             }
+            return p + 2;
         }
         ++p;
         return fail_at(error_code::comment_start, p);
@@ -2402,7 +2413,14 @@ indent_done:
                 return false;
             }
             p = r.p;
-            push_node(node_kind::string, node_flags::escaped, 0, r.start, r.len);
+#if JSON_DIAGNOSTIC_POSITIONS
+            // the decoded string is in the arena: next keeps the source offset
+            // of the opening quote plus one (0: unknown) for materialize()
+            const std::uint64_t second = static_cast<std::uint64_t>(r.len) | (static_cast<std::uint64_t>(s - b) << 32);
+#else
+            const std::uint64_t second = r.len;
+#endif
+            push_node(node_kind::string, node_flags::escaped, 0, r.start, second);
             return true;
         }
     };
@@ -5099,7 +5117,8 @@ constexpr std::uint64_t image_limit = 0xFFFFFFF0u;
 /// Copy the current structure of an edited document into nodes in document
 /// order, as the parser would have written them. Text written by edits is
 /// appended to text_tail (number tokens) and arena_tail (strings); floats that
-/// are not finite become null, as dump() writes them.
+/// are not finite become null, as dump() writes them. Nodes keep the flag
+/// is_new: they have no source position (JSON_DIAGNOSTIC_POSITIONS).
 inline void compact_nodes(const document_data& d, std::size_t arena_size, std::vector<node>& out, std::string& text_tail, std::string& arena_tail)
 {
     struct frame
@@ -5122,16 +5141,18 @@ inline void compact_nodes(const document_data& d, std::size_t arena_size, std::v
             arena_tail.append(d.str(s), s.len);
             r.flags = node_flags::escaped;
         }
+        r.flags = static_cast<std::uint8_t>(r.flags | (s.flags & node_flags::is_new));
         return r;
     };
     const auto copy_node = [&](const node * v)
     {
         node r = *v;
+        const auto is_new = static_cast<std::uint8_t>(v->flags & node_flags::is_new);
         switch (static_cast<value_t>(v->kind))
         {
             case value_t::object:
             case value_t::array:
-                r.flags = 0;
+                r.flags = is_new;
                 r.extra = 0;
                 r.off = (v->flags & (node_flags::moved | node_flags::is_new)) != 0 ? 0 : v->off;
                 r.len = 0;  // counted below
@@ -5148,7 +5169,7 @@ inline void compact_nodes(const document_data& d, std::size_t arena_size, std::v
                     r.off = static_cast<std::uint32_t>(d.size + text_tail.size());
                     text_tail.append(d.str(*v), number_length(*v));
                 }
-                r.flags = 0;
+                r.flags = is_new;
                 break;
             case value_t::number_float:
                 if ((v->flags & node_flags::storage) == node_flags::edited)
@@ -5158,22 +5179,23 @@ inline void compact_nodes(const document_data& d, std::size_t arena_size, std::v
                     {
                         r = node{}; // nan and infinity: null, as dump() writes them
                         r.kind = node_kind::null;
+                        r.flags = is_new;
                         break;
                     }
                     r.off = static_cast<std::uint32_t>(d.size + text_tail.size());
                     text_tail.append(t, v->len);
                     r.extra = 0xFFFFu; // the digit layout is not recorded
                 }
-                r.flags = 0;
+                r.flags = is_new;
                 break;
             case value_t::boolean:
-                r.flags = static_cast<std::uint8_t>(v->flags & node_flags::is_true);
+                r.flags = static_cast<std::uint8_t>(v->flags & (node_flags::is_true | node_flags::is_new));
                 break;
             case value_t::null:
             case value_t::binary:
             case value_t::discarded:
             default:
-                r.flags = 0;
+                r.flags = is_new;
                 break;
         }
         out.push_back(r);
@@ -5534,13 +5556,15 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
     std::vector<float_range> floats;
     const auto check_string = [&](const node & n) -> bool
     {
-        if ((n.flags & ~node_flags::escaped) != 0 || n.extra != 0)
+        if ((n.flags & ~(node_flags::escaped | node_flags::is_new)) != 0 || n.extra != 0)
         {
             return false;
         }
         const bool decoded = (n.flags & node_flags::escaped) != 0;
         const std::size_t limit = decoded ? arena_size : text_size;
-        if (n.off > limit || n.len > limit - n.off)
+        // (next: the source offset of a decoded string's opening quote plus
+        // one, or 0; see node)
+        if (n.off > limit || n.len > limit - n.off || n.next > text_size)
         {
             return false;
         }
@@ -5612,13 +5636,13 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
         {
             case value_t::null:
                 // (the offset of a literal is read to size the output of dump())
-                if (n.flags != 0 || n.extra != 0 || n.off > text_size)
+                if ((n.flags & ~node_flags::is_new) != 0 || n.extra != 0 || n.off > text_size)
                 {
                     return false;
                 }
                 break;
             case value_t::boolean:
-                if ((n.flags & ~node_flags::is_true) != 0 || n.extra != 0 || n.off > text_size)
+                if ((n.flags & ~(node_flags::is_true | node_flags::is_new)) != 0 || n.extra != 0 || n.off > text_size)
                 {
                     return false;
                 }
@@ -5632,7 +5656,7 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
             case value_t::number_integer:
             case value_t::number_unsigned:
             case value_t::number_float:
-                if (n.flags != 0 || !number_in_bounds(n))
+                if ((n.flags & ~node_flags::is_new) != 0 || !number_in_bounds(n))
                 {
                     return false;
                 }
@@ -5654,7 +5678,7 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
             case value_t::object:
             {
                 const std::size_t limit = stack.empty() ? count : stack.back().end;
-                if (n.flags != 0 || n.extra != 0 || n.next == 0 || n.next > limit - i || n.off > text_size)
+                if ((n.flags & ~node_flags::is_new) != 0 || n.extra != 0 || n.next == 0 || n.next > limit - i || n.off > text_size)
                 {
                     return false;
                 }
@@ -6257,6 +6281,8 @@ NLOHMANN_JSON_NAMESPACE_END
 
 // #include <nlohmann/detail/view/number.hpp>
 
+// #include <nlohmann/detail/view/scan.hpp>
+
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
@@ -6264,6 +6290,189 @@ namespace detail
 namespace view
 {
 
+#if JSON_DIAGNOSTIC_POSITIONS
+/*!
+@brief the source positions of the values materialize() replays
+
+Stands in for the lexer of json_sax_dom_parser, which reads the positions of
+the values it stores from these three functions (diagnostic_positions). npos
+is a value without a source position. One position_source serves a whole
+materialize() call: before each value is handed to the handler, the range of
+that value is set (or cleared), overwriting that of the value before.
+*/
+struct position_source
+{
+    /// the token, of which diagnostic_positions only reads the length
+    struct token
+    {
+        std::size_t length;
+        std::size_t size() const noexcept
+        {
+            return length;
+        }
+    };
+
+    std::size_t start = std::string::npos; ///< the first byte of the next value
+    std::size_t end = std::string::npos;   ///< one past the next value (start_object/start_array: one past the bracket)
+
+    std::size_t get_chars_read_total() const noexcept
+    {
+        return end;
+    }
+    std::size_t get_token_start_position() const noexcept
+    {
+        return start;
+    }
+    token get_string() const noexcept
+    {
+        return token{end - start};
+    }
+
+    /// the range [first, last), or none if either is npos
+    void set(std::size_t first, std::size_t last) noexcept
+    {
+        if (first == std::string::npos || last == std::string::npos)
+        {
+            clear();
+            return;
+        }
+        start = first;
+        end = last;
+    }
+
+    /// no range: the next value has no source position
+    void clear() noexcept
+    {
+        start = std::string::npos;
+        end = std::string::npos;
+    }
+
+    /// one past the closing quote of the string whose opening quote is at
+    /// src[quote], or npos (the scan is bounded by size, as images can be
+    /// loaded without a check)
+    static std::size_t string_end(const char* src, std::size_t size, std::size_t quote) noexcept
+    {
+        for (std::size_t i = quote + 1; i < size; ++i)
+        {
+            if (src[i] == '\\')
+            {
+                ++i;
+            }
+            else if (src[i] == '"')
+            {
+                return i + 1;
+            }
+        }
+        return std::string::npos;
+    }
+
+    /// one past the closing bracket of the array or object whose last element
+    /// ends at src[pos] (or whose opening bracket is at src[pos - 1]), or npos;
+    /// in between, there can only be whitespace, comments, and a trailing comma
+    /// (the source was validated when it was parsed)
+    static std::size_t container_end(const char* src, std::size_t size, std::size_t pos) noexcept
+    {
+        const auto* const b = reinterpret_cast<const unsigned char*>(src); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast): the text as bytes, as the builder reads it
+        const unsigned char* const e = b + size;
+        while (pos < size)
+        {
+            switch (src[pos])
+            {
+                case ' ':
+                case '\t':
+                case '\n':
+                case '\r':
+                case ',':
+                    ++pos;
+                    break;
+                case ']':
+                case '}':
+                    return pos + 1;
+                case '/':
+                    if (pos + 1 < size && src[pos + 1] == '/')
+                    {
+                        pos = static_cast<std::size_t>(skip_line_comment(b + pos + 2, e) - b);
+                        break;
+                    }
+                    if (pos + 1 < size && src[pos + 1] == '*')
+                    {
+                        // (unterminated: pos is size, which ends the loop)
+                        pos = static_cast<std::size_t>(find_block_comment_end(b + pos + 2, e) - b) + 2;
+                        break;
+                    }
+                    return std::string::npos;
+                default:
+                    return std::string::npos;
+            }
+        }
+        return std::string::npos;
+    }
+
+    /// the range of the scalar n of document d
+    void set_scalar(const document_data& d, const node& n) noexcept
+    {
+        if ((n.flags & node_flags::is_new) != 0)
+        {
+            clear();
+            return;
+        }
+        std::size_t first = std::string::npos;
+        std::size_t last = std::string::npos;
+        switch (n.kind)
+        {
+            case node_kind::string:
+                if ((n.flags & node_flags::storage) == 0)
+                {
+                    // off is the first byte after the opening quote
+                    if (n.off != 0)
+                    {
+                        first = n.off - 1;
+                        last = n.off + std::size_t{n.len} + 1;
+                    }
+                }
+                else if ((n.flags & node_flags::storage) == node_flags::escaped && n.next != 0)
+                {
+                    // next is the offset of the opening quote plus one
+                    first = n.next - 1;
+                    last = string_end(d.base[0], d.size, first);
+                }
+                break;
+            case node_kind::number_integer:
+            case node_kind::number_unsigned:
+            case node_kind::number_float:
+                if ((n.flags & node_flags::storage) == 0)
+                {
+                    first = n.off;
+                    last = n.off + number_length(n);
+                }
+                break;
+            case node_kind::boolean:
+                first = n.off;
+                last = n.off + ((n.flags & node_flags::is_true) != 0 ? 4u : 5u);
+                break;
+            case node_kind::null:
+                first = n.off;
+                last = n.off + 4u;
+                break;
+            case node_kind::object:
+            case node_kind::array:
+            case node_kind::link:
+            default:
+                break;
+        }
+        // (a crafted image can point past the text)
+        if (last == std::string::npos || last > d.size)
+        {
+            clear();
+        }
+        else
+        {
+            set(first, last);
+        }
+    }
+};
+#endif
+
 /*!
 @brief the basic_json value of the subtree at n
 
@@ -6271,14 +6480,24 @@ The subtree is replayed into the SAX handler that parse() uses to build its
 values, so the result is the value parse() would produce: duplicate keys keep
 the last value, and with JSON_DIAGNOSTICS the parent pointers are set. It is
 iterative, so the nesting depth is limited by memory only, as for parse().
-Without a lexer the handler records no source positions
-(JSON_DIAGNOSTIC_POSITIONS).
+
+With JSON_DIAGNOSTIC_POSITIONS, the values get their source positions as with
+parse(): position_source stands in for the lexer. Values written by edits have
+none (npos), and neither has an array or object whose elements changed, or
+whose last element has none (the end of its closing bracket is found by
+scanning from the end of the last element).
 */
 template<typename BasicJsonType, bool Editable>
 BasicJsonType materialize(const document_data& d, const node* n)
 {
     using string_t = typename BasicJsonType::string_t;
-    using sax_t = json_sax_dom_parser<BasicJsonType, iterator_input_adapter<const char*>, true>;
+    using input_t = iterator_input_adapter<const char*>;
+#if JSON_DIAGNOSTIC_POSITIONS
+    using lexer_t = position_source;
+#else
+    using lexer_t = lexer<BasicJsonType, input_t>; // (the default: unused, as no lexer is passed)
+#endif
+    using sax_t = json_sax_dom_parser<BasicJsonType, input_t, true, lexer_t>;
     using nav = navigation<Editable>;
 
     // the open containers: their next element (or key of the next member),
@@ -6290,9 +6509,15 @@ BasicJsonType materialize(const document_data& d, const node* n)
         const node* pos;
         const node* end;
         bool object;
+#if JSON_DIAGNOSTIC_POSITIONS
+        std::size_t start;    ///< the opening bracket (npos: unknown)
+        std::size_t last_end; ///< the end of the last element read (npos: unknown)
+#endif
     };
 
+#if !JSON_DIAGNOSTIC_POSITIONS
     // a scalar needs neither the handler nor the stack of open containers
+    // (with positions, it goes through the handler, which sets them)
     switch (static_cast<value_t>(n->kind))
     {
         case value_t::string:
@@ -6314,10 +6539,16 @@ BasicJsonType materialize(const document_data& d, const node* n)
         default:
             break;
     }
+#endif
 
     BasicJsonType result;
+#if JSON_DIAGNOSTIC_POSITIONS
+    position_source positions;
+    sax_t sax(result, true, &positions);
+#else
     sax_t sax(result, true);
-    const string_t no_token{};
+#endif
+    const string_t no_token {};
     // (shallow subtrees on the stack: a call for a small value then allocates only for the value)
     std::array<frame, 16> shallow; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): filled as containers open
     std::vector<frame> deep{};
@@ -6332,6 +6563,16 @@ BasicJsonType materialize(const document_data& d, const node* n)
     std::size_t depth = 0;
     for (;;)
     {
+#if JSON_DIAGNOSTIC_POSITIONS
+        if (!is_container(*n))
+        {
+            positions.set_scalar(d, *n);
+            if (depth != 0)
+            {
+                open[depth - 1].last_end = positions.end;
+            }
+        }
+#endif
         // false positive: n comes from nav::value(), which never returns null for a valid index
         // @infer-ignore NULLPTR_DEREFERENCE
         switch (static_cast<value_t>(n->kind))
@@ -6340,6 +6581,17 @@ BasicJsonType materialize(const document_data& d, const node* n)
             case value_t::array:
             {
                 const bool object = n->kind == node_kind::object;
+#if JSON_DIAGNOSTIC_POSITIONS
+                // (moved containers are also new)
+                if ((n->flags & node_flags::is_new) != 0 || n->off >= d.size)
+                {
+                    positions.clear();
+                }
+                else
+                {
+                    positions.set(std::size_t{n->off}, std::size_t{n->off} + 1);
+                }
+#endif
                 if (object)
                 {
                     sax.start_object(n->len);
@@ -6356,7 +6608,13 @@ BasicJsonType materialize(const document_data& d, const node* n)
                     open = deep.data();
                     capacity = deep.size();
                 }
-                open[depth++] = frame{nav::first(d, n), nav::end(d, n), object};
+                // (with positions: until an element is read, the container's
+                // own bracket is the last thing read)
+                open[depth++] = frame{nav::first(d, n), nav::end(d, n), object
+#if JSON_DIAGNOSTIC_POSITIONS
+                                      , positions.start, positions.end
+#endif
+                                     };
                 break;
             }
             case value_t::string:
@@ -6397,6 +6655,31 @@ BasicJsonType materialize(const document_data& d, const node* n)
             frame& f = open[depth - 1];
             if (f.pos == f.end)
             {
+#if JSON_DIAGNOSTIC_POSITIONS
+                if (f.start == std::string::npos || f.last_end == std::string::npos)
+                {
+                    positions.clear();
+                }
+                else
+                {
+                    const std::size_t end = position_source::container_end(d.base[0], d.size, f.last_end);
+                    if (end == std::string::npos)
+                    {
+                        positions.clear();
+                    }
+                    else
+                    {
+                        // the closing bracket, as the lexer reports it (end_object()
+                        // and end_array() only read its end; the start of the
+                        // container was set when it was opened)
+                        positions.set(end - 1, end);
+                    }
+                }
+                if (depth > 1)
+                {
+                    open[depth - 2].last_end = positions.end;
+                }
+#endif
                 if (f.object)
                 {
                     sax.end_object();