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Niels Lohmann
a0b98325cf
basic_json_document gets a second template parameter, Editable (false by default), plus the aliases json_editable_document, json_editable_view, ordered_json_editable_document and ordered_json_editable_view. Editable documents can change values and structure without rewriting the source text: set()/push_back() on values, keys, array indices and JSON pointers; insert() before an array element; erase() of an object key, array index or JSON pointer. New values and element sequences go into edit storage that the document owns and never moves, so views keep referring to their value across edits and a parsed node never moves. Read-only documents walk the plain node array and are unaffected. Strings are checked for UTF-8 on entry, so dump() of an editable document never throws type_error.316. Binary values cannot be stored (type_error.319). A seeded differential test applies random edits to an editable document and to the equivalent ordered_json and compares both after every step. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
140 lines
4.3 KiB
C++
140 lines
4.3 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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#pragma once
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#include <cstdint> // int64_t, uint8_t
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#include <string> // string
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#include <vector> // vector
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#include <nlohmann/json.hpp>
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#include <nlohmann/detail/view/document_data.hpp>
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#include <nlohmann/detail/view/macro_scope.hpp>
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#include <nlohmann/detail/view/node.hpp>
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#include <nlohmann/detail/view/number.hpp>
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NLOHMANN_JSON_NAMESPACE_BEGIN
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namespace detail
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{
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namespace view
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{
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/*!
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@brief the basic_json value of the subtree at n
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The subtree is replayed into the SAX handler that parse() uses to build its
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values, so the result is the value parse() would produce: duplicate keys keep
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the last value, and with JSON_DIAGNOSTICS the parent pointers are set. It is
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iterative, so the nesting depth is limited by memory only, as for parse().
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Without a lexer the handler records no source positions
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(JSON_DIAGNOSTIC_POSITIONS).
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*/
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template<typename BasicJsonType, bool Editable>
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BasicJsonType materialize(const document_data& d, const node* n)
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{
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using string_t = typename BasicJsonType::string_t;
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using sax_t = json_sax_dom_parser<BasicJsonType, iterator_input_adapter<const char*>>;
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using nav = navigation<Editable>;
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struct frame
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{
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const node* pos; ///< next element, or key of the next member
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const node* end;
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bool object;
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};
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BasicJsonType result;
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sax_t sax(result, true);
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const string_t no_token{};
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std::vector<frame> open;
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for (;;)
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{
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// false positive: n comes from nav::value(), which never returns null for a valid index
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// @infer-ignore NULLPTR_DEREFERENCE
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switch (static_cast<value_t>(n->kind))
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{
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case value_t::object:
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case value_t::array:
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{
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const bool object = n->kind == static_cast<std::uint8_t>(value_t::object);
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if (object)
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{
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sax.start_object(n->len);
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}
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else
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{
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sax.start_array(n->len);
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}
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open.push_back(frame{nav::first(d, n), nav::end(d, n), object});
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break;
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}
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case value_t::string:
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{
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string_t s(d.str(*n), n->len);
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sax.string(s);
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break;
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}
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case value_t::number_integer:
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sax.number_integer(static_cast<typename BasicJsonType::number_integer_t>(static_cast<std::int64_t>(integer_bits(*n))));
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break;
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case value_t::number_unsigned:
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sax.number_unsigned(static_cast<typename BasicJsonType::number_unsigned_t>(integer_bits(*n)));
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break;
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case value_t::number_float:
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sax.number_float(float_value<typename BasicJsonType::number_float_t>(d, *n), no_token);
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break;
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case value_t::boolean:
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sax.boolean((n->flags & node_flags::is_true) != 0);
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break;
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case value_t::null:
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case value_t::binary:
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case value_t::discarded:
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default:
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sax.null();
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break;
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}
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// the next value: close finished containers, then read the key
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for (;;)
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{
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if (open.empty())
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{
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return result;
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}
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frame& f = open.back();
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if (f.pos == f.end)
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{
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if (f.object)
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{
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sax.end_object();
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}
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else
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{
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sax.end_array();
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}
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open.pop_back();
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continue;
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}
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const node* entry = f.pos;
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if (f.object)
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{
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string_t key(d.str(*entry), entry->len);
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sax.key(key);
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++entry;
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}
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n = nav::value(entry);
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f.pos = document_data::after(entry);
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break;
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}
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}
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}
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} // namespace view
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} // namespace detail
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NLOHMANN_JSON_NAMESPACE_END
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