🔨 realized callback parser wirh SAX interface #971
This commit is contained in:
Niels Lohmann
parent
4f6b2b6429
commit
5f723bbec6
4 changed files with 273 additions and 698 deletions
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@ -242,7 +242,7 @@ class json_sax_dom_parser : public json_sax<BasicJsonType>
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return false;
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}
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bool is_errored() const
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constexpr bool is_errored() const
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{
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return errored;
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}
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@ -303,7 +303,7 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
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using parse_event_t = typename BasicJsonType::parse_event_t;
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json_sax_dom_callback_parser(BasicJsonType& r,
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const parser_callback_t cb = nullptr,
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const parser_callback_t cb,
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const bool allow_exceptions_ = true)
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: root(r), callback(cb), allow_exceptions(allow_exceptions_)
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{
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@ -348,15 +348,21 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
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bool start_object(std::size_t len) override
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{
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const bool keep = callback(ref_stack.size() + 1, parse_event_t::object_start, discarded);
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// check callback for object start
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const bool keep = callback(static_cast<int>(ref_stack.size()) + 1, parse_event_t::object_start, discarded);
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keep_stack.push_back(keep);
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ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
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auto val = handle_value(BasicJsonType::value_t::object);
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ref_stack.push_back(val.second);
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if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
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// check object limit
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if (ref_stack.back())
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{
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JSON_THROW(out_of_range::create(408,
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"excessive object size: " + std::to_string(len)));
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if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
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{
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JSON_THROW(out_of_range::create(408,
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"excessive object size: " + std::to_string(len)));
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}
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}
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return true;
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@ -365,38 +371,73 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
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bool key(string_t& val) override
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{
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BasicJsonType k = BasicJsonType(val);
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const bool keep = callback(ref_stack.size(), parse_event_t::key, k);
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// add null at given key and store the reference for later
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object_element = &(ref_stack.back()->m_value.object->operator[](val));
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// check callback for key
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const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::key, k);
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key_keep_stack.push_back(keep);
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// add discarded value at given key and store the reference for later
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if (keep and ref_stack.back())
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{
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object_element = &(ref_stack.back()->m_value.object->operator[](val) = discarded);
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}
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return true;
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}
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bool end_object() override
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{
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const bool keep = callback(ref_stack.size() - 1, parse_event_t::object_end, *ref_stack.back());
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if (not keep)
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bool keep = true;
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if (ref_stack.back())
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{
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// discard object
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*ref_stack.back() = discarded;
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keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back());
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if (not keep)
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{
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// discard object
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*ref_stack.back() = discarded;
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}
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}
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assert(not ref_stack.empty());
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assert(not keep_stack.empty());
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ref_stack.pop_back();
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keep_stack.pop_back();
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if (not ref_stack.empty() and ref_stack.back())
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{
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// remove discarded value
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if (ref_stack.back()->is_object())
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{
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for (auto it = ref_stack.back()->begin(); it != ref_stack.back()->end(); ++it)
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{
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if (it->is_discarded())
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{
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ref_stack.back()->erase(it);
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break;
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}
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}
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}
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}
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return true;
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}
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bool start_array(std::size_t len) override
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{
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const bool keep = callback(ref_stack.size() + 1, parse_event_t::array_start, discarded);
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const bool keep = callback(static_cast<int>(ref_stack.size()) + 1, parse_event_t::array_start, discarded);
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keep_stack.push_back(keep);
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ref_stack.push_back(handle_value(BasicJsonType::value_t::array));
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auto val = handle_value(BasicJsonType::value_t::array);
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ref_stack.push_back(val.second);
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if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
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// check array limit
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if (ref_stack.back())
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{
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JSON_THROW(out_of_range::create(408,
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"excessive array size: " + std::to_string(len)));
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if (JSON_UNLIKELY(len != json_sax<BasicJsonType>::no_limit and len > ref_stack.back()->max_size()))
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{
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JSON_THROW(out_of_range::create(408,
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"excessive array size: " + std::to_string(len)));
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}
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}
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return true;
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@ -404,15 +445,32 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
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bool end_array() override
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{
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const bool keep = callback(ref_stack.size() - 1, parse_event_t::array_end, *ref_stack.back());
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if (not keep)
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bool keep = true;
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if (ref_stack.back())
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{
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// discard array
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*ref_stack.back() = discarded;
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keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::array_end, *ref_stack.back());
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if (not keep)
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{
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// discard array
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*ref_stack.back() = discarded;
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}
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}
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assert(not ref_stack.empty());
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assert(not keep_stack.empty());
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ref_stack.pop_back();
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keep_stack.pop_back();
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// remove discarded value
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if (not keep and not ref_stack.empty())
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{
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if (ref_stack.back()->is_array())
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{
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ref_stack.back()->m_value.array->pop_back();
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}
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}
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return true;
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}
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@ -442,7 +500,7 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
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return false;
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}
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bool is_errored() const
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constexpr bool is_errored() const
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{
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return errored;
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}
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@ -453,28 +511,59 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
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root.
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@invariant If the ref stack contains a value, then it is an array or an
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object to which we can add elements
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@return pair of boolean (whether value should be kept) and pointer (to the
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passed value in the ref_stack hierarchy; nullptr if not kept)
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*/
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template<typename Value>
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BasicJsonType* handle_value(Value&& v)
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std::pair<bool, BasicJsonType*> handle_value(Value&& v)
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{
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assert(not keep_stack.empty());
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// do not handle this value if we know it would be added to a discarded
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// container
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if (not keep_stack.back())
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{
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return {false, nullptr};
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}
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// create value and check callback
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auto value = BasicJsonType(std::forward<Value>(v));
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const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::value, value);
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// do not handle this value if we just learnt it shall be discarded
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if (not keep)
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{
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return {false, nullptr};
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}
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if (ref_stack.empty())
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{
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root = BasicJsonType(std::forward<Value>(v));
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return &root;
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root = std::move(value);
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return {true, &root};
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}
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else
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{
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assert(ref_stack.back()->is_array() or ref_stack.back()->is_object());
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if (ref_stack.back()->is_array())
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{
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ref_stack.back()->m_value.array->emplace_back(std::forward<Value>(v));
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return &(ref_stack.back()->m_value.array->back());
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ref_stack.back()->m_value.array->push_back(std::move(value));
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return {true, &(ref_stack.back()->m_value.array->back())};
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}
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else
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{
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// check if we should store an element for the current key
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assert(not key_keep_stack.empty());
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const bool store_element = key_keep_stack.back();
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key_keep_stack.pop_back();
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if (not store_element)
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{
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return {false, nullptr};
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}
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assert(object_element);
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*object_element = BasicJsonType(std::forward<Value>(v));
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return object_element;
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*object_element = std::move(value);
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return {true, object_element};
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}
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}
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}
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@ -485,6 +574,8 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
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std::vector<BasicJsonType*> ref_stack;
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/// stack to manage which values to keep
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std::vector<bool> keep_stack;
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/// stack to manage which object keys to keep
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std::vector<bool> key_keep_stack;
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/// helper to hold the reference for the next object element
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BasicJsonType* object_element = nullptr;
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/// whether a syntax error occurred
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