82 lines
1.7 KiB
C++
82 lines
1.7 KiB
C++
#include <iostream>
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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struct find_id : nlohmann::json_sax<json>
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{
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bool next_is_id = false;
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json::number_unsigned_t id = 0;
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bool key(std::string& name) override
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{
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next_is_id = (name == "id");
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return true;
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}
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bool number_unsigned(json::number_unsigned_t value) override
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{
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if (next_is_id)
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{
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id = value;
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return false; // found: stop parsing
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}
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return true;
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}
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bool null() override
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{
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return true;
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}
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bool boolean(bool /*val*/) override
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{
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return true;
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}
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bool number_integer(json::number_integer_t /*val*/) override
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{
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return true;
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}
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bool number_float(json::number_float_t /*val*/, const std::string& /*s*/) override
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{
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return true;
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}
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bool string(std::string& /*val*/) override
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{
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return true;
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}
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bool binary(json::binary_t& /*val*/) override
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{
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return true;
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}
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bool start_object(std::size_t /*elements*/) override
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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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return true;
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}
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bool start_array(std::size_t /*elements*/) override
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{
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return true;
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}
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bool end_array() override
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{
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return true;
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}
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bool parse_error(std::size_t /*position*/, const std::string& /*last_token*/, const json::exception& /*ex*/) override
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{
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return false;
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}
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};
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int main()
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{
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find_id handler;
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const bool completed = json::sax_parse(R"({"x": [1, 2, 3], "id": 42, "rest": [4, 5, 6]})", &handler);
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std::cout << std::boolalpha;
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std::cout << "parse completed: " << completed << '\n';
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std::cout << "id: " << handler.id << '\n';
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}
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