43 lines
1.4 KiB
C++
43 lines
1.4 KiB
C++
#include <cstdint>
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#include <iostream>
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#include <vector>
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// accept 16 values per byte of input instead of 4; define the macro before the
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// first inclusion of the header, and to the same value in every translation unit
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#define JSON_UBJSON_VALUELESS_ELEMENTS_PER_BYTE 16
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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// the bytes version 3.12.0 wrote for a table of 1100 rows of 1000 null values
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// with to_ubjson(table, true, true): `[$[#I` and the number of rows, then
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// `$Z#I` and the number of elements for every row
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std::vector<std::uint8_t> table_written_by_3_12_0()
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{
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std::vector<std::uint8_t> bytes = {'[', '$', '[', '#', 'I', 1100 >> 8, 1100 & 0xFF};
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for (int row = 0; row < 1100; ++row)
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{
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bytes.insert(bytes.end(), {'$', 'Z', '#', 'I', 1000 >> 8, 1000 & 0xFF});
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}
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return bytes;
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}
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int main()
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{
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// 6607 bytes announce 1,100,000 values, which is below 1,048,576 plus 16
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// for every byte read
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json table = json::from_ubjson(table_written_by_3_12_0());
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std::cout << table.size() << " rows of " << table[0].size() << " values\n";
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// a single container is still limited to 1,048,576 elements
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const std::vector<std::uint8_t> too_long = {'[', '$', 'Z', '#', 'l', 0x00, 0x10, 0x00, 0x01};
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try
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{
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json j = json::from_ubjson(too_long);
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}
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catch (const json::out_of_range& e)
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{
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std::cout << e.what() << '\n';
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}
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}
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