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https://github.com/nlohmann/json.git
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Niels Lohmann
061c30310e
- API pages for basic_json_document and basic_json_view, one per member, and for the four aliases, each with an example - features/json_view.md: the problem the view solves, ownership and lifetime, what matches basic_json::parse() and what differs, and when to choose json, ordered_json, SAX, or the view - the examples show why one would use the view, not only how: borrowed vs. owned input, reading a few fields and materializing one subtree, reusing a document across many messages - registered in the mkdocs navigation, llms.txt, the docset, the exceptions page (out_of_range.416), architecture.md, the integration page, and the README; the yyjson credit is added to the README and license.md Signed-off-by: Niels Lohmann <mail@nlohmann.me>
34 lines
1.2 KiB
C++
34 lines
1.2 KiB
C++
#include <array>
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#include <iostream>
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#include <nlohmann/json_view.hpp>
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using json_document = nlohmann::json_document;
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int main()
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{
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// three incoming messages; skip the ones that are not useful without ever
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// building a nlohmann::json value for them
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json_document heartbeat = json_document::parse("null");
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json_document empty_batch = json_document::parse("[]");
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json_document batch = json_document::parse(R"([{"id": 1}, {"id": 2}, {"id": 3}])");
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std::array<const json_document*, 3> messages = {{&heartbeat, &empty_batch, &batch}};
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for (const json_document* d : messages)
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{
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// is_array()/empty() only look at the flat index: a discarded
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// heartbeat or an empty batch is never turned into a nlohmann::json
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// value, so no per-element allocation happens for them
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if (!d->root().is_array() || d->root().empty())
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{
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std::cout << "skipped\n";
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continue;
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}
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// materialize() replays the subtree through the same SAX builder
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// basic_json::parse() uses, so the result is exactly what
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// basic_json::parse() would have produced for the same text
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nlohmann::json value = d->root().materialize();
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std::cout << value.dump() << '\n';
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}
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}
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