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https://github.com/nlohmann/json.git
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Niels Lohmann
54455afa40
- 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
1.0 KiB
C++
34 lines
1.0 KiB
C++
#include <iostream>
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#include <string>
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#include <nlohmann/json.hpp>
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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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std::cout << std::boolalpha;
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// an lvalue std::string is BORROWED: the document only stores a pointer
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// into `text`, so `text` must outlive `borrowed`
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std::string text = R"({"count": 3})";
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json_document borrowed = json_document::parse(text);
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std::cout << borrowed.owns_source() << '\n'; // false
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// an rvalue std::string is MOVED into the document -- no copy of the text
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json_document owned = json_document::parse(std::string(R"({"count": 3})"));
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std::cout << owned.owns_source() << '\n'; // true
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// errors are identical to basic_json::parse: same exception id, message,
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// and position, because the library parser runs on the same bytes on a
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// failing input
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try
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{
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static_cast<void>(json_document::parse(R"({"count": )"));
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}
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catch (const nlohmann::json::parse_error& e)
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{
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std::cout << e.id << '\n';
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}
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}
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