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https://github.com/nlohmann/json.git
synced 2026-10-04 05:30:31 +00:00
Niels Lohmann
a496c709f4
Add API reference pages for basic_json_document::insert and basic_json_document::erase, matching the style of set.md and push_back.md: signatures, parameters, return values, exception safety, exceptions with their exact ids and messages, complexity, notes on duplicate keys and view/iterator validity, and an example. Add example programs basic_json_document__insert.cpp and basic_json_document__erase.cpp with their expected output, each comparing an edit on an editable document with the same edit on a plain json value to show what is preserved: member order, the spelling of untouched numbers, and, for insert, that a view taken before the insert keeps referring to the same element after its index shifts. Register both new pages in mkdocs.yml, docSet.sql, and the member list of basic_json_document/index.md, add cross-references to them from set.md and push_back.md, and mention insert/erase in the "Editing a document" section of features/json_view.md. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
39 lines
1.5 KiB
C++
39 lines
1.5 KiB
C++
#include <iostream>
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#include <nlohmann/json_view.hpp>
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using json = nlohmann::json;
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using json_editable_document = nlohmann::json_editable_document;
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using json_editable_view = nlohmann::json_editable_view;
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int main()
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{
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// a deployment plan -- "budget" is written with a trailing zero that has
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// no effect on its value
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const std::string text = R"({
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"release": "2026.09",
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"steps": ["build", "test", "deploy"],
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"budget": 19.90
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})";
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json_editable_document doc = json_editable_document::parse(text);
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const std::size_t deploy_index = 2;
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const auto deploy = doc.root()["steps"][deploy_index]; // held across the insert
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doc.insert(doc.root()["steps"], deploy_index, "smoke-test"); // insert before "deploy"
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// the held view still refers to "deploy", even though its index moved
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// from 2 to 3, and nothing else in the document was touched
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std::cout << deploy.dump() << '\n';
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std::cout << doc.root().dump(2, ' ', false, json_editable_view::number_format::source) << "\n\n";
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// the same edit on a plain json value: an index held from before the
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// insert now refers to whatever moved into that slot, and dump()
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// rewrites "budget" to its shortest form even though it was never
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// touched
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json plain = json::parse(text);
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plain["steps"].insert(plain["steps"].begin() + static_cast<std::ptrdiff_t>(deploy_index), "smoke-test");
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std::cout << plain["steps"][deploy_index].dump() << '\n';
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std::cout << plain.dump(2) << '\n';
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}
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