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json/docs/mkdocs/docs/examples/basic_json_document__set.cpp
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Niels Lohmann 330fbead59 Document clang-tidy exclusions, drop unneeded ones, and clean up doc examples (#5909)
* Document clang-tidy exclusions and drop unneeded ones

Re-enable every excluded check in a run of clang-tidy 22 over all tests
and remove the seven that never fire (cert-err58-cpp,
clang-analyzer-webkit.NoUncountedMemberChecker,
cppcoreguidelines-virtual-class-destructor, google-readability-function-size,
hicpp-function-size, hicpp-no-assembler, readability-function-size).

Document the reason for every remaining exclusion at the top of the file.

Exclude in advance the checks that only exist in clang-tidy 23 and are
noise here (bugprone-signed-bitwise, *-explicit-constructor,
readability-trailing-comma, modernize-use-string-view), plus
modernize-use-integer-sign-comparison, which needs C++20 std::cmp_less
and flags deliberate casts.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix clang-tidy findings in documentation examples and replace redundant aliases

Apply clang-tidy fixes to the documentation examples:
- performance-avoid-endl: std::endl -> '\n'
- readability-qualified-auto: auto -> auto* / const auto*
- performance-for-range-copy: copy -> const reference
- google-readability-casting: C-style cast -> static_cast

Replace redundant aliases (readability-redundant-qualified-alias) such as
"using json = nlohmann::json;" with "using nlohmann::json;" in the
documentation, README, examples, tests, and benchmarks. Aliases at class
scope and aliases of other types (with_base_class_t etc.) are kept.

No changes to the library or its public API. All changed examples were
compiled and run; their output matches the stored .output files (except
max_size and meta, which depend on the platform and compiler).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Format doc examples with the pinned astyle

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-25 12:07:51 +01:00

42 lines
1.5 KiB
C++

#include <iostream>
#include <nlohmann/json_view.hpp>
using nlohmann::json;
using nlohmann::json_editable_document;
using nlohmann::json_editable_view;
int main()
{
// a configuration file, as it might be read from disk -- "price" is
// written with a trailing zero that has no effect on its value
const std::string text = R"({
"name": "cache",
"host": "db1",
"port": 6379,
"price": 19.90,
"replicas": ["db2", "db3"],
"timeout": 30
})";
json_editable_document doc = json_editable_document::parse(text);
doc.set(doc.root()["port"], 6380); // (1) replace a value
doc.set(doc.root(), "region", "us-east"); // (2) add a member
doc.set(doc.root()["replicas"], 0, "db4"); // (3) assign an element
doc.set(json::json_pointer("/timeout"), 45); // (4) via a JSON pointer
// members stay in document order (the new one at the end), and a number
// that was not itself edited keeps its exact spelling
std::cout << doc.root().dump(2, ' ', false, json_editable_view::number_format::source) << "\n\n";
// the same edits on a plain json value: object_t is a std::map, so
// parsing already sorted the keys, and dump() rewrites every number to
// its shortest form, even "price", which was never touched
json plain = json::parse(text);
plain["port"] = 6380;
plain["region"] = "us-east";
plain["replicas"][0] = "db4";
plain[json::json_pointer("/timeout")] = 45;
std::cout << plain.dump(2) << '\n';
}