mirror of
https://github.com/nlohmann/json.git
synced 2026-10-26 07:48:55 +00:00
Niels Lohmann
330fbead59
* 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>
2.0 KiB
2.0 KiB
JSON_ASSERT
#define JSON_ASSERT(x) /* value */
This macro controls which code is executed for runtime assertions of the library.
Parameters
x(in)- expression of a scalar type
Default definition
The default value is #!cpp assert(x).
#define JSON_ASSERT(x) assert(x)
Therefore, assertions can be switched off by defining NDEBUG.
Notes
- The library uses numerous assertions to guarantee invariants and to abort in case of otherwise undefined behavior
(e.g., when calling operator[] with a missing object key on a
constobject). See page runtime assertions for more information. - Defining the macro to code that does not call
std::abortmay leave the library in an undefined state. - The macro is undefined outside the library.
Examples
??? example "Example: default behavior"
The following code will trigger an assertion at runtime:
```cpp
#include <nlohmann/json.hpp>
using nlohmann::json;
int main()
{
const json j = {{"key", "value"}};
auto v = j["missing"];
}
```
Output:
```
Assertion failed: (m_value.object->find(key) != m_value.object->end()), function operator[], file json.hpp, line 2144.
```
??? example "Example: user-defined behavior"
The assertion reporting can be changed by defining `JSON_ASSERT(x)` differently.
```cpp
#include <cstdio>
#include <cstdlib>
#define JSON_ASSERT(x) if(!(x)){fprintf(stderr, "assertion error in %s\n", __FUNCTION__); std::abort();}
#include <nlohmann/json.hpp>
using nlohmann::json;
int main()
{
const json j = {{"key", "value"}};
auto v = j["missing"];
}
```
Output:
```
assertion error in operator[]
```
See also
- Runtime Assertions - overview documentation
Version history
- Added in version 3.9.0.