template<typename InputType> static bool accept(InputType&& input, const bool ignore_comments = false, const bool ignore_trailing_commas = false);
Checks whether the input is valid JSON, accepting and rejecting exactly what BasicJsonType::accept() does, with the same options. Unlike parse(), this function never throws an exception for invalid input, and the returned #!cpp bool is the only result -- no document is returned.
The result is the same as that of BasicJsonType::accept() by design; the difference is how the check is made. This function runs the document's index builder (and discards the index), while BasicJsonType::accept() runs the SAX parser with a handler that ignores every event. Use this one if you go on to parse the same input with parse() anyway, so that both use the same code; either is fine for a plain yes/no answer.
InputType : A compatible input; see parse.
input (in) : Input to check.
ignore_comments (in) : whether comments should be ignored and treated like whitespace (#!cpp true) or yield a parse error (#!cpp false); (optional, #!cpp false by default)
ignore_trailing_commas (in) : whether trailing commas in arrays or objects should be ignored and treated like whitespace (#!cpp true) or yield a parse error (#!cpp false); (optional, #!cpp false by default)
Whether the input is valid JSON.
Strong guarantee: this function itself never throws for an invalid input; it can only throw what allocating the input's own copy (for inputs that are always read into a buffer) throws.
Linear in the length of the input.
An integer argument that is not a #!cpp bool where the flags are expected, such as #!cpp accept(ptr, len), does not compile; see parse.
??? example
```cpp
#include <iostream>
#include <nlohmann/json.hpp>
#include <nlohmann/json_view.hpp>
using json_document = nlohmann::json_document;
int main()
{
std::cout << std::boolalpha;
// accept() behaves exactly like basic_json::accept(): the same inputs are
// accepted or rejected, with the same ignore_comments/ignore_trailing_commas
// options
std::cout << json_document::accept(R"({"a": 1})") << '\n';
std::cout << json_document::accept(R"({"a": 1,})") << '\n'; // trailing comma: rejected by default
std::cout << json_document::accept(R"({"a": 1,})", false, true) << '\n'; // ignore_trailing_commas
std::cout << (json_document::accept(R"({"a": 1})") == nlohmann::json::accept(R"({"a": 1})")) << '\n';
}
```
Output:
```json
true
false
true
true
```
BasicJsonType::accept - the corresponding function of basic_json