Florian Albrechtskirchinger 078673fdd9 Rework basic_json element access to accept more key types

Rework basic_json element access member functions and operators to
accept any type that meets the requirements defined by type trait
detail::is_usable_as_key_type.

Member functions and operators:
* at()
* operator[]
* value()
* erase()
* find()
* count()
* contains()

Update documentation to reflect these changes.

Add unit tests to excercise the new functions using std::string_view.

Co-authored-by: Niels Lohmann <niels.lohmann@gmail.com>

2022-04-27 12:09:03 +02:00

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nlohmann::basic_json::to_cbor

// (1)
static std::vector<std::uint8_t> to_cbor(const basic_json& j);

// (2)
static void to_cbor(const basic_json& j, detail::output_adapter<std::uint8_t> o);
static void to_cbor(const basic_json& j, detail::output_adapter<char> o);

Serializes a given JSON value j to a byte vector using the CBOR (Concise Binary Object Representation) serialization format. CBOR is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse.

Returns a byte vector containing the CBOR serialization.
Writes the CBOR serialization to an output adapter.

The exact mapping and its limitations is described on a dedicated page.

Parameters

j (in): JSON value to serialize
o (in): output adapter to write serialization to

Return value

CBOR serialization as byte vector
(none)

Exception safety

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Complexity

Linear in the size of the JSON value j.

Examples

??? example

The example shows the serialization of a JSON value to a byte vector in CBOR format.
 
```cpp
--8<-- "examples/to_cbor.cpp"
```

Output:

```json
--8<-- "examples/to_cbor.output"
```

Version history

Added in version 2.0.9.
Compact representation of floating-point numbers added in version 3.8.0.

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