nlohmann::basic_json::from_bon8

// (1)
template<typename InputType>
static basic_json from_bon8(InputType&& i,
                            const bool strict = true,
                            const bool allow_exceptions = true);
// (2)
template<typename IteratorType, typename SentinelType = IteratorType>
static basic_json from_bon8(IteratorType first, SentinelType last,
                            const bool strict = true,
                            const bool allow_exceptions = true);

Deserializes a given input to a JSON value using the BON8 (Binary Object Notation 8) serialization format.

Reads from a compatible input.
Reads from an iterator range, or an iterator and a sentinel of a different type (C++20 ranges support).

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

Template parameters

InputType

A compatible input, for instance:

an std::istream object
a FILE pointer
a C-style array of characters
a pointer to a null-terminated string of single byte characters
a container obj for which begin(obj) and end(obj) produce a valid pair of iterators (as found via ADL or member functions, with semantics compatible to std::begin and std::end)

IteratorType

a compatible iterator type

SentinelType

defaults to IteratorType; may be a different type comparable to IteratorType via operator!=, for instance.

a custom sentinel type for C++20 ranges
std::default_sentinel_t, when IteratorType is std::counted_iterator

Parameters

i (in): an input in BON8 format convertible to an input adapter
first (in): iterator to the start of the input
last (in): iterator to the end of the input, or a sentinel value that compares equal to the end iterator with operator!=
strict (in): whether to expect the input to be consumed until EOF (#!cpp true by default)
allow_exceptions (in): whether to throw exceptions in case of a parse error (optional, #!cpp true by default)

Return value

deserialized JSON value; in case of a parse error and allow_exceptions set to #!cpp false, the return value will be value_t::discarded. The latter can be checked with is_discarded.

Exception safety

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

Exceptions

Throws parse_error.110 if the given input ends prematurely or the end of the file was not reached when strict was set to true
Throws parse_error.112 if a parse error occurs, for instance an invalid byte, a string that is not valid UTF-8, or an object key that is not a string

Complexity

Linear in the size of the input.

Examples

??? example

The example shows the deserialization of a byte vector in BON8 format to a JSON value.
 
```cpp
#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main()
{
    // create byte vector
    std::vector<std::uint8_t> v = {0x89, 0x63, 0x6f, 0x6d, 0x70, 0x61, 0x63, 0x74,
                                   0xf9, 0x66, 0x6f, 0x72, 0x6d, 0x61, 0x74, 0xff,
                                   0x42, 0x4f, 0x4e, 0x38, 0xff, 0x73, 0x63, 0x68,
                                   0x65, 0x6d, 0x61, 0x90
                                  };

    // deserialize it with BON8
    json j = json::from_bon8(v);

    // print the deserialized JSON value
    std::cout << std::setw(2) << j << std::endl;
}

```

Output:

```json
{
  "compact": true,
  "format": "BON8",
  "schema": 0
}

```

Version history

Added in version 3.13.0.

!!! warning "Deprecation"

- Overload (2) replaces calls to `from_bon8` with a pointer and a length as first two parameters, which has been
  deprecated in version 3.13.0. In version 4.0.0, this overload
  will be deleted (`= delete`) rather than removed. Please replace all calls like
  `#!cpp from_bon8(ptr, len, ...);` with `#!cpp from_bon8(ptr, ptr+len, ...);`.

You should be warned by your compiler with a `-Wdeprecated-declarations` warning if you are using a deprecated
function.

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