mirror of
https://github.com/nlohmann/json.git
synced 2026-09-29 22:10:47 +01:00
109 lines
3.6 KiB
Markdown
109 lines
3.6 KiB
Markdown
# <small>nlohmann::basic_json::</small>from_bon8
|
|
|
|
```cpp
|
|
// (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.
|
|
|
|
1. Reads from a compatible input.
|
|
2. 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](../../features/binary_formats/bon8.md).
|
|
|
|
## 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`](is_discarded.md).
|
|
|
|
## Exception safety
|
|
|
|
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
|
|
|
|
## Exceptions
|
|
|
|
- Throws [parse_error.110](../../home/exceptions.md#jsonexceptionparse_error110) 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](../../home/exceptions.md#jsonexceptionparse_error112) 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
|
|
--8<-- "examples/from_bon8.cpp"
|
|
```
|
|
|
|
Output:
|
|
|
|
```json
|
|
--8<-- "examples/from_bon8.output"
|
|
```
|
|
|
|
## See also
|
|
|
|
- [to_bon8](to_bon8.md) create a BON8 serialization of a JSON value
|
|
- [from_cbor](from_cbor.md) create a JSON value from an input in CBOR format
|
|
- [from_msgpack](from_msgpack.md) create a JSON value from an input in MessagePack format
|
|
- [from_bson](from_bson.md) create a JSON value from an input in BSON format
|
|
- [from_ubjson](from_ubjson.md) create a JSON value from an input in UBJSON format
|
|
- [from_bjdata](from_bjdata.md) create a JSON value from an input in BJData format
|
|
|
|
## Version history
|
|
|
|
- Added in version 3.13.0.
|