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95 lines
2.7 KiB
Markdown
95 lines
2.7 KiB
Markdown
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# basic_json::from_cbor
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```cpp
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// (1)
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template<typename InputType>
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static basic_json from_cbor(InputType&& i,
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const bool strict = true,
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const bool allow_exceptions = true,
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const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error);
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// (2)
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template<typename IteratorType>
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static basic_json from_cbor(IteratorType first, IteratorType last,
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const bool strict = true,
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const bool allow_exceptions = true,
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const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error);
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```
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Deserializes a given input to a JSON value using the CBOR (Concise Binary Object Representation) serialization format.
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1. Reads from a compatible input.
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2. Reads from an iterator range.
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## Template parameters
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`InputType`
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: A compatible input, for instance:
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- an `std::istream` object
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- a `FILE` pointer
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- a C-style array of characters
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- a pointer to a null-terminated string of single byte characters
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- an object `obj` for which `begin(obj)` and `end(obj)` produces a valid pair of iterators.
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`IteratorType`
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: a compatible iterator type
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## Parameters
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`i` (in)
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: an input in CBOR format convertible to an input adapter
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`first` (in)
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: iterator to start of the input
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`last` (in)
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: iterator to end of the input
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`strict` (in)
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: whether to expect the input to be consumed until EOF (`#!cpp true` by default)
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`allow_exceptions` (in)
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: whether to throw exceptions in case of a parse error (optional, `#!cpp true` by default)
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`tag_handler` (in)
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: how to treat CBOR tags (optional, `error` by default); see [`cbor_tag_handler_t`](cbor_tag_handler_t.md) for more
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information
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## Return value
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deserialized JSON value; in case of a parse error and `allow_exceptions` set to `#!cpp false`, the return value will be
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`value_t::discarded`. The latter can be checked with [`is_discarded`](is_discarded.md).
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## Exception safety
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Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
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## Complexity
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Linear in the size of the input.
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## Example
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??? example
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The example shows the deserialization of a byte vector in CBOR format to a JSON value.
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```cpp
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--8<-- "examples/from_cbor.cpp"
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```
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Output:
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```json
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--8<-- "examples/from_cbor.output"
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```
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## Version history
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- Added in version 2.0.9.
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- Parameter `start_index` since version 2.1.1.
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- Changed to consume input adapters, removed `start_index` parameter, and added `strict` parameter in version 3.0.0.
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- Added `allow_exceptions` parameter in version 3.2.0.
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- Added `tag_handler` parameter in version 3.9.0.
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