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◆ from_msgpack() [2/2]
static basic_json nlohmann::basic_json::from_msgpack |
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detail::input_adapter && |
i, |
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const bool |
strict = true , |
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const bool |
allow_exceptions = true |
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inlinestatic |
Deserializes a given input i to a JSON value using the MessagePack serialization format.
The library maps MessagePack types to JSON value types as follows:
MessagePack type | JSON value type | first byte |
positive fixint | number_unsigned | 0x00..0x7F |
fixmap | object | 0x80..0x8F |
fixarray | array | 0x90..0x9F |
fixstr | string | 0xA0..0xBF |
nil | null | 0xC0 |
false | false | 0xC2 |
true | true | 0xC3 |
float 32 | number_float | 0xCA |
float 64 | number_float | 0xCB |
uint 8 | number_unsigned | 0xCC |
uint 16 | number_unsigned | 0xCD |
uint 32 | number_unsigned | 0xCE |
uint 64 | number_unsigned | 0xCF |
int 8 | number_integer | 0xD0 |
int 16 | number_integer | 0xD1 |
int 32 | number_integer | 0xD2 |
int 64 | number_integer | 0xD3 |
str 8 | string | 0xD9 |
str 16 | string | 0xDA |
str 32 | string | 0xDB |
array 16 | array | 0xDC |
array 32 | array | 0xDD |
map 16 | object | 0xDE |
map 32 | object | 0xDF |
negative fixint | number_integer | 0xE0-0xFF |
- Warning
- The mapping is incomplete in the sense that not all MessagePack types can be converted to a JSON value. The following MessagePack types are not supported and will yield parse errors:
- bin 8 - bin 32 (0xC4..0xC6)
- ext 8 - ext 32 (0xC7..0xC9)
- fixext 1 - fixext 16 (0xD4..0xD8)
- Note
- Any MessagePack output created to_msgpack can be successfully parsed by from_msgpack.
- Parameters
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[in] | i | an input in MessagePack format convertible to an input adapter |
[in] | strict | whether to expect the input to be consumed until EOF (true by default) |
[in] | allow_exceptions | whether to throw exceptions in case of a parse error (optional, true by default) |
- Returns
- deserialized JSON value; in case of a parse error and allow_exceptions set to
false , the return value will be value_t::discarded.
- Exceptions
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parse_error.110 | if the given input ends prematurely or the end of file was not reached when strict was set to true |
parse_error.112 | if unsupported features from MessagePack were used in the given input i or if the input is not valid MessagePack |
parse_error.113 | if a string was expected as map key, but not found |
- Complexity
- Linear in the size of the input i.
- Example
- The example shows the deserialization of a byte vector in MessagePack format to a JSON value.
3 #include <nlohmann/json.hpp>
10 std::vector<uint8_t> v = {0x82, 0xa7, 0x63, 0x6f, 0x6d, 0x70, 0x61, 0x63,
11 0x74, 0xc3, 0xa6, 0x73, 0x63, 0x68, 0x65, 0x6d,
19 std::cout << std::setw(2) << j << std::endl;
Output (play with this example online): {
"compact": true,
"schema": 0
}
The example code above can be translated withg++ -std=c++11 -Isingle_include doc/examples/from_msgpack.cpp -o from_msgpack
- See also
- http://msgpack.org
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to_msgpack(const basic_json&) for the analogous serialization
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from_cbor(detail::input_adapter&&, const bool, const bool) for the related CBOR format
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from_ubjson(detail::input_adapter&&, const bool, const bool) for the related UBJSON format
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from_bson(detail::input_adapter&&, const bool, const bool) for the related BSON format
- Since
- version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0; added allow_exceptions parameter since 3.2.0
Definition at line 21636 of file json.hpp.
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