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◆ from_msgpack() [1/2]
template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer>
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
-
[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
- Exceptions
-
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; basic_json<> json default JSON class
static basic_json from_msgpack(detail::input_adapter &&i, const bool strict=true, const bool allow_exceptions=true) create a JSON value from an input in MessagePack format
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
-
to_msgpack(const basic_json&) for the analogous serialization
-
from_cbor(detail::input_adapter&&, const bool, const bool) for the related CBOR format
-
from_ubjson(detail::input_adapter&&, const bool, const bool) for the related UBJSON format
-
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 19323 of file json.hpp.
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