Differences between JSON and YAML implementation

YAML

The possible types of a YAML::Node are:

• Undefined
• Null
• Map
• Sequence
• Scalar

Undefined

The result of querying any member of Null, querying non-existing members of Map, or non-existing indices of Sequence.

Note that for Maps string conversion applies map[0] could be valid, given a key "0", while for Sequences string index parsing does NOT happen seq["0"] will return Undefined even if the sequence is non-empty.

Querying or otherwise accessing an Undefined (other than operator bool or IsDefined) usually throws.

Null

The value of parsing an empty document, the value of a Map item with empty value, the value of an omitted Sequence item.

key1:      # this is a Null
key2: ''   # this is a Scalar, the empty string
arr:
  - one
  -        # Null as well
  - three

Scalar

A string value, all conversions to numbers happen on the fly.

Conversions

1. ::as<std::string>

• Null --> "null"
• Scalar --> the string value
• others --> throws

2. ::as<YAML::Node>

It was used in multiple places, it seems to throw on Undefined and return itself for all other types.

JSON

In contrast to these JSON has real bools, numbers, strings, there is no string-to-int conversion happening.