The content of a mapping node is an unordered set of key/value node pairs, with the restriction that each of the keys is unique.
The changes proposed here check the uniqueness of scalar mapping keys, throwing a NonUniqueMapKey exception when by inserting a new key/value pair an identical scalar key is already present in a mapping. Non identical but equivalent scalar content, for example “0o13” (octal) or “0xB” (hexadecimal), are not considered.
According to YAML spec 1.2.2:
The changes proposed here check the uniqueness of scalar mapping keys, throwing a
NonUniqueMapKeyexception when by inserting a new key/value pair an identical scalar key is already present in a mapping. Non identical but equivalent scalar content, for example “0o13” (octal) or “0xB” (hexadecimal), are not considered.Address https://github.com/jbeder/yaml-cpp/issues/60.