YAML::Node has no comparison operator

[GoogleCodeExporter]

It isn't possible to use YAML::Node in std::set or std::map due to a lack of 
any comparison operator.

I have a scenario where I need deserialisation of a particular node to always 
return the same instance of the deserialised class. YAML::Node implements the 
equality operator, which means I can easily check if two nodes are actually 
identical, but it has no comparison operator, so I can push them into an 
std::map.

I attempted to write my own comparison operator for the std::map, but I can't 
see any publicly accessible members or accessors to do it.

Furthermore, attempts to use the comparison operator actually work, but it 
looks like the node is implicitly converted to a bool via 
YAML_CPP_OPERATOR_BOOL(). This means the comparison operator always returns 
false.

Is there any sensible way of comparison? I'd settle for internal pointer 
comparison, but it may be more sensible to compare by location in YAML tree or 
something similar.

Original issue reported on code.google.com by sho...@gmail.com on 13 Nov 2014 at 1:51

[dwightguth]

For those of you stumbling upon this later, one nasty hack you can do to get around this is to store a pointer to the value you want as a scalar integer in a node whose key is a complex yaml key. This will allow you to have a "map" whose keys are yaml nodes. Of course, it would still be vastly better if std::hash and operator< were implemented properly instead of the former being unimplementable and the latter being functionally incorrect.