Equality/Identity/HashCode

[ftomassetti]

For the same AST Node we can different equality (and hashcode) functions, depending on the application

• If I have two IntegerLiterals with value 1 are they the same? Or should I consider the position?
• Should I consider all descendants or not?
• Should I consider also where the node is placed? Is a value passed to a function call? Is it part of a SumExpression?
• If a comment was associated with the Node (currently we have no support for comments), would that affect equality?
• The field parseTreeNode may or may not be relevant
• Some metadata may be relevant for the identity function (e.g., declaration)

We could have an interface Equality with methods hashCode and equals.
We could have collections (Set, List, Map) that would use this concept of equality.