SourceFileRef

Identifies a source file. It is intended to be implemented by a concrete data class, that uniquely identifies the file in a domain-specific way.

Implementors must ensure that ref1.equals(ref2) returns true iff both refs actually identify the same file.

Note that there is no restriction as to where this file is physically located. It may identify a real file, a network file, or a pseudo-handle to identify an in-memory string, etc.