Two {@link DFAState} instances are equal if their ATN configuration sets
are the same. This method is used to see if a state already exists.
<p>Because the number of alternatives and number of ATN configurations are
finite, there is a finite number of DFA states that can be processed.
This is necessary to show that the algorithm terminates.</p>
<p>Cannot test the DFA state numbers here because in
{@link ParserATNSimulator#addDFAState} we need to know if any other state
exists that has this exact set of ATN configurations. The
{@link #stateNumber} is irrelevant.</p>
@uml
@override
Two {@link DFAState} instances are equal if their ATN configuration sets are the same. This method is used to see if a state already exists.
<p>Because the number of alternatives and number of ATN configurations are finite, there is a finite number of DFA states that can be processed. This is necessary to show that the algorithm terminates.</p>
<p>Cannot test the DFA state numbers here because in {@link ParserATNSimulator#addDFAState} we need to know if any other state exists that has this exact set of ATN configurations. The {@link #stateNumber} is irrelevant.</p> @uml @override