public final void setState(int atnState) {
//		System.err.println("setState "+atnState);
		_stateNumber = atnState;
//		if ( traceATNStates ) _ctx.trace(atnState);
	}
Indicate that the recognizer has changed internal state that is
 consistent with the ATN state passed in.  This way we always know
 where we are in the ATN as the parser goes along. The rule
 context objects form a stack that lets us see the stack of
 invoking rules. Combine this and we have complete ATN
 configuration information.
runtime/Java/src/org/antlr/v4/runtime/Recognizer.java