protected Handle action(GrammarAST node, LexerAction lexerAction) {
		ATNState left = newState(node);
		ATNState right = newState(node);
		boolean isCtxDependent = false;
		int lexerActionIndex = getLexerActionIndex(lexerAction);
		ActionTransition a =
			new ActionTransition(right, currentRule.index, lexerActionIndex, isCtxDependent);
		left.addTransition(a);
		node.atnState = left;
		Handle h = new Handle(left, right);
		return h;
	}
Maps from a {@link LexerAction} object to the action index.
tool/src/org/antlr/v4/automata/LexerATNFactory.java