public int defineStringLiteral(String lit, int ttype) {
		if ( !stringLiteralToTypeMap.containsKey(lit) ) {
			stringLiteralToTypeMap.put(lit, ttype);
			// track in reverse index too
			if ( ttype>=typeToStringLiteralList.size() ) {
				Utils.setSize(typeToStringLiteralList, ttype+1);
			}
			typeToStringLiteralList.set(ttype, lit);

			setTokenForType(ttype, lit);
			return ttype;
		}
		return Token.INVALID_TYPE;
	}
Return a new unique integer in the channel value space.
tool/src/org/antlr/v4/tool/Grammar.java