@Override
	public final void consume() {
		if (size - position == 0) {
			assert LA(1) == IntStream.EOF;
			throw new IllegalStateException("cannot consume EOF");
		}
		position = position + 1;
	}
Constructs a named {@link CodePointCharStream} which provides access
to the Unicode code points stored in {@code codePointBuffer}.
runtime/Java/src/org/antlr/v4/runtime/CodePointCharStream.java