Method consume

parser/parser.cc:454–460

        index_(0) {}

  void consume() override {
    if (ABSL_PREDICT_FALSE(index_ >= size_)) {
      ABSL_ASSERT(LA(1) == IntStream::EOF);
      throw antlr4::IllegalStateException("cannot consume EOF");
    }
    index_++;
  }

  size_t LA(ptrdiff_t i) override {
    if (ABSL_PREDICT_FALSE(i == 0)) {