Method Advance

test/gtest/gtest.h:13812–13820

Advance should not be called on beyond-of-range iterators so no component iterators must be beyond end of range, either.

    // Advance should not be called on beyond-of-range iterators
    // so no component iterators must be beyond end of range, either.
    virtual void Advance() {
      assert(!AtEnd());
      ++current2_;
      if (current2_ == end2_) {
        current2_ = begin2_;
        ++current1_;
      }
      ComputeCurrentValue();
    }
    virtual ParamIteratorInterface<ParamType>* Clone() const {
      return new Iterator(*this);
    }