Class ComparisonBase

tests/gtest/gtest.h:9432–9467

// a "bare" type (i.e. neither 'const T' nor 'T&').
template <typename D, typename Rhs, typename Op>
class ComparisonBase {
 public:
  explicit ComparisonBase(const Rhs& rhs) : rhs_(rhs) {}
  template <typename Lhs>
  operator Matcher<Lhs>() const {
    return Matcher<Lhs>(new Impl<const Lhs&>(rhs_));
  }

 private:
  template <typename T>
  static const T& Unwrap(const T& v) { return v; }
  template <typename T>
  static const T& Unwrap(std::reference_wrapper<T> v) { return v; }

  template <typename Lhs, typename = Rhs>
  class Impl : public MatcherInterface<Lhs> {
   public:
    explicit Impl(const Rhs& rhs) : rhs_(rhs) {}
    bool MatchAndExplain(Lhs lhs,
                         MatchResultListener* /* listener */) const override {
      return Op()(lhs, Unwrap(rhs_));
    }
    void DescribeTo(::std::ostream* os) const override {
      *os << D::Desc() << " ";
      UniversalPrint(Unwrap(rhs_), os);
    }
    void DescribeNegationTo(::std::ostream* os) const override {
      *os << D::NegatedDesc() <<  " ";
      UniversalPrint(Unwrap(rhs_), os);
    }

   private:
    Rhs rhs_;
  };
  Rhs rhs_;
};

template <typename Rhs>
class EqMatcher : public ComparisonBase<EqMatcher<Rhs>, Rhs, AnyEq> {