Add support for range based loop in functions.

    return size_sbdm[index];

  }

  // Begin and end methods for compatibility with range for loop.

  scalartype* begin() {

    return fnc_values;

  }

  scalartype* end() {

    return fnc_values + Nb_elements;

  }

  const scalartype* begin() const {

    return fnc_values;

  }

  const scalartype* end() const {

    return fnc_values + Nb_elements;

  }

  // Returns a pointer to the function's elements.

  scalartype* values() {

    return fnc_values;

        ++count;

      }

}

TEST(FunctionTest, RangeBasedLoop) {

  using Dmn = dmn_variadic<dmn_0<dmn<5>>, dmn_0<dmn<7>>>;

  dca::func::function<float, Dmn> f;

  int i = 0;

  for (auto& x : f)

    x = i++;

  for (int i = 0; i < f.size(); ++i)

    EXPECT_EQ(i, f(i));

}