[RFC PATCH v2 05/12] ipa: libipa: vector: Generalize arithmetic operators

[Milan Zamazal]

Laurent Pinchart <laurent.pinchart at ideasonboard.com> writes:

> Instead of hand-coding all arithmetic operators, implement them based on
> a generic apply() function that takes an operator-specific
> std::function. This will simplify adding missing arithmetic operators.

I always welcome deduplication!

> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/ipa/libipa/vector.h | 48 ++++++++++++++++++++++++-----------------
>  1 file changed, 28 insertions(+), 20 deletions(-)
>
> diff --git a/src/ipa/libipa/vector.h b/src/ipa/libipa/vector.h
> index 9dabdc28a540..8c4edfbaf85f 100644
> --- a/src/ipa/libipa/vector.h
> +++ b/src/ipa/libipa/vector.h
> @@ -74,36 +74,24 @@ public:
>  		return ret;
>  	}
>  
> -	constexpr Vector<T, Rows> operator-(const Vector<T, Rows> &other) const
> +	constexpr Vector operator-(const Vector &other) const
>  	{
> -		Vector<T, Rows> ret;
> -		for (unsigned int i = 0; i < Rows; i++)
> -			ret[i] = data_[i] - other[i];
> -		return ret;
> +		return apply(*this, other, [](T a, T b) { return a - b; });
>  	}

Could std::minus be used here (and similarly for the other methods)?

With or without this:

Reviewed-by: Milan Zamazal <mzamazal at redhat.com>

> -	constexpr Vector<T, Rows> operator+(const Vector<T, Rows> &other) const
> +	constexpr Vector operator+(const Vector &other) const
>  	{
> -		Vector<T, Rows> ret;
> -		for (unsigned int i = 0; i < Rows; i++)
> -			ret[i] = data_[i] + other[i];
> -		return ret;
> +		return apply(*this, other, [](T a, T b) { return a + b; });
>  	}
>  
> -	constexpr Vector<T, Rows> operator*(T factor) const
> +	constexpr Vector operator*(T factor) const
>  	{
> -		Vector<T, Rows> ret;
> -		for (unsigned int i = 0; i < Rows; i++)
> -			ret[i] = data_[i] * factor;
> -		return ret;
> +		return apply(*this, factor, [](T a, T b) { return a * b; });
>  	}
>  
> -	constexpr Vector<T, Rows> operator/(T factor) const
> +	constexpr Vector operator/(T factor) const
>  	{
> -		Vector<T, Rows> ret;
> -		for (unsigned int i = 0; i < Rows; i++)
> -			ret[i] = data_[i] / factor;
> -		return ret;
> +		return apply(*this, factor, [](T a, T b) { return a / b; });
>  	}
>  
>  	constexpr T dot(const Vector<T, Rows> &other) const
> @@ -178,6 +166,26 @@ public:
>  	}
>  
>  private:
> +	static constexpr Vector apply(const Vector &lhs, const Vector &rhs, std::function<T(T, T)> func)
> +	{
> +		Vector result;
> +		std::transform(lhs.data_.begin(), lhs.data_.end(),
> +			       rhs.data_.begin(), result.data_.begin(),
> +			       func);
> +
> +		return result;
> +	}
> +
> +	static constexpr Vector apply(const Vector &lhs, T rhs, std::function<T(T, T)> func)
> +	{
> +		Vector result;
> +		std::transform(lhs.data_.begin(), lhs.data_.end(),
> +			       result.data_.begin(),
> +			       [&func, rhs](T v) { return func(v, rhs); });
> +
> +		return result;
> +	}
> +
>  	std::array<T, Rows> data_;
>  };