[libcamera-devel] [PATCH 06/19] libcamera: bound_method: Use std::index_sequence

[Niklas Söderlund]

Hi Laurent,

Thanks for your work.

On 2020-01-20 02:24:24 +0200, Laurent Pinchart wrote:
> Now that we're using C++-14, replace the manual implementation of
> std::integer_sequence with std::index_sequence, a specialization of
> std::integer_sequence with the integer type equal to std::size_t.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>

> ---
>  include/libcamera/bound_method.h | 38 +++++++++-----------------------
>  1 file changed, 10 insertions(+), 28 deletions(-)
> 
> diff --git a/include/libcamera/bound_method.h b/include/libcamera/bound_method.h
> index ca501493bce2..7ffd2e426e18 100644
> --- a/include/libcamera/bound_method.h
> +++ b/include/libcamera/bound_method.h
> @@ -10,6 +10,7 @@
>  #include <memory>
>  #include <tuple>
>  #include <type_traits>
> +#include <utility>
>  
>  namespace libcamera {
>  
> @@ -71,25 +72,6 @@ public:
>  	virtual void invokePack(BoundMethodPackBase *pack) = 0;
>  
>  protected:
> -#ifndef __DOXYGEN__
> -	/*
> -	 * This is a cheap partial implementation of std::integer_sequence<>
> -	 * from C++14.
> -	 */
> -	template<int...>
> -	struct sequence {
> -	};
> -
> -	template<int N, int... S>
> -	struct generator : generator<N-1, N-1, S...> {
> -	};
> -
> -	template<int... S>
> -	struct generator<0, S...> {
> -		typedef sequence<S...> type;
> -	};
> -#endif
> -
>  	bool activatePack(std::shared_ptr<BoundMethodPackBase> pack,
>  			  bool deleteMethod);
>  
> @@ -107,11 +89,11 @@ public:
>  	using PackType = BoundMethodPack<R, Args...>;
>  
>  private:
> -	template<int... S>
> -	void invokePack(BoundMethodPackBase *pack, BoundMethodBase::sequence<S...>)
> +	template<std::size_t... I>
> +	void invokePack(BoundMethodPackBase *pack, std::index_sequence<I...>)
>  	{
>  		PackType *args = static_cast<PackType *>(pack);
> -		args->ret_ = invoke(std::get<S>(args->args_)...);
> +		args->ret_ = invoke(std::get<I>(args->args_)...);
>  	}
>  
>  public:
> @@ -120,7 +102,7 @@ public:
>  
>  	void invokePack(BoundMethodPackBase *pack) override
>  	{
> -		invokePack(pack, typename BoundMethodBase::generator<sizeof...(Args)>::type());
> +		invokePack(pack, std::make_index_sequence<sizeof...(Args)>{});
>  	}
>  
>  	virtual R activate(Args... args, bool deleteMethod = false) = 0;
> @@ -134,12 +116,12 @@ public:
>  	using PackType = BoundMethodPack<void, Args...>;
>  
>  private:
> -	template<int... S>
> -	void invokePack(BoundMethodPackBase *pack, BoundMethodBase::sequence<S...>)
> +	template<std::size_t... I>
> +	void invokePack(BoundMethodPackBase *pack, std::index_sequence<I...>)
>  	{
> -		/* args is effectively unused when the sequence S is empty. */
> +		/* args is effectively unused when the sequence I is empty. */
>  		PackType *args [[gnu::unused]] = static_cast<PackType *>(pack);
> -		invoke(std::get<S>(args->args_)...);
> +		invoke(std::get<I>(args->args_)...);
>  	}
>  
>  public:
> @@ -148,7 +130,7 @@ public:
>  
>  	void invokePack(BoundMethodPackBase *pack) override
>  	{
> -		invokePack(pack, typename BoundMethodBase::generator<sizeof...(Args)>::type());
> +		invokePack(pack, std::make_index_sequence<sizeof...(Args)>{});
>  	}
>  
>  	virtual void activate(Args... args, bool deleteMethod = false) = 0;
> -- 
> Regards,
> 
> Laurent Pinchart
> 
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel at lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel

-- 
Regards,
Niklas Söderlund