Re: [PATCH 12/13] strvec: implement swapping two strvecs

From: Patrick Steinhardt <ps@pks.im>
To: "brian m. carlson" <sandals@crustytoothpaste.net>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Matthew John Cheetham <mjcheetham@outlook.com>,
	M Hickford <mirth.hickford@gmail.com>
Subject: Re: [PATCH 12/13] strvec: implement swapping two strvecs
Date: Wed, 27 Mar 2024 09:02:45 +0100	[thread overview]
Message-ID: <ZgPSpYVSSmQ9Muec@tanuki> (raw)
In-Reply-To: <20240324011301.1553072-13-sandals@crustytoothpaste.net>

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On Sun, Mar 24, 2024 at 01:13:00AM +0000, brian m. carlson wrote:
> In a future commit, we'll want the ability to efficiently swap the
> contents of two strvec instances without needing to copy any data.
> Since a strvec is simply a pointer and two sizes, swapping them is as
> simply as copying the two pointers and sizes, so let's do that.
> 
> We use a temporary here simply because C doesn't provide a standard
> swapping function, unlike C++ and Rust, but a good optimizing compiler
> will recognize this syntax and handle it appropriately using an
> optimization pass.
> 
> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> ---
>  strvec.c | 7 +++++++
>  strvec.h | 5 +++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/strvec.c b/strvec.c
> index 178f4f3748..93006f1e63 100644
> --- a/strvec.c
> +++ b/strvec.c
> @@ -106,3 +106,10 @@ const char **strvec_detach(struct strvec *array)
>  		return ret;
>  	}
>  }
> +
> +void strvec_swap(struct strvec *a, struct strvec *b)
> +{
> +	struct strvec t = *a;
> +	*a = *b;
> +	*b = t;
> +}

Isn't this equivalent to `SWAP(*a, *b)`?

Patrick

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