From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 22 Jan 2021 20:32:34 GMT
Subject: Re: [PATCH v2 2/3] range-diff/format-patch: handle commit ranges other than A..B
Message-ID: <xmqqv9bo7lwd.fsf@gitster.c.googlers.com>
In-Reply-To: <2c2744333ecf5662d4198bdddeee80ff4adf6acd.1611339373.git.gitgitgadget@gmail.com>

"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> +	i = strlen(range);
> +	c = i > 2 ? range[--i] : 0;
> +	if (c == '!')
> +		i--; /* might be ...^! */
> +	else if (isdigit(c)) {
> +		/* handle ...^-<n> */
> +		while (i > 2 && isdigit(range[--i]))
> +			; /* keep trimming trailing digits */
> +		if (i < 2 || range[i--] != '-')
> +			return 0;
> +	} else
> +		return 0;
> +
> +	/* Before the `!` or the `-<n>`, we expect `<rev>^` */
> +	return i > 0 && range[i] == '^';

This is still way too complex for my liking, but at least I cannot
immediately spot a glaring off-by-one like the previous round ;-)

This is a tangent ([*1*]), but we often equate an omission to
implicitly specified HEAD; e.g. "git log @{u}.." is what we did
since we started building on top of our upstream.  I wonder if it
makes sense to allow similar short-hand so that ^! alone would mean
HEAD^!, ^@ alone would mean HEAD^@, and so on.

Thanks.


[Footnote]

*1* read: this has nothing to do with how ready I think this patch
    is, but the topic reminds me of it strongly enough that I raise
    it here, because I know the opinions on this unrelated thing on
    recipients of this response are worth listening to.