From: Linus Torvalds <torvalds@osdl.org>
Date: Sat, 22 Oct 2005 01:26:27 GMT
Subject: Re: git-rev-list: add "--dense" flag
Message-ID: <Pine.LNX.4.64.0510211814050.10477@g5.osdl.org>
In-Reply-To: <20051022003733.GA8351@pasky.or.cz>



On Sat, 22 Oct 2005, Petr Baudis wrote:
> 
> There is no documentation for the --dense flag and it is even missing
> from the usage string.

I'm not much for docs ;)

The whole path argument also isn't even there (and without paths, --dense 
doesn't matter)

> But my main concern is - will it be possible to do the rename detection
> here as well?

Yes. Note that git-rev-list doesn't actually _do_ the diff, it only checks 
whether the tree is changed. You still just get a list of commits out of 
it, and it is up to you to decide what to do with it.

If you're just going to feed them to diff-tree _anyway_, then you might as 
well not even do the dense thing, because quite frankly, you're just doing 
extra work.

But let's say that you want to follow a certain filename, what you can do 
is basically (fake shell syntax with "goto restart")

	rev=HEAD
   restart:

	git-rev-list $rev --dense --parents -- "$filename" |
		while read commit parent1 restofparents
		do
			if [ "$restofparents" ]; then
				.. it's a merge, do whatever it is you do
				   with merges ..
			else
				shaold=$(git-ls-tree $parent -- "$filename")
				shanew=$(git-ls-tree $commit -- "$filename")

				# Did it disappear?
				# Maybe it got renamed from something
				if [ -z "$shaold" ]; then
					old=$(git-diff-tree -M -r $commit |
						grep " R .* $filename")
					echo "rename? $old"
					filename=figure-it-out-from-$old
					rev=$parent
					goto restart
				fi
				git-diff-tree -p $commit -- "$filename"
			fi
		while

or something similar. 

In other words: you'll basically have to figure out the renames on your 
own, and follow the renaming, but something like the above should do it.

			Linus