view contrib/plan9/9diff @ 46154:ecbb2fc9418c

copies-rust: rename Oracle.is_ancestor to Oracle.is_overwrite

The core information that we want here is about "does information from revision
X overwrite information in Y". To do so, we check is X is an ancestors of Y, but
this is an implementation details, they could be other ways. We update the
naming to clarify this (and align more with wording used in upcoming changesets.

For people curious about other ways: for example we could record the overwrite
graph as it happens and reuse that to check if X overwrite Y, without having to
do potential expensive `is_ancestor` call on the revision graph.

Differential Revision: https://phab.mercurial-scm.org/D9496

#!/bin/rc
# 9diff - Mercurial extdiff wrapper for diff(1)

rfork e

fn getfiles {
	cd $1 &&
	for(f in `{du -as | awk '{print $2}'})
		test -f $f && echo `{cleanname $f}
}

fn usage {
	echo >[1=2] usage: 9diff [diff options] parent child root
	exit usage
}

opts=()
while(~ $1 -*){
	opts=($opts $1)
	shift
}
if(! ~ $#* 3)
	usage

# extdiff will set the parent and child to a single file if there is
# only one change. If there are multiple changes, directories will be
# set. diff(1) does not cope particularly with directories; instead we
# do the recursion ourselves and diff each file individually.
if(test -f $1)
	diff $opts $1 $2
if not{
	# extdiff will create a snapshot of the working copy to prevent
	# conflicts during the diff. We circumvent this behavior by
	# diffing against the repository root to produce plumbable
	# output. This is antisocial.
	for(f in `{sort -u <{getfiles $1} <{getfiles $2}}){
		file1=$1/$f; test -f $file1 || file1=/dev/null
		file2=$3/$f; test -f $file2 || file2=/dev/null
		diff $opts $file1 $file2
	}
}
exit ''