hgmerge

Protocol switch from using generators to stream-like objects.

This allows the the pull side to precisely control how much data is
read so that another encapsulation layer is not needed.

An http client gets a response with a finite size. Because ssh clients
need to keep the stream open, we must not read more data than is sent
in a response. But due to the streaming nature of the changegroup
scheme, only the piece that's parsing the data knows how far it's
allowed to read.

This means the generator scheme isn't fine-grained enough. Instead we
need file-like objects with a read(x) method. This switches everything
for push/pull over to using file-like objects rather than generators.

#!/bin/sh
#
# hgmerge - default merge helper for Mercurial
#
# This tries to find a way to do three-way merge on the current system.
# The result ought to end up in $1.

set -e # bail out quickly on failure

LOCAL=$1
BASE=$2
OTHER=$3

EDITOR="${EDITOR:-vi}"

# Back up our file
cp $LOCAL $LOCAL.orig

# Attempt to do a non-interactive merge
if which merge > /dev/null ; then
    if merge $LOCAL $BASE $OTHER 2> /dev/null; then
	# success!
	exit 0
    fi
    cp $LOCAL.orig $LOCAL
elif which diff3 > /dev/null ; then
    if diff3 -m $LOCAL.orig $BASE $OTHER > $LOCAL ; then
	# success
	exit 0
    fi
    cp $LOCAL.orig $LOCAL
fi

if [ -n "$DISPLAY" ]; then
    # try using kdiff3, which is fairly nice
    if which kdiff3 > /dev/null ; then
	if kdiff3 --auto $BASE $LOCAL $OTHER -o $LOCAL ; then
	    exit 0
	else
	    exit 1
	fi
    fi

    # try using tkdiff, which is a bit less sophisticated
    if which tkdiff > /dev/null ; then
	if tkdiff $LOCAL $OTHER -a $BASE -o $LOCAL ; then
	    exit 0
	else
	    exit 1
	fi
    fi
fi

# Attempt to do a merge with $EDITOR
if which merge > /dev/null ; then
    echo "conflicts detected in $LOCAL"
    merge $LOCAL $BASE $OTHER 2>/dev/null || $EDITOR $LOCAL
    exit 0
fi

if which diff3 > /dev/null ; then
    echo "conflicts detected in $LOCAL"
    diff3 -m $LOCAL.orig $BASE $OTHER > $LOCAL || $EDITOR $LOCAL
    exit 0
fi

# attempt to manually merge with diff and patch
if which diff > /dev/null ; then
    if which patch > /dev/null ; then
	T=`mktemp`
	diff -u $BASE $OTHER > $T
	if patch $LOCAL < $T ; then
	    exit 0
	else
	    $EDITOR $LOCAL $LOCAL.rej
	fi
	rm $T
	exit 1
    fi
fi

echo "hgmerge: unable to find merge, tkdiff, kdiff3, or diff+patch!"
exit 1