add-with-mergetool

#!/bin/bash
#
# add-with-mergetool
# Author: Stuart Berg (http://github.com/stuarteberg)
#
# This little script is like 'git add --patch', except that
# it launches a merge-tool to perform the merge.

# TODO: For now, this script hard-codes MERGETOOL and MERGECMD for kdiff3.
#       Modify those variables for your own tool if you wish.
#       In the future, it would be nice if we could somehow read
#       MERGETOOL and MERGECMD from the user's git-config.

# Configure for kdiff3
# (and hide warnings on about modalSession, from kdiff3 on OSX)
MERGETOOL=${MERGETOOL-kdiff3}
MERGECMD=${MERGECMD-'"${MERGETOOL}" "${LOCAL}" "${REMOTE}" -o "${MERGED}"'\
                2>&1 | grep -iv modalSession}

main() {
    check_for_errors "$@"
    process_all "$@"
}

check_for_errors() {
which "${MERGETOOL}" > /dev/null
if [[ $? == 1 ]]; then
    echo "Error: Can't find mergetool: '${MERGETOOL}'" 1>&2
    exit 1
fi

if [[ "$1" == "-h" ]]; then
    echo "Usage: $(basename $0) [<pathspec>...]" 1>&2
    exit 0
fi

# Exit early if we're not in a git repo
git status > /dev/null || exit $?
}

process_all() {
repo_toplevel=$(git rev-parse --show-toplevel)

# If no args given, add everything (like 'git add -p')
if [[ $# == 0 ]]; then
    set -- "$repo_toplevel"
fi

# For each given file/directory...
args=( "$@" )
for arg in "${args[@]}"
do
    # Find the modified file(s)
    changed_files=( $(git diff --name-only -- "$arg") )
    (
        # Switch to toplevel, to easily handle 'git diff' output
        cd "$repo_toplevel"

        # For each modified file...
        for f in "${changed_files[@]}"
        do
            if [[ $startmsg_shown != "yes" ]]; then
                echo "Starting $(basename $0).  Use Ctrl+C to stop early."
                echo "To skip a file, quit ${MERGETOOL} without saving."
                echo
                startmsg_shown="yes"
            fi

            # This is where the magic happens.
            patch_file_and_add "$f"
        done
    ) || exit $? # exit early if loop body failed
done
}

# This helper function launches the mergetool for a single file,
#  and then adds it to the git index (if the user saved the new file).
patch_file_and_add() {
f="$1"
git show :"$f" > "$f.from_index" # Copy from the index
(
    set -e
    trap "echo && exit 130" INT # Ctrl+C should trigger abnormal exit

    # Execute 2-file merge
    echo "Launching ${MERGETOOL} for '$f'."
    LOCAL="$f.from_index"
    REMOTE="$f"
    MERGED="$f.to_add"
    eval "${MERGECMD}"

    if [[ -e "$f.to_add" ]]; then
        mv "$f" "$f.from_working" # Backup original from working-tree
        mv "$f.to_add" "$f"       # Replace with patched version
        git add "$f"              # Add to the index
        mv "$f.from_working" "$f" # Restore the working-tree version
    fi
)
status=$?
rm "$f.from_index" # Discard the old index version
if [ $status == 130 ]; then
    echo "User interrupted." 1>&2
    exit $status
elif [ $status != 0 ]; then
    echo "Error: Interactive add-patch stopped early!" 1>&2
    exit $status
fi
}

main "$@"