view hgeditor @ 32719:f75d0aa5dc83

revset: lookup descendents for negative arguments to ancestor operator

Negative offsets to the `~` operator now search for descendents. The search is
aborted when a node has more than one child as we do not have a definition for
'nth child'. Optionally we can introduce such a notion and take the nth child
ordered by rev number.

The current revset language does provides a short operator for ancestor lookup
but not for descendents. This gives user a simple revset to move to the previous
changeset, e.g. `hg up '.~1'` but not to the 'next' changeset. With this change
userse can now use `.~-1` as a shortcut to move to the next changeset.
This fits better into allowing users to specify revisions via revsets and
avoiding the need for special `hg next` and `hg prev` operations.

The alternative to negative offsets is adding a new operator. We do not have
many operators in ascii left that do not require bash escaping (',', '_', and
'/' come to mind). If we decide that we should add a more convenient short
operator such as ('/', e.g. './1') we can later add it and allow ascendents
lookup via negative numbers.

#!/bin/sh
#
# This is an example of using HGEDITOR to create of diff to review the
# changes while committing.

# If you want to pass your favourite editor some other parameters
# only for Mercurial, modify this:
case "${EDITOR}" in
    "")
        EDITOR="vi"
        ;;
    emacs)
        EDITOR="$EDITOR -nw"
        ;;
    gvim|vim)
        EDITOR="$EDITOR -f -o"
        ;;
esac


HGTMP=""
cleanup_exit() {
    rm -rf "$HGTMP"
}

# Remove temporary files even if we get interrupted
trap "cleanup_exit" 0 # normal exit
trap "exit 255" HUP INT QUIT ABRT TERM

HGTMP=$(mktemp -d ${TMPDIR-/tmp}/hgeditor.XXXXXX)
[ x$HGTMP != x -a -d $HGTMP ] || {
  echo "Could not create temporary directory! Exiting." 1>&2
  exit 1
}

(
    grep '^HG: changed' "$1" | cut -b 13- | while read changed; do
        "$HG" diff "$changed" >> "$HGTMP/diff"
    done
)

cat "$1" > "$HGTMP/msg"

MD5=$(which md5sum 2>/dev/null) || \
    MD5=$(which md5 2>/dev/null)
[ -x "${MD5}" ] && CHECKSUM=`${MD5} "$HGTMP/msg"`
if [ -s "$HGTMP/diff" ]; then
    $EDITOR "$HGTMP/msg" "$HGTMP/diff" || exit $?
else
    $EDITOR "$HGTMP/msg" || exit $?
fi
[ -x "${MD5}" ] && (echo "$CHECKSUM" | ${MD5} -c >/dev/null 2>&1 && exit 13)

mv "$HGTMP/msg" "$1"

exit $?