#!/bin/bash -e

# Don Marti <dmarti@zgp.org>
# (If you need a license on this in order to use it,
# mail me and I'll put a license on it.  Otherwise,
# de minimis non curat lex.)

# re-run make, with the supplied arguments, when a
# Makefile prerequisite changes.  Example:
#   makewatch test
# Fun to use with Auto Reload (Firefox) or Tincr (Chrome) and Pandoc
#   https://addons.mozilla.org/en-US/firefox/addon/auto-reload/
#   http://tin.cr/
#   http://johnmacfarlane.net/pandoc/
# Requires inotifywait.  Probably requires GNU Make to
# get the right "-dnr" output.  Not tested with other
# "make" implementations

# If $MAKEWATCH is set to an existing file or
# space-separated list of files, also checks those.

make_prereqs() {
    # Make "make" figure out what files it's interested in.
    echo "Makefile"
    find $MAKEWATCH
    gmake -dnr $* | tr ' ' '\n' | \
        grep ".*'.$" | grep -o '\w.*\b'
}

prereq_files() {
    # prerequisites mentioned in a Makefile
    # that are extant files
    echo ' '
    for f in `make_prereqs $* | sort -u`; do
        [ -e $f ] && echo -n "$f ";
    done
    echo
}

make $*
while true; do
    fl=$(prereq_files $*)
    ev=$(inotifywait --quiet --format %e $fl)
    if [ "xOPEN" != "x$ev" ]; then
        sleep 1
        make $*
    fi
done