pp.expand

#
# {}-expansion is a tricky problem. Not all shells seem to be the same,
# but this is such a useful thing to have. It turns out that some korn
# shells have something similar available when bourne shells don't.
# The glob format is @(word|word|word) instead of {word,word,word}.
#

pp_expand_path=

#@ pp_expand_test_usr_bin(): returns true if input is /usr and /bin
pp_expand_test_usr_bin () {
	awk '$1 == "/usr" || $2 == "/usr" {usr++}
	     $1 == "/bin" || $2 == "/bin" {bin++}
	     END { if (usr == 1 && bin == 1) exit(0); else exit(1); }'
}

#@ pp_set_expand_converter_or_reexec(arg...): sets $pp_expand_path
pp_set_expand_converter_or_reexec () {
    test -d /usr -a -d /bin ||
	pp_die "missing /usr or /bin"
    echo /usr /bin | pp_expand_test_usr_bin || pp_die "pp_expand_test_usr_bin?"
    if (eval "echo /{usr,bin}" | pp_expand_test_usr_bin) 2>/dev/null; then
	pp_expand_path=pp_expand_path_brace
    elif (eval "echo /@(usr|bin)" | pp_expand_test_usr_bin) 2>/dev/null; then
	pp_expand_path=pp_expand_path_at
    else
	test x"$pp_expand_rexec" != x"true" ||
	    pp_die "problem finding shell that can do brace expansion"
	for shell in bash ksh ksh93; do
	    if ($shell -c 'echo /{usr,bin}' |
			pp_expand_test_usr_bin) 2>/dev/null ||
	       ($shell -c 'echo /@(usr|bin)' |
			pp_expand_test_usr_bin) 2>/dev/null
	    then
                pp_debug "switching to shell $shell"
		pp_expand_rexec=true exec $shell "$0" "$@"
	    fi
	done
	pp_die "cannot find a shell that does brace expansion"
    fi
}

#@ pp_expand_path_brace(path): writes all expansions of path to stdout
pp_expand_path_brace () {
	typeset f
	eval "for f in $1; do echo \"\$f\"; done|sort -u"
}

#@ pp_expand_path_at(path): writes all expansions of path to stdout
#   works by translating {word,word} into @(word|word) then evaluating
#   FIXME: this function will break if there are commas, braces or escapes
pp_expand_path_at () {
	typeset f
	eval "for f in `
	    echo "$1" | sed -e 's/{/@(/g' -e 's/}/)/g' -e 's/,/|/g'
		`; do echo \"\$f\"; done|sort -u"
}