#!/bin/sh

# Expands bash-style {} expressions.

# See <http://www.gnu.org/software/bash/manual/bash.html#Brace-Expansion>.

# Filters each line from stdin to stdout.

# Warning: Due to shell limitations, a blank line will be interpreted as EOF.

sedEreFlag="$(test "$(uname)" = Darwin && echo E || echo r)"

sed () { "$(which sed)" -"$sedEreFlag" "$@";}

echoEach () { local line; for line in "$@"; do echo "$line"; done; }

braceKeepRe="./'{'"

braceKeepRepl="./{"

while true; do

    line="$(head -1)" # get next line from stdin; $() strips trailing newlines

    test -z "$line" && break # EOF if no line or empty line

    line="$(echo "$line"|sed -e "s/[^{,}]+/'&'/g")" # escape special chars

    line="${line//$braceKeepRe/$braceKeepRepl}" # don't expand ./{

    eval "echoEach $line" # brace-expand $line

done