ERE → BRE

test_re.sh

#!/bin/sh

# Check with the examples from the spec (http://vimdoc.sourceforge.net/htmldoc/options.html#modeline) 
# ./test_re.sh 'vi:noai:sw=3 ts=6' '/\* vim: set ai tw=75: \*/' '# kak: se ft=sh'

old_parse() {
    printf %s\\n "$1" | gsed -r          \
        -e 's/^(.+\s\w+:\s?(set?)?\s)//' \
        -e 's/:?\s[^a-zA-Z0-9_=-]+$//'   \
        -e 's/:/ /g'
}

new_parse() {
    printf %s\\n "$2" | $1             \
	-e 's/^[^:]\{1,\}://'          \
        -e 's/[ \t]*set\{0,1\}[ \t]//' \
	-e 's/:[^a-zA-Z0-9_=-]*$//'    \
        -e 's/:/ /g'
}

check() {
    echo $(old_parse "$1")
    echo $(new_parse sed "$1")
    echo $(new_parse gsed "$1")
}

for arg in "$@"; do
    printf '> "%s"\n' "$arg"
    echo =====
    check "$arg"
    echo =====
done