(da)sh substring match/replace speed tests

wtf_replace_old() { echo "$@" | sed -re 's/%F/4/g'; }

substr_match() {
    local a b
    a=$1; shift; b=${#@}; a=${@#*$a}; a=${#a}
    [ $a -ne $b ]
}

wtf_match() { substr_match '%F' "$@"; }

# dirty
wtf_replace_new_v1() {
    local x="$@"
    while is_af_loose "$x"; do x=${x%%\%F*}4${x#*%F}; done
    echo "$x"
}

# kind of accurate
wtf_replace_new_v2() {
    local x
    for x; do
        while is_af_loose "$x"; do x=${x%%\%F*}4${x#*%F}; done
        if substr_match ' ' "$x"; then echo "'$x'"; else echo "$x"; fi
    done
}



date --rfc-3339=ns
for i in $(seq 1 10000); do
    wtf_replace_old "abc1337def%Fghi${i}klm%Fzyx"
done > /dev/null
date --rfc-3339=ns

# 2018-04-19 01:36:38.196838148
# 2018-04-19 01:36:47.792090732



date --rfc-3339=ns
for i in $(seq 1 10000); do
    wtf_replace_new_v1 "abc1337def%Fghi${i}klm%Fzyx"
done > /dev/null
date --rfc-3339=ns

# 2018-04-19 01:36:47.792755513
# 2018-04-19 01:36:48.047608340



date --rfc-3339=ns
for i in $(seq 1 10000); do
    wtf_replace_new_v2 "abc1337def%Fghi${i}klm%Fzyx"
done > /dev/null
date --rfc-3339=ns

# 2018-04-19 01:36:48.048289043
# 2018-04-19 01:36:48.362512638



date --rfc-3339=ns
for i in $(seq 1 50000); do
    wtf_replace_new_v1 "abc1337def%Fghi${i}klm%Fzyx"
done > /dev/null
date --rfc-3339=ns

# 2018-04-19 01:36:48.363150082
# 2018-04-19 01:36:49.632880751



date --rfc-3339=ns
for i in $(seq 1 50000); do
    wtf_replace_new_v2 "abc1337def%Fghi${i}klm%Fzyx"
done > /dev/null
date --rfc-3339=ns

# 2018-04-19 01:36:49.633568684
# 2018-04-19 01:36:51.242995435