#!/usr/bin/env sh
# compat: +ash +bash +dash +zsh YES_BB_AWK

sv() { ### @-
    ### collect the lastmost value of every key.
    ### the field separator can be given as its sole argument,
    ### it defaults to a single space otherwise.
    ###
    ### ```
    ### $ echo "alpha=first\nbeta=second\nalpha=third" | sv =
    ### alpha=third
    ### beta=second
    ### ```
    ###
    ### this next example uses `sv` to only print the lastmost line
    ### matching a pattern in each file. in other words, it uses
    ### the filename printed by grep as the key in its key-value pairs.
    ###
    ### ```
    ### $ cd ~/play/hash && grep -r 'ing$' . | sv :
    ### ./dic_win32.txt:WriteProfileString
    ### ./cracklib-small.txt:zoning
    ### ./english-words.txt:zooming
    ### ./usernames-125k.txt:flats_gaming
    ### ./cain.txt:zoografting
    ### ./pokemon.txt:Fletchling
    ### ./pokemon8.txt:Fletchling
    ### ```
    ###
    ### **TODO:** rename because busybox(1) sv already exists.
    [ $# -le 1 ] || { printf "%s\n" "$0: too many arguments" >&2; return 1; }
    awk "-F${1:- }" '
    NF>1{f[$1]=substr($0,length($1)+1+length(FS))}END{for(k in f)print k FS f[k]}
    '
}

[ -n "${preload+-}" ] || sv "$@"