bashup.hooks

#!/usr/bin/env bash

hook.exists() { declare -F -- "$1";} >/dev/null
hook.before() { hook.quote-args REPLY "${@:2}"; hook.eval-before  "$1" "$REPLY";}
hook.after()  { hook.quote-args REPLY "${@:2}"; hook.eval-after   "$1" "$REPLY";}
hook.without(){ hook.quote-args REPLY "${@:2}"; hook.eval-without "$1" "$REPLY";}
hook.on() { hook.after "$@";}

hook.around(){
    hook.body "$1" ":;"; local old=$REPLY
    hook.body "$2" "$3;"; local wrap=$REPLY
    eval "$1() ${wrap/#{/{ $3() $old}"
}

hook.quote-args() { printf -v "$1" ' %q' "${@:2}";}
hook.eval-before(){ hook.body "$1" "" "{ $2" "}";  eval "$1() $REPLY";}
hook.eval-after() { hook.body "$1" "" "{" "$2 ;}"; eval "$1() $REPLY";}

hook.eval-without() {
    local l=$'\n}' r='^~hooktmp~^'; eval $r$'() {\n'"$2"$'\n}'; hook.body $r "" "" ""
    unset -f $r; r=${REPLY%$'\n'}; hook.body "$1"
    while [[ $REPLY =~ "$r"\;?' '*$'\n' ]]; do REPLY=${REPLY//"${BASH_REMATCH[0]}"/$'\n'}; done
    eval "$1() ${REPLY/#{$l/{ :$l}";
}

hook.body() {
    local lf=$'\n' b="}" r
    r="$(declare -f -- "$1")" && { r=${r#*{ }; r=${r%\}*}; } || r=$lf$2$lf
    REPLY="${3-{}$r${4-$b}"
}