#!/bin/bash
setglobal json = $[</dev/stdin], oldlang = $LANG, LANG = 'C'
setglobal str = ''("(\\.|[^\\"])*")''                 # regexes to match json types
setglobal num = '"(-?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?)'"
setglobal val = '"((str|num|obj|arr)[a-j]+|true|false|null)'"
setglobal arr = ""\[($val(,$val)*)?]""
setglobal obj = ""\{(str[a-j]+:$val(,str[a-j]+:$val)*)?}""
setglobal tr = '('TODO {a..j}{a..j}{a..j})                 # to avoid adding more numbers
declare -n match = ''

proc pushTODO  { declare -gn list = "$(type)_list"; setglobal list = '('"${BASH_REMATCH[1]}"); }
proc match
  for match in str num obj arr; do      # remove whitespace asap
    [[ ${!match} != str && ! i++ -ne 0 ]] && json=${json//[$' \t\n\r']}
    [[ $json =~ $match(.*) ]] && { type=${!match}; return; }
  done

while match { push                    # push to stack, replace with pointer
  setglobal json = "$(json%"$BASH_REMATCH")$type$(tr[${#list[@]}-1])$(BASH_REMATCH[-1])"
}TODO 
#####  done!   a json parser in 20 lines of bash!    \o/   #####


[[ $json =~ ^$val$ ]] || exit           # silly "error detection"

declare -A rt = ''                           # inverse of tr, naming things is hard
# pretty printing
for i in [$(tr[@])] { sh-expr 'rt[$i]=j++'; }
set -f; setglobal LANG = $oldlang, IFS = ':,', regex = ''(\\[nftrb]|\\\\|\\u[a-f0-9]{4})''
shopt -s nocasematch
proc printfor arg in @Argv {                              # plenty of error checking here!
  match $arg {
    with obj* [[ $json = obj* ]] || do { setglobal json = 'null'; break; }
      setglobal json = $(obj_list[rt[${json:3}]]), object = '('$json)
      while sh-expr '${#object[@]}' {
        if [[ ${str_list[rt[${object:3}]]} = "${arg:5}" ]] {
          setglobal json = $(object[1])
          continue 2
        } else { setglobal object = '('"${object[@]:2}")
        }
      }
      setglobal json = 'null'; break 
    with arr* [[ $json = arr* ]] || do { setglobal json = 'null'; break; }
      setglobal json = $(arr_list[rt[${json:3}]]), array = '('$json)
      sh-expr '${#array[@]} >= ${arg:5} ' || do { setglobal json = 'null'; break; }
      setglobal json = $(array[${arg:5}]) 
  }
}
print $json; echo