# usage: echo '{"foo":"bar"}' | json_tokenize | json_parse

json_print()
  local value
  json_value ${value:ref} $@ || return 1
  echo $value

json_print_type()
  local type
  json_type ${type:ref} $@ || return 1
  echo $type

json_value()
  json_property value $@

json_type()
  json_property type $@


json_property(kind out start_id values)
  shift 3
  local id type value
  if $start_id match ^[0-9]+$
    shift
  else
    values=$start_id
    start_id=1
  json_get_id ${id:ref} $start_id $values $@ || return 1
  expand
    type=${~values[$id:type]}
    value=${~values[$id:value]}
  switch $kind
    case type
      out:ref=$type
    case value
      switch $type
        case object|array
          out:ref=$id
        case *
          out:ref=$value

json_get_id(out id values)
  shift 3
  if not ismap? $values
    echo "ERROR: in json_get: $values is not a json object"
    return 1
  expand
    for key in $@
      id=${~values[$id-$key]}
  out:ref=$id

json_parse(__out __string)
  declare map __objects
  test _json_parse $__out $__string or return 1
  copy_map __objects $__out

_json_parse(out string)
  #
  local index=0
  local c
  local state="top"
  #
  local unicode1 unicode2
  #
  local key=''
  local value=''
  declare array value_id_stack
  declare integer value_stack_pos
  declare integer value_id
  declare integer previous_id
  declare integer next_id
  #
  value_id_stack[0]=0
  value_stack_pos=0
  value_id=0
  next_id=1
  #
  declare integer state_depth
  declare array state_list
  state_depth=0
  #
  declare integer line
  declare integer collumn
  line=0
  collumn=0
  #
  state_pop()
    if $state_depth > 0
      state_depth-=1
      state=$state_list[$state_depth]
  #
  state_push(v)
    state_list[$state_depth]=$state
    state_depth+=1
    state=$v
  #
  state_replace(v)
    state_pop
    state_push $v
  #
  set_type(t)
    __objects["$value_id:type"]=$t
  #
  add_value_to_object()
    __objects["$previous_id-$key"]=$value_id
  #
  add_value_to_array()
    local index=$__objects[$previous_id:length]
    __objects["$previous_id-$index"]=$value_id
    __objects["$previous_id:length"]=$(math index+1)
  #
  start_value()
    previous_id=$value_id
    value_id=$next_id
    next_id+=1
    value_stack_pos+=1
    value_id_stack[$value_stack_pos]=$value_id
    state_push 'value'
  #
  end_value()
    __objects["$value_id:value"]="$value"
    value=
    value_stack_pos-=1
    value_id=$previous_id
    previous_id=$value_id_stack[$(math value_stack_pos-1)]
    state_pop
  #
  start_array()
    __objects["$value_id:length"]=0
  #
  error(msg)
    echo "ERROR:$line:$collumn: while parsing json: $msg" >&2
  #
  if not ismap? $out
    error "expected an associative array as an argument, but $out isn't one"; return 1
  #
  start_value
  while $index < ${string:length}
    c=${string:index index}
    index+=1
    #
    if $c is $NL
      newline+=1
      collumn=0
    else
      collumn+=1
    #
    switch $state
      case 'value'
        switch $c
          case [[:space:]]
            pass
          case '{'
            state_push 'object'
            state_push 'object-key'
          case '['
            start_array
            state_push 'array-start'
          case '"'
            state_push 'string'
          case '-'
            state_push 'negative'
            value='-'
          case '0'
            state_push 'after-integer'
            value='0'
          case [1-9]
            value&=$c
            set_type 'number'
            state_push 'integer'
          case 't'
            value=${string:slice index-1 length 5}
            switch $value
              case 'true'|'true'[[:space:]]
                set_type 'bool'
                value='true'
                end_value
                index+=4
              case 'true,'|'true]'|'true}'
                set_type 'bool'
                value='true'
                end_value
                index+=3
              case *
                error "unexpected character $c: didn't lead to 'true' ($value...)"; return 1
          case 'f'
            value=${string:slice index-1 length 6}
            switch $value
              case 'false'|'false'[[:space:]]
                set_type 'bool'
                value='false'
                end_value
                index+=5
              case 'false,'|'false]'|'false}'
                set_type 'bool'
                value='false'
                end_value
                index+=4
              case *
                error "unexpected character $c: didn't lead to 'false' ($value...)"; return 1
          case *
            error "unexpected character $c"; return 1
      case 'object-key'
        switch $c
          case [[:space:]]
            pass
          case '"'
            state_pop
            state_push 'object-colon'
            state_push 'string'
          case '}'
            state_pop
            end_value
          case *
            error "unexpected character $c: expected a string as a object key"; return 1
      case 'object-colon'
        switch $c
          case [[:space:]]
            pass
          case ':'
            state_pop
            start_value
            add_value_to_object
          case *
            error "unexpected character $c: expected a colon (:) after the object key"; return 1
      case 'object'
        switch $c
          case [[:space:]]
            pass
          case ','
            state_push 'object-key'
          case '}'
            set_type 'object'
            state_pop
            end_value
          case *
            error "unexpected character $c: expected ',' or '}' in object"; return 1
      case 'array-start'
        switch $c
          case ']'
            set_type 'array'
            state_pop
            end_value
          case *
            index-=1
            state_replace 'array'
            start_value
            add_value_to_array
      case 'array'
        switch $c
          case [[:space:]]
            pass
          case ','
             start_value
             add_value_to_array
          case ']'
            set_type 'array'
            state_pop
            end_value
          case *
            error "expected ',' or '}' in array"; return 1
      case 'string'
        switch $c
          case '"'
            set_type 'string'
            state_pop
            if $state is 'value'
              end_value
            elif $state is 'object-colon'
              key="$value"
              value=''
          case '\'
            state_push 'escape'
          case *
            value&=$c
      case 'escape'
        state_pop
        switch $c
          case '"'|'\'|'/'
            value&=$c
          case [bfnrt]
            local v
            printf -v v "\\$c"
            value&=$v
          case u
            local unicode offset
            parse_utf16 -r ${unicode:ref} -o ${offset:ref} ${string:slice index+1 length 8} || return 1
            value&=$unicode
            index+=$offset
          case *
            error "invalid escape character: $c"; return 1
      case 'negative'
        switch $c
          case 0
            state_replace 'after-integer'
            value&=0
          case [1-9]
            state_replace 'integer'
            value&=$c
          case *
             error "unexpected character $c: expected a digit from 0 to 9"; return 1
      case 'integer'
        switch $c
          case [0-9]
            value&=$c
          case '.'
            value&='.'
            state_replace 'floating-point'
          case [[:space:]]
            state_pop
            set_type 'number'
            end_value
          case ','|']'|'}'
            state_pop
            set_type 'number'
            end_value
            index-=1
          case *
             error "unexpected character $c: expected a digit from 0 to 9, . or whitespace"; return 1
      case 'after-integer'
        switch $c
          case '.'
            value&='.'
            state_replace 'floating-point-start'
          case [[:space:]]
            state_pop
            set_type 'number'
            end_value
          case ','|']'|'}'
            state_pop
            set_type 'number'
            end_value
            index-=1
          case *
             error "unexpected character $c: expected . or whitespace"; return 1
      case 'floating-point-start'
        switch $c
          case [0-9]
            value&=$c
            state_replace 'floating-point'
          case *
             error "unexpected character $c: expected a digit from 0 to 9 after ."; return 1
      case 'floating-point'
        switch $c
          case [0-9]
            value&=$c
          case [eE]
            value&=e
            state_replace 'float-e'
          case [[:space:]]
            state_pop
            set_type 'number'
            end_value
          case ','|']'|'}'
            state_pop
            set_type 'number'
            end_value
            index-=1
          case *
             error "unexpected character $c: expected a digit from 0 to 9, e/E or whitespace."; return 1
      case 'float-e'
        switch $c
          case [0-9]|+|-
            value&=$c
            state_replace 'float-e-value'
          case *
             error "unexpected character $c: expected a digit from 0 to 9, + or -."; return 1
      case 'float-e-value'
        switch $c
          case [0-9]
            value&=$c
          case [[:space:]]
            state_pop
            set_type 'number'
            end_value
  while $state isnt 'top'
    switch $state
      case 'integer'|'floating-point'|'float-e-value'
        state_pop
        end_value
      case *
        error "premature end of input. ($state)"
        return 1