module ActiveRecord::ConnectionAdapters::PostgreSQL::ArrayParser

def add_item_to_array(array, current_item, quoted)
  return if !quoted && current_item.length == 0
  if !quoted && current_item == 'NULL'
    array.push nil
  else
    array.push current_item
  end
end

def parse_array_contents(array, string, index)
  is_escaping  = false
  is_quoted    = false
  was_quoted   = false
  current_item = ''
  local_index = index
  while local_index
    token = string[local_index]
    if is_escaping
      current_item << token
      is_escaping = false
    else
      if is_quoted
        case token
        when DOUBLE_QUOTE
          is_quoted = false
          was_quoted = true
        when BACKSLASH
          is_escaping = true
        else
          current_item << token
        end
      else
        case token
        when BACKSLASH
          is_escaping = true
        when COMMA
          add_item_to_array(array, current_item, was_quoted)
          current_item = ''
          was_quoted = false
        when DOUBLE_QUOTE
          is_quoted = true
        when BRACKET_OPEN
          internal_items = []
          local_index,internal_items = parse_array_contents(internal_items, string, local_index + 1)
          array.push(internal_items)
        when BRACKET_CLOSE
          add_item_to_array(array, current_item, was_quoted)
          return local_index,array
        else
          current_item << token
        end
      end
    end
    local_index += 1
  end
  return local_index,array
end

def parse_pg_array(string) # :nodoc:
  local_index = 0
  array = []
  while(local_index < string.length)
    case string[local_index]
    when BRACKET_OPEN
      local_index,array = parse_array_contents(array, string, local_index + 1)
    when BRACKET_CLOSE
      return array
    end
    local_index += 1
  end
  array
end