class Pry::Command::ShellCommand

def cd_path_env
  ENV['CDPATH']
end

def cd_path_exists?
  cd_path_env && cd_path_env.length.nonzero?
end

def parse_destination(dest)
  return "~" if dest.empty?
  return dest unless dest == "-"
  state.old_pwd || raise(CommandError, "No prior directory available")
end

def path_from_cd_path(dest)
  return if !(dest && cd_path_exists?) || special_case_path?(dest)
  cd_path_env.split(File::PATH_SEPARATOR).each do |path|
    if File.directory?(path) && path.split(File::SEPARATOR).last == dest
      return path
    end
  end
  return nil
end

def process(cmd)
  if cmd =~ /^cd\s*(.*)/i
    process_cd parse_destination($1)
  else
    pass_block(cmd)
    if command_block
      command_block.call `#{cmd}`
    else
      _pry_.config.system.call(output, cmd, _pry_)
    end
  end
end

def process_cd(dest)
  begin
    state.old_pwd = Dir.pwd
    Dir.chdir(File.expand_path(path_from_cd_path(dest) || dest))
  rescue Errno::ENOENT
    raise CommandError, "No such directory: #{dest}"
  end
end

def special_case_path?(dest)
  ['.', '..', '-'].include?(dest) || dest =~ /\A[#{File::PATH_SEPARATOR}~]/
end