support variables in values

[icyleaf]

STR=foo
INT =42
SINGLE_VARIABLE=$STR
MULTIPLE_VARIABLE1=$STR$INT
MULTIPLE_VARIABLE2=$STR$INT1
MULTIPLE_VARIABLE3=$STR $INT
SINGLE_BLOCK_VARIABLE=${STR}${INT}
SINGLE_QUOTES_VARIABLE='hello $STR!'
DOUBLE_QUOTES_VARIABLE="hello ${STR}, my email is ${USERNAME}"

becomes

  {
   "STR" => "foo",
   "INT" => "42",
   "SINGLE_VARIABLE" => "foo",
   "MULTIPLE_VARIABLE1" => "foo42",
   "MULTIPLE_VARIABLE2" => "foo$INT1",
   "MULTIPLE_VARIABLE3" => "foo 42",
   "SINGLE_BLOCK_VARIABLE" => "foo42",
   "SINGLE_QUOTES_VARIABLE" => "hello $STR!",
   "DOUBLE_QUOTES_VARIABLE" => "hello foo, my email is ${USERNAME}"
}