Input:

• An array containing three integers: 0, 1 and 2 in any order (i.e. [2, 0, 1])
• And a string of length >= 2 only containing alphabetic letters (both lower- and uppercase) and digits (i.e. a1B2c3)

Output:

Based on the array we sort and output the string.
How does this work?

• The array indicates the order precedence of a-z, A-Z and 0-9, the first being 0; second being 1; and third being 2.
• The individual characters of the string can then be ordered based on that.

Example:

• Array: [2, 0, 1]
• String: a1B2c3

Based on the array, we know our order precedence is 0-9a-zA-Z.
Based on that, we can convert and output the string: 123acB.

Challenge rules:

• For the array you can choose to use 0-indexed or 1-indexed input, so [3, 1, 2] is also a valid input if you prefer to use 1-indexed arrays.
• The string (both input and output) only contains valid characters: abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.
• If your language doesn't support arrays (or if you choose to), you are free to use strings resembling arrays in the form of [0,1,2] for the first parameter.

General rules:

• This is code-golf, so shortest answer in bytes wins.
  Don't let code-golf languages discourage you from posting answers with non-codegolfing languages. Try to come up with an as short as possible answer for 'any' programming language.
• Standard rules apply for your answer, so you are allowed to use STDIN/STDOUT, functions/method with the proper parameters, full programs. Your call.
• Default Loopholes are forbidden.
• If possible, please add a link with a test for your code.
• Also, please add an explanation if necessary.

Test cases:

[2, 0, 1] & a1B2c3 -> 123acB [2, 1, 0] & aAaA909UuHWw9gh2 -> 02999AAHUWaaghuw [2, 1, 0] & 6Bx43 -> 346Bx [1, 0, 2] & jfjf33g -> ffgjj33 [0, 2, 1] & AbC13 -> b13AC [1, 2, 0] & Qfl0l -> Q0fll [0, 1, 2] & 9870abcABC -> abcABC0789 [0, 2, 1] & test123 -> estt123 [2, 0, 1] & WHAT -> AHTW [2, 0, 1] & WhAt -> htAW [1, 0, 2] & 102BACbac -> ABCabc012