best solution by far. very easy to read and simple to understand

(Java) Clicking "Attempt" results in errors:

src/test/java/RS5_Tests.java:1010: error: cannot find symbol
            TOKENIZER    = Pattern.compile(String.join("|", Arrays.asList(WHITE_COMMENTS, ID_PATT_BRA, ".")), Pattern.DOTALL),
                                                                                                                     ^
  symbol:   variable DOTALL
  location: class Pattern
src/test/java/RS5_Tests.java:1011: error: incompatible types: String cannot be converted to Env
            VALID_TOKEN  = Pattern.compile(ID_PATT_BRA),
                                           ^
src/test/java/RS5_Tests.java:1012: error: cannot find symbol
            IS_CMT_WHITE = Pattern.compile(WHITE_COMMENTS, Pattern.DOTALL);
                                                                  ^
  symbol:   variable DOTALL
  location: class Pattern
src/test/java/RS5_Tests.java:1034: error: cannot find symbol
            Matcher m = TOKENIZER.matcher(source);
                                 ^
  symbol:   method matcher(String)
  location: variable TOKENIZER of type Pattern
src/test/java/RS5_Tests.java:1037: error: cannot find symbol
                if (IS_CMT_WHITE.matcher(tok).matches())  continue;
                                ^
  symbol:   method matcher(String)
  location: variable IS_CMT_WHITE of type Pattern
src/test/java/RS5_Tests.java:1038: error: cannot find symbol
                if (VALID_TOKEN.matcher(tok).matches()) tokens.add(tok);
                               ^
  symbol:   method matcher(String)
  location: variable VALID_TOKEN of type Pattern
Note: src/main/java/RSUProgram.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
6 errors

(Java) When I click "Attempt" I get a bunch of errors:

src/test/java/SolutionTest.java:212: error: cannot find symbol
    final static private Pattern P_TOKENS  = Pattern.compile("p(\\d+)(.*?)q"),
                                                    ^
  symbol:   method compile(String)
  location: class Pattern
src/test/java/SolutionTest.java:213: error: cannot find symbol
                                 TOKENIZER = Pattern.compile("(R+|F+|L+|[P)(]|p.+?q)(\\d*)");
                                                    ^
  symbol:   method compile(String)
  location: class Pattern
src/test/java/SolutionTest.java:260: error: cannot find symbol
        Matcher m = P_TOKENS.matcher(code);
                            ^
  symbol:   method matcher(String)
  location: variable P_TOKENS of type Pattern
src/test/java/SolutionTest.java:279: error: cannot find symbol
        Matcher m = TOKENIZER.matcher(code);
                             ^
  symbol:   method matcher(String)
  location: variable TOKENIZER of type Pattern
4 errors

I do not use Pattern and Matcher in my solution.