Got AC with a 34-lines Java program.

5 lines for the RE:
     "('[^']*'|#\\d+)|"+            // 1: str
     "(\\d+(?:\\.\\d+)?)|"+            // 2: num
     "(\\{[^}]*\\}|//[^\\r\\n]*)|"+ // 3: comment
     "([a-z_][a-z_0-9]*)|"+            // 4: ID
     "(.)"                    // 5: anything else

5 lines of kw:
    {"and", "array", "begin", "case", "class", "const", "div", "do", "else", "end", "for",
     "function", "if", "implementation", "interface", "mod", "not", "of", "or", "procedure",
     "program", "record", "repeat", "shl", "shr", "string", "then", "to", "type", "unit",
     "until", "uses", "var", "while", "with"};

and 10 copy/pasted lines of the main loop:
while in.findWithinHorizon is not null, check which group matched and print accordingly

Pitfalls:

The list of the keywords in the statement is not sorted and thus binarySearch in it fails.

The statement about "//..." comments is simply wrong: line feed is \n, in reality test 6 uses carriage-return (\r).