Trying to build a regular expression to check pattern - 2

Question

I was wondering if more checks could be added: [Previously answered question]( Trying to build a regular expression to check pattern).

The above problem is brilliantly solved using this regex by Brian Rogers:

/^([1-9]|[12][0-9]|3[01])(-([1-9]|[12][0-9]|3[01]))?(,([1-9]|[12][0-9]|3[01])(-([1-9]|[12][0-9]|3[01]))?)*$/  

[For Reference, posting the older problem again]

1. Start and end with a number
2. Hyphen should start and end with a number
3. Comma should start and end with a number
4. Range of number should be from 1-31
5. If a number starts with a hyphen (-), it cannot end with any other character other than a comma AND follow all rules listed above.

E.g. 2-2,1 OR 2,2-1 is valid while 1-1-1-1 is not valid.

E.g.:
- 1-5,5,15-29
- 1,28,1-31,15
- 15,25,3 - 1-24,5-6,2-9

Could this go a step further and add other validations?

1) The numbers should be in ascending order
E.g:
- 1,2-3 - Valid
- 4-6,23 - Valid
- 23,4-5 - Invalid

2) The numbers should not repeat
E.g:
a) 2,2,2 - Invalid
b) 2,3-6,3 - Invalid
c) 2,5,7-20 - Valid

3) If possible
Number should not repeat if previously defined in range
E.g:
a) 2,3-6, 4 - Invalid, because 4 is already a number between 3 and 6
b) 12-16, 14-18 - Invalid, because 14,15 and 16 are already defined in 12-16
c) 9-13, 15, 17-19 - Valid

Answer 1

Regular expression is supposed to check a pattern and not to handle business logic. The moment you start stating your problem with "if ... then ... else", it's not something regular expression is supposed to handle.