Question

I’m trying to developing a code validation system for an in-house markup language but I’m having a little trouble due to my inexperience with regexes. The tags in the language follow the format of:

{ tag : number : phrase 1 | phrase 2 … | phrase n}

where number is a number in the range (3.0, 3.5, 4.0 … 8.5) and exactly one of the phrases must have an asterisk at its end and there must be at least two phrases. Please note that the tags are case-insensitive and whitespace does not matter.

The regex I’m using is:

\{ ?(mw) ?: ?[3-8]{1}(.0|.5)? ?((((\| ?(\w ?)+[\p{P}]? ?)*)+((\| ?(\w\ ?)+[\p{P}]?)* ?\* ?)+((\| ?(\w ?)+[\p{P}]? ?)*)?)|(((\| ?(\w ?)+[\p{P}]? ?)*)?((\| ?(\w ?)+[\p{P}]?)* ?\* ?)+((\| ?(\w ?)+[\p{P}]? ?)*)+))( ?\})

which does match the correct case of:

{ mw : 3.5 | phrase 1 | phrase 2* | phrase 3}

but also the incorrect cases of:

{ mw : 3.5 | phrase 1* | phrase 2* | phrase 3} [Two asterisks]

and

{ mw : 3.5* | phrase 1 | phrase 2* | phrase 3} [An asterisk with the number value]

Thanks for any help.

And if anyone wants to offer any insight into how data validation systems typically work I would appreciate the insight.

Answer 1

Here:

\{\s*(\w+)\s*:\s*([3-8]\.[05])\s*(\|[^|*\n]*)*(\|[^|*\n]*\*\s*)(\|[^|*\n]*)*\}

Here’s a demo, tested with the following input:

{ mw : 3.5  | hello,  world  | says  | i  }
{ mw : 3.5  | hello,* world  | says  | i  }
{ mw : 3.5  | hello,  world* | says  | i  }
{ mw : 3.5  | hello,  world  | says* | i  }
{ mw : 3.5  | hello,  world  | says  | i* }
{ mw : 3.5    }
{ mw : 3.5  | }
{ mw : 3.5* | }
{ mw : 3.5  | hello, world  }
{ mw : 3.5  | hello, world* }

UPDATE

Some notes.

1. In your original regex,  ? says “0 or 1 space characters”. You may have meant \s* which means “0 or more whitespace characters”.
2. In your original regex, note that (.0|.5) actually matches A0 and B5.
3. You may need to modify my regex to reincorporate whatever you were doing with [\p{P}]?.
4. It looks like you were on the right track but you may have overcomplicated some things, and most likely something funky with your whitespace expressions messed up your regex. I encourage using the tool I linked above, regexpal.com, testing your regex piece by piece to see where things aren’t working as expected.

UPDATE 2

Highly doubt you’re able to add flags, but the x flag would shorten this regex considerably:

\{(\w+):([3-8]\.[05])(\|[^|*\n]*)*(\|[^|*\n]*\*)(\|[^|*\n]*)*\}