Regex to extract portions of string about shipment

Question

The Problem

I'll be extracting up to 4 parts of a String that come from user-input. All 4 parts need to be in order i.e. (1-4) below in that order

The first capturing group is required and the last few are not. The named capturing groups are described below

1. KEY (This can be either CONF|ESD|TRACKING and needs to be followed be either [:;'\s]\*s) -- This group is required
2. DATA This can be any text except for any of the 2 patterns described below (Should assume multiple whitespace can lead this following KEY
3. LINE_DATA This is a string in the following kind of format "1,2,3" or "1(2),3(4),5(6)" and should account for spaces in between chars i.e. " 1 ( 2 ) , 3(4 ), 5 6) " This capture can only come after a match of "L[:';\s]\s*]"...but I don't want to capture this part. I just want to capture the "1(2),3(4)..." part (and exclude any trailing and leading whitespace). LINE_DATA is optional
4. INITIALS This is the last part of the string and would come before a \s*$. It's a pattern that would be *[a-zA-Z]+ i.e. "*sm", "*jdm", "*pL" should all match. Again...this group can be optional too and I don't want any leading/trailing whitespace.

Note: this is all case-insensitive too.

Examples with expectations

1. INPUT: "CONF: FEDEX 12345 L: 12(2),2(9),32 *SM"

   MATCHES [KEY=>'CONF' , DATA => 'FEDEX 12345', LINE_DATA => '12(2),2(9),32', INITIALS=>'*SM']

2. INPUT: "ESD: 12/12/92"

   MATCHES: [KEY: 'ESD', DATA: '12/12/92']

3. INPUT: "tRacking' my data L: 1,2,3(4) ";

   MATCHES: [KEY=>'tRacking', DATA=>'my data' LINE_DATA: '1,2,3(4)']

My regex is below /^(?<KEY>CONF|ESD|TRACKING)[:;'\s]\s*(?<DATA>.*?)\s*(?:L[:;'\s]\s*\K(?<LINE_DATA>[\d\s,\(\)]+?))?\s*(?<INITIALS>\*[a-zA-Z]+)?\s*\K$/i

https://regex101.com/r/Sw8UXC/1 is an interactive playground with the regex.

What I'm looking for in review

1. Are there any flaws with this regex and are there foreseeable issues where it would fail with what I need?
2. Is there a way to simplify it further?
3. Any other assumptions I should be making because this comes from user-input?

I'm a little unsure of the '\Ks, but it made it so that I only got the 4 parts I needed (i.e. no whitespace in between groups was also matched on (regardless of being captured)

Answer 1

I've gone back to the drawing board with your pattern.

1. I personally never use named capture groups in PHP because they only bloat the pattern and the output array. If you need named keys, just assign them from the matches array.

2. When using pattern modifier i, you don't need to list upper and lower case letters in your character class.

3. There is no benefit to your pattern by inserting \K to restart the fullstring match -- just omit those.

4. Use non-capturing groups and the zero or one quantifier to make subsequent capture groups optional.

5. Instead of using .*? to lazily match the LINE data, match non-whitespace characters delimited by one or more whitespaces -- this will improve pattern performance by reducing the amount of backtracking that is necessary.

6. Instead of loosely validating a predictable LINE_DATA substring pattern with [\d\s,\(\)]+?, explicitly validate each delimited segment of that group. This improves the validation strength of your pattern.

7. Admittedly, my linebreaks, subpattern tabbing, and inline commenting is excessively long and wide -- certainly violating PSR-12 guidelines. This is a sacrifice that I am making to explain in great detail how the pattern works. Few development teams are 100% comprised of regex gurus, so it is important that you aim to inform the weakest regex user who might read your script. I often include a link to a regex101.com demo with a battery of test cases in my professional projects because I want my team to be very sure about how it works and how extensively it was tested.

Working Code (Demo) Regex101 Demo

$regex = <<<REGEX
~
^                                  # start of string anchor
(CONF|ESD|TRACKING)                # start capture group 1 KEY, three literal words
(?:                                # start non-capturing group 1
  \h*[:;'\h]\h*                    # require a listed punctuation or space with optional leading or trailing spaces 
  (\S+(?:\h+\S+)*?)                # start capture group 2 LINE, require one or more non-whitespace characters then lazily match zero or more repetitions of whitespace then non-whitespace substrings
  (?:                              # start non-capturing group 2
    \h*L\h*[:;'\h]\h*              # require literal L then a listed punctuation or space with optional leading or trailing spaces
    (                              # start capture group 3 LINE_DATA
      (?:\d+(?:\(\d+\))?)          # require a number optionally followed by another number in parentheses
      (?:\h*,\h*\d+(?:\(\d+\))?)*  # optionally match zero or more repetitions of the previous expression if separated by an optionally space-padded comma
    )                              # end capture group 3 and make it optional
  )?                               # end non-capturing group 2
  (?:                              # start non-capturing group 3
    \h*                            # match zero or more whitespaces
    (                              # start capture group 4 INITIALS
      \*[.a-z]+                    # match literal asterisk, then one or more dots and letters
    )                              # end capture group 4
  )?                               # end non-capturing group 3 and make it optional
)?                                 # end non-capturing group 2 and make it optional
\h*                                # allow trailing whitespaces 
$                                  # end of string anchor
~ix
REGEX;

$tests = [
    "esd  hedf L:1,2,3   *sm   ",
    "CONF: FEDEX 12345 L: 12(2),2(9),32 *SM",
    "Tracking *cool",
    "ESD: 12/12/92 L: ",
    "tRacking' my data L: 1,2,3(4) ",
    "conf something *asterisk",
    "tracking",
    "ConF''' something '' L: 6",
    "esd test 24(7)",
];

foreach ($tests as $i => $test) {
    if (preg_match($regex, $test, $m, PREG_UNMATCHED_AS_NULL)) {
        var_export([
            "test index" => $i,
            "KEY" => $m[1],
            "LINE" => $m[2] ?? null,
            "LINE_DATA" => $m[3] ?? null,
            "INITIALS" => $m[4] ?? null
        ]);
        echo "\n";
    }
}

Output:

array (
  'test index' => 0,
  'KEY' => 'esd',
  'LINE' => 'hedf',
  'LINE_DATA' => '1,2,3',
  'INITIALS' => '*sm',
)
array (
  'test index' => 1,
  'KEY' => 'CONF',
  'LINE' => 'FEDEX 12345',
  'LINE_DATA' => '12(2),2(9),32',
  'INITIALS' => '*SM',
)
array (
  'test index' => 2,
  'KEY' => 'Tracking',
  'LINE' => '*cool',
  'LINE_DATA' => NULL,
  'INITIALS' => NULL,
)
array (
  'test index' => 3,
  'KEY' => 'ESD',
  'LINE' => '12/12/92 L:',
  'LINE_DATA' => NULL,
  'INITIALS' => NULL,
)
array (
  'test index' => 4,
  'KEY' => 'tRacking',
  'LINE' => 'my data',
  'LINE_DATA' => '1,2,3(4)',
  'INITIALS' => NULL,
)
array (
  'test index' => 5,
  'KEY' => 'conf',
  'LINE' => 'something',
  'LINE_DATA' => NULL,
  'INITIALS' => '*asterisk',
)
array (
  'test index' => 6,
  'KEY' => 'tracking',
  'LINE' => NULL,
  'LINE_DATA' => NULL,
  'INITIALS' => NULL,
)
array (
  'test index' => 7,
  'KEY' => 'ConF',
  'LINE' => '\'\' something \'\'',
  'LINE_DATA' => '6',
  'INITIALS' => NULL,
)
array (
  'test index' => 8,
  'KEY' => 'esd',
  'LINE' => 'test 24(7)',
  'LINE_DATA' => NULL,
  'INITIALS' => NULL,
)

Answer 2

Are there any flaws with this regex and are there foreseeable issues where it would fail with what I need?

Should the INITIALS have a minimum or maximum number of characters, e.g. 2-3? or more? Also, while it likely doesn't happen very often, a person could include a digit in their initials - e.g. RG3 - A.K.A. Robert Griffin III

Is there a way to simplify it further?

(?<INITIALS>\*[a-zA-Z]+)

Because the /i modifier is used, this can be simplified to:

 (?<INITIALS>\*[a-z]+)

This is demonstrated in this playground example.

Answer 3

The biggest change I see as necessary here: your regex is complex enough to effectively be a "subroutine unto itself", and as such needs better whitespace for legibility. Replace your /i with /ix and add ?# comments to be able to write

^
(?<KEY>CONF|ESD|TRACKING)
[:;'\s]\s*
(?<DATA>.*?)
\s*
(?:
    L[:;'\s]\s*\K
    (?<LINE_DATA>[\d\s,\(\)]+?)
)?
\s*
(?<INITIALS>\*[a-zA-Z]+)?
\s*\K
$

I've not shown inline comments above because your playground doesn't support them, but PHP should.