Regex - more compact/elegant form - regex

Question

I would like to write this regex (later simplified form) in a more compact/ elegant/ systematic. PCRE or Python (newer engine) preferred. Shortly, I would like to capture each artery name (iliac, femoral, popliteal and so on), regardless of the string between them . Ideally, the resulted regex won't depend on any kind of regex flavor.
LE2: Even more simplified regex, but not working correctly: https://www.regex101.com/r/cK5wB6/7. I've eliminated DEFINE section - this was added only for modularity purposes, and DEFINE is not compatible with Python anyway (newer, v1 engine added this feature). I want capture all the artery names, equivalent of getting a vector of all artery names, regardless of number of names, or strings between them.
(arteries:.{0,25}?)
((?<art>iliac|femoral|popliteal|peroneal|tibial).*?)*
(?<artfinal>(?&art))
The problem is that some arteries are still not recognized correctly (at least visually). I'm trying to capture those names, without explicitly write capturing groups like in this.
LE4: The last variant actually ignore all names, aside the 1st and the last two.

Answer 1

First, regex flavour independent pattern is a myth. Regex engines are different, have different features, and even a same pattern that only uses common tokens between two or more regex engines can return different results.
An example with the Python regex module that has interesting features like the ability to use a set (\L<arteries> in the pattern) and the ability to store repeated capture groups:
import regex
s = '''arteries: jhjh iliac jdfd femoral
arteries: sdsdsd iliac jdfd femoral fd d popliteal
arteries: hgv popliteal,sddsdsds iliac tibial nkjkknperoneal nkjkkn
arteries: iliac, peroneal jm tibia nktibial nkjkkn
arteries: m bkjkjnperoneal vc peroneal fdfd femoral n tibial jnmmmmm tibial jnnjnjmbn n iliacbjk
arteries:m bkjnkjnperoneal mm femoral jnnbn n right femoralbjkkbb jk'''
arteries_set = ['femoral', 'iliac', 'peroneal', 'tibial']
p = regex.compile(r'^arteries: (?: [^\w\n]* (?>\w+[^\w\n]+)*? (\L<arteries>) \M)+', regex.M | regex.I | regex.X, arteries=arteries_set)
for m in p.finditer(s):
print(m.captures(1))
I voluntary removed the "less than 25 characters" condition to build a more efficient pattern, but feel free to replace [^\w\n]* (?>\w+[^\w\n]+)*? with .{0,25}? \m
(\m and \M are word boundaries, respectively for the start and the end of a word)

Answer 2

I want capture all the artery names,
The problem is that some arteries are still not recognized correctly (at least visually)
The problem with this regex:
((?<art>iliac|femoral|popliteal|peroneal|tibial).*?)*
is that the group art continuously overwrites its capture with the last match. This is an expected behaviour by design.
I want to recognize all the arteries given in the list (see definition
of ) The same artery could appear 1...n to and in any position.
The strings between artery names could be anything of max. 25 chars.
As of flavors, let's stick with PCRE
Provided you're working with PCRE, instead of matching all occurences of arteries at once, I would suggest matching 1 artery at a time. And to achieve that, we can use \G to match at the end of last match.
Regex:
/\G # Match anchor (BoS or EoLastMatch)
(?:
(?!^) # With previous match
|
.*? # Or first occurence
arteries: # of arteries:
)
.{1,25}? # Separated by max 25 chars
(?P<art> # Group 1 (capture 1 artery)
\b # List of arteries
(?:iliac|femoral|popliteal|peroneal|tibial)
\b # in between word boundaries
# Modif: global, caseless, singleline, extra
)/gixs
This will capture each artery in group art (group 1).
DEMO
Notes about other flavours:
As for compatibility with other regex flavours, you could loop each match in your code to simulate \G (which is not implemented in almost any other flavour). Another option is to split the text with the expression:
(arteries:|\b(?:iliac|femoral|popliteal|peroneal|tibial)\b)
and then check the length of each token to guarantee there isn't more than 25 chars in between.
the code will have to be migrated to Python one (not so distant) day
Update: Migrating to Python:
You can use \G in Python since the regex module implemented it, but if you do use that module, take advantage if its ability to retrieve repeated captures from a group with the .captures method. Check #CasimiretHippolyte's answer, a perfect example of using captures in this case.
On the other hand, if you stick to the standard re module, I'd recommend looping each match to simulate the same behaviour.
Code:
import re
text = '''arteries: jhjh iliac jdfd femoral
arteries: sdsdsd iliac jdfd femoral fd d popliteal
some arteries: hgv popliteal,sddsdsds iliac tibial nkjkknperoneal nkjkkn
arteries: iliac, peroneal jm tibia nktibial nkjkkn
arteries: m bkjkjnperoneal vc peroneal fdfd femoral n tibial jnmmmmm tibial jnnjnjmbn n iliacbjk
arteries:m bkjnkjnperoneal mm femoral jnnbn n right femoralbjkkbb jk'''
n = 0
pattern_from = re.compile( r'arteries:', re.I)
pattern_token = re.compile( r'.{1,25}?\b(iliac|femoral|popliteal|peroneal|tibial)\b', re.I)
for match_from in pattern_from.finditer(text):
n = n + 1
print( '\nMatch #%s:' % n, end="")
match_token = pattern_token.match( text, match_from.end())
while match_token:
print( '[%s:%s]="%s" ' % (match_token.start(1), match_token.end(1), match_token.group(1)), end="")
match_token = pattern_token.match( text, match_token.end())
Output:
Match #1:[15:20]="iliac" [26:33]="femoral"
Match #2:[52:57]="iliac" [63:70]="femoral" [76:85]="popliteal"
Match #3:[106:115]="popliteal" [125:130]="iliac" [132:138]="tibial"
Match #4:[171:176]="iliac" [179:187]="peroneal"
Match #5:[243:251]="peroneal" [257:264]="femoral" [267:273]="tibial" [282:288]="tibial"
Match #6:[344:351]="femoral"
ideone DEMO