How to do preg_replace that only matches particular conditions? - php

Question

I am struggling to write a preg_replace command that achieves what I need.
Essentially I have the following array (all the items follow one of these four patterns):
$array = array('Dogs/Cats', 'Dogs/Cats/Mice', 'ANIMALS/SPECIES Dogs/Cats/Mice', '(Animals/Species) Dogs/Cats/Mice' );
I need to be able to get the following result:
Dogs/Cats = Dogs or Cats
Dogs/Cats/Mice = Dogs or Cats or Mice
ANIMALS/SPECIES Dogs/Cats/Mice = ANIMALS/SPECIES Dogs or Cats or Mice
(Animals/Species) Dogs/Cats/Mice = (Animals/Species) Dogs or Cats or Mice
So basically replace slashes in anything that isn't capital letters or brackets.
I am starting to grasp it but still need some guidance:
preg_replace('/(\(.*\)|[A-Z]\W[A-Z])[\W\s\/]/', '$1 or', $array);
As you can see this recognises the first patterns but I don't know where to go from there
Thanks!

Answer 1

You might use the \G anchors to assert the position at the previous match and use \K to forget what was matched to match only a /.
You could optionally match ANIMALS/SPECIES or (Animals/Species) at the start.
(?:^(?:\(\w+/\w+\)\h+|[A-Z]+/[A-Z]+\h+)?|\G(?!^))\w+\K/
Explanation
(?: Non capturing group
^ Assert start of string
(?: Non capturing group, match either
\(\w+/\w+\)\h+ Match between (....) 1+ word chars with a / between ending with 1+ horizontal whitespace chars
| Or
[A-Z]+/[A-Z]+\h+ Match 1+ times [A-Z], / and again 1+ times [A-Z]
)? Close non capturing group and make it optional
| Or
\G(?!^) Assert position at the previous match
)\w+ Close non capturing group and match 1+ times a word char
\K/ Forget what was matched, and match a /
Regex demo | Php demo
In the replacement use a space, or and a space
For example
$array = array('Dogs/Cats', 'Dogs/Cats/Mice', 'ANIMALS/SPECIES Dogs/Cats/Mice', '(Animals/Species) Dogs/Cats/Mice');
$re = '~(?:^(?:\(\w+/\w+\)\h+|[A-Z]+/[A-Z]+\h+)?|\G(?!^))\w+\K/~';
$array = preg_replace($re, " or ", $array);
print_r($array);
Result:
Array
(
[0] => Dogs or Cats
[1] => Dogs or Cats or Mice
[2] => ANIMALS/SPECIES Dogs or Cats or Mice
[3] => (Animals/Species) Dogs or Cats or Mice
)

Answer 2

The way you present your problem with your example strings, doing:
$result = preg_replace('~(?:\S+ )?[^/]*+\K.~', ' or ', $array);
looks enough. In other words, you only have to check if there's a space somewhere to consume the beginning of the string until it and to discard it from the match result using \K.
But to avoid future disappointments, it is sometimes useful to put yourself in the shoes of the Devil to consider more complex cases and ask embarrassing questions:
What if a category, a subcategory or an item contains a space?
~
(?:^
(?:
\( [^)]* \)
|
\p{Lu}+ (?> [ ] \p{Lu}+ \b )*
(?> / \p{Lu}+ (?> [ ] \p{Lu}+ \b )* )*
)
[ ]
)?
[^/]*+ \K .
~xu
demo
In the same way, to deal with hyphens, single quotes or whatever, you can replace [ ] with [^\pL/] (a class that excludes letters and the slash) or something more specific.