Regex - Ignore some parts of string in match

Question

Here's my string:

address='St Marks Church',notes='The North East\'s premier...'

The regex I'm using to grab the various parts using match_all is

'/(address|notes)='(.+?)'/i'

The results are:

address => St Marks Church
notes => The North East\

How can I get it to ignore the \' character for the notes?

Answer 1

Because you have posted that you are using match_all and the top tags in your profile are php and wordpress, I think it is fair to assume you are using preg_match_all() with php.

The following patterns will match the substrings required to buildyour desired associative array:

Patterns that generate a fullstring match and 1 capture group:

1. /(address|notes)='\K(?:\\\'|[^'])*/ (166 steps, demo link)
   
2. /(address|notes)='\K.*?(?=(?<!\\)')/ (218 steps, demo link)

Patterns that generate 2 capture groups:

3. /(address|notes)='((?:\\\'|[^'])*)/ (168 steps, demo link)
   
4. /(address|notes)='(.*?(?<!\\))'/ (209 steps, demo link)

Code: (Demo)

$string = "address='St Marks Church',notes='The North East\'s premier...'";

preg_match_all(
    "/(address|notes)='\K(?:\\\'|[^'])*/",
    $string,
    $out
);
var_export(array_combine($out[1], $out[0]));

echo "\n---\n";

preg_match_all(
    "/(address|notes)='((?:\\\'|[^'])*)/",
    $string,
    $out,
    PREG_SET_ORDER
);
var_export(array_column($out, 2, 1));

Output:

array (
  'address' => 'St Marks Church',
  'notes' => 'The North East\\\'s premier...',
)
---
array (
  'address' => 'St Marks Church',
  'notes' => 'The North East\\\'s premier...',
)

Patterns #1 and #3 use alternatives to allow non-apostrophe characters or apostrophes not preceded by a backslash.

Patterns #2 and #4 (will require an additional backslash when implemented with php demo) use lookarounds to ensure that apostrophes preceded by a backslash don't end the match.

Some notes:

• Using capture groups, alternatives, and lookarounds often costs pattern efficiency. Limiting the use of these components often improves performance. Using negated character classes with greedy quantifiers often improves performance.

• Using \K (which restarts the fullstring match) is useful when trying to reduce capture groups and it reduces the size of the output array.