[RESOLVED] Searching a string, then running a function once a result is found?

Immulsifier

I am building a small attachments system and am wanting to search a string for all instances of [attach] and then run a function once this is found. I know I can do something like this:

$str = preg_replace("'\[b\](.*?)\[/b\]'", '<b>\\1</b>', $str);

which will replace text with <b>text</b>, but what I want to happen is when for example is found, i can run a function instead of just replacing text. Can anyone give me any suggestions on how to do this.

Thanks 🙂

jkurrle

Let me see if I have this straight, you have a sample text like below:

"I have a sample attachment in this text. [attach] If you can see it fine."

Where the [attach] is located, you want to run a function name, correct?

why not do a preg_replace() and replace the [attach] with the function name?

jkurrle

example:

$text="I have a sample attachment in this text. [attach] If you can see it fine."
$search[0]="[attach]";
$replace[0]="\" . function_name() . \"";
$newtext=preg_replace($search, $replace, $text);

I added in some quote marks in the replace string, in case you are echoing the text or something.

bradgrafelman

While the above code won't work, it's close:

$pattern = '@\[b\](.*?)\[/b\]@e';
$replace = 'myFunction("$1")';
preg_replace($pattern, $replace, $text);

What the above code snippet will do is match the text inside the [b][/b] brackets, call myFunction() with that text as the parameter, and then replace the matched text with whatever was returned from the function.

Note that the difference is the 'e' modifier on the end of the regexp pattern. You might also want to add 's' and 'i' which, respectively, allow for line breaks to match the "." and make the pattern case-insensitive.

Weedpacket

You could also use [man]preg_replace_callback[/man] which searches for a pattern and runs a function on any matches it finds.

Immulsifier

preg_replace_callback was what I used in the end and it works really well 🙂

jkurrle

Brad, in your example above I have a couple of questions:

1) How does the $1 work in this case? I haven't ever seen a positional variable used in PHP code before. How does the code know that $1 is coming from the search pattern and not from somewhere else?

2) Why do you use single quotes around the replace pattern? Won't the single quotes turn the function into a literal and return the function, instead of the result of the function?

bradgrafelman

Weedpacket: Indeed - the callback function seems more appropriate for this situation.

jkurrle:

1) The $1 works the same way it would in a normal regexp replacement string - it replaces it with the first matched group.

2) The 'e' modifier is essentially telling PHP to evalulate the replacement string as PHP code.

So, to answer both questions at once: the regexp replaces $1 in the replacement string with the first matched subset and then evalulates that string as PHP code - just as if you'd used the [man]eval/man function.

Immulsifier: Don't forget to mark this thread resolved.