replace string pattern in HTML text with PHP

Question

For my customer I wrote a custom web-based WYSIWYG HTML editor. It allows them to format basic HTML text and insert images. When they insert images I insert them with pattern like ##image1##. The produced HTML can be something like this:

<p>some text and some more text</p>
<p>some text and some <b>bold text</b></p>
<div>##image1##</div>
<p>more text can follow here</p>
<div>##image2##</div>

When outing this HTML I am searching trough it and replacing occurrences for images and replacing ##image1##, ##image2## and so on with HTML markup that actually display images. My replace code is here:

// first find all occurrences of image string
preg_match_all('|##(.+)##|', $inputHTML, $matches);

for every match in $inputHTML
    $output = preg_replace('|##(.+)##|', $imageHTML, $inputHTML, 1 );

This will work mot of the times, but in some variations of input HTML will parse strange result. One of the HTML that produces strange result is:

<div>##image1##</div><p class="align-justify"><strong>Peter Dekleva</strong>, <strong>Damir Lisica</strong>, <strong>Anej Kočevar</strong> in <strong>Gregor Jakac</strong> so glasbeniki, ki v svoji glasbi združujejo silovite  instrumentalne vložke, markantne melodije in močna besedila.</p><div>##image2##</div><p class="align-justify">Video dvojček skladbe Brez strahu torej prikazuje oblico sproščenih trenutkov iz zaodrja, veličasnih posnetkov s koncertnega dogajanja, priprav na nastope, nepredvidljive zaključke noči.</p>

If I edit that HTML and add a line brake before <div>##image2##</div> then it will parse it OK. Any idea what is happening here and why I have problems?

I am also opened to suggestions for a better way of doing this. I can insert something else instead ##image1## when inserting image in my WYSIWYG editor... Thanks

because of the nature of the hole app... hard to explain but it's a reason why is not done in that way! — Primoz Rome
– Primoz Rome, Commented Mar 6, 2012 at 19:16
@DamienPirsy in the previous question I asked how to find matches and the answers were correct. That solution has evolved since and I decided to ask new Quesiton — Primoz Rome
– Primoz Rome, Commented Mar 6, 2012 at 19:18

Community · Accepted Answer · 2017-05-23 10:24:24Z

1

This is because the + modifier is greedy. So it will match everything until the last instance of ##. Try adding a ? after the + to change it to ungreedy.

|##(.+?)##|

The reason that a line break fixes the problem is because by default the . doesn't match line breaks. however if you had done instead: |##(.+)##|s the line break wouldn't have fixed the problem.

Edit I just noticed that churk's answer to your previous question would have also worked correctly.

edited May 23, 2017 at 10:24

CommunityBot

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answered Mar 6, 2012 at 19:14

Jacob Eggers

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2 Comments

Primoz Rome Over a year ago

the ? did solve the problem in this case! thank you very much. Hope this will be the final solution for this, though I see when this kind of parsing can also fail... Someone putting ## somewhere inside HTML text...

Jacob Eggers Over a year ago

@Primoz yep that would be a problem, but you could always do something like: /\{\{#([\s\S]+?)\}\}/ for {{#image1}}. It would be pretty unlikely for someone to use {{# in the html.

Aprillion · Accepted Answer · 2012-03-06 19:25:51Z

0

you should create <img/> directly - but anyway, if you don't use # for your image names, use ^# instead of .

also if you are not sure that ## won't be used in other HTML, test for <div> too

<div>##(^#+)##</div>

answered Mar 6, 2012 at 19:25

Aprillion

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1 Comment

Primoz Rome Over a year ago

inserting directly image in WYSIWYG editor brings all sorts of problems, from formatting issues and so on... if you used any of the WYSIWYG editors you should know that. And if there are several parameters you can bind to the inserted image, then this problem gets obvious even more. That's why I decided to go this way. Works perfectly, just needed to solve this issue I'm having!

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