Question

I am stuck working on a function that translates HTML to bbcode.
I have written my own [spoiler] bbcode tag which translates properly into the HTML equivalent.

But when I try to turn it back into bbcode it doesn’t seem to match seemingly identical strings…

After slowly rebuilding it piece by piece to see where the problem is, it turns out that it only fails when I add onclick="showSpoiler(this)"

to

#<div><input type="button" onclick="showSpoiler(this)"/><div>(.*)</div></div>#ig'

I narrowed it further down to the ( brackets. I have tried to escape them like this \(

the html code that is generated from the [spoiler] tag is:

`$1

and the string that it is matched against is this

'#<div><input type="button" onclick="showSpoiler(this)"/><div>(.*)</div></div>#ig'

here are the conversion functions

<?php
//This function let convert BBcode to HTML
function bbcode_to_html($text)
{
    $text = nl2br(htmlentities($text, ENT_QUOTES, 'UTF-8'));
    $in = array(
            '#\[b\](.*)\[/b\]#Usi',
            '#\[i\](.*)\[/i\]#Usi',
            '#\[u\](.*)\[/u\]#Usi',
            '#\[s\](.*)\[/s\]#Usi',
            '#\[img\](.*)\[/img\]#Usi',
            '#\[url\]((ht|f)tps?\:\/\/(.*))\[/url\]#Usi',
            '#\[url=((ht|f)tps?\:\/\/(.*))\](.*)\[/url\]#Usi',
            '#\[left\](.*)\[/left\]#Usi',
            '#\[center\](.*)\[/center\]#Usi',
            '#\[right\](.*)\[/right\]#Usi',
            '#\[spoiler\](.*)\[/spoiler\]#Usi',
            '#\[fuck\](.*)\[/fuck\]#Usi'
        );
    $out = array(
            '<strong>$1</strong>',
            '<em>$1</em>',
            '<span style="text-decoration:underline;">$1</span>',
            '<span style="text-decoration:line-through;">$1</span>',
            '<img src="$1" alt="Image" />',
            '<a href="$1">$1</a>',
            '<a href="$1">$4</a>',
            '<div style="text-align:left;">$1</div>',
            '<div style="text-align:center;">$1</div>',
            '<div style="text-align:right;">$1</div>',
            '<div><input type="button" onclick="showSpoiler(this)" value="Show/Hide" /><div class="inner" style="display:none;">$1</div></div>',
            '<div><input type="button" onclick="showSpoiler(this)"/><div>$1</div></div>'
        );
    $count = count($in)-1;
    for($i=0;$i<=$count;$i++)
    {
        $text = preg_replace($in[$i],$out[$i],$text);
    }
    return $text;
}
//This function let convert HTML to BBcode
function html_to_bbcode($text)
{
    $text = str_replace('<br />','',$text);
    $in = array(
        '#<strong>(.*)</strong>#Usi',
        '#<em>(.*)</em>#Usi',
        '#<span style="text-decoration:underline;">(.*)</span>#Usi',
        '#<span style="text-decoration:line-through;">(.*)</span>#Usi',
        '#<img src="(.*)" alt="Image" />#Usi',
        '#<a href="(.*)">(.*)</a>#Usi',
        '#<div style="text-align:left;">(.*)</div>#Usi',
        '#<div style="text-align:center;">(.*)</div>#Usi',
        '#<div style="text-align:right;">(.*)</div>#Usi',
        '#<div><input type="button" onclick="showSpoiler(this)" value="Show/Hide" /><div class="inner" style="display:none;">(.*)</div></div>#Ui',
        '#<div><input type="button" onclick="showSpoiler(this)"/><div>(.*)</div></div>#ig'
    );
    $out = array(
        '[b]$1[/b]',
        '[i]$1[/i]',
        '[u]$1[/u]',
        '[s]$1[/s]',
        '[img]$1[/img]',
        '[url=$1]$2[/url]',
        '[left]$1[/left]',
        '[center]$1[/center]',
        '[right]$1[/right]',
        '[spoiler]$1[/spoiler]',
        '[fuck]$1[/fuck]'
    );
    $count = count($in)-1;
    for($i=0;$i<=$count;$i++)
    {
        $text = preg_replace($in[$i],$out[$i],$text);
    }
    return $text;
}
?>

Answer 1

In your regex you need to escape the braces like so:

showSpoiler\(this\)

Take care with regular expressions, they are a language on it’s own and hard to debug unless you add more functions that do the debugging (e.g. what was matched, output that etc.).

BTW you can run multiple search and replace operations by directly passing the arrays into the function. You don’t need to iterate over them.

So better read the manual page about preg_replace again and look forward how you can more easily debug your patterns. E.g. test them before putting them into the function and similar.