PHP code to convert text blocks indented by four spaces into a <pre><code> block [Markdown]

I'm not very good at PHP and would like to have a PHP function which turns this (text block indented by four spaces):

    printf("goodbye world!");  /* his suicide note
                                  was in C */

Into this:

<pre><code>    开发者_JAVA技巧printf("goodbye world!");  /* his suicide note
                              was in C */</code></pre>

Leaving all other lines intact.

This is what Markdown does. I found this PHP port of Markdown (see function doCodeBlocks()), but I don't want to use the entire Markdown file, I just want this one function.

Can someone provide me with the minimal PHP code required to get this to work? So I can do this:

<?php echo markdownPre('Here goes some code:

    var x = 1, y = 2;
    alert(x + y);

That should be a pre block.'); ?>

I have not tried, but I think you can preg_replace the regex

/((?:^(?: {4}|\t).*$\n+)+)/m

with <pre><code>$1</code></pre>.

Although Kenny's expression works, i'd suggest replacing with callback for flexibility:

function markdownPre($in) {
    if(is_array($in)) {
        $code = $in[0];
        // post-process the code, e.g. remove leading spaces
        $code = preg_replace('~^(\x20{4}|\t)~m', '', $code);
        return "<pre>$code</pre>";
    }

    return preg_replace_callback('~(
        ^
        (\x20{4} | \t)
        (.+)
        \n
    )+~mx', __FUNCTION__, $in);
}

In the "post-process" phase you can do interesting things, for example, syntax highlighting.

I don't understand the problem correctly. Do you want something like -

function markdownPre($str){ return '< pre>< code>'.$str.''; }

this will return

<pre><code>    printf("goodbye world!");  /* his suicide note
                              was in C */</code></pre>

if you pass

echo markdownPre('printf("goodbye world!"); /* his suicide note was in C */')

to it.