Match all lines prefixed with four spaces

Question

I'm trying to wrap all lines that are prefixed with 4 space chars with pre tags. This is what I have so far

Text = Text.replace(new RegExp("( {4}.+?)<br />", "g"), "$1\n");
Text = Text.replace(new RegExp("( {4}.+?)\n", "g"), "<pre class=\"brush: js;\">$1</pre>");

It works but it wraps every line in a pre. I need it to wrap the whole block.

Answer 1

Maybe something like this would work? It matches multiple lines in a row..

( {4}.*(\n {4}.*)*)\n

Answer 2

Do you really need to do this with regular expressions? Regexes are cool and useful but they're not the only tool in your toolbox and sometimes it is best to do something straight forward and move on to real problems. I'd just bust it into lines and parse it line-by-line with an accumulator for the things that need to be pre-ified:

var lines = text.split('\n');
var pre   = [ ];
var out   = [ ];
for(var i = 0; i < lines.length; ++i) {
    if(lines[i].match(/^    /)) {
        pre.push(lines[i]);
    }
    else if(pre.length > 0) {
        out.push('<pre>' + pre.join('\n') + '</pre>' + '\n');
        out.push(lines[i]);
        pre = [ ];
    }
    else {
        out.push(lines[i]);
    }
}
if(pre.length > 0) {
    out.push('<pre>' + pre.join('\n') + '</pre>' + '\n');
}
text = out.join('\n');

That may not be as clever as an incomprehensible regex but at least you'll be able to understand what it is doing six months down the road.

http://jsfiddle.net/ambiguous/tFNyv/

Answer 3

Please try:

Text = Text.replace(new RegExp("(( {4}.+?\n)+)", "g"), "<pre class=\"brush: js;\">$1</pre>");

Assuming the
replacement has already been done.

It worked for:

    lalalal
    noway it's block1
    greetings

    foobar
    block2
    indeed block2

And produced, line breaks are hidden :

<pre class="brush: js;">    lalalal
    noway it's block1
    greetings
</pre>
<pre class="brush: js;">    foobar
    block2
    indeed block2
</pre>