Regex to create html from custom code

Question

I have a field of text where users can write specific command to get some html.

For example:

Text Text Text Text

[*] first entry
[*] second entry
[*] 3rd...

Text Text

This text should be converted with regex to something like this:

text text

<ol>
 <li>FirstEntry</li>
 <li>Second</li>
 ..
</ol>

text text

Any suggestion?

The regex that matches the line with entry is something like this:

/\[\*\].+/i

The problem is how to insert correctly the <ol> and </ol>

My solution

I was thinking I could parse all line of text and when the parser encouter the first line that starts with [*] then put an <ol> Same thing for the </ol>

Until now I have made the script that converst single [*] ... to <li> ...

http://codepad.org/yzRVupON

preg_replace('/\[\*\](.+)/i','<li>$1</li>',$str);

I need the <ol> part

My implementation

http://codepad.org/NNgC6uko

You want to take a look at phps regex function `preg_replace_callback()`. — arkascha, Nov 10 '12 at 14:56
Thanks for the input.. but I knew that function and I Don't see how I could use that — , Nov 10 '12 at 14:58
Why, you use a regex to match the patterns `[*] first entry` and so on and for each such match the callback function you implement is called. Inside that function you can output whatever markup you want, for example `
That's not the question :). The question is more like how to insert correctly
and — , Nov 10 '12 at 15:00
Well, maybe by doing the same using another regex pattern? Though that is even easier, you don't need a callback but can use the plain `preg_replace()` function. — arkascha, Nov 10 '12 at 15:02
Sorry, no, I won't make your homework :-) You claim you know how to use the functions, so use them. Post what you have so far, your attempts and say what specific part it is you cannot get to work the way you want to. Please understand that this is not a forum to get free labor. — arkascha, Nov 10 '12 at 15:04
@arkascha: that's not an homework. It is a suggestiong how to proceed. I have made the simple script that converts that with

score 2 · Accepted Answer · edited May 23 '17 at 12:15

2

Doing this kind of parsing with regular expressions is probably not the way to go; it might be OK for very simple scenarios but the more features you try to put in the harder it will get -- until the point where it becomes unmaintainable.

I would suggest borrowing parsing techniques from e.g. various MarkDown parsers out there; see these questions for more information (there are others too).

Back to the original question: if you are constrained to only using regular expressions you could try matching the whole "list block" first with something like

/^(\s*\[\*\].*?$)+/m

(the multiline mode modifier is essential)

You can then produce the output by breaking the matched text down into individual list items with your current regex and then surrounding the result with <ol></ol>.

edited May 23 '17 at 12:15

Community

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answered Nov 10 '12 at 15:07

Jon

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What About if i put every line into an array... Then I parse the whole array and when I see there is the first line starting with [*] i insert an `
– dynamic Nov 10 '12 at 15:14
That's the description of a very simple parser, so it's a step in the right direction. But check out existing code first, there's no sense in writing your own if you can adapt something that' been tested. – Jon Nov 10 '12 at 15:18
that's the problem of reinventing the wheel. But I don't need al the features of markdown or other parser... – dynamic Nov 10 '12 at 15:21

Anirudh Ramanathan · Answer 2 · 2012-11-10T16:22:08.550

1

Why not use preg_replace to put tags on either side? Something like the below perhaps.

$string = <<<EOF
Text Text Text Text

[*] first entry
[*] second entry
[*] 3rd...

Text Text
EOF;

$pattern = '/(\[\*\])([\d\D]+)(\[\*\].*)/';
$replacement = '<ol> ${1}${2}${3} </ol>';
$string = preg_replace($pattern, $replacement, $string);

$pattern = '/\[\*\](.+)/i';
$replacement = '<li>${1}</li>';

echo  preg_replace($pattern, $replacement, $string);

Output:

Text Text Text Text

    <ol>
        <li> first entry </li>
        <li> second entry </li>
        <li> tag 3rd... </li>
    </ol>

Text Text

edited Nov 10 '12 at 16:22

answered Nov 10 '12 at 15:06

Anirudh Ramanathan

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@m.buettner Oh. Will look for a cooler regex. Thanks for pointing that out. – Anirudh Ramanathan Nov 10 '12 at 15:34
1

check my answer... i have made a little script – dynamic Nov 10 '12 at 15:44
1

@yes123 cool. I'm still going to try to write purely `preg_match` solution. (for the fun of it) ;) – Anirudh Ramanathan Nov 10 '12 at 15:46
@yes123's script is much better though, easily extensible, to a more generic solution. I agree. – Anirudh Ramanathan Nov 10 '12 at 16:24

score 1 · Answer 3 · answered Nov 10 '12 at 15:42

That's my implementation. Working code: http://codepad.org/NNgC6uko

This scritp is easly customizabile with any sort of translation from a command to HTML

function parseText($txt) {

    $lines = preg_split('/[\r\n]+/',$txt,null,PREG_SPLIT_NO_EMPTY);
    $newLines = array();

    $lastTag = '';
    foreach($lines as $k=>$v) {

        $currentTag = $v[0];

        //$newLine = $v;
        $newLine = preg_replace('/^\* (.+)$/','<li>$1</li>',$v);

        if ($currentTag=='*' && $lastTag != '*')
            $newLines[] = '<ol>';

        else if ( $lastTag == '*' && $currentTag != '*' )
            $newLines[] = '</ol>';  

        $newLines[] = $newLine;



        $lastTag = $currentTag;

    }

    print_r($newLines);
}

This looks good, but use explode() instead of preg_split to get your new lines. It should be faster for a larger string. Regex is an awesome tool, but more expensive to use. http://stackoverflow.com/questions/1483497/how-to-put-string-in-array-split-by-new-line. E.G. $lines = explode("\n", $txt); — Joshua Kaiser, Nov 10 '12 at 15:52
\n is only for linux... windows uses \r\n... also using explode multiple lines will be sperated.. \n\n\n — dynamic, Nov 10 '12 at 18:28

Regex to create html from custom code

My solution

My implementation

3 Answers3