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For some reason I have to have one HTML tag per line. So if the following is the input:

<p><div class="class1 <%= "class3" %>class2">div content</div></p>

Output should be:

<p>
<div class="class1 <%= "class3" %>class2">div content
</div>
</p>

The regular expression should be able to recognize the difference between the erb script tag and HTML tag. Indentation is not needed.

How can this be done through regular expression?

intellidiot
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    See: http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags – Paul Rosania Jun 30 '11 at 05:46
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    Regex is the wrong tool for this, and your sample code is the perfect illustration of that. Your example will break nearly any sane regex, and it will get more complex as you go along. Use a parser instead. – Justin Morgan - On strike Jun 30 '11 at 06:01
  • I am convinced by the suggestion given by both @Paul and @Justin. Regex is not a perfect fit for this type of jobs. I'm taking @Kobi's answer as correct, because it serves a solution for the example provided. – intellidiot Jun 30 '11 at 06:12

2 Answers2

3

You can replace (?=<[\w/]) with \n. This is a lookahed that matched the position before a < sign, the is followed by a letter or a slash. (another option is (?=<(?!%))).

This works for your posted code, but fails on quite a few scenarios, notionally < in attributes, or < in server-side scripts and JavaScript blocks. If you need anything more complex, you may need a stronger solution, like an erb parser.

Kobi
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replace "(?<!%)>\s*<(?=!%))" with ">\n<" and replace "(?<!(\s|^))</" with "\n</"

this makes sure that % is not found either before or after >whitespace<. then always break on </

i think kobi's answer is better :)

Bohemian
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