ActionScript HTML Regexp Selector

Question

I am really bad when it comes to using regexp, so please bear with me on this one.

I have piece of ActionScript code which is supposed to evaluate a string of HTML and break it up into individual pieces. So a string like HiHi<a href="index.php">Hi</a> would be translated into:

1. <p>Hi</p>
2. <span>Hi</span>
3. <a href="index.php">Hi</a>
...

However, when I run a test version of this code, I get a value of null in return. I'm pretty sure my regexp string is good, but I'm doing something wrong in ActionScript. Could you please point in the right direction? My code is below:

var evaluatedInput:RegExp = new RegExp('/<([A-Z][A-Z0-9]*)\b[^>]*>(.*?)</\1>/');
var output:Object = evaluatedInput.exec("<p>Hi</p><span>Hi</span><a href=\"index.php\">Hi</a>");
trace(output);

Thank you for your time,
spryno724

Alan Moore · Accepted Answer · 2011-04-26 03:19:14Z

1

In ActionScript you're supposed to create a RegExp object one of two ways. You can enclose the expression in /.../ delimiters to form a regex literal:

/<([A-Z][A-Z0-9]*)\b[^>]*>(.*?)<\/\1>/gi

...or you can write it as a string literal, which you pass to the the RegExp constructor:

new RegExp('<([A-Z][A-Z0-9]*)\\b[^>]*>(.*?)</\\1>', 'gi')

You seem to be using an amalgam of the two methods and getting garbage as a result. Some other points of interest:

Because regex literals use forward-slash as the delimiter, any / in the regex itself needs to be escaped with a backslash, e.g., <\/\1>
In the string version it's the backslash you have to escape (e.g., </\\1>). Otherwise the AS compiler tries to treat it as part a string-literal escape sequence like \" or \n. In your code, the \b represents a backspace, not a word boundary, and \1 is probably treated as a syntax error, not a back-reference as you intended.
Your regex needs both the g ("global") and i ("ignore-case") modifiers; I've demonstrated how to apply them.

edited Apr 26, 2011 at 3:19

answered Apr 26, 2011 at 3:10

Alan Moore

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2 Comments

Oliver Spryn Over a year ago

Wow, thanks Alan. I'm getting closer, but, due to my poor regexp understanding, I'm not quite there. Using your regexp selector, I'm getting the following output Hi,p,Hi. It is possible to get only Hi!,Hi,<a href="index.php">Hi</a> and not just the tag or tag contents?

Oliver Spryn Over a year ago

Never mind, I got it! Thanks for fixing the regexp and for the good explanation!

Community · Accepted Answer · 2017-05-23 11:51:35Z

1

Example Usage

Adapted from here
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/RegExp.html#exec()

     var myPattern:RegExp = /\>\</g;  
     var str:String = "<p>Hi</p><span>Hi</span><a href=\"index.php\">Hi</a>";
     var result:Object = myPattern.exec(str);

     //To loop through all results manually
     while (result != null) {             
         trace ( result.index, "\t", result);            
         result = myPattern.exec(str);
     }

     //or, just replace. Note this does not required the myPattern.exec(str);
     str.replace(myPattern, ">\n<");

Original Answer

See this answer:

AS3 RegEx returns null

At the very least, the tool from gSkinner should be a solution to your issue(s).

Specifically, to do what you want to do, you would use the following regex expression:

/\>\</g

And on your matches, use the index value, and replace with:

>\n<

You can test this yourself on the gskinner Regexr tool using the Replace tab.

edited May 23, 2017 at 11:51

CommunityBot

11 silver badge

answered Apr 26, 2011 at 1:57

user562566

6 Comments

Oliver Spryn Over a year ago

Thank your for your help, but my regexp skills are so poor right now that I am having a hard time following you. Could you post a corrected version of the ActionScript regexp selector I posted above?

Oliver Spryn Over a year ago

Hmm... thanks for the update, but I tried your example and it didn't return anything. :(

user562566 Over a year ago

Sorry wasn't done. Fully updated, should work fine. I've tested, works as expected.

Alan Moore Over a year ago

< and > have no special meaning in AS3 regexes (or in most other flavors, either). But in some flavors, \< and \> do have special meanings (i.e., word boundaries), so it's best not to escape them.

user562566 Over a year ago

Thanks Alan, you're right... although escaping them doesn't hurt either. :)

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