Problem with Actionscript Regular Expressions

Question

I have to parse out color information from HTML data. The colors can either be RGB colors or file names to a swatch image.

I used http://www.gskinner.com/RegExr/ to develop and test the patterns. I copied the AS regular expression code verbatim from the tool into Flex Builder. But, when I exec the pattern against the string I get a null.

Here are the patterns and an example of the string (I took the correct HTML tags out so the strings would show correctly):

DIV data:

<div style="background-color:rgb(2,2,2);width:10px;height:10px;">

DIV pattern:

/([0-9]{1,3},[0-9]{1,3},[0-9]{1,3})/

IMG data:

<img src="/media/swatches/jerzeesbirch.gif" width="10" height="10" alt="Birch">

IMG pattern:

/[a-z0-9_-]+/[a-z0-9_-]+/[a-z0-9_-]+\.[a-z0-9_-]+/

Here's my Actionscript code:

var divPattern : RegExp = new RegExp("/([0-9]{1,3},[0-9]{1,3},[0-9]{1,3})/");
var imgPattern : RegExp = new RegExp("/[a-z0-9_-]+/[a-z0-9_-]+/[a-z0-9_-]+\.[a-z0-9_-]+/");

var divResult : Array = divPattern.exec(object.swatch);
var imgResult : Array = imgPattern.exec(object.swatch);

Both of the arrays are null.

This is my first foray into AS coding, so I think I'm declaring something wrong.

Steve

I assume you've checked that trace(object.swatch); returns a valid string? — Richard Inglis
– Richard Inglis, Commented Feb 15, 2010 at 13:51

kennytm · Accepted Answer · 2010-02-15 13:30:18Z

(I don't know ActionScript but I know Javascript and they should be close enough to solve your problem.)

To construct a RegExp object for e.g. the pattern ^[a-z]+$, you either use

var pattern : RegExp = new RegExp("^[a-z]+$");

or, better,

var pattern : RegExp = /^[a-z]+$/

The code new RegExp("/^[a-z]+$/") is wrong because this expects a slash before the ^ and after the $.

Therefore, your DIV pattern should be written as

var divPattern : RegExp = /([0-9]{1,3},[0-9]{1,3},[0-9]{1,3})/;

but, as you know, the ( and ) are special characters for capturing, you need to escape them:

var divPattern : RegExp = /\([0-9]{1,3},[0-9]{1,3},[0-9]{1,3}\)/;

For the IMG pattern, as / delimitates a RegEx, you need to escape it as well:

var imgPattern : RegExp = /[a-z0-9_-]+\/[a-z0-9_-]+\/[a-z0-9_-]+\.[a-z0-9_-]+/

Finally, you could use \d in place of [0-9] and \w in place of [a-zA-Z0-9_].

Community · Accepted Answer · 2017-05-23 11:48:42Z

0

I don't know enough to tell if your regex patterns are correct, but from the docs on the AS3 RegExp class, it looks like your new RegExp() call needs a second argument to declare flags for case sensitivity etc.

EDIT: Also, as Bart K has pointed out, you don't need the / delimiters when using the new method.

So you can use either:

var divPattern:RegExp = new RegExp("([0-9]{1,3},[0-9]{1,3},[0-9]{1,3})", "");

OR you can also use the alternate syntax with /:

var divPattern:RegExp = /([0-9]{1,3},[0-9]{1,3},[0-9]{1,3})/;

... in which case the flag string (if any) is included after the final /

edited May 23, 2017 at 11:48

CommunityBot

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answered Feb 15, 2010 at 14:13

Richard Inglis

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4 Comments

Bart Kiers Over a year ago

No, when using new new RegExp(...) no delimiters are needed (see the link you posted).

Richard Inglis Over a year ago

You can omit the () delimiters, but if you DO use them you I think you need to supply a second argument (even if it's an empty string as shown in Adobe's example). And spdaly's code uses the delimiters.

Bart Kiers Over a year ago

No, I was talking about the / delimiters. Instantiating a RegExp is done by doing either var pattern:RegExp = /\w/; or var pattern:RegExp = new RegExp("\w");. The new RegExp(... syntax expects a plain string (without the delimiters!). See: livedocs.adobe.com/flex/3/html/…

Richard Inglis Over a year ago

Aahh - see what you mean now, thanks for pointing that out. I will update my answer.

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