Programming Forums > Application Development > C#

Master · Jul 18th, 2006, 9:50 PM

I need help matching the follow string with regexp

if(something)
   if(something)
      do_something
   end
end

I want the regexp to match nested ifs not matter what how many levels it is and also match the outer if.
Here is the code i use to match, but it is not matching correctly

(Toggle Plain Text)

(if)(?(if)([\w\W]*?)|([\w\W]*?)\n([\w\W]*?))(end)

btw, i am not master in regexp. Thanks

Dameon · Jul 19th, 2006, 1:35 AM

I'd reccomend Expresso

lectricpharaoh · Jul 19th, 2006, 3:11 AM

You can use a stack data structure. Imagine you have opening tokens ("if") and closing tokens ("end"), as well as miscellaneous tokens (operators, function calls, etc). You then iterate through the stream of tokens, and every time you come upon an opening token, you push it onto the stack. When you encounter a closing token, you peek at the top of the stack, and if there is a corresponding opening token there, you pop it off. If there is not a matching token, you know there is a syntax error (unmatched closing token). Likewise, if you have parsed all tokens, and the stack is not empty, you have an error (unmatched opening token).

This approach lets you define more than one set of tokens. For example, you can use it to match braces, parentheses, and brackets by defining "{", "(", "[", "}", ")", and "]" as opening and closing tokens.

Master · Jul 19th, 2006, 12:12 PM

Thanks for the suggestions

kurifu · Jul 29th, 2006, 11:51 AM

http://www.regexlib.com a great resource

Jul 18th, 2006, 9:50 PM	#1
Master Programmer Join Date: Sep 2005 Location: GA Posts: 99 Rep Power: 4	Regular Expression Patterns I need help matching the follow string with regexp (Toggle Plain Text) if(something) if(something) do_something end end if(something) if(something) do_something end end I want the regexp to match nested ifs not matter what how many levels it is and also match the outer if. Here is the code i use to match, but it is not matching correctly (Toggle Plain Text) (if)(?(if)([\w\W]?)\|([\w\W]?)\n([\w\W]?))(end) (if)(?(if)([\w\W]?)\|([\w\W]?)\n([\w\W]?))(end) btw, i am not master in regexp. Thanks

Jul 19th, 2006, 1:35 AM	#2
Dameon Troll Join Date: Apr 2005 Location: Texas Posts: 732 Rep Power: 4	I'd reccomend Expresso __________________ MD5(sig) = bcef75433db02e9ad9bf81d6f7c5c270

Jul 19th, 2006, 3:11 AM	#3
lectricpharaoh SEXY SHOELESS GOD OF WAR! Join Date: Jun 2005 Location: Wet west coast of Canada Posts: 1,197 Rep Power: 5	You can use a stack data structure. Imagine you have opening tokens ("if") and closing tokens ("end"), as well as miscellaneous tokens (operators, function calls, etc). You then iterate through the stream of tokens, and every time you come upon an opening token, you push it onto the stack. When you encounter a closing token, you peek at the top of the stack, and if there is a corresponding opening token there, you pop it off. If there is not a matching token, you know there is a syntax error (unmatched closing token). Likewise, if you have parsed all tokens, and the stack is not empty, you have an error (unmatched opening token). This approach lets you define more than one set of tokens. For example, you can use it to match braces, parentheses, and brackets by defining "{", "(", "[", "}", ")", and "]" as opening and closing tokens. __________________ And once again, Probability proves itself willing to sneak into a back alley and service Drama as would a copper-piece harlot. - Vaarsuvius, Order of the Stick

Jul 29th, 2006, 11:51 AM	#5
kurifu Expert Programmer Join Date: Jul 2004 Location: Halifax, Nova Scotia (Canada) Posts: 784 Rep Power: 5	http://www.regexlib.com a great resource __________________ Clifford Matthew Roche <geek@cliffordroche.com> Web Hosting: http://www.crd-hosting.com Consulting: http://www.crdev-consulting.com

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Jul 19th, 2006, 12:12 PM	#4
Master Programmer Join Date: Sep 2005 Location: GA Posts: 99 Rep Power: 4	Thanks for the suggestions

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