Regular Expression Conditionals (?(if)then|else) in VBA?

[Lazzaroni]

Does the VBScript_RegExp_55.RegExp object support conditionals?

According to http://www.regular-expressions.info/refflavors.html .NET allows
for conditionals using the (?(if)then|else) structure, and I thought that the
VBScript RegExp object used the .NET flavor of RegEx. But when I try to use
it, the object returns an error message.

When I try to do the following:
objRegExp.Pattern = “^(<)?test(?(1)>|)$”
I get the following error message:
Method 'Test' of object 'IRegExp2' failed

I am trying to use RegEx conditionals to ensure that a string with an
opening bracket has a closing bracket. So the RegEx above would accept “test”
or “<test>”, but it would not accept “<test” or “test>”.

I have looked all over for documentation on the VBScript=RegExp_55.RegExp
flavor of RegEx, but have had little success.

Any help would be greatly appreciated.

Thank you.

[Lazzaroni]

http://msdn.microsoft.com/en-us/library/1400241x(VS.85).aspx

That's a link to the Regular Expression Syntax for VBScript. It appears that
conditionals are not supported.

Too bad. That would have been incredibly useful.

[Ron Rosenfeld]

On Wed, 8 Oct 2008 08:46:31 -0700, Lazzaroni

Post by Lazzaroni
Does the VBScript_RegExp_55.RegExp object support conditionals?
According to http://www.regular-expressions.info/refflavors.html .NET allows
for conditionals using the (?(if)then|else) structure, and I thought that the
VBScript RegExp object used the .NET flavor of RegEx. But when I try to use
it, the object returns an error message.
objRegExp.Pattern = “^(<)?test(?(1)>|)$”
Method 'Test' of object 'IRegExp2' failed
I am trying to use RegEx conditionals to ensure that a string with an
opening bracket has a closing bracket. So the RegEx above would accept “test”
or “<test>”, but it would not accept “<test” or “test>”.
I have looked all over for documentation on the VBScript=RegExp_55.RegExp
flavor of RegEx, but have had little success.
Any help would be greatly appreciated.
Thank you.

The VBScript regex object uses the Javascript flavor.
--ron

[Lazzaroni]

Ron:

Too bad it doesn't use the .NET flavor, which is much more robust.

Thanks.

[Ron Rosenfeld]

On Wed, 8 Oct 2008 12:09:02 -0700, Lazzaroni

Post by Lazzaroni
Too bad it doesn't use the .NET flavor, which is much more robust.
Thanks.

I'm not sure exactly what you want to do, but

"<test>|(^|[^<])test(?!>)"

might match what you wrote for a specific string, so long as it doesn't include
embedded delimiters.

--ron

[Rick Rothstein]

Without using regular expressions, does this do what you want?

If Variable Like "[!<]*[!>]" or Variable Like "<*>" Then
--
Rick (MVP - Excel)

Post by Lazzaroni
Does the VBScript_RegExp_55.RegExp object support conditionals?
According to http://www.regular-expressions.info/refflavors.html .NET allows
for conditionals using the (?(if)then|else) structure, and I thought that the
VBScript RegExp object used the .NET flavor of RegEx. But when I try to use
it, the object returns an error message.
objRegExp.Pattern = “^(<)?test(?(1)>|)$”
Method 'Test' of object 'IRegExp2' failed
I am trying to use RegEx conditionals to ensure that a string with an
opening bracket has a closing bracket. So the RegEx above would accept “test”
or “<test>”, but it would not accept “<test” or “test>”.
I have looked all over for documentation on the VBScript=RegExp_55.RegExp
flavor of RegEx, but have had little success.
Any help would be greatly appreciated.
Thank you.

[Lazzaroni]

Rick:

That is correct, but within a larger string. I am looking for unclosed
brackets using a data validation application that uses rules written in
RegEx. It checks the contents of cells in Excel, based on a unique column
identifier.

Thanks.

Thomas

[Rick Rothstein]

Okay, but if I understand your larger goal (checking to ensure multiple
left/right brackets in a text string are paired), this (again, non-RegEx)
code might work for you...

If UBound(Split(Variable, "<")) = UBound(Split(Variable, ">")) And _
Not Variable Like "*<[!>]<*" And Not Variable Like "*<[!>]<*" Then
--
Rick (MVP - Excel)

Post by Lazzaroni
That is correct, but within a larger string. I am looking for unclosed
brackets using a data validation application that uses rules written in
RegEx. It checks the contents of cells in Excel, based on a unique column
identifier.
Thanks.
Thomas