VL: Regular ExpressionsFebruary 20, 2019 posted by: joreg
we have regular expressions in vl. What the? Here is the gist:
Regular expressions provide a powerful, flexible, and efficient method for processing text. The extensive pattern-matching notation of regular expressions enables you to quickly parse large amounts of text to find specific character patterns; to validate text to ensure that it matches a predefined pattern (such as an email address); to extract, edit, replace, or delete text substrings.
vvvv beta comes with the RegExpr (String)node which is quite handy but doesn’t cover all cases. vuxuser provides a RegExpr (String Replace)node via the addonpack, which adds the “replace” case, but there is more. So let’s see what we got in shop for vvvv gamma:
The simplest case: Just figure out if a given string matches a given pattern:
Is the input a valid email address?
Replacing by pattern
Sometimes a simple replace by string is not enough. See this example where we’re stripping a string of all occurences of html-tags, ie. replacing them with nothing.
Removing html tags from a string
Splitting by pattern
Sometimes a split by string is not enough. See this example where we’re splitting a string by any multiple occurances of lowercase letters:
Splitting a string at a pattern
Finding occurences by pattern
Find all substrings that match a given pattern. Imagine a string that contains many dates written in the format “Month Day, Year” and you want to get all of those:
Extracting all occurences of dates in the input string
The last pin on all of the above nodes is the Options enum pin. Since this enum allows multiple selections (ie. a bitwise combination of its member values), there is a RegexOptions node that allows you to set multiple of the options at the same time:
Choosing multiple regex options at the same time
The above should cover most typical usecases. But regular expressions can do even more. Luckily with vl you’re not restricted to what we decide to provide for you, but you have direct access to the full set of functionality .NET regular expressions offer. For example there are situations where you want to use the static operations that .NET provides instead of the process nodes shown above. If so, simply choose “Advanced” in the nodebrowser and, navigate to the “Regex” type and choose the static operations from there…
Static regex operations available among the advanced nodes
Available for testing in latest alphas now!
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