RegEx for LINQ like syntax

Question

I have a string in the format:

MyList.Where(abc).GroupBy(def).Sum(ghi)

The Where & GroupBy parts are optional as is the argument to the function, so.

ThisList.Count

is also valid.

I'm trying to find a RegEx string that will match this and return the values:
The List name (e.g. MyList), the where condition (e.g. abc), the GroupBy attribute (e.g def), the function name (e.g. Sum) and the function attribute (e.g. ghi).

Clarification:
The List name is one word
abc can be a complex expression, but there will be no close brackets which are not in quotation marks
def will be a single word
ghi will be a single word or a list of words separated by ","

Answer 1

(?<list>\w+)\s*
([.]\s*Where\s*[(]\s*(?<wherearg>.*?)\s*[)]\s*)?
([.]\s*GroupBy\s*[(]\s*(?<groupbyarg>.*?)\s*[)]\s*)?
[.]\s*(?<func>\w+)\s*[(]\s*(?<funcarg>.*?)\s*[)]

Answer 2

You can use a regex to validate the syntax, like:

^[A-Za-z]+(\.[A-Za-z]+\([A-Za-z]+\))*(\.[A-Za-z]+)?

but this will result in a valid or invalid decision.

I am not sure if you really want to grep the method names and values at the same time. That would limit your syntax: for instance all methods (GroupBy, Where) have to be in the right order. Maybe it is easier to split the string by . and extract the parts you need one by one.

Answer 3

Assuming where/groupby/function parameters to be words, you can use:

^(\w+)(?:\.Where\((\w+)\))?(?:\.GroupBy\((\w+)\))?\.(\w+)(?:\((\w+)\))?$

• Group 1 would have the list name
• Group 2 would have the where condition or null
• Group 3 would have the group by condition or null
• Group 4 would have the function
• Group 5 would have the function parameter or null

If they're going to be complex C# expressions, the corresponding regex will be quite complex that you'll hate yourself tomorrow for choosing regex for this.

Answer 4

This gives you the expected result.

^(?<List>[^\.]\*)|\.(?<Op>[^\(\.]*)\(*(?<Param>[^\)\.]*)