Resharper Quickfix for ?? order of operations

Question

I have a common problem where the order of operations is not respected when using the ? or ?? operators. In the following code, the programmer intended to set price to bigPrice + 5, defaulting bigPrice to 0 if it is null.

var price = bigPrice ?? 0 + 5;

Obviously the order of operations for the ?? operator evaluates the entire expression to the right as the argument, but it is a common mistake. Is it possible to alleviate this with a resharper quick fix / structural find and replace, essentially requiring parenthesis around your ?? statements? I've tried, but can't get a macro that identifies multi part arguments (0 + 5).

I'd like to know if this is possible / what the best way to do this is.

Answer 1

You could do a find and replace in Visual Studio using regular expression,

In the find-replace dialog (Ctrl+H), enter the following,

Find what: {:i:b??:b:z:b}{[+-/*]:b:z};
Replace with: (\\1) \\2;
Look in: Current project

Initial code,

var price = bigPrice ?? 0 + 5;

After replacement,

var price = (bigPrice ?? 0 ) + 5;

A quick explaination of the find and replace expressions,

• Find Expression: {:i:b??:b:z:b}{[+-/*]:b:z}; : {xxx} represents tagged expression ie it is a grouping of the expression found. :z stands for integer, :b stands for blank space, :i stands for identifier. [xxx] stands for any character in the set. And \\ is used to escape special characters. So in your case tagExpression1 evaluates to bigPrice ?? 0 bigPrice ?? 0 while tagExpression2 evaluates to + 5 .

• Replace expression: (\\1) \\2; : \\1 stands for first tag expression and \\2 stands for the second tag expression. The expression results in ( ) being placed around the first tag expression followed by a blank space and then the second tag expression.