Question

I have an IList of type Breadcrumb which is just a lightweight class that has NavigationTitle, NavigationUrl and IsCurrent properties. It is cached on the webserver. I have a method that builds out the current breadcrumb trail up until the first Breadcrumb that has IsCurrent set to true… using the code below. Its very ugly and definitely a quick dirtbag willie solution, but I was curious, can this be easily refactored into LINQ?

IList<Breadcrumb> crumbs = new List<Breadcrumb>(); bool foundCurrent = false; for (int a = 0; a < cachedCrumbs.Count; a++) {     crumbs.Add(crumbs[a]);     if (foundCurrent)     {       break;     }     foundCurrent = (crumbs[a + 1] != null && ((Breadcrumb)crumbs[a + 1]).IsCurrent); } 

Answer 1

I’m typing this as I think, so that it shows a train of thought as well as just an answer.

• Your source is just cachedCrumbs
• You want to add the first crumb which does have IsCurrent set, but nothing afterwards
• TakeWhile sounds like the way to go, but getting the ‘previous value had IsCurrent’ is a bit of a pain
• We can use a closure to effectively keep a variable determining whether the last value had IsCurrent set
• We can do a somewhat ‘no-op’ select to keep the TakeWhile separate from the working out of whether to keep going

So, we end up with:

bool foundCurrent = false;  var crumbs = cachedCrumbs.TakeWhile(crumb => !foundCurrent)                          .Select(crumb => {                                   foundCurrent = crumb == null || !crumb.IsCurrent;                                   return crumb; }); 

I haven’t tried this, but I think it should work… there might be a simpler way though.

EDIT: I’d argue that actually a straight foreach loop is simpler in this case. Having said that, you could write another extension method which acted like TakeWhile except it also returned the element which caused the condition to fail. Then it would be as simple as:

var crumbs = cachedCrumbs.NewMethod(crumb => crumb == null || !crumb.IsCurrent); 

(I can’t think of a decent name for the method at the moment, hence NewMethod !)