Evaluating boolean expression in C#

Question

I have written the code below to evaluate a boolean expression. The expression is coded in the form of objects.

It's one of those moments when I look at the code and think: I'm sure there's a better way to code that, using less boolean variables but can't see the right way to go. Any help? Unit tests have been written and are passing for a variety of inputs.

if (tree == null || !tree.IsActive || tree.FilterNodes == null)
{
     return false;
}
var result = false;
foreach (var filter in tree.FilterNodes.Where(a => a.IsActive && a.ConditionNodes != null))
{
     var tempBool = false;
     foreach (var condition in filter.ConditionNodes.Where(a => a.IsActive))
     {
          if (!string.IsNullOrWhiteSpace(condition.FieldName) && values.ContainsKey(condition.FieldName))
          {
               var value = values[condition.FieldName];
               if (filter.LogicalOperator == LogicalOperator.Or && ApplyCondition(condition.ConditionOperator, value, condition.FieldValue))
               {
                   tempBool = true;
                   break;
               }
               else if (filter.LogicalOperator == LogicalOperator.And)
               {
                   tempBool = ApplyCondition(condition.ConditionOperator, value, condition.FieldValue);
                   if (!tempBool)
                   {
                        break;
                   }
               }
               else
               {
                   tempBool = false;
               }
           }
           else if (!string.IsNullOrWhiteSpace(condition.FieldName) && filter.LogicalOperator == LogicalOperator.And)
           {
                tempBool = false;
           }
     }
     result = tempBool;
     if (!result)
     {
          break;
     }
}
return result;

Answer 1

You could set tempBool = false first thing in the loop and leave out the else and last else if:

 foreach (var condition in filter.ConditionNodes.Where(a => a.IsActive))
 {
      tempBool = false;
      if (!string.IsNullOrWhiteSpace(condition.FieldName) && values.ContainsKey(condition.FieldName))
      {
           var value = values[condition.FieldName];
           if (filter.LogicalOperator == LogicalOperator.Or && ApplyCondition(condition.ConditionOperator, value, condition.FieldValue))
           {
               tempBool = true;
               break;
           }
           else if (filter.LogicalOperator == LogicalOperator.And)
           {
               tempBool = ApplyCondition(condition.ConditionOperator, value, condition.FieldValue);
               if (!tempBool)
               {
                    break;
               }
           }
       }
 }

EDIT

It gets even simpler:

 foreach (var condition in filter.ConditionNodes.Where(a => a.IsActive))
 {
      tempBool = false;
      if (!string.IsNullOrWhiteSpace(condition.FieldName) && values.ContainsKey(condition.FieldName))
      {
           var value = values[condition.FieldName];
           tempBool == ApplyCondition(condition.ConditionOperator, value, condition.FieldValue);

           if ((filter.LogicalOperator == LogicalOperator.And && !tempBool) || (filter.LogicalOperator == LogicalOperator.Or && tempBool))
           {
                break;
           }
       }
 }

In the if you need ApplyCondition to be true and then set tempBool to true (also the result of ApplyCondition). In the else if you set tempBoolto the result of ApplyCondition. That means you can set tempBoolto the result of ApplyConditionin the first place. Now you just need to decide if you need to break.