Implement IEquatable for sort and filter terms, closes #38

Sieve/Models/FilterTerm.cs

@@ -4,7 +4,7 @@ using System.Text.RegularExpressions;
 
 namespace Sieve.Models
 {
-    public class FilterTerm : IFilterTerm
+    public class FilterTerm : IFilterTerm, IEquatable<FilterTerm>
     {
         public FilterTerm() { }
 
@@ -76,5 +76,13 @@ namespace Sieve.Models
         }
 
         public bool OperatorIsCaseInsensitive { get; private set; }
+
+        public bool Equals(FilterTerm other)
+        {
+            return Names.SequenceEqual(other.Names)
+                && Values.SequenceEqual(other.Values)
+                && Operator == other.Operator;
+        }
+
     }
 }

Sieve/Models/SortTerm.cs

@@ -1,6 +1,8 @@
-namespace Sieve.Models
+using System;
+
+namespace Sieve.Models
 {
-    public class SortTerm : ISortTerm
+    public class SortTerm : ISortTerm, IEquatable<SortTerm>
     {
         public SortTerm() { }
 
@@ -17,5 +19,11 @@
         public string Name => (_sort.StartsWith("-")) ? _sort.Substring(1) : _sort;
 
         public bool Descending => _sort.StartsWith("-");
+
+        public bool Equals(SortTerm other)
+        {
+            return Name == other.Name
+                && Descending == other.Descending;
+        }
     }
 }