fix prerelease update alerts shown for non-prerelease players

1 files changed, 32 insertions, 0 deletions

diff --git a/src/SMAPI.Toolkit/SemanticVersionComparer.cs b/src/SMAPI.Toolkit/SemanticVersionComparer.cs
new file mode 100644
index 00000000..9f6b57a2
--- /dev/null
+++ b/src/SMAPI.Toolkit/SemanticVersionComparer.cs
@@ -0,0 +1,32 @@
+using System.Collections.Generic;
+
+namespace StardewModdingAPI.Toolkit
+{
+    /// <summary>A comparer for semantic versions based on the <see cref="SemanticVersion.CompareTo(ISemanticVersion)"/> field.</summary>
+    public class SemanticVersionComparer : IComparer<ISemanticVersion>
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A singleton instance of the comparer.</summary>
+        public static SemanticVersionComparer Instance { get; } = new SemanticVersionComparer();
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <inheritdoc />
+        public int Compare(ISemanticVersion x, ISemanticVersion y)
+        {
+            if (object.ReferenceEquals(x, y))
+                return 0;
+
+            if (x is null)
+                return -1;
+            if (y is null)
+                return 1;
+
+            return x.CompareTo(y);
+        }
+    }
+}