add update check (#154)

1 files changed, 49 insertions, 2 deletions

diff --git a/src/StardewModdingAPI/Version.cs b/src/StardewModdingAPI/Version.cs
index db5a21d4..b1903d7b 100644
--- a/src/StardewModdingAPI/Version.cs
+++ b/src/StardewModdingAPI/Version.cs
@@ -1,12 +1,21 @@
 using System;
+using System.Text.RegularExpressions;
 using Newtonsoft.Json;
 
 namespace StardewModdingAPI
 {
     /// <summary>A semantic version with an optional release tag.</summary>
-    public struct Version
+    public struct Version : IComparable<Version>
     {
         /*********
+        ** Properties
+        *********/
+        /// <summary>A regular expression matching a semantic version string.</summary>
+        /// <remarks>Derived from https://github.com/maxhauser/semver.</remarks>
+        private static readonly Regex Regex = new Regex(@"^(?<major>\d+)(\.(?<minor>\d+))?(\.(?<patch>\d+))?(?<build>.*)$", RegexOptions.CultureInvariant | RegexOptions.ExplicitCapture);
+
+
+        /*********
         ** Accessors
         *********/
         /// <summary>The major version incremented for major API changes.</summary>
@@ -43,6 +52,44 @@ namespace StardewModdingAPI
             this.Build = build;
         }
 
+        /// <summary>Construct an instance.</summary>
+        /// <param name="version">The semantic version string.</param>
+        internal Version(string version)
+        {
+            var match = Version.Regex.Match(version);
+            if (!match.Success)
+                throw new FormatException($"The input '{version}' is not a semantic version.");
+            
+            this.MajorVersion = int.Parse(match.Groups["major"].Value);
+            this.MinorVersion = match.Groups["minor"].Success ? int.Parse(match.Groups["minor"].Value) : 0;
+            this.PatchVersion = match.Groups["patch"].Success ? int.Parse(match.Groups["patch"].Value) : 0;
+            this.Build = (match.Groups["build"].Success ? match.Groups["build"].Value : "").Trim(' ', '-', '.');
+        }
+
+        /// <summary>Get an integer indicating whether this version precedes (less than 0), supercedes (more than 0), or is equivalent to (0) the specified version.</summary>
+        /// <param name="other">The version to compare with this instance.</param>
+        public int CompareTo(Version other)
+        {
+            // compare version numbers
+            if (this.MajorVersion != other.MajorVersion)
+                return this.MajorVersion - other.MajorVersion;
+            if (this.MinorVersion != other.MinorVersion)
+                return this.MinorVersion - other.MinorVersion;
+            if (this.PatchVersion != other.PatchVersion)
+                return this.PatchVersion - other.PatchVersion;
+
+            // stable version (without tag) supercedes prerelease (with tag)
+            bool curHasTag = !string.IsNullOrWhiteSpace(this.Build);
+            bool otherHasTag = !string.IsNullOrWhiteSpace(other.Build);
+            if (!curHasTag && otherHasTag)
+                return 1;
+            if (curHasTag && !otherHasTag)
+                return -1;
+
+            // else compare by string
+            return string.Compare(this.ToString(), other.ToString(), StringComparison.InvariantCultureIgnoreCase);
+        }
+
         /// <summary>Get a string representation of the version.</summary>
         public override string ToString()
         {
@@ -66,7 +113,7 @@ namespace StardewModdingAPI
         /// <param name="tag">The tag to normalise.</param>
         private string GetNormalisedTag(string tag)
         {
-            tag = tag?.Trim().Trim('-');
+            tag = tag?.Trim().Trim('-', '.');
             if (string.IsNullOrWhiteSpace(tag) || tag == "0")
                 return null;
             return tag;