1 files changed, 126 insertions, 0 deletions
diff --git a/src/SMAPI.Toolkit/Framework/SemanticVersionReader.cs b/src/SMAPI.Toolkit/Framework/SemanticVersionReader.cs
new file mode 100644
index 00000000..489e1c4d
--- /dev/null
+++ b/src/SMAPI.Toolkit/Framework/SemanticVersionReader.cs
@@ -0,0 +1,126 @@
+namespace StardewModdingAPI.Toolkit.Framework
+{
+    /// <summary>Reads strings into a semantic version.</summary>
+    internal static class SemanticVersionReader
+    {
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Parse a semantic version string.</summary>
+        /// <param name="versionStr">The version string to parse.</param>
+        /// <param name="allowNonStandard">Whether to recognize non-standard semver extensions.</param>
+        /// <param name="major">The major version incremented for major API changes.</param>
+        /// <param name="minor">The minor version incremented for backwards-compatible changes.</param>
+        /// <param name="patch">The patch version for backwards-compatible fixes.</param>
+        /// <param name="platformRelease">The platform-specific version (if applicable).</param>
+        /// <param name="prereleaseTag">An optional prerelease tag.</param>
+        /// <param name="buildMetadata">Optional build metadata. This is ignored when determining version precedence.</param>
+        /// <returns>Returns whether the version was successfully parsed.</returns>
+        public static bool TryParse(string versionStr, bool allowNonStandard, out int major, out int minor, out int patch, out int platformRelease, out string prereleaseTag, out string buildMetadata)
+        {
+            // init
+            major = 0;
+            minor = 0;
+            patch = 0;
+            platformRelease = 0;
+            prereleaseTag = null;
+            buildMetadata = null;
+
+            // normalize
+            versionStr = versionStr?.Trim();
+            if (string.IsNullOrWhiteSpace(versionStr))
+                return false;
+            char[] raw = versionStr.ToCharArray();
+
+            // read major/minor version
+            int i = 0;
+            if (!TryParseVersionPart(raw, ref i, out major) || !TryParseLiteral(raw, ref i, '.') || !TryParseVersionPart(raw, ref i, out minor))
+                return false;
+
+            // read optional patch version
+            if (TryParseLiteral(raw, ref i, '.') && !TryParseVersionPart(raw, ref i, out patch))
+                return false;
+
+            // read optional non-standard platform release version
+            if (allowNonStandard && TryParseLiteral(raw, ref i, '.') && !TryParseVersionPart(raw, ref i, out platformRelease))
+                return false;
+
+            // read optional prerelease tag
+            if (TryParseLiteral(raw, ref i, '-') && !TryParseTag(raw, ref i, out prereleaseTag))
+                return false;
+
+            // read optional build tag
+            if (TryParseLiteral(raw, ref i, '+') && !TryParseTag(raw, ref i, out buildMetadata))
+                return false;
+
+            // validate
+            return i == versionStr.Length; // valid if we're at the end
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Try to parse the next characters in a queue as a numeric part.</summary>
+        /// <param name="raw">The raw characters to parse.</param>
+        /// <param name="index">The index of the next character to read.</param>
+        /// <param name="part">The parsed part.</param>
+        private static bool TryParseVersionPart(char[] raw, ref int index, out int part)
+        {
+            part = 0;
+
+            // take digits
+            string str = "";
+            for (int i = index; i < raw.Length && char.IsDigit(raw[i]); i++)
+                str += raw[i];
+
+            // validate
+            if (str.Length == 0)
+                return false;
+            if (str.Length > 1 && str[0] == '0')
+                return false; // can't have leading zeros
+
+            // parse
+            part = int.Parse(str);
+            index += str.Length;
+            return true;
+        }
+
+        /// <summary>Try to parse a literal character.</summary>
+        /// <param name="raw">The raw characters to parse.</param>
+        /// <param name="index">The index of the next character to read.</param>
+        /// <param name="ch">The expected character.</param>
+        private static bool TryParseLiteral(char[] raw, ref int index, char ch)
+        {
+            if (index >= raw.Length || raw[index] != ch)
+                return false;
+
+            index++;
+            return true;
+        }
+
+        /// <summary>Try to parse a tag.</summary>
+        /// <param name="raw">The raw characters to parse.</param>
+        /// <param name="index">The index of the next character to read.</param>
+        /// <param name="tag">The parsed tag.</param>
+        private static bool TryParseTag(char[] raw, ref int index, out string tag)
+        {
+            // read tag length
+            int length = 0;
+            for (int i = index; i < raw.Length && (char.IsLetterOrDigit(raw[i]) || raw[i] == '-' || raw[i] == '.'); i++)
+                length++;
+
+            // validate
+            if (length == 0)
+            {
+                tag = null;
+                return false;
+            }
+
+            // parse
+            tag = new string(raw, index, length);
+            index += length;
+            return true;
+        }
+    }
+}