perf: cache `PythonVersion` objects (#461)

src/Microsoft.ComponentDetection.Detectors/pip/IPyPiClient.cs

@@ -201,7 +201,7 @@ public class PyPiClient : IPyPiClient
         {
             try
             {
-                var parsedVersion = new PythonVersion(release.Key);
+                var parsedVersion = PythonVersion.Create(release.Key);
                 if (release.Value != null && release.Value.Count > 0 &&
                     parsedVersion.Valid && parsedVersion.IsReleasedPackage &&
                     PythonVersionUtilities.VersionValidForSpec(release.Key, spec.DependencySpecifiers))

src/Microsoft.ComponentDetection.Detectors/pip/PythonVersion.cs

@@ -14,9 +14,11 @@ public class PythonVersion : IComparable<PythonVersion>
 
     private static readonly Dictionary<string, int> PreReleaseMapping = new Dictionary<string, int> { { "a", 0 }, { "alpha", 0 }, { "b", 1 }, { "beta", 1 }, { "c", 2 }, { "rc", 2 }, { "pre", 2 }, { "preview", 2 } };
 
+    private static readonly Dictionary<string, PythonVersion> Cache = new();
+
     private readonly Match match;
 
-    public PythonVersion(string version)
+    private PythonVersion(string version)
     {
         var toOperate = version;
         if (version.EndsWith(".*"))
@@ -105,6 +107,23 @@ public class PythonVersion : IComparable<PythonVersion>
 
     public static bool operator <=(PythonVersion operand1, PythonVersion operand2) => operand1.CompareTo(operand2) <= 0;
 
+    public static PythonVersion Create(string version)
+    {
+        if (version == null)
+        {
+            throw new ArgumentNullException(nameof(version));
+        }
+
+        if (Cache.TryGetValue(version, out var cachedVersion))
+        {
+            return cachedVersion;
+        }
+
+        var pythonVersion = new PythonVersion(version);
+        Cache.Add(version, pythonVersion);
+        return pythonVersion;
+    }
+
     public int CompareTo(PythonVersion other)
     {
         if (other == null || !other.Valid)

src/Microsoft.ComponentDetection.Detectors/pip/PythonVersionComparer.cs

@@ -5,8 +5,8 @@ public class PythonVersionComparer : IComparer<string>
 {
     public int Compare(string x, string y)
     {
-        var xVer = new PythonVersion(x);
-        var yVer = new PythonVersion(y);
+        var xVer = PythonVersion.Create(x);
+        var yVer = PythonVersion.Create(y);
 
         return xVer.CompareTo(yVer);
     }

src/Microsoft.ComponentDetection.Detectors/pip/PythonVersionUtilities.cs

@@ -95,8 +95,8 @@ public static class PythonVersionUtilities
 
         var op = spec[..i];
 
-        var targetVer = new PythonVersion(version);
-        var specVer = new PythonVersion(spec[i..]);
+        var targetVer = PythonVersion.Create(version);
+        var specVer = PythonVersion.Create(spec[i..]);
 
         if (!targetVer.Valid)
         {

test/Microsoft.ComponentDetection.Detectors.Tests/PythonVersionTests.cs

@@ -14,7 +14,7 @@ public class PythonVersionTests
     [TestMethod]
     public void TestBasicVersionConstruction()
     {
-        var pythonVersion = new PythonVersion("4!3.2.1.1rc2.post99.dev2");
+        var pythonVersion = PythonVersion.Create("4!3.2.1.1rc2.post99.dev2");
 
         Assert.AreEqual(4, pythonVersion.Epoch);
         Assert.AreEqual("3.2.1.1", pythonVersion.Release);
@@ -27,7 +27,7 @@ public class PythonVersionTests
     [TestMethod]
     public void TestDefaultDevVersionConstruction()
     {
-        var pythonVersion = new PythonVersion("4!3.2.1.1rc2.post90.dev");
+        var pythonVersion = PythonVersion.Create("4!3.2.1.1rc2.post90.dev");
 
         Assert.AreEqual(4, pythonVersion.Epoch);
         Assert.AreEqual("3.2.1.1", pythonVersion.Release);
@@ -69,7 +69,7 @@ public class PythonVersionTests
             "2.10.0.dev1",
             "v2.10.0.dev2",
             "v2.10.0",
-        }.Select(x => new { Raw = x, Version = new PythonVersion(x) }).ToList();
+        }.Select(x => new { Raw = x, Version = PythonVersion.Create(x) }).ToList();
 
         for (var i = 1; i < versionItems.Count; i++)
         {