From d9cf9c8db5cf7453191c7a1356584d2802e80604 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Sun, 26 Feb 2023 00:35:22 +0000
Subject: [PATCH] Add Nullable<T>.TryGetValue (resolves #61)

---
 CHANGELOG.md                         |  1 +
 X10D.Tests/src/Core/NullableTests.cs | 24 +++++++++++++++++++
 X10D/src/Core/NullableExtensions.cs  | 35 ++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+)
 create mode 100644 X10D.Tests/src/Core/NullableTests.cs
 create mode 100644 X10D/src/Core/NullableExtensions.cs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e43fa92..93cf30f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@
 - X10D: Added `IList<T>.Swap(IList<T>)` (#62)
 - X10D: Added `IReadOnlyList<T>.IndexOf(T[, int[, int]])`
 - X10D: Added `IReadOnlyList<T>.Slice(int[, int]])`
+- X10D: Added `Nullable<T>.TryGetValue(out T)` (#61)
 - X10D: Added `Point.IsOnLine(LineF)`, `Point.IsOnLine(PointF, PointF)`, and `Point.IsOnLine(Vector2, Vector2)`
 - X10D: Added `PointF.IsOnLine(LineF)`, `PointF.IsOnLine(PointF, PointF)`, and `PointF.IsOnLine(Vector2, Vector2)`
 - X10D: Added `Point.ToSize()`
diff --git a/X10D.Tests/src/Core/NullableTests.cs b/X10D.Tests/src/Core/NullableTests.cs
new file mode 100644
index 0000000..eda6883
--- /dev/null
+++ b/X10D.Tests/src/Core/NullableTests.cs
@@ -0,0 +1,24 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using X10D.Core;
+
+namespace X10D.Tests.Core;
+
+[TestClass]
+public class NullableTests
+{
+    [TestMethod]
+    public void TryGetValue_ShouldBeTrue_GivenValue()
+    {
+        int? value = 42;
+        Assert.IsTrue(value.TryGetValue(out int returnedValue));
+        Assert.AreEqual(value, returnedValue);
+    }
+
+    [TestMethod]
+    public void TryGetValue_ShouldBeFalse_GivenNull()
+    {
+        int? value = null;
+        Assert.IsFalse(value.TryGetValue(out int returnedValue));
+        Assert.AreEqual(default, returnedValue);
+    }
+}
diff --git a/X10D/src/Core/NullableExtensions.cs b/X10D/src/Core/NullableExtensions.cs
new file mode 100644
index 0000000..4c066e9
--- /dev/null
+++ b/X10D/src/Core/NullableExtensions.cs
@@ -0,0 +1,35 @@
+namespace X10D.Core;
+
+/// <summary>
+///     Extension methods for <see cref="Nullable{T}" />
+/// </summary>
+public static class NullableExtensions
+{
+    /// <summary>
+    ///     Attempts to get the value of a <see cref="Nullable{T}" />, and returns a value indicating the success of the
+    ///     operation. 
+    /// </summary>
+    /// <param name="value">The nullable value.</param>
+    /// <param name="result">
+    ///     When this method returns, contains the result of <see cref="Nullable{T}.Value" />, if
+    ///     <see cref="Nullable{T}.HasValue" /> is <see langword="true" />; otherwise, returns the default value for
+    ///     <typeparamref name="T" />.
+    /// </param>
+    /// <typeparam name="T">The type of the value.</typeparam>
+    /// <returns>
+    ///     <see langword="true" /> if the value's <see cref="Nullable{T}.HasValue" /> is <see langword="true" />; otherwise,
+    ///     <see langword="false" />.
+    /// </returns>
+    public static bool TryGetValue<T>(this T? value, out T result)
+        where T : struct
+    {
+        if (value.HasValue)
+        {
+            result = value.Value;
+            return true;
+        }
+
+        result = default;
+        return false;
+    }
+}