Added support of functional interfaces

Author: sakno

src/DotNext.Tests/Runtime/ValueReferenceTests.cs

@@ -8,7 +8,7 @@ public sealed class ValueReferenceTests : Test
     [Fact]
     public static void MutableFieldRef()
     {
-        var obj = new MyClass() { AnotherField = string.Empty };
+        var obj = new MyClass { AnotherField = string.Empty };
         var reference = new ValueReference<int>(obj, ref obj.Field);
 
         obj.Field = 20;
@@ -22,7 +22,7 @@ public static void MutableFieldRef()
     [Fact]
     public static void ImmutableFieldRef()
     {
-        var obj = new MyClass() { AnotherField = string.Empty };
+        var obj = new MyClass { AnotherField = string.Empty };
         var reference = new ReadOnlyValueReference<int>(obj, in obj.Field);
 
         obj.Field = 20;
@@ -35,7 +35,7 @@ public static void ImmutableFieldRef()
     [Fact]
     public static void MutableToImmutableRef()
     {
-        var obj = new MyClass() { AnotherField = string.Empty };
+        var obj = new MyClass { AnotherField = string.Empty };
         var reference = new ValueReference<int>(obj, ref obj.Field);
         ReadOnlyValueReference<int> roReference = reference;
 
@@ -49,7 +49,7 @@ public static void MutableToImmutableRef()
     [Fact]
     public static void MutableRefEquality()
     {
-        var obj = new MyClass() { AnotherField = string.Empty };
+        var obj = new MyClass { AnotherField = string.Empty };
         var reference1 = new ValueReference<int>(obj, ref obj.Field);
         var reference2 = new ValueReference<int>(obj, ref obj.Field);
 
@@ -59,7 +59,7 @@ public static void MutableRefEquality()
     [Fact]
     public static void ImmutableRefEquality()
     {
-        var obj = new MyClass() { AnotherField = string.Empty };
+        var obj = new MyClass { AnotherField = string.Empty };
         var reference1 = new ReadOnlyValueReference<int>(obj, in obj.Field);
         var reference2 = new ReadOnlyValueReference<int>(obj, in obj.Field);
 
@@ -82,23 +82,28 @@ public static void ReferenceToArray()
     [Fact]
     public static void MutableEmptyRef()
     {
-        var reference = default(ValueReference<float>);
+        var reference = default(ValueReference<string>);
         True(reference.IsEmpty);
         Null(reference.ToString());
 
-        Span<float> span = reference;
+        Span<string> span = reference;
         True(span.IsEmpty);
+
+        Throws<NullReferenceException>((Func<string>)reference);
+        Throws<NullReferenceException>(((Action<string>)reference).Bind(string.Empty));
     }
 
     [Fact]
     public static void ImmutableEmptyRef()
     {
-        var reference = default(ReadOnlyValueReference<float>);
+        var reference = default(ReadOnlyValueReference<string>);
         True(reference.IsEmpty);
         Null(reference.ToString());
 
-        ReadOnlySpan<float> span = reference;
+        ReadOnlySpan<string> span = reference;
         True(span.IsEmpty);
+        
+        Throws<NullReferenceException>((Func<string>)reference);
     }
 
     [Fact]
@@ -107,10 +112,18 @@ public static void AnonymousValue()
         var reference = new ValueReference<int>(42);
         Equal(42, reference.Value);
 
+        ((Action<int>)reference).Invoke(52);
+        Equal(52, ToFunc<ValueReference<int>, int>(reference).Invoke());
+
         ReadOnlyValueReference<int> roRef = reference;
-        Equal(42, roRef.Value);
+        Equal(52, roRef.Value);
+        Equal(52, ToFunc<ReadOnlyValueReference<int>, int>(reference).Invoke());
     }
 
+    private static Func<T> ToFunc<TSupplier, T>(TSupplier supplier)
+        where TSupplier : ISupplier<T>
+        => supplier.ToDelegate();
+
     [Fact]
     public static void StaticObjectAccess()
     {
@@ -124,6 +137,7 @@ public static void StaticObjectAccess()
 
         True(reference == new ValueReference<string>(ref MyClass.StaticObject));
         Same(MyClass.StaticObject, reference.Value);
+        Same(MyClass.StaticObject, ToFunc<ValueReference<string>, string>(reference).Invoke());
     }
 
     [Fact]
@@ -193,6 +207,8 @@ public static void ReadOnlySpanInterop()
         True(Unsafe.AreSame(in reference.Value, in span[0]));
     }
 
+    
+
     private record class MyClass : IResettable
     {
         internal static string StaticObject;

src/DotNext/Runtime/ValueReference.cs

@@ -7,6 +7,8 @@
 
 namespace DotNext.Runtime;
 
+using Runtime.CompilerServices;
+
 /// <summary>
 /// Represents a mutable reference to the field.
 /// </summary>
@@ -17,7 +19,9 @@ namespace DotNext.Runtime;
 [EditorBrowsable(EditorBrowsableState.Advanced)]
 public readonly struct ValueReference<T>(object owner, ref T fieldRef) :
     IEquatable<ValueReference<T>>,
-    IEqualityOperators<ValueReference<T>, ValueReference<T>, bool>
+    IEqualityOperators<ValueReference<T>, ValueReference<T>, bool>,
+    ISupplier<T>,
+    IConsumer<T>
 {
     private readonly nint offset = RawData.GetOffset(owner, in fieldRef);
 
@@ -76,8 +80,47 @@ public ValueReference(ref T staticFieldRef)
     /// </summary>
     public ref T Value => ref RawData.GetObjectData<T>(owner, offset);
 
+    /// <inheritdoc cref="IConsumer{T}.Invoke(T)"/>
+    void IConsumer<T>.Invoke(T value) => Value = value;
+
+    /// <inheritdoc cref="IFunctional{T}.ToDelegate()"/>
+    Action<T> IFunctional<Action<T>>.ToDelegate() => ToAction();
+
+    /// <inheritdoc cref="ISupplier{T}.Invoke()"/>
+    T ISupplier<T>.Invoke() => Value;
+
+    /// <inheritdoc cref="IFunctional{T}.ToDelegate()"/>
+    Func<T> IFunctional<Func<T>>.ToDelegate() => ToFunc();
+
     private bool SameObject(object? other) => ReferenceEquals(owner, other);
 
+    private Func<T> ToFunc()
+        => Intrinsics.ChangeType<ValueReference<T>, ReadOnlyValueReference<T>>(in this).ToFunc();
+    
+    private Action<T> ToAction()
+    {
+        Action<T> result;
+
+        if (IsEmpty)
+        {
+            result = ThrowNullReferenceException;
+        }
+        else if (ReferenceEquals(owner, Sentinel.Instance))
+        {
+            result = new StaticFieldAccessor<T>(offset).SetValue;
+        }
+        else
+        {
+            IConsumer<T> consumer = this;
+            result = consumer.Invoke;
+        }
+
+        return result;
+        
+        [DoesNotReturn]
+        static void ThrowNullReferenceException(T value) => throw new NullReferenceException();
+    }
+
     /// <inheritdoc/>
     public override string? ToString()
         => owner is not null ? RawData.GetObjectData<T>(owner, offset)?.ToString() : null;
@@ -126,6 +169,22 @@ public static implicit operator ReadOnlyValueReference<T>(ValueReference<T> refe
     /// <returns>The span that contains <see cref="Value"/>; or empty span if <paramref name="reference"/> is empty.</returns>
     public static implicit operator Span<T>(ValueReference<T> reference)
         => reference.IsEmpty ? new() : new(ref reference.Value);
+
+    /// <summary>
+    /// Returns a setter for the memory location.
+    /// </summary>
+    /// <param name="reference">A reference to a value.</param>
+    /// <returns>A setter for the memory location.</returns>
+    public static explicit operator Action<T>(ValueReference<T> reference)
+        => reference.ToAction();
+
+    /// <summary>
+    /// Returns a getter for the memory location.
+    /// </summary>
+    /// <param name="reference">A reference to a value.</param>
+    /// <returns>A getter for the memory location.</returns>
+    public static explicit operator Func<T>(ValueReference<T> reference)
+        => reference.ToFunc();
 }
 
 /// <summary>
@@ -138,7 +197,8 @@ public static implicit operator Span<T>(ValueReference<T> reference)
 [EditorBrowsable(EditorBrowsableState.Advanced)]
 public readonly struct ReadOnlyValueReference<T>(object owner, ref readonly T fieldRef) :
     IEquatable<ReadOnlyValueReference<T>>,
-    IEqualityOperators<ReadOnlyValueReference<T>, ReadOnlyValueReference<T>, bool>
+    IEqualityOperators<ReadOnlyValueReference<T>, ReadOnlyValueReference<T>, bool>,
+    ISupplier<T>
 {
     private readonly nint offset = RawData.GetOffset(owner, in fieldRef);
 
@@ -179,6 +239,36 @@ public ReadOnlyValueReference(ref readonly T staticFieldRef)
     /// </summary>
     public ref readonly T Value => ref RawData.GetObjectData<T>(owner, offset);
 
+    /// <inheritdoc cref="ISupplier{T}.Invoke()"/>
+    T ISupplier<T>.Invoke() => Value;
+
+    /// <inheritdoc cref="IFunctional{T}.ToDelegate()"/>
+    Func<T> IFunctional<Func<T>>.ToDelegate() => ToFunc();
+
+    internal Func<T> ToFunc()
+    {
+        Func<T> result;
+        if (IsEmpty)
+        {
+            result = ThrowNullReferenceException;
+        }
+        else if (ReferenceEquals(owner, Sentinel.Instance))
+        {
+            result = new StaticFieldAccessor<T>(offset).GetValue;
+        }
+        else
+        {
+            ISupplier<T> supplier = this;
+            result = supplier.Invoke;
+        }
+
+        return result;
+        
+        [DoesNotReturn]
+        static T ThrowNullReferenceException()
+            => throw new NullReferenceException();
+    }
+
     private bool SameObject(object? other) => ReferenceEquals(owner, other);
 
     /// <inheritdoc/>
@@ -221,6 +311,14 @@ public bool Equals(ReadOnlyValueReference<T> reference)
     /// <returns>The span that contains <see cref="Value"/>; or empty span if <paramref name="reference"/> is empty.</returns>
     public static implicit operator ReadOnlySpan<T>(ReadOnlyValueReference<T> reference)
         => reference.IsEmpty ? new() : new(in reference.Value);
+
+    /// <summary>
+    /// Returns a getter for the memory location.
+    /// </summary>
+    /// <param name="reference">A reference to a value.</param>
+    /// <returns>A getter for the memory location.</returns>
+    public static explicit operator Func<T>(ReadOnlyValueReference<T> reference)
+        => reference.ToFunc();
 }
 
 [SuppressMessage("Performance", "CA1812", Justification = "Used for reinterpret cast")]
@@ -259,4 +357,11 @@ internal static ref T GetObjectData<T>(object owner, nint offset)
         ref var rawData = ref Unsafe.As<RawData>(owner).data;
         return ref Unsafe.As<byte, T>(ref Unsafe.Add(ref rawData, offset));
     }
+}
+
+file sealed class StaticFieldAccessor<T>(nint offset)
+{
+    public T GetValue() => RawData.GetObjectData<T>(Sentinel.Instance, offset);
+
+    public void SetValue(T value) => RawData.GetObjectData<T>(Sentinel.Instance, offset) = value;
 }