Feat: Add Sum extension methods for Span and ReadOnlySpan

Author: AnnaSasDev

src/CodeOfChaos.Extensions/SpanLinq/SpanLinqSumExtensions.cs

@@ -0,0 +1,60 @@
+// ---------------------------------------------------------------------------------------------------------------------
+// Imports
+// ---------------------------------------------------------------------------------------------------------------------
+// ReSharper disable once CheckNamespace
+namespace System;
+
+// ---------------------------------------------------------------------------------------------------------------------
+// Code
+// ---------------------------------------------------------------------------------------------------------------------
+public static class SpanLinqSumExtensions {
+    public static int Sum<T>(this in Span<T> span, Func<T, int> selector, int length = -1) {
+        int totalGroups = 0;
+        length = length switch {
+            < -1 => throw new ArgumentOutOfRangeException(nameof(length)),
+            -1 => span.Length,
+            _ => length
+        };
+
+        for (int index = 0; index < length; index++) {
+            totalGroups += selector(span[index]);
+        }
+        return totalGroups;
+    }
+    
+    public static int Sum<T>(this in Span<T> span, Func<T, int> selector, Range range) {
+        int totalGroups = 0;
+        ReadOnlySpan<T> slice = span[range];
+        int length = slice.Length;
+
+        for (int index = 0; index < length; index++) {
+            totalGroups += selector(slice[index]);
+        }
+        return totalGroups;
+    }
+    
+    public static int Sum<T>(this in ReadOnlySpan<T> span, Func<T, int> selector, int length = -1) {
+        int totalGroups = 0;
+        length = length switch {
+            < -1 => throw new ArgumentOutOfRangeException(nameof(length)),
+            -1 => span.Length,
+            _ => length
+        };
+
+        for (int index = 0; index < length; index++) {
+            totalGroups += selector(span[index]);
+        }
+        return totalGroups;
+    }
+    
+    public static int Sum<T>(this in ReadOnlySpan<T> span, Func<T, int> selector, Range range) {
+        int totalGroups = 0;
+        ReadOnlySpan<T> slice = span[range];
+        int length = slice.Length;
+
+        for (int index = 0; index < length; index++) {
+            totalGroups += selector(slice[index]);
+        }
+        return totalGroups;
+    }
+}

tests/Tests.CodeOfChaos.Extensions/SpanLinq/SpanLinqSumTests.cs

@@ -0,0 +1,122 @@
+// ---------------------------------------------------------------------------------------------------------------------
+// Imports
+// ---------------------------------------------------------------------------------------------------------------------
+namespace Tests.CodeOfChaos.Extensions.SpanLinq;
+
+// ---------------------------------------------------------------------------------------------------------------------
+// Code
+// ---------------------------------------------------------------------------------------------------------------------
+public class SpanLinqSumTests {
+    private record TestItem(int Value);
+    
+    [Test]
+    public async Task Sum_Span_WithDefaultLength_ShouldSumAllElements() {
+        // Arrange
+        Span<int> numbers = [1, 2, 3, 4, 5];
+        
+        // Act
+        int result = numbers.Sum(x => x);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(15);
+    }
+    
+    [Test]
+    public async Task Sum_Span_WithSpecificLength_ShouldSumSpecifiedElements() {
+        // Arrange
+        Span<int> numbers = [1, 2, 3, 4, 5];
+        
+        // Act
+        int result = numbers.Sum(x => x, 3);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(6); // Sum of first 3 elements: 1 + 2 + 3
+    }
+    
+    [Test]
+    public async Task Sum_Span_WithRange_ShouldSumElementsInRange() {
+        // Arrange
+        Span<int> numbers = [1, 2, 3, 4, 5];
+        var range = 1..4; // Elements at index 1, 2, and 3
+        
+        // Act
+        int result = numbers.Sum(x => x, range);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(9); // Sum of elements 2 + 3 + 4
+    }
+    
+    [Test]
+    public async Task Sum_Span_WithSelector_ShouldApplySelector() {
+        // Arrange
+        Span<int> numbers = [1, 2, 3];
+        
+        // Act
+        int result = numbers.Sum(x => x * 2);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(12); // (1*2) + (2*2) + (3*2)
+    }
+    
+    [Test]
+    public async Task Sum_ReadOnlySpan_WithDefaultLength_ShouldSumAllElements() {
+        // Arrange
+        ReadOnlySpan<int> numbers = [1, 2, 3, 4, 5];
+        
+        // Act
+        int result = numbers.Sum(x => x);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(15);
+    }
+    
+    [Test]
+    public async Task Sum_ReadOnlySpan_WithSpecificLength_ShouldSumSpecifiedElements() {
+        // Arrange
+        ReadOnlySpan<int> numbers = [1, 2, 3, 4, 5];
+        
+        // Act
+        int result = numbers.Sum(x => x, 3);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(6); // Sum of first 3 elements
+    }
+    
+    [Test]
+    public async Task Sum_ReadOnlySpan_WithRange_ShouldSumElementsInRange() {
+        // Arrange
+        ReadOnlySpan<int> numbers = [1, 2, 3, 4, 5];
+        Range range = 1..4;
+        
+        // Act
+        int result = numbers.Sum(x => x, range);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(9); // Sum of elements 2 + 3 + 4
+    }
+    
+    [Test]
+    public void Sum_InvalidLength_ShouldThrowArgumentOutOfRangeException() {
+        Assert.Throws<ArgumentOutOfRangeException>(() => {
+            Span<int> numbers = [1, 2, 3];
+            numbers.Sum(x => x, -2);
+        });
+    }
+    
+    [Test]
+    public async Task Sum_WithCustomType_ShouldSumSelectedValues() {
+        // Arrange
+        var items = new TestItem[] {
+            new(1),
+            new(2),
+            new(3)
+        };
+        Span<TestItem> span = items;
+        
+        // Act
+        int result = span.Sum(x => x.Value);
+        
+        // Assert
+        await Assert.That(result).IsEqualTo(6);
+    }
+}