(feature): expression extensions

src/MaksIT.Core.Tests/Extensions/ExpressionExtensionsTests.cs

@@ -0,0 +1,59 @@
+using System.Linq.Expressions;
+
+using MaksIT.Core.Extensions;
+
+
+namespace MaksIT.Core.Tests.Extensions;
+
+public class ExpressionExtensionsTests {
+  [Fact]
+  public void CreateContainsPredicate_ShouldReturnTrue_WhenIdIsInList() {
+    // Arrange
+    var ids = new List<Guid> { Guid.NewGuid(), Guid.NewGuid(), Guid.NewGuid() };
+    var targetId = ids[1];
+    var predicate = ExpressionExtensions.CreateContainsPredicate<TestEntity>(ids, nameof(TestEntity.Id));
+
+    // Act
+    var result = predicate.Compile()(new TestEntity { Id = targetId });
+
+    // Assert
+    Assert.True(result);
+  }
+
+  [Fact]
+  public void CreateContainsPredicate_ShouldReturnFalse_WhenIdIsNotInList() {
+    // Arrange
+    var ids = new List<Guid> { Guid.NewGuid(), Guid.NewGuid(), Guid.NewGuid() };
+    var targetId = Guid.NewGuid();
+    var predicate = ExpressionExtensions.CreateContainsPredicate<TestEntity>(ids, nameof(TestEntity.Id));
+
+    // Act
+    var result = predicate.Compile()(new TestEntity { Id = targetId });
+
+    // Assert
+    Assert.False(result);
+  }
+
+  [Fact]
+  public void CombineWith_ShouldCombineTwoPredicates() {
+    // Arrange
+    Expression<Func<TestEntity, bool>> firstPredicate = x => x.Age > 18;
+    Expression<Func<TestEntity, bool>> secondPredicate = x => x.Name.StartsWith("A");
+
+    // Act
+    var combinedPredicate = firstPredicate.CombineWith(secondPredicate);
+    var compiledPredicate = combinedPredicate.Compile();
+
+    // Assert
+    Assert.True(compiledPredicate(new TestEntity { Age = 20, Name = "Alice" }));
+    Assert.False(compiledPredicate(new TestEntity { Age = 17, Name = "Alice" }));
+    Assert.False(compiledPredicate(new TestEntity { Age = 20, Name = "Bob" }));
+  }
+
+  private class TestEntity {
+    public Guid Id { get; set; }
+    public int Age { get; set; }
+    public string Name { get; set; }
+  }
+}
+

src/MaksIT.Core/Extensions/ExpressionExtensions.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+
+
+namespace MaksIT.Core.Extensions;
+
+public static class ExpressionExtensions {
+
+  public static Expression<Func<T, bool>> CreateContainsPredicate<T>(IEnumerable<Guid> ids, string propertyName) {
+    var parameter = Expression.Parameter(typeof(T), "x");
+    var property = Expression.Property(parameter, propertyName);
+    var containsMethod = typeof(List<Guid>).GetMethod("Contains", new[] { typeof(Guid) });
+    var containsCall = Expression.Call(Expression.Constant(ids), containsMethod!, property);
+
+    return Expression.Lambda<Func<T, bool>>(containsCall, parameter);
+  }
+
+  public static Expression<Func<T, bool>> CombineWith<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second) {
+    var parameter = first.Parameters[0];
+    var visitor = new SubstituteParameterVisitor(second.Parameters[0], parameter);
+    var secondBody = visitor.Visit(second.Body);
+    var combinedBody = Expression.AndAlso(first.Body, secondBody);
+
+    return Expression.Lambda<Func<T, bool>>(combinedBody, parameter);
+  }
+
+  private class SubstituteParameterVisitor : ExpressionVisitor {
+    private readonly ParameterExpression _oldParameter;
+    private readonly ParameterExpression _newParameter;
+
+    public SubstituteParameterVisitor(ParameterExpression oldParameter, ParameterExpression newParameter) {
+      _oldParameter = oldParameter;
+      _newParameter = newParameter;
+    }
+
+    protected override Expression VisitParameter(ParameterExpression node) {
+      // Replace old parameter with the new one
+      return node == _oldParameter ? _newParameter : base.VisitParameter(node);
+    }
+  }
+}
+

src/MaksIT.Core/MaksIT.Core.csproj

@@ -8,7 +8,7 @@
 
     <!-- NuGet package metadata -->
     <PackageId>MaksIT.Core</PackageId>
-    <Version>1.1.0</Version>
+    <Version>1.1.1</Version>
     <Authors>Maksym Sadovnychyy</Authors>
     <Company>MAKS-IT</Company>
     <Product>MaksIT.Core</Product>