feat: combine existing predicates (#227)

Expressif.Testing/Predicates/PredicateCombinerTest.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Expressif.Predicates.Text;
+using Expressif.Predicates;
+
+namespace Expressif.Testing.Predicates;
+public class PredicateCombinerTest
+{
+    [Test]
+    [TestCase("Nikola Tesla", true)]
+    [TestCase("Albert Einstein", false)]
+    public void Build_Combination_Success(string value, bool expected)
+    {
+        var combiner = new PredicateCombiner();
+        var combination = combiner.With(new StartsWith(() => "Alb"))
+                            .Or(new EndsWith(() => "sla"))
+                            .And(new StartsWith(() => "Nik"));
+        var combined = combination.Build();
+        Assert.That(combined.Evaluate(value), Is.EqualTo(expected));
+    }
+
+    [Test]
+    [TestCase("Nikola Tesla", true)]
+    [TestCase("Albert Einstein", false)]
+    public void Build_CombinationWithNot_Success(string value, bool expected)
+    {
+        var combiner = new PredicateCombiner();
+        var combination = combiner.WithNot(new StartsWith(() => "Alb"))
+                            .Or(new EndsWith(() => "ring"))
+                            .And(new StartsWith(() => "Nik"));
+        var combined = combination.Build();
+        Assert.That(combined.Evaluate(value), Is.EqualTo(expected));
+    }
+
+    [Test]
+    [TestCase("Nikola Tesla", true)]
+    [TestCase("Albert Einstein", false)]
+    public void Build_CombinationUsingNot_Success(string value, bool expected)
+    {
+        var combiner = new PredicateCombiner();
+        var combination = combiner.With(new StartsWith(() => "Nik"))
+                            .Or(new EndsWith(() => "stein"))
+                            .AndNot(new StartsWith(() => "Alb"));
+        var combined = combination.Build();
+        Assert.That(combined.Evaluate(value), Is.EqualTo(expected));
+    }
+}

Expressif/Predicates/PredicateCombiner.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Expressif.Predicates.Operators;
+
+namespace Expressif.Predicates;
+public class PredicateCombiner
+{
+    protected UnaryOperatorFactory UnaryFactory { get; }
+    protected BinaryOperatorFactory BinaryFactory { get; }
+
+    public PredicateCombiner()
+        : this(new(), new()) { }
+
+    public PredicateCombiner(UnaryOperatorFactory unaryFactory , BinaryOperatorFactory binaryFactory)
+        => (UnaryFactory, BinaryFactory) = (unaryFactory, binaryFactory);
+
+    public PredicateRightCombiner With(IPredicate left)
+        => new(UnaryFactory, BinaryFactory, left);
+
+    public PredicateRightCombiner WithNot(IPredicate left)
+        => new(UnaryFactory, BinaryFactory, UnaryFactory.Instantiate("!", left));
+
+    public class PredicateRightCombiner
+    {
+        protected UnaryOperatorFactory UnaryFactory { get; }
+        protected BinaryOperatorFactory BinaryFactory { get; }
+        private IPredicate State { get; }
+
+        internal PredicateRightCombiner(UnaryOperatorFactory unaryFactory, BinaryOperatorFactory binaryFactory, IPredicate state)
+            => (UnaryFactory, BinaryFactory, State) = (unaryFactory, binaryFactory, state);
+
+        public PredicateRightCombiner Or(IPredicate right)
+            => new(UnaryFactory, BinaryFactory, BinaryFactory.Instantiate("OR", State, right));
+
+        public PredicateRightCombiner OrNot(IPredicate right)
+            => Or(UnaryFactory.Instantiate("!", right));
+
+        public PredicateRightCombiner And(IPredicate right)
+            => new(UnaryFactory, BinaryFactory, BinaryFactory.Instantiate("AND", State, right));
+
+        public PredicateRightCombiner AndNot(IPredicate right)
+            => And(UnaryFactory.Instantiate("!", right));
+
+        public PredicateRightCombiner Xor(IPredicate right)
+            => new(UnaryFactory, BinaryFactory, BinaryFactory.Instantiate("XOR", State, right));
+
+        public PredicateRightCombiner XorNot(IPredicate right)
+            => Xor(UnaryFactory.Instantiate("!", right));
+
+        public IPredicate Build()
+                => State!;
+    }
+}