Merge branch 'index-encoding'

Author: benbierens

Tests/FrameworkTests/Utils/RunLengthEncodingRunTests.cs

@@ -0,0 +1,193 @@
+using NUnit.Framework;
+using NUnit.Framework.Interfaces;
+using static FrameworkTests.Utils.RunLengthEncodingTests;
+
+namespace FrameworkTests.Utils
+{
+    [TestFixture]
+    public class RunLengthEncodingRunTests
+    {
+        [Test]
+        [Combinatorial]
+        public void RunIncludes(
+            [Values(0, 1, 2, 3)] int start,
+            [Values(1, 2, 3, 4)] int length)
+        {
+            var run = new Run(start, length);
+
+            var shouldInclude = Enumerable.Range(start, length).ToArray();
+            var shouldExclude = new int[]
+            {
+                shouldInclude.Min() - 1,
+                shouldInclude.Max() + 1
+            };
+
+            foreach (var incl in shouldInclude)
+            {
+                Assert.That(run.Includes(incl));
+            }
+            foreach (var excl in shouldExclude)
+            {
+                Assert.That(!run.Includes(excl));
+            }
+        }
+
+        [Test]
+        public void RunExpandToInclude()
+        {
+            var run = new Run(2, 3);
+            Assert.That(run.Includes(2));
+            Assert.That(run.Includes(4));
+            Assert.That(!run.Includes(5));
+
+            Assert.That(run.ExpandToInclude(1), Is.False);
+            Assert.That(run.ExpandToInclude(2), Is.False);
+            Assert.That(run.ExpandToInclude(4), Is.False);
+            Assert.That(run.ExpandToInclude(6), Is.False);
+
+            Assert.That(run.ExpandToInclude(5), Is.True);
+            Assert.That(run.Includes(5));
+            Assert.That(!run.Includes(6));
+        }
+
+        [Test]
+        public void RunCanUnsetLastIndex()
+        {
+            var run = new Run(0, 3);
+            Assert.That(run.Includes(2));
+            var update = run.Unset(2);
+            Assert.That(!run.Includes(2));
+
+            Assert.That(update.NewRuns.Length, Is.EqualTo(0));
+            Assert.That(update.RemoveRuns.Length, Is.EqualTo(0));
+        }
+
+        [Test]
+        public void RunCanSplit()
+        {
+            var run = new Run(0, 6); // 0, 1, 2, 3, 4, 5
+            var update = run.Unset(2);
+
+            Assert.That(run.Start, Is.EqualTo(0));
+            Assert.That(run.Length, Is.EqualTo(2)); // 0, 1
+            Assert.That(!run.Includes(2));
+
+            Assert.That(update.NewRuns.Length, Is.EqualTo(1));
+            Assert.That(update.RemoveRuns.Length, Is.EqualTo(0));
+
+            Assert.That(!update.NewRuns[0].Includes(2));
+            Assert.That(update.NewRuns[0].Start, Is.EqualTo(3));
+            Assert.That(update.NewRuns[0].Length, Is.EqualTo(3)); // 3, 4, 5
+            Assert.That(!update.NewRuns[0].Includes(6));
+        }
+
+        [Test]
+        public void RunReplacesSelfWhenUnsetFirstIndex()
+        {
+            var run = new Run(0, 5);
+            var update = run.Unset(0);
+
+            Assert.That(update.NewRuns.Length, Is.EqualTo(1));
+            Assert.That(update.RemoveRuns.Length, Is.EqualTo(1));
+
+            Assert.That(update.RemoveRuns[0], Is.SameAs(run));
+            Assert.That(update.NewRuns[0].Start, Is.EqualTo(1));
+            Assert.That(update.NewRuns[0].Length, Is.EqualTo(4));
+        }
+
+        [Test]
+        public void CanIterateIndices()
+        {
+            var run = new Run(2, 4);
+            var seen = new List<int>();
+            run.Iterate(i => seen.Add(i));
+
+            CollectionAssert.AreEqual(new[] { 2, 3, 4, 5 }, seen);
+        }
+    }
+
+    public class Run
+    {
+        public Run(int start, int length)
+        {
+            Start = start;
+            Length = length;
+        }
+
+        public int Start { get; }
+        public int Length { get; private set; }
+
+        public bool Includes(int index)
+        {
+            return index >= Start && index < (Start + Length);
+        }
+
+        public bool ExpandToInclude(int index)
+        {
+            if (index == (Start + Length))
+            {
+                Length++;
+                return true;
+            }
+            return false;
+        }
+
+        public RunUpdate Unset(int index)
+        {
+            if (!Includes(index))
+            {
+                return new RunUpdate();
+            }
+
+            if (index == Start)
+            {
+                // First index: Replace self with new run at next index, unless empty.
+                if (Length == 1)
+                {
+                    return new RunUpdate(Array.Empty<Run>(), new[] { this });
+                }
+                return new RunUpdate(
+                    newRuns: new[] { new Run(Start + 1, Length - 1) },
+                    removeRuns: new[] { this }
+                );
+            }
+
+            if (index == (Start + Length - 1))
+            {
+                // Last index: Become one smaller.
+                Length--;
+                return new RunUpdate();
+            }
+
+            // Split:
+            var newRunLength = (Start + Length - 1) - index;
+            Length = index - Start;
+            return new RunUpdate(new[] { new Run(index + 1, newRunLength) }, Array.Empty<Run>());
+        }
+        
+        public void Iterate(Action<int> action)
+        {
+            for (var i = 0; i < Length; i++)
+            {
+                action(Start + i);
+            }
+        }
+    }
+
+    public class RunUpdate
+    {
+        public RunUpdate()
+            : this(Array.Empty<Run>(), Array.Empty<Run>())
+        {
+        }
+
+        public RunUpdate(Run[] newRuns, Run[] removeRuns)
+        {
+            NewRuns = newRuns;
+            RemoveRuns = removeRuns;
+        }
+
+        public Run[] NewRuns { get; }
+        public Run[] RemoveRuns { get; }
+    }
+}