TextVariationHandler can now clear its previous history

- Uses XorShift style bit mixing on hashes to avoid collisions when input and section are identical
- Added tests to verify basic text variation is working as required.

Assets/Fungus/Scripts/Utils/TextVariationHandler.cs

@@ -70,6 +70,11 @@ namespace Fungus
 
         static Dictionary<int, int> hashedSections = new Dictionary<int, int>();
 
+        static public void ClearHistory()
+        {
+            hashedSections.Clear();
+        }
+
         /// <summary>
         /// Simple parser to extract depth matched []. 
         /// 
@@ -190,7 +195,14 @@ namespace Fungus
 
                 //fetched hashed value
                 int index = -1;
-                int key = input.GetHashCode() ^ curSection.entire.GetHashCode() ^ parentHash;
+                
+                //as input and entire can be the same thing we need to shuffle these bits
+                //we use some xorshift style mixing
+                int inputHash = input.GetHashCode();
+                inputHash ^= inputHash << 13;
+                int curSecHash = curSection.entire.GetHashCode();
+                curSecHash ^= curSecHash >> 17;
+                int key = inputHash ^ curSecHash ^ parentHash;
 
                 int foundVal = 0;
                 if (hashedSections.TryGetValue(key, out foundVal))

Assets/Tests/StringSubstitution/Editor.meta

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Assets/Tests/StringSubstitution/Editor/FungusTextVariationSelectionTests.cs

@@ -0,0 +1,114 @@
+using UnityEngine;
+using UnityEngine.TestTools;
+using NUnit.Framework;
+using System.Collections;
+
+public class FungusTextVariationSelectionTests
+{
+    [Test]
+    public void SimpleSequenceSelection()
+    {
+        Fungus.TextVariationHandler.ClearHistory();
+
+        string startingText = @"This is test [a|b|c]";
+        string startingTextA = @"This is test a";
+        string startingTextB = @"This is test b";
+        string startingTextC = @"This is test c";
+
+        string res = string.Empty;
+
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextA);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextB);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextC);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextC);
+    }
+
+    [Test]
+    public void SimpleCycleSelection()
+    {
+        Fungus.TextVariationHandler.ClearHistory();
+
+        string startingText = @"This is test [&a|b|c]";
+        string startingTextA = @"This is test a";
+        string startingTextB = @"This is test b";
+        string startingTextC = @"This is test c";
+
+        string res = string.Empty;
+
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextA);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextB);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextC);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextA);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextB);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextC);
+    }
+
+    [Test]
+    public void SimpleOnceSelection()
+    {
+        Fungus.TextVariationHandler.ClearHistory();
+
+        string startingText = @"This is test [!a|b|c]";
+        string startingTextA = @"This is test a";
+        string startingTextB = @"This is test b";
+        string startingTextC = @"This is test c";
+        string startingTextD = @"This is test ";
+
+        string res = string.Empty;
+
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextA);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextB);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextC);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextD);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextD);
+    }
+
+    [Test]
+    public void NestedSelection()
+    {
+        Fungus.TextVariationHandler.ClearHistory();
+
+        string startingText = @"This is test [a||sub [~a|b]|[!b|[~c|d]]]";
+        string startingTextA = @"This is test a";
+        string startingTextBlank = @"This is test ";
+        string startingTextSubA = @"This is test sub a";
+        string startingTextSubB = @"This is test sub b";
+        string startingTextB = @"This is test b";
+        string startingTextC = @"This is test c";
+        string startingTextD = @"This is test d";
+
+        string res = string.Empty;
+
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextA);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextBlank);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        if(res != startingTextSubA && res != startingTextSubB)
+        {
+            Assert.Fail();
+        }
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        Assert.AreEqual(res, startingTextB);
+        res = Fungus.TextVariationHandler.SelectVariations(startingText);
+        if (res != startingTextC && res != startingTextD)
+        {
+            Assert.Fail();
+        }
+    }
+}

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