From c434699322a5669167c27642fc86af73e5253b1f Mon Sep 17 00:00:00 2001
From: John Maxwell <maxwellparc@gmail.com>
Date: Thu, 14 Nov 2024 11:07:45 -0800
Subject: [PATCH] Try ignoring duplicate shapes to fix LT-21988

---
 .../AnalysisLanguageRule.cs                   |  5 +++-
 .../AnalysisStratumRule.cs                    | 23 +++++++++++++++++++
 .../XmlLanguageSerializationTests.cs          | 11 +++++++++
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/src/SIL.Machine.Morphology.HermitCrab/AnalysisLanguageRule.cs b/src/SIL.Machine.Morphology.HermitCrab/AnalysisLanguageRule.cs
index b4673ca55..8c700a09a 100644
--- a/src/SIL.Machine.Morphology.HermitCrab/AnalysisLanguageRule.cs
+++ b/src/SIL.Machine.Morphology.HermitCrab/AnalysisLanguageRule.cs
@@ -31,6 +31,8 @@ public IEnumerable<Word> Apply(Word input)
 
                 HashSet<Word> outputSet = tempSet;
                 outputSet.Clear();
+                AnalysisStratumRule stratumRule = _rules[i] as AnalysisStratumRule;
+                stratumRule?.InitializeDuplicationDetection();
 
                 foreach (Word inData in inputSet)
                 {
@@ -41,9 +43,10 @@ public IEnumerable<Word> Apply(Word input)
                     }
                 }
 
+                stratumRule?.ClearDuplicationDetection();
                 tempSet = inputSet;
                 inputSet = outputSet;
-            }
+            } 
 
             return results;
         }
diff --git a/src/SIL.Machine.Morphology.HermitCrab/AnalysisStratumRule.cs b/src/SIL.Machine.Morphology.HermitCrab/AnalysisStratumRule.cs
index 97c31c2e4..00972d41c 100644
--- a/src/SIL.Machine.Morphology.HermitCrab/AnalysisStratumRule.cs
+++ b/src/SIL.Machine.Morphology.HermitCrab/AnalysisStratumRule.cs
@@ -14,6 +14,7 @@ internal class AnalysisStratumRule : IRule<Word, ShapeNode>
         private readonly IRule<Word, ShapeNode> _templatesRule;
         private readonly Stratum _stratum;
         private readonly Morpher _morpher;
+        private HashSet<Shape> _shapeSet;
 
         public AnalysisStratumRule(Morpher morpher, Stratum stratum)
         {
@@ -58,6 +59,16 @@ public AnalysisStratumRule(Morpher morpher, Stratum stratum)
             }
         }
 
+        public void InitializeDuplicationDetection()
+        {
+            _shapeSet = new HashSet<Shape>(FreezableEqualityComparer<Shape>.Default);
+        }
+
+        public void ClearDuplicationDetection()
+        {
+            _shapeSet = null;
+        }
+
         public IEnumerable<Word> Apply(Word input)
         {
             if (_morpher.TraceManager.IsTracing)
@@ -117,6 +128,18 @@ private IEnumerable<Word> ApplyMorphologicalRules(Word input)
 
         private IEnumerable<Word> ApplyTemplates(Word input)
         {
+            if (_shapeSet != null)
+            {
+                // Ignore shapes that we have already tried at this level of the stratum.
+                // ApplyTemplates is called at the very beginning of applying the analysis stratum.
+                // It is also called recursively by ApplyMorphologicalRules if the rules are unordered.
+                // In this case, we can still use the same shapeSet since the templates and morphological
+                // rules continue to be applied until there are no more changes, and so
+                // trying this shape again won't change the results.
+                if (_shapeSet.Contains(input.Shape))
+                    yield break;
+                _shapeSet.Add(input.Shape);
+            }
             foreach (Word tempOutWord in _templatesRule.Apply(input).Distinct(FreezableEqualityComparer<Word>.Default))
             {
                 switch (_stratum.MorphologicalRuleOrder)
diff --git a/tests/SIL.Machine.Morphology.HermitCrab.Tests/XmlLanguageSerializationTests.cs b/tests/SIL.Machine.Morphology.HermitCrab.Tests/XmlLanguageSerializationTests.cs
index 390c67c05..0ace2578f 100644
--- a/tests/SIL.Machine.Morphology.HermitCrab.Tests/XmlLanguageSerializationTests.cs
+++ b/tests/SIL.Machine.Morphology.HermitCrab.Tests/XmlLanguageSerializationTests.cs
@@ -1,4 +1,5 @@
 using NUnit.Framework;
+using System.Diagnostics;
 
 namespace SIL.Machine.Morphology.HermitCrab;
 
@@ -27,4 +28,14 @@ public void RoundTripXml()
                 File.Delete(TempXmlFileName);
         }
     }
+
+    [Test]
+    public void TestParseWord()
+    {
+        Language language = XmlLanguageLoader.Load("C:\\Users\\PC\\AppData\\Local\\Temp\\Mbugwe LizzieHC practice.xml");
+        Morpher morpher = new Morpher(new TraceManager(), language);
+        var output = morpher.ParseWord("wa", out _);
+        Debug.WriteLine(output);
+    }
+
 }