Add MergeEquivalentAnalyses

src/SIL.Machine.Morphology.HermitCrab/AnalysisStratumRule.cs

@@ -72,6 +72,11 @@ public IEnumerable<Word> Apply(Word input)
 
             _prulesRule.Apply(input);
             input.Freeze();
+            IDictionary<Shape, Word> shapeWord = null;
+            // Don't merge if tracing because it messes up the tracing.
+            bool mergeEquivalentAnalyses = _morpher.MergeEquivalentAnalyses && !_morpher.TraceManager.IsTracing;
+            if (mergeEquivalentAnalyses)
+                shapeWord = new Dictionary<Shape, Word>(FreezableEqualityComparer<Shape>.Default);
 
             // AnalysisStratumRule.Apply should cover the inverse of SynthesisStratumRule.Apply.
             IEnumerable<Word> mruleOutWords = ApplyTemplates(input).Concat(ApplyMorphologicalRules(input));
@@ -82,6 +87,16 @@ public IEnumerable<Word> Apply(Word input)
                 _morpher.TraceManager.EndUnapplyStratum(_stratum, input);
             foreach (Word mruleOutWord in mruleOutWords)
             {
+                if (mergeEquivalentAnalyses)
+                {
+                    Shape shape = mruleOutWord.Shape;
+                    if (shapeWord.ContainsKey(shape))
+                    {
+                        shapeWord[shape].Alternatives.Add(mruleOutWord);
+                         continue;
+                    }
+                    shapeWord[shape] = mruleOutWord;
+                }
                 output.Add(mruleOutWord);
                 if (_morpher.TraceManager.IsTracing)
                     _morpher.TraceManager.EndUnapplyStratum(_stratum, mruleOutWord);

src/SIL.Machine.Morphology.HermitCrab/Morpher.cs

@@ -56,6 +56,7 @@ public Morpher(ITraceManager traceManager, Language lang)
             _synthesisRule = lang.CompileSynthesisRule(this);
             MaxStemCount = 2;
             MaxUnapplications = 0;
+            MergeEquivalentAnalyses = true;
             LexEntrySelector = entry => true;
             RuleSelector = rule => true;
 
@@ -78,6 +79,12 @@ public ITraceManager TraceManager
         /// </summary>
         public int MaxUnapplications { get; set; }
 
+        /// <summary>
+        /// Merge analyses that have equivalent shapes.
+        /// Merged analyses will be expanded if lexical lookup succeeds.
+        /// </summary>
+        public bool MergeEquivalentAnalyses { get; set; }
+
         public Func<LexEntry, bool> LexEntrySelector { get; set; }
         public Func<IHCRule, bool> RuleSelector { get; set; }
 
@@ -304,10 +311,13 @@ private IEnumerable<Word> Synthesize(string word, ConcurrentQueue<Word> analyses
                             analyses.TryDequeue(out Word analysisWord);
                             foreach (Word synthesisWord in LexicalLookup(analysisWord))
                             {
-                                foreach (Word validWord in _synthesisRule.Apply(synthesisWord).Where(IsWordValid))
+                                foreach (Word alternativeSynthesis in synthesisWord.ExpandAlternatives())
                                 {
-                                    if (IsMatch(word, validWord))
-                                        matches.Add(validWord);
+                                    foreach (Word validWord in _synthesisRule.Apply(alternativeSynthesis).Where(IsWordValid))
+                                    {
+                                        if (IsMatch(word, validWord))
+                                            matches.Add(validWord);
+                                    }
                                 }
                             }
                         }

src/SIL.Machine.Morphology.HermitCrab/Word.cs

@@ -31,6 +31,8 @@ public class Word : Freezable<Word>, IAnnotatedData<ShapeNode>, ICloneable<Word>
         private bool _isPartial;
         private readonly Dictionary<string, HashSet<int>> _disjunctiveAllomorphIndices;
         private int _mruleAppCount = 0;
+        private readonly Word _cloneOf = null;
+        private readonly IList<Word> _alternatives = new List<Word>();
 
         public Word(RootAllomorph rootAllomorph, FeatureStruct realizationalFS)
         {
@@ -92,6 +94,7 @@ protected Word(Word word)
                 kvp => new HashSet<int>(kvp.Value)
             );
             _mruleAppCount = word._mruleAppCount;
+            _cloneOf = word;
         }
 
         public IEnumerable<Annotation<ShapeNode>> Morphs
@@ -396,6 +399,52 @@ internal void NonHeadUnapplied(Word nonHead)
             _nonHeadAppIndex++;
         }
 
+        internal Word CloneOf
+        {
+            get { return _cloneOf; }
+        }
+
+        internal IList<Word> Alternatives
+        {
+            get { return _alternatives; }
+        }
+
+        internal IList<Word> ExpandAlternatives()
+        {
+            IList<Word> alternatives = new List<Word>();
+            IList<Word> originals = _cloneOf?.ExpandAlternatives();
+            // Update the alternatives of _cloneOf with any changes made since the clone.
+            if (originals == null || originals.Count < 2)
+            {
+                // Special case.
+                alternatives.Add(this);
+            }
+            else
+            {
+                foreach (Word original in originals)
+                {
+                    Word alternative = original.Clone();
+                    alternative._shape = this.Shape;
+                    // Add new rules to alternative.
+                    foreach (IMorphologicalRule rule in MorphologicalRules)
+                    {
+                        if (_cloneOf != null && _cloneOf.MorphologicalRules.Contains(rule))
+                            continue;
+                        alternative.MorphologicalRuleUnapplied(rule);
+                    }
+                    if (RootAllomorph != null)
+                        alternative.RootAllomorph = RootAllomorph;
+                    alternative.Freeze();
+                    alternatives.Add(alternative);
+                }
+
+            }
+            // Add local alternatives.
+            foreach (Word alternative in _alternatives)
+                alternatives.AddRange(alternative.ExpandAlternatives());
+            return alternatives;
+        }
+
         public Allomorph GetAllomorph(Annotation<ShapeNode> morph)
         {
             var alloID = (string)morph.FeatureStruct.GetValue(HCFeatureSystem.Allomorph);