Dictionary: SearchAround

Nixill · Jun 13, 2021 · ebea75d · ebea75d
1 parent 6742a22
commit ebea75d
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Showing 2 changed files with 47 additions and 38 deletions.
diff --git a/CSharp.Nixill/src/Collections/AVLTree/AVLTreeDictionary.cs b/CSharp.Nixill/src/Collections/AVLTree/AVLTreeDictionary.cs
@@ -17,7 +17,7 @@ public class AVLTreeDictionary<K, V> : INavigableDictionary<K, V> {
     #region Implementing IDictionary<K, V>
     public V this[K key] {
       get {
-        AVLTreeSet<KeyValuePair<K, V>>.NodeTriplet nodes = BackingSet.SearchAround(new KeyValuePair<K, V>(key, DefaultValue));
+        NodeTriplet<KeyValuePair<K, V>> nodes = BackingSet.SearchAround(new KeyValuePair<K, V>(key, DefaultValue));
         if (nodes.HasEqualValue) {
           return nodes.EqualValue.Value;
         }
@@ -80,6 +80,16 @@ public AVLTreeDictionary(IEnumerable<KeyValuePair<K, V>> elems, Comparison<K> co
     #region Public Methods
     /// Documented in GitHub.
     public bool IsEmpty() => BackingSet.IsEmpty();
+
+    public NodeTriplet<KeyValuePair<K, V>> EntriesAround(K from) => BackingSet.SearchAround(new KeyValuePair<K, V>(from, default(V)));
+
+    public NodeTriplet<K> KeysAround(K from) {
+      var entries = EntriesAround(from);
+      var lesser = (entries.HasLesserValue) ? new AVLTreeSet<K>.Node<K> { Data = entries.LesserValue.Key } : null;
+      var equal = (entries.HasLesserValue) ? new AVLTreeSet<K>.Node<K> { Data = entries.LesserValue.Key } : null;
+      var greater = (entries.HasLesserValue) ? new AVLTreeSet<K>.Node<K> { Data = entries.LesserValue.Key } : null;
+      return new NodeTriplet<K>((lesser, equal, greater));
+    }
     #endregion
 
     #region Interface Implementations
@@ -239,7 +249,7 @@ public void Add(K key, V value) {
 
     // Documented in GitHub.
     public bool TryGetValue(K key, out V value) {
-      AVLTreeSet<KeyValuePair<K, V>>.NodeTriplet nodes = BackingSet.SearchAround(new KeyValuePair<K, V>(key, DefaultValue));
+      NodeTriplet<KeyValuePair<K, V>> nodes = BackingSet.SearchAround(new KeyValuePair<K, V>(key, DefaultValue));
       if (nodes.HasEqualValue) {
         value = nodes.EqualValue.Value;
         return true;

diff --git a/CSharp.Nixill/src/Collections/AVLTree/AVLTreeSet.cs b/CSharp.Nixill/src/Collections/AVLTree/AVLTreeSet.cs
@@ -295,8 +295,8 @@ public void Print() {
     /// Returns the value requested if the collection contains it, as well
     /// as the next higher and lower values.
     /// </summary>
-    public NodeTriplet SearchAround(T value) {
-      return new NodeTriplet(SearchBounded(value));
+    public NodeTriplet<T> SearchAround(T value) {
+      return new NodeTriplet<T>(SearchBounded(value));
     }
 
     /// <summary>
@@ -1072,51 +1072,50 @@ public void Visit(VisitNodeHandler<Node<TElem>> visitor, int level) {
       #endregion
     }
 
+    #endregion
+  }
 
-    public class NodeTriplet {
-      private readonly NodeValue Lesser;
-      private readonly NodeValue Equal;
-      private readonly NodeValue Greater;
+  public class NodeTriplet<T> {
+    internal readonly NodeValue Lesser;
+    internal readonly NodeValue Equal;
+    internal readonly NodeValue Greater;
 
-      public bool HasLesserValue => Lesser != null;
-      public bool HasEqualValue => Equal != null;
-      public bool HasGreaterValue => Greater != null;
+    public bool HasLesserValue => Lesser != null;
+    public bool HasEqualValue => Equal != null;
+    public bool HasGreaterValue => Greater != null;
 
-      public T LesserValue {
-        get {
-          if (HasLesserValue) return Lesser.Value;
-          else throw new InvalidOperationException("No lesser value exists.");
-        }
+    public T LesserValue {
+      get {
+        if (HasLesserValue) return Lesser.Value;
+        else throw new InvalidOperationException("No lesser value exists.");
       }
+    }
 
-      public T EqualValue {
-        get {
-          if (HasEqualValue) return Equal.Value;
-          else throw new InvalidOperationException("No equal value exists.");
-        }
+    public T EqualValue {
+      get {
+        if (HasEqualValue) return Equal.Value;
+        else throw new InvalidOperationException("No equal value exists.");
       }
+    }
 
-      public T GreaterValue {
-        get {
-          if (HasGreaterValue) return Greater.Value;
-          else throw new InvalidOperationException("No greater value exists.");
-        }
+    public T GreaterValue {
+      get {
+        if (HasGreaterValue) return Greater.Value;
+        else throw new InvalidOperationException("No greater value exists.");
       }
+    }
 
-      internal NodeTriplet((AVLTreeSet<T>.Node<T> L, AVLTreeSet<T>.Node<T> E, AVLTreeSet<T>.Node<T> G) nodes) {
-        if (nodes.L != null) Lesser = new NodeValue(nodes.L.Data);
-        if (nodes.E != null) Equal = new NodeValue(nodes.E.Data);
-        if (nodes.G != null) Greater = new NodeValue(nodes.G.Data);
-      }
+    internal NodeTriplet((AVLTreeSet<T>.Node<T> L, AVLTreeSet<T>.Node<T> E, AVLTreeSet<T>.Node<T> G) nodes) {
+      if (nodes.L != null) Lesser = new NodeValue(nodes.L.Data);
+      if (nodes.E != null) Equal = new NodeValue(nodes.E.Data);
+      if (nodes.G != null) Greater = new NodeValue(nodes.G.Data);
+    }
 
-      private class NodeValue {
-        public readonly T Value;
-        public NodeValue(T val) {
-          Value = val;
-        }
+    internal class NodeValue {
+      public readonly T Value;
+      public NodeValue(T val) {
+        Value = val;
       }
     }
-
-    #endregion
   }
 }