feat: initial commit

dotnet/MaigoLabs.NeedLe.Common/Trie.cs

@@ -0,0 +1,33 @@
+namespace MaigoLabs.NeedLe.Common;
+
+public class TrieNode
+{
+    public required TrieNode? Parent { get; set; }
+    public required Dictionary<int, TrieNode> Children { get; set; } // Unicode code point -> child node
+    public required List<int> TokenIds { get; set; }
+    public required List<int> SubTreeTokenIds { get; set; } // Empty on root.
+}
+
+public static class TrieNodeExtensions
+{
+    public static TrieNode? TraverseStep(this TrieNode? node, int codePoint, bool isIgnorable = false) =>
+        (node?.Children.TryGetValue(codePoint, out var child) ?? false)
+            ? child
+            : isIgnorable ? node : null;
+
+    public static TrieNode? Traverse(this TrieNode? node, int[] codePoints, bool isIgnorable = false)
+    {
+        if (node == null) return null;
+        foreach (var codePoint in codePoints)
+        {
+            node = node?.TraverseStep(codePoint, isIgnorable);
+            if (node == null) return null;
+        }
+        return node;
+    }
+
+    public static List<int> GetTokenIds(this TrieNode? node, bool includeSubTree = false) =>
+        (includeSubTree ? node?.SubTreeTokenIds : node?.TokenIds) ?? [];
+
+    public static bool IsTokenExactMatch(this TrieNode? node, int tokenId) => node?.TokenIds.Contains(tokenId) ?? false;
+}