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AspClassic.Scripting/Runtime/ContextId.cs

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+using System;
+using System.Collections.Generic;
+
+namespace AspClassic.Scripting.Runtime;
+
+[Serializable]
+public struct ContextId : IEquatable<ContextId>
+{
+	private int _id;
+
+	private static Dictionary<object, ContextId> _contexts = new Dictionary<object, ContextId>();
+
+	private static int _maxId = 1;
+
+	public static readonly ContextId Empty = default(ContextId);
+
+	public int Id => _id;
+
+	internal ContextId(int id)
+	{
+		_id = id;
+	}
+
+	public static ContextId RegisterContext(object identifier)
+	{
+		lock (_contexts)
+		{
+			if (_contexts.TryGetValue(identifier, out var _))
+			{
+				throw Error.LanguageRegistered();
+			}
+			ContextId result = default(ContextId);
+			result._id = _maxId++;
+			return result;
+		}
+	}
+
+	public static ContextId LookupContext(object identifier)
+	{
+		lock (_contexts)
+		{
+			if (_contexts.TryGetValue(identifier, out var value))
+			{
+				return value;
+			}
+		}
+		return Empty;
+	}
+
+	public bool Equals(ContextId other)
+	{
+		return _id == other._id;
+	}
+
+	public override int GetHashCode()
+	{
+		return _id;
+	}
+
+	public override bool Equals(object obj)
+	{
+		if (!(obj is ContextId contextId))
+		{
+			return false;
+		}
+		return contextId._id == _id;
+	}
+
+	public static bool operator ==(ContextId self, ContextId other)
+	{
+		return self.Equals(other);
+	}
+
+	public static bool operator !=(ContextId self, ContextId other)
+	{
+		return !self.Equals(other);
+	}
+}