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mod/PLibCore/Detours/LazyDetouredField.cs

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+/*
+ * Copyright 2022 Peter Han
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+ * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+using System;
+
+namespace PeterHan.PLib.Detours {
+	/// <summary>
+	/// Stores delegates used to read and write fields or properties. This version is lazy and
+	/// only calculates the destination when it is first used.
+	/// 
+	/// This class is not thread safe.
+	/// </summary>
+	/// <typeparam name="P">The containing type of the field or property.</typeparam>
+	/// <typeparam name="T">The element type of the field or property.</typeparam>
+	internal sealed class LazyDetouredField<P, T> : IDetouredField<P, T> {
+		/// <summary>
+		/// Invoke to get the field/property value.
+		/// </summary>
+		public Func<P, T> Get {
+			get {
+				Initialize();
+				return getter;
+			}
+		}
+
+		/// <summary>
+		/// The field name.
+		/// </summary>
+		public string Name { get; }
+
+		/// <summary>
+		/// Invoke to set the field/property value.
+		/// </summary>
+		public Action<P, T> Set {
+			get {
+				Initialize();
+				return setter;
+			}
+		}
+
+		/// <summary>
+		/// The function to get the field value.
+		/// </summary>
+		private Func<P, T> getter;
+
+		/// <summary>
+		/// The function to set the field value.
+		/// </summary>
+		private Action<P, T> setter;
+
+		/// <summary>
+		/// The target type.
+		/// </summary>
+		private readonly Type type;
+
+		internal LazyDetouredField(Type type, string name) {
+			this.type = type ?? throw new ArgumentNullException(nameof(type));
+			Name = name ?? throw new ArgumentNullException(nameof(name));
+			getter = null;
+			setter = null;
+		}
+
+		/// <summary>
+		/// Initializes the getter and setter functions immediately if necessary.
+		/// </summary>
+		public void Initialize() {
+			if (getter == null && setter == null) {
+				var dt = PDetours.DetourField<P, T>(Name);
+				getter = dt.Get;
+				setter = dt.Set;
+			}
+		}
+
+		public override string ToString() {
+			return string.Format("LazyDetouredField[type={1},name={0}]", Name, type.FullName);
+		}
+	}
+}