84 lines
2.8 KiB
C#
84 lines
2.8 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Reflection;
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using System.Reflection.Emit;
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using System.Collections.Concurrent;
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using System.ComponentModel;
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namespace BizHawk.Common
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{
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public class SettingsUtil
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{
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private sealed class DefaultValueSetter
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{
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public Action<object, object[]> SetDefaultValues;
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public object[] DefaultValues;
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}
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private static IDictionary<Type, DefaultValueSetter> DefaultValueSetters = new ConcurrentDictionary<Type, DefaultValueSetter>();
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/// <summary>
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/// set all properties (not fields!) of obj with a DefaultValueAttribute to that value
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/// </summary>
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/// <typeparam name="T"></typeparam>
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/// <param name="obj">the obj to act on</param>
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public static void SetDefaultValues<T>(T obj)
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{
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DefaultValueSetter f;
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if (!DefaultValueSetters.TryGetValue(typeof(T), out f))
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{
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f = CreateSetter(typeof(T));
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DefaultValueSetters[typeof(T)] = f;
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}
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f.SetDefaultValues(obj, f.DefaultValues);
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}
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private static DefaultValueSetter CreateSetter(Type t)
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{
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//var dyn = new DynamicMethod("SetDefaultValues_" + t.Name, null, new[] { t }, true);
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var dyn = new DynamicMethod("SetDefaultValues_" + t.Name, null, new[] { typeof(object), typeof(object[]) }, false);
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var il = dyn.GetILGenerator();
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List<object> DefaultValues = new List<object>();
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il.Emit(OpCodes.Ldarg_0); // arg0: object to set properties of
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il.Emit(OpCodes.Castclass, t); // cast to appropriate type
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foreach (var prop in t.GetProperties())
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{
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if (!prop.CanWrite)
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continue;
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MethodInfo method = prop.GetSetMethod(true);
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foreach (object attr in prop.GetCustomAttributes(true))
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{
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if (attr is DefaultValueAttribute)
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{
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object value = (attr as DefaultValueAttribute).Value;
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Type desiredType = method.GetParameters()[0].ParameterType;
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if (!desiredType.IsAssignableFrom(value.GetType()))
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throw new InvalidOperationException(string.Format("Default value assignment will fail for {0}.{1}", t.Name, prop.Name));
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int idx = DefaultValues.Count;
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DefaultValues.Add(value);
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il.Emit(OpCodes.Dup); // object to act on
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il.Emit(OpCodes.Ldarg_1); // arg1: array of default values
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il.Emit(OpCodes.Ldc_I4, idx); // load index
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il.Emit(OpCodes.Ldelem, typeof(object)); // get default value at appropriate index
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il.Emit(OpCodes.Unbox_Any, desiredType); // cast to expected type of set method
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il.Emit(OpCodes.Callvirt, method);
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}
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}
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}
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il.Emit(OpCodes.Pop);
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il.Emit(OpCodes.Ret);
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return new DefaultValueSetter
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{
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SetDefaultValues = (Action<object, object[]>)dyn.CreateDelegate(typeof(Action<object, object[]>)),
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DefaultValues = DefaultValues.ToArray()
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};
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}
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}
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}
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