73 lines
2.9 KiB
C#
73 lines
2.9 KiB
C#
using System;
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using System.Linq;
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using System.Reflection;
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namespace Server.Utilities
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{
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public static class ActivatorUtil
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{
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public static ConstructorInfo GetConstructor(Type type)
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{
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try
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{
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return type.GetConstructor(Type.EmptyTypes)
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?? type.GetConstructors().Single(info => info.GetParameters().All(x => x.IsOptional))
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?? throw new TypeInitializationException(type.ToString(), new Exception($"There is no empty/default constructor for {type}"));
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}
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catch (Exception e)
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{
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throw new TypeInitializationException(type.ToString(), e);
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}
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}
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public static ConstructorInfo GetConstructor(Type type, params Type[] args)
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{
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try
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{
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return args.All(x => x != null) ? type.GetConstructor(args) : null ?? type.GetConstructors().Single(info =>
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{
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var paramList = info.GetParameters().ToList();
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// If more args are given than parameters, skip.
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if (args.Length > paramList.Count)
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return false;
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// check all given args map to params.
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for (int i = 0; i < args.Length; i++)
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{
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// if a null reference is passed, but the type is not nullable
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if ((args[i] == null && paramList[i].ParameterType.IsValueType)
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// or if an arg is not null and is not assignable to the parameter type, skip.
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|| !(args[i] == null || paramList[i].ParameterType.IsAssignableFrom(args[i])))
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return false;
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}
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// If there are more parameters, check if they any are not optional, if any are not, skip.
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// Otherwise all checks have passed. We have found a match
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return args.Length <= paramList.Count || paramList.GetRange(args.Length, paramList.Count - args.Length).All(x => x.IsOptional);
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}) ?? throw new Exception($"There is no empty/default constructor for {type}");
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}
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catch (Exception e)
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{
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throw new TypeInitializationException(type.ToString(), e);
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}
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}
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public static object CreateInstance(Type type)
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{
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var cctor = GetConstructor(type);
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var args = cctor.GetParameters();
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if (args.Length == 0)
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return cctor.Invoke(Type.EmptyTypes);
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var argList = new object[args.Length];
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Array.Fill(argList, Type.Missing);
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return cctor.Invoke(argList);
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}
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public static object CreateInstance(Type type, params object[] args)
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{
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if (args == null || args.Length == 0)
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return CreateInstance(type);
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var cctor = GetConstructor(type, args.Select(x => x?.GetType()).ToArray());
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return cctor.Invoke(args);
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}
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public static T CreateInstance<T>() => (T)CreateInstance(typeof(T));
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public static T CreateInstance<T>(params object[] args) => (T)CreateInstance(typeof(T), args);
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}
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}
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