126 lines
4.2 KiB
C#
126 lines
4.2 KiB
C#
using System;
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using System.Collections.Generic;
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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, Predicate<ConstructorInfo> predicate = null)
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{
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ConstructorInfo emptyCtor = type.GetConstructor(Type.EmptyTypes);
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if (emptyCtor != null && predicate?.Invoke(emptyCtor) != false)
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{
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return emptyCtor;
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}
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ConstructorInfo optionalCtor = type.GetConstructors().SingleOrDefault(info =>
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predicate?.Invoke(info) != false && info.GetParameters().All(x => x.IsOptional));
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if (optionalCtor != null)
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{
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return optionalCtor;
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}
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throw new TypeInitializationException(type.ToString(),
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new Exception($"There is no empty/default constructor for {type} that matches predicate."));
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}
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public static ConstructorInfo GetConstructor(Type type, Predicate<ConstructorInfo> predicate, params Type[] args)
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{
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try
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{
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ConstructorInfo ctor;
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if (args.All(x => x != null))
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{
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ctor = type.GetConstructor(args);
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if (ctor != null && predicate?.Invoke(ctor) != false)
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{
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return ctor;
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}
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}
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else
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{
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ctor = type.GetConstructors().SingleOrDefault(info =>
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{
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if (predicate?.Invoke(info) == false)
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{
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return false;
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}
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List<ParameterInfo> 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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{
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return false;
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}
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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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{
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return false;
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}
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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)
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.All(x => x.IsOptional);
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});
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if (ctor != null)
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{
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return ctor;
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}
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}
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throw new Exception($"There is no empty/default constructor for {type} that matches predicate.");
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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, Predicate<ConstructorInfo> constructorPredicate = null)
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{
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ConstructorInfo cctor = GetConstructor(type, constructorPredicate);
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ParameterInfo[] args = cctor.GetParameters();
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if (args.Length == 0)
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{
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return cctor.Invoke(Type.EmptyTypes);
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}
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object[] 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, Predicate<ConstructorInfo> constructorPredicate = null,
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params object[] args)
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{
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if (args == null || args.Length == 0)
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{
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return CreateInstance(type, constructorPredicate);
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}
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ConstructorInfo cctor = GetConstructor(type, constructorPredicate, args.Select(x => x?.GetType()).ToArray());
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return cctor.Invoke(args);
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}
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public static object CreateInstance(Type type, params object[] args) => CreateInstance(type, null, args);
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public static T CreateInstance<T>(Predicate<ConstructorInfo> constructorPredicate = null) => (T)CreateInstance(typeof(T), constructorPredicate);
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public static T CreateInstance<T>(params object[] args) => (T)CreateInstance(typeof(T), null, args);
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}
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}
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