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using System;
using System.Diagnostics;
using System.Reflection;
namespace IPA.Utilities
{
/// <summary>
/// A class to store a reference for passing to methods which cannot take ref parameters.
/// </summary>
/// <typeparam name="T">the type of the value</typeparam>
public class Ref<T> : IComparable<T>, IComparable<Ref<T>>
{
private T _value;
/// <summary>
/// The value of the reference
/// </summary>
public T Value
{
get
{
if (Error != null) throw Error;
return _value;
}
set => _value = value;
}
private Exception _error;
/// <summary>
/// An exception that was generated while creating the value.
/// </summary>
public Exception Error
{
get
{
return _error;
}
set
{
value.SetStackTrace(new StackTrace(1));
_error = value;
}
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="reference">the initial value of the reference</param>
public Ref(T reference)
{
_value = reference;
}
/// <summary>
/// Converts to referenced type, returning the stored reference.
/// </summary>
/// <param name="self">the object to be de-referenced</param>
/// <returns>the value referenced by the object</returns>
public static implicit operator T(Ref<T> self)
{
return self.Value;
}
/// <summary>
/// Converts a value T to a reference to that object. Will overwrite the reference in the left hand expression if there is one.
/// </summary>
/// <param name="toConvert">the value to wrap in the Ref</param>
/// <returns>the Ref wrapping the value</returns>
public static implicit operator Ref<T>(T toConvert)
{
return new Ref<T>(toConvert);
}
/// <summary>
/// Throws error if one was set.
/// </summary>
public void Verify()
{
if (Error != null) throw Error;
}
/// <inheritdoc />
public int CompareTo(T other)
{
if (Value is IComparable<T> compare)
return compare.CompareTo(other);
return Equals(Value, other) ? 0 : -1;
}
/// <inheritdoc />
public int CompareTo(Ref<T> other)
{
return CompareTo(other.Value);
}
}
internal static class ExceptionUtilities
{
private static readonly FieldInfo StackTraceStringFi = typeof(Exception).GetField("_stackTraceString", BindingFlags.NonPublic | BindingFlags.Instance);
private static readonly Type TraceFormatTi = Type.GetType("System.Diagnostics.StackTrace")?.GetNestedType("TraceFormat", BindingFlags.NonPublic);
private static readonly MethodInfo TraceToStringMi = typeof(StackTrace).GetMethod("ToString", BindingFlags.NonPublic | BindingFlags.Instance, null, new[] { TraceFormatTi }, null);
public static Exception SetStackTrace(this Exception target, StackTrace stack)
{
var getStackTraceString = TraceToStringMi.Invoke(stack, new[] { Enum.GetValues(TraceFormatTi).GetValue(0) });
StackTraceStringFi.SetValue(target, getStackTraceString);
return target;
}
}
}