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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Globalization;
namespace System.ComponentModel;
internal static class TypeConverterHelper
{
// Feature switch, when set to true, used for trimming to access ComponentModel in a trim safe manner
[FeatureSwitchDefinition("System.Windows.Forms.Primitives.TypeConverterHelper.UseComponentModelRegisteredTypes")]
#pragma warning disable IDE0075 // Simplify conditional expression - the simpler expression is hard to read
private static bool UseComponentModelRegisteredTypes { get; } =
AppContext.TryGetSwitch("System.Windows.Forms.Primitives.TypeConverterHelper.UseComponentModelRegisteredTypes", out bool isEnabled)
? isEnabled
: false;
#pragma warning restore IDE0075
/// <summary>
/// Converts the given text to list of objects, using the specified context and culture information.
/// </summary>
/// <param name="context">An ITypeDescriptorContext that provides a format context.</param>
/// <param name="culture">A CultureInfo. If null is passed, the current culture is assumed.</param>
/// <param name="text">The chars to convert.</param>
/// <param name="output">The converted text chunks</param>
/// <typeparam name="T"></typeparam>
/// <returns>true if text was converted successfully; otherwise, false.</returns>
public static bool TryParseAsSpan<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] T>(ITypeDescriptorContext? context, CultureInfo? culture, ReadOnlySpan<char> text, Span<T> output)
{
culture ??= CultureInfo.CurrentCulture;
using BufferScope<Range> tokens = new(stackalloc Range[16]);
int tokensCount = text.Split(tokens, culture.TextInfo.ListSeparator[0]);
if (tokensCount != output.Length)
{
return false;
}
TypeConverter converter;
if (!UseComponentModelRegisteredTypes)
{
converter = TypeDescriptor.GetConverter(typeof(T));
}
else
{
// Call the trim safe API
TypeDescriptor.RegisterType<T>();
converter = TypeDescriptor.GetConverterFromRegisteredType(typeof(T));
}
for (int i = 0; i < output.Length; i++)
{
// Note: ConvertFromString will raise exception if value cannot be converted.
output[i] = (T)converter.ConvertFromString(context, culture, text[tokens[i]].ToString())!;
}
return true;
}
}
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