// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Globalization;
using System.Threading;
namespace System.ComponentModel
{
///
/// Specifies the default value for a property.
///
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1019:DefineAccessorsForAttributeArguments")]
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1813:AvoidUnsealedAttributes")]
[AttributeUsage(AttributeTargets.All)]
public class DefaultValueAttribute : Attribute
{
///
/// This is the default value.
///
private object _value;
// Delegate ad hoc created 'TypeDescriptor.ConvertFromInvariantString' reflection object cache
static object s_convertFromInvariantString;
///
/// Initializes a new instance of the class, converting the
/// specified value to the
/// specified type, and using the U.S. English culture as the
/// translation
/// context.
///
public DefaultValueAttribute(Type type, string value)
{
// The try/catch here is because attributes should never throw exceptions. We would fail to
// load an otherwise normal class.
try
{
if (TryConvertFromInvariantString(type, value, out object convertedValue))
{
_value = convertedValue;
}
else if (type.IsSubclassOf(typeof(Enum)))
{
_value = Enum.Parse(type, value, true);
}
else if (type == typeof(TimeSpan))
{
_value = TimeSpan.Parse(value);
}
else
{
_value = Convert.ChangeType(value, type, CultureInfo.InvariantCulture);
}
return;
// Looking for ad hoc created TypeDescriptor.ConvertFromInvariantString(Type, string)
bool TryConvertFromInvariantString(Type typeToConvert, string stringValue, out object conversionResult)
{
conversionResult = null;
// lazy init reflection objects
if (s_convertFromInvariantString == null)
{
Type typeDescriptorType = Type.GetType("System.ComponentModel.TypeDescriptor, System.ComponentModel.TypeConverter", throwOnError: false);
Volatile.Write(ref s_convertFromInvariantString, typeDescriptorType == null ? new object() : Delegate.CreateDelegate(typeof(Func), typeDescriptorType, "ConvertFromInvariantString", ignoreCase: false));
}
if (!(s_convertFromInvariantString is Func convertFromInvariantString))
return false;
conversionResult = convertFromInvariantString(typeToConvert, stringValue);
return true;
}
}
catch
{
}
}
///
/// Initializes a new instance of the class using a Unicode
/// character.
///
public DefaultValueAttribute(char value)
{
_value = value;
}
///
/// Initializes a new instance of the class using an 8-bit unsigned
/// integer.
///
public DefaultValueAttribute(byte value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a 16-bit signed
/// integer.
///
public DefaultValueAttribute(short value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a 32-bit signed
/// integer.
///
public DefaultValueAttribute(int value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a 64-bit signed
/// integer.
///
public DefaultValueAttribute(long value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a
/// single-precision floating point
/// number.
///
public DefaultValueAttribute(float value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a
/// double-precision floating point
/// number.
///
public DefaultValueAttribute(double value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a
/// value.
///
public DefaultValueAttribute(bool value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a .
///
public DefaultValueAttribute(string value)
{
_value = value;
}
///
/// Initializes a new instance of the
/// class.
///
public DefaultValueAttribute(object value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a
/// value.
///
[CLSCompliant(false)]
public DefaultValueAttribute(sbyte value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a
/// value.
///
[CLSCompliant(false)]
public DefaultValueAttribute(ushort value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a
/// value.
///
[CLSCompliant(false)]
public DefaultValueAttribute(uint value)
{
_value = value;
}
///
/// Initializes a new instance of the class using a
/// value.
///
[CLSCompliant(false)]
public DefaultValueAttribute(ulong value)
{
_value = value;
}
///
///
/// Gets the default value of the property this
/// attribute is
/// bound to.
///
///
public virtual object Value
{
get
{
return _value;
}
}
public override bool Equals(object obj)
{
if (obj == this)
{
return true;
}
if (obj is DefaultValueAttribute other)
{
if (Value != null)
{
return Value.Equals(other.Value);
}
else
{
return (other.Value == null);
}
}
return false;
}
public override int GetHashCode()
{
return base.GetHashCode();
}
protected void SetValue(object value)
{
_value = value;
}
}
}