private bool ArraySetLength([NotNull] PropertyDescriptor descriptor)
{
//https://tc39.github.io/ecma262/#sec-arraysetlength
var descriptorValue = descriptor.Value;
if (!descriptorValue.HasValue)
{
return(base.DefineOwnProperty("length", descriptor));
}
var newLengthDescriptor = descriptor.Copy();
var newLength = Agent.ToUint32(descriptorValue.Value);
var numberLength = Agent.ToNumber(descriptorValue.Value);
// ReSharper disable once CompareOfFloatsByEqualityOperator
if (newLength != numberLength)
{
throw Agent.CreateRangeError();
}
newLengthDescriptor.Value = newLength;
var oldLengthDescriptor = GetOwnProperty("length");
Debug.Assert(!oldLengthDescriptor?.IsAccessorDescriptor == true);
Debug.Assert(oldLengthDescriptor.Value != null, "oldLengthDescriptor.Value != null");
var oldLength = (uint)(double)oldLengthDescriptor.Value.Value;
if (newLength >= oldLength)
{
return(base.DefineOwnProperty("length", newLengthDescriptor));
}
if (!oldLengthDescriptor.Writable)
{
return(false);
}
bool newWritable;
if (!newLengthDescriptor.Writable.HasValue || newLengthDescriptor.Writable)
{
newWritable = true;
}
else
{
//Need to defer setting the [[Writable]] attribute to false in case any elements cannot be deleted.
newWritable = false;
newLengthDescriptor.Writable = true;
}
var succeeded = base.DefineOwnProperty("length", newLengthDescriptor);
if (!succeeded)
{
return(false);
}
while (newLength < oldLength)
{
oldLength--;
var deleteSucceeded = Delete(oldLength.ToString(CultureInfo.InvariantCulture));
if (!deleteSucceeded)
{
newLengthDescriptor.Value = oldLength + 1;
if (!newWritable)
{
newLengthDescriptor.Writable = false;
}
base.DefineOwnProperty("length", newLengthDescriptor);
return(false);
}
}
if (!newWritable)
{
return(base.DefineOwnProperty("length", new PropertyDescriptor
{
Writable = false
}));
}
return(true);
}