public void SequenceDecoderTest()
{
var codec = SequenceDecoder.Instance;
var items = new List <PyObject>()
{
new PyInt(1), new PyInt(2), new PyInt(3)
};
//SequenceConverter can only convert to any ICollection
using var pyList = new PyList(items.ToArray());
using var listType = pyList.GetPythonType();
//it can convert a PyList, since PyList satisfies the python sequence protocol
Assert.IsFalse(codec.CanDecode(listType, typeof(bool)));
Assert.IsFalse(codec.CanDecode(listType, typeof(IList <int>)));
Assert.IsFalse(codec.CanDecode(listType, typeof(System.Collections.IEnumerable)));
Assert.IsFalse(codec.CanDecode(listType, typeof(IEnumerable <int>)));
Assert.IsTrue(codec.CanDecode(listType, typeof(ICollection <float>)));
Assert.IsTrue(codec.CanDecode(listType, typeof(ICollection <string>)));
Assert.IsTrue(codec.CanDecode(listType, typeof(ICollection <int>)));
//convert to collection of int
ICollection <int> intCollection = null;
Assert.DoesNotThrow(() => { codec.TryDecode(pyList, out intCollection); });
CollectionAssert.AreEqual(intCollection, new List <object> {
1, 2, 3
});
//no python exception should have occurred during the above conversion and check
Runtime.CheckExceptionOccurred();
//convert to collection of string. This will not work.
//The SequenceWrapper class will throw a python exception when it tries to access any element.
//TryDecode is a lossless conversion so there will be no exception at that point
//interestingly, since the size of the python sequence can be queried without any conversion,
//the IList will report a Count of 3.
ICollection <string> stringCollection = null;
Assert.DoesNotThrow(() => { codec.TryDecode(pyList, out stringCollection); });
Assert.AreEqual(3, stringCollection.Count());
Assert.Throws(typeof(InvalidCastException), () => {
string[] array = new string[3];
stringCollection.CopyTo(array, 0);
});
Runtime.CheckExceptionOccurred();
//can't convert python iterable to collection (this will require a copy which isn't lossless)
//python iterables do not satisfy the python sequence protocol
var foo = GetPythonIterable();
var fooType = foo.GetPythonType();
Assert.IsFalse(codec.CanDecode(fooType, typeof(ICollection <int>)));
//python tuples do satisfy the python sequence protocol
var pyTuple = new PyTuple(items.ToArray());
var pyTupleType = pyTuple.GetPythonType();
Assert.IsTrue(codec.CanDecode(pyTupleType, typeof(ICollection <float>)));
Assert.IsTrue(codec.CanDecode(pyTupleType, typeof(ICollection <int>)));
Assert.IsTrue(codec.CanDecode(pyTupleType, typeof(ICollection <string>)));
//convert to collection of int
ICollection <int> intCollection2 = null;
Assert.DoesNotThrow(() => { codec.TryDecode(pyTuple, out intCollection2); });
CollectionAssert.AreEqual(intCollection2, new List <object> {
1, 2, 3
});
//no python exception should have occurred during the above conversion and check
Runtime.CheckExceptionOccurred();
//convert to collection of string. This will not work.
//The SequenceWrapper class will throw a python exception when it tries to access any element.
//TryDecode is a lossless conversion so there will be no exception at that point
//interestingly, since the size of the python sequence can be queried without any conversion,
//the IList will report a Count of 3.
ICollection <string> stringCollection2 = null;
Assert.DoesNotThrow(() => { codec.TryDecode(pyTuple, out stringCollection2); });
Assert.AreEqual(3, stringCollection2.Count());
Assert.Throws(typeof(InvalidCastException), () => {
string[] array = new string[3];
stringCollection2.CopyTo(array, 0);
});
Runtime.CheckExceptionOccurred();
}