private object GetItem(int offset)
{
TypecodeOps.DecomposeTypecode(_format, out char byteorder, out char typecode);
object result = PackBytes(typecode, _buffer !.AsReadOnlySpan().Slice(offset, _itemSize));
return(PythonOps.ConvertToPythonPrimitive(result));
}
public int __hash__(CodeContext context)
{
if (_storedHash != null)
{
return(_storedHash.Value);
}
CheckBuffer();
if (!_isReadOnly)
{
throw PythonOps.ValueError("cannot hash writable memoryview object");
}
TypecodeOps.DecomposeTypecode(_format, out _, out char typecode);
if (!TypecodeOps.IsByteCode(typecode))
{
throw PythonOps.ValueError("memoryview: hashing is restricted to formats 'B', 'b' or 'c'");
}
_storedHash = tobytes().GetHashCode();
return(_storedHash.Value);
}
public object tolist()
{
CheckBuffer();
TypecodeOps.DecomposeTypecode(_format, out char byteorder, out char typecode);
return(subdimensionToList(_buffer !.AsReadOnlySpan(), _offset, dim: 0));
object subdimensionToList(ReadOnlySpan <byte> source, int ofs, int dim)
{
if (dim >= _shape.Count)
{
// extract individual element (scalar)
return(PackBytes(typecode, source.Slice(ofs)));
}
object[] elements = new object[_shape[dim]];
for (int i = 0; i < _shape[dim]; i++)
{
elements[i] = subdimensionToList(source, ofs, dim + 1);
ofs += _strides[dim];
}
return(PythonList.FromArrayNoCopy(elements));
}
}
private void SetItem(int offset, object?value)
{
if (value == null)
{
throw PythonOps.TypeError("memoryview: invalid type for format '{0}'", _format);
}
TypecodeOps.DecomposeTypecode(_format, out char byteorder, out char typecode);
switch (typecode)
{
case 'd': // double
case 'f': // float
if (!Converter.TryConvertToDouble(value, out double convertedValueDouble))
{
throw PythonOps.TypeError("memoryview: invalid type for format '{0}'", _format);
}
value = convertedValueDouble;
break;
case 'c': // bytechar
if (!(value is Bytes b))
{
throw PythonOps.TypeError("memoryview: invalid type for format '{0}'", _format);
}
if (b.Count != 1)
{
throw PythonOps.ValueError("memoryview: invalid value for format '{0}'", _format);
}
break;
case 'b': // signed byte
case 'B': // unsigned byte
case 'h': // signed short
case 'H': // unsigned short
case 'i': // signed int
case 'I': // unsigned int
case 'l': // signed long
case 'L': // unsigned long
case 'n': // signed index
case 'N': // unsigned index
case 'q': // signed long long
case 'Q': // unsigned long long
if (!PythonOps.IsNumericObject(value))
{
throw PythonOps.TypeError("memoryview: invalid type for format '{0}'", _format);
}
if (TypecodeOps.CausesOverflow(value, typecode))
{
throw PythonOps.ValueError("memoryview: invalid value for format '{0}'", _format);
}
if (typecode == 'Q')
{
value = Converter.ConvertToUInt64(value);
}
else
{
value = Converter.ConvertToInt64(value);
}
break;
case 'P': // void pointer
if (!PythonOps.IsNumericObject(value))
{
throw PythonOps.TypeError("memoryview: invalid type for format '{0}'", _format);
}
var bi = Converter.ConvertToBigInteger(value);
if (TypecodeOps.CausesOverflow(bi, typecode))
{
throw PythonOps.ValueError("memoryview: invalid value for format '{0}'", _format);
}
value = bi;
break;
case 'r': // .NET signed pointer
case 'R': // .NET unsigned pointer
if (value is UIntPtr uptr)
{
if (typecode == 'r')
{
value = new IntPtr(unchecked ((Int64)uptr.ToUInt64()));
}
break;
}
if (value is IntPtr iptr)
{
if (typecode == 'R')
{
value = new UIntPtr(unchecked ((UInt64)iptr.ToInt64()));
}
break;
}
throw PythonOps.TypeError("memoryview: invalid type for format '{0}'", _format);
default:
break; // This could be a variety of types, let the UnpackBytes decide
}
UnpackBytes(typecode, value, _buffer !.AsSpan().Slice(offset, _itemSize));
}
public MemoryView cast([NotNull] string format, [NotNull, AllowNull] object shape)
{
if (!_isCContig)
{
throw PythonOps.TypeError("memoryview: casts are restricted to C-contiguous views");
}
if (_shape.Contains(0) || _strides.Contains(0))
{
throw PythonOps.TypeError("memoryview: cannot cast view with zeros in shape or strides");
}
PythonTuple?shapeAsTuple = null;
if (shape != null)
{
if (!(shape is PythonList) && !(shape is PythonTuple))
{
throw PythonOps.TypeError("shape must be a list or a tuple");
}
shapeAsTuple = PythonTuple.Make(shape);
int newNDim = shapeAsTuple.Count;
if (newNDim > MaximumDimensions)
{
throw PythonOps.TypeError("memoryview: number of dimensions must not exceed {0}", MaximumDimensions);
}
if (_numDims != 1 && newNDim != 1)
{
throw PythonOps.TypeError("memoryview: cast must be 1D -> ND or ND -> 1D");
}
}
if (!TypecodeOps.TryDecomposeTypecode(format, out char byteorder, out char typecode) ||
!IsSupportedTypecode(typecode) ||
byteorder != '@'
)
{
throw PythonOps.ValueError(
"memoryview: destination format must be a native single character format prefixed with an optional '@'");
}
if (!TypecodeOps.IsByteCode(typecode))
{
TypecodeOps.DecomposeTypecode(_format, out _, out char thisTypecode);
if (!TypecodeOps.IsByteCode(thisTypecode))
{
throw PythonOps.TypeError("memoryview: cannot cast between two non-byte formats");
}
}
int newItemsize = TypecodeOps.GetTypecodeWidth(typecode);
if ((_numItems * _itemSize) % newItemsize != 0)
{
throw PythonOps.TypeError("memoryview: length is not a multiple of itemsize");
}
int newLength = _numItems * _itemSize / newItemsize;
int[] newShape;
if (shapeAsTuple != null)
{
newShape = new int[shapeAsTuple.Count];
int lengthGivenShape = 1;
for (int i = 0; i < shapeAsTuple.Count; i++)
{
newShape[i] = Converter.ConvertToInt32(shapeAsTuple[i]);
lengthGivenShape *= newShape[i];
}
if (lengthGivenShape != newLength)
{
throw PythonOps.TypeError("memoryview: product(shape) * itemsize != buffer size");
}
}
else
{
newShape = new int[] { newLength };
}
return(new MemoryView(this, format, newItemsize, newShape));
}
