import numpy as np
import dpctl
import dpctl.memory as dpmem

class View:
    def __init__(self, buffer, shape, strides, offset):
        self.buffer=buffer
        self.shape=shape
        self.strides=strides
        self.offset = offset

    @property
    def __sycl_usm_array_interface__(self):
        sua_iface = self.buffer.__sycl_usm_array_interface__
        sua_iface['offset'] = self.offset
        sua_iface['shape'] = self.shape
        sua_iface['strides'] = self.strides
        return sua_iface

# Allocate 32 bytes, and fill them with canary numbers
buf = dpmem.MemoryUSMShared(32)
buf.copy_from_host(np.full((32,), 77, dtype='|u1'))

# View of 10 bytes, starting with byte 8, and going every other byte
v = View(buf, (10,), strides=(2,), offset=8)

# Create USMShared buffer from the view 
# spanning from the lowest byte, offset=8 to highest byte, offset=8 +(10-1)*2
buf2 = dpmem.MemoryUSMShared(v)
# That is total of 19 bytes, (counting the last one too)
assert buf2.nbytes == 19
# populate this buffer with different values
buf2.copy_from_host(np.full((19,), 1, dtype="|u1"))
# copy content of the parent buffer to host
res = buf.copy_to_host()
del buf
del buf2
print(res)