How to use the zstandard.BufferWithSegments function in zstandard

def test_multiple(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        b = zstd.BufferWithSegments(
            b"foofooxfooxy", b"".join([ss.pack(0, 3), ss.pack(3, 4), ss.pack(7, 5)])
        )
        self.assertEqual(len(b), 3)
        self.assertEqual(b.size, 12)
        self.assertEqual(b.tobytes(), b"foofooxfooxy")

        self.assertEqual(b[0].tobytes(), b"foo")
        self.assertEqual(b[1].tobytes(), b"foox")
        self.assertEqual(b[2].tobytes(), b"fooxy")

frames = cctx.multi_compress_to_buffer(original)

        # Check round trip.
        dctx = zstd.ZstdDecompressor()

        decompressed = dctx.multi_decompress_to_buffer(frames, threads=3)

        self.assertEqual(len(decompressed), len(original))

        for i, data in enumerate(original):
            self.assertEqual(data, decompressed[i].tobytes())

        # And a manual mode.
        b = b"".join([frames[0].tobytes(), frames[1].tobytes()])
        b1 = zstd.BufferWithSegments(
            b, struct.pack("=QQQQ", 0, len(frames[0]), len(frames[0]), len(frames[1]))
        )

        b = b"".join([frames[2].tobytes(), frames[3].tobytes(), frames[4].tobytes()])
        b2 = zstd.BufferWithSegments(
            b,
            struct.pack(
                "=QQQQQQ",
                0,
                len(frames[2]),
                len(frames[2]),
                len(frames[3]),
                len(frames[2]) + len(frames[3]),
                len(frames[4]),
            ),
        )

def test_invalid_offset(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        with self.assertRaisesRegex(
            ValueError, "offset within segments array references memory"
        ):
            zstd.BufferWithSegments(b"foo", ss.pack(0, 4))

b"foo3" * 3,
            b"foo4" * 4,
            b"foo5" * 5,
        ]

        frames = [cctx.compress(c) for c in original]

        b = b"".join([original[0], original[1]])
        b1 = zstd.BufferWithSegments(
            b,
            struct.pack(
                "=QQQQ", 0, len(original[0]), len(original[0]), len(original[1])
            ),
        )
        b = b"".join([original[2], original[3], original[4]])
        b2 = zstd.BufferWithSegments(
            b,
            struct.pack(
                "=QQQQQQ",
                0,
                len(original[2]),
                len(original[2]),
                len(original[3]),
                len(original[2]) + len(original[3]),
                len(original[4]),
            ),
        )

        c = zstd.BufferWithSegmentsCollection(b1, b2)

        result = cctx.multi_compress_to_buffer(c)

def test_arguments(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        with self.assertRaises(TypeError):
            zstd.BufferWithSegments()

        with self.assertRaises(TypeError):
            zstd.BufferWithSegments(b"foo")

        # Segments data should be a multiple of 16.
        with self.assertRaisesRegex(
            ValueError, "segments array size is not a multiple of 16"
        ):
            zstd.BufferWithSegments(b"foo", b"\x00\x00")

def test_buffer_with_segments_input(self):
        cctx = zstd.ZstdCompressor(write_checksum=True)

        if not hasattr(cctx, "multi_compress_to_buffer"):
            self.skipTest("multi_compress_to_buffer not available")

        original = [b"foo" * 4, b"bar" * 6]
        frames = [cctx.compress(c) for c in original]

        offsets = struct.pack(
            "=QQQQ", 0, len(original[0]), len(original[0]), len(original[1])
        )
        segments = zstd.BufferWithSegments(b"".join(original), offsets)

        result = cctx.multi_compress_to_buffer(segments)

        self.assertEqual(len(result), 2)
        self.assertEqual(result.size(), 47)

        self.assertEqual(result[0].tobytes(), frames[0])
        self.assertEqual(result[1].tobytes(), frames[1])

def test_length(self):
        if not hasattr(zstd, "BufferWithSegmentsCollection"):
            self.skipTest("BufferWithSegmentsCollection not available")

        b1 = zstd.BufferWithSegments(b"foo", ss.pack(0, 3))
        b2 = zstd.BufferWithSegments(
            b"barbaz", b"".join([ss.pack(0, 3), ss.pack(3, 3)])
        )

        c = zstd.BufferWithSegmentsCollection(b1)
        self.assertEqual(len(c), 1)
        self.assertEqual(c.size(), 3)

        c = zstd.BufferWithSegmentsCollection(b2)
        self.assertEqual(len(c), 2)
        self.assertEqual(c.size(), 6)

        c = zstd.BufferWithSegmentsCollection(b1, b2)
        self.assertEqual(len(c), 3)
        self.assertEqual(c.size(), 9)

kwargs = {}
        if fn.threads_arg:
            kwargs["threads"] = batch_threads

        # Pass compressed frames in a BufferWithSegments rather than a list
        # of bytes.
        if fn.chunks_as_buffer:
            s = struct.Struct("=QQ")
            offsets = io.BytesIO()
            current_offset = 0
            for chunk in compressed_chunks:
                offsets.write(s.pack(current_offset, len(chunk)))
                current_offset += len(chunk)

            chunks_arg = zstd.BufferWithSegments(
                b"".join(compressed_chunks), offsets.getvalue()
            )

        if fn.decompressed_sizes_arg:
            # Ideally we'd use array.array here. But Python 2 doesn't support the
            # Q format.
            s = struct.Struct("=Q")
            kwargs["decompressed_sizes"] = b"".join(s.pack(len(c)) for c in orig_chunks)

        results = timer(lambda: fn(chunks_arg, dopts, **kwargs))
        format_results(results, fn.title, prefix, total_size)

for fn in get_benches("discrete", "compress"):
        chunks_arg = chunks

        kwargs = {}
        if fn.threads_arg:
            kwargs["threads"] = batch_threads

        if fn.chunks_as_buffer:
            s = struct.Struct("=QQ")
            offsets = io.BytesIO()
            current_offset = 0
            for chunk in chunks:
                offsets.write(s.pack(current_offset, len(chunk)))
                current_offset += len(chunk)

            chunks_arg = zstd.BufferWithSegments(b"".join(chunks), offsets.getvalue())

        results = timer(lambda: fn(chunks_arg, zparams, **kwargs))
        format_results(results, fn.title, prefix, total_size)