Use tobytes in hex to make data C contiguous
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To cutdown on attribute inspection within `hex`, simply import `hexlify` from `binascii` in the global scope. That way `hexlify` can be accessed quickly and used easily from the `hex` function.
Only copy the data in `hex` using `tobytes` if it is not C contiguous. That way if the data is already C contiguous, a view onto the original data can be used instead saving time and memory. The copy is needed for non-C contiguous data to get a consistent representation in hex as `memoryview` and other objects do. As Python 2's `binascii.hexlify` supports the (new) buffer protocol, it won't introduce any additional copies as long as something implementing the (new) buffer protocol is provided. On Python 3, we leverage `memoryview`'s `hex` method, which also avoids copying if the data is C contiguous. It provides a fast path to `hex`, which is equivalent to the `bytes` method `hex`. Thus in both cases, the hex conversion will avoid any additional copies of the data. So this should in the best case avoid a copy when constructing the hex result, but may still copy the data if it is not contiguous in the way we expect, which is better than before.
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Only copy the data in
hexusingtobytesif it is not C contiguous. That way if the data is already C contiguous, a view onto the original data can be used instead saving time and memory. The copy is needed for non-C contiguous data to get a consistent representation in hex asmemoryviewand other objects do. As Python 2'sbinascii.hexlifysupports the (new) buffer protocol, it won't introduce any additional copies as long as something implementing the (new) buffer protocol is provided. On Python 3, we leveragememoryview'shexmethod, which also avoids copying if the data is C contiguous. It provides a fast path tohex, which is equivalent to thebytesmethodhex. Thus in both cases, the hex conversion will avoid any additional copies of the data. So this should in the best case avoid a copy when constructing the hex result, but may still copy the data if it is not contiguous in the way we expect, which is better than before.