Support upper and lower in strings_udf

[brandon-b-miller]

This PR adds support for the following two functions in strings_udf:

• str.upper()
• str.lower()

Part of #9639

[davidwendt]

Just curious why these are not void* as well?

[brandon-b-miller]

Let me make sure all is right here. Each of the functions that return a pointer to an input mapping table returns its own type of pointer. For the flags table its uint8_t*, for the cases table its uint16_t. For the special case mapping table it's a special_case_mapping*. Would the correct thing to do in this case be to receive each of these as a uintptr_t in the cython and then carry them through the python into the lowering as a np.uintp? Then these shim functions could accept a uintptr_t here.

[davidwendt]

I think it would be more correct for these to be pointer types than int64_t types.

[wence-]

If you can interact with ctypes I think you can carry around a ctypes.cvoidp.

[wence-]

A bunch of nits around cross-calling ABI and type-punning pointers and integers.

[wence-]

Does this need to be a void ** or can it just be a void * (I note that inside you cast to string_view * and then dereference, so I think you can strip a * everywhere).

[brandon-b-miller]

I am not sure I follow here. This follows the pattern from the rest of the shim functions when a string_view is an arg. IIUC st is pointing directly to the struct, so only one level of pointing right?

[wence-]

Most functions here (e.g.

cudf/python/strings_udf/cpp/src/strings/udf/shim.cu

Lines 186 to 193 in 418cbc6

	extern "C" __device__ int pyisalnum(bool* nb_retval, void const* str, std::uintptr_t chars_table)
	{
	auto str_view = reinterpret_cast<cudf::string_view const*>(str);
	*nb_retval = is_alpha_numeric(
	reinterpret_cast<cudf::strings::detail::character_flags_table_type*>(chars_table), *str_view);
	return 0;
	}

) that take a pointer to string_view take the argument as void const *, not void* const *. Why is this different?

[brandon-b-miller]

ah you're right! updated this. Nice catch

[brandon-b-miller]

rerun tests

[wence-]

Thanks @brandon-b-miller

[davidwendt]

Approving C++ code.

[brandon-b-miller]

some test failures here that seem to be related to a previous PR that I am looking into now.

[brandon-b-miller]

I am thinking these CI failures might be transient. Going to rerun tests just to make sure, as things seem to pass locally for me.

[brandon-b-miller]

rerun tests

[brandon-b-miller]

@gpucibot merge