prepare_iter_for_array PR

[chaburkland]

Closes#9

[chaburkland]

Current performance

cls func ak ref ref/ak
IsGenCopyValues main 0.2276659 0.39814382 1.74880746
PrepareIterForArray iter_small 1.07673633 1.28456536 1.19301757
PrepareIterForArray iter_large 1.46419539 2.07376239 1.41631534 

[flexatone]

I have optimized the Python implementation of this function, which reduces and clarifies the requirements of this function. The new implementation is as follows:

defprepare_iter_for_array(
values: tp.Iterable[tp.Any],
restrict_copy: bool=False
) ->tp.Tuple[DtypeSpecifier, bool, tp.Sequence[tp.Any]]:
is_gen, copy_values=is_gen_copy_values(values)
ifnotis_genandlen(values) ==0: #type: ignorereturnNone, False, values#type: ignoreifrestrict_copy:
copy_values=Falsev_iter=valuesifis_genelseiter(values)
ifcopy_values:
values_post= []
resolved=None# None is valid specifier if the type is not ambiguoushas_tuple=Falsehas_str=Falsehas_non_str=Falsehas_inexact=Falsehas_big_int=Falseforvinv_iter:
ifcopy_values:
# if a generator, have to make a copy while iteratingvalues_post.append(v)
value_type=type(v)
if (value_typeisstrorvalue_typeisnp.str_orvalue_typeisbytesorvalue_typeisnp.bytes_):
# must compare to both string typeshas_str=Trueelifhasattr(v, '__len__'):
# identify SF types by if they have STATIC attr they also must be assigned after array creation, so we treat them like tupleshas_tuple=Trueresolved=objectbreakelifisinstance(v, Enum):
# must check isinstance, as Enum types are always derived from Enumresolved=objectbreakelse:
has_non_str=Trueifvalue_typeinINEXACT_TYPES:
has_inexact=Trueelifvalue_typeisintandabs(v) >INT_MAX_COERCIBLE_TO_FLOAT:
has_big_int=Trueif (has_strandhas_non_str) or (has_big_intandhas_inexact):
resolved=objectbreakifcopy_values:
# v_iter is an iter, we need to finish itvalues_post.extend(v_iter)
returnresolved, has_tuple, values_postreturnresolved, has_tuple, values#type: ignore

[flexatone]

A new PR has a fresh implementation of this with shared resources for 1D elementwise function application.

#226