bkietz commented on code in PR #43302:
URL: https://github.com/apache/arrow/pull/43302#discussion_r1693545712
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cpp/src/arrow/compute/kernels/scalar_cast_string.cc:
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@@ -305,19 +310,198 @@ BinaryToBinaryCastExec(KernelContext* ctx, const
ExecSpan& batch, ExecResult* ou
ctx, input, out->array_data().get());
}
+// View -> Span
+template <typename O, typename I>
+enable_if_t<is_binary_view_like_type<I>::value &&
is_base_binary_type<O>::value, Status>
+BinaryToBinaryCastExec(KernelContext* ctx, const ExecSpan& batch, ExecResult*
out) {
+ using OutputBuilderType = typename TypeTraits<O>::BuilderType;
+ const CastOptions& options = checked_cast<const
CastState&>(*ctx->state()).options;
+ const ArraySpan& input = batch[0].array;
+
+ if constexpr (!I::is_utf8 && O::is_utf8) {
+ if (!options.allow_invalid_utf8) {
+ InitializeUTF8();
+ ArraySpanVisitor<I> visitor;
+ Utf8Validator validator;
+ RETURN_NOT_OK(visitor.Visit(input, &validator));
+ }
+ }
+
+ // XXX: a more efficient implementation that zero-copies the validity bitmap
+ // is possible, but requires a more complex implementation for building the
+ // offsets and data buffers
+ OutputBuilderType builder(options.to_type.GetSharedPtr(),
ctx->memory_pool());
+ RETURN_NOT_OK(builder.Resize(input.length));
Review Comment:
Not without visiting the whole array to sum the sizes. It would for example
be legal to have all N views reference the same 1MB span of a data buffer
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