[C++] Support casting to and from utf8_view/binary_view

[felipecrv]

Describe the enhancement requested

There are 3 categories of binary/string-like types in Arrow:

• Span = utf8 | large_utf8 | binary | large_binary
• Fixed = fixed_size_binary
• View = utf8_view | binary_view

They can cast between themselves when a View is not involved:

Input	Output	CanCast
Span	Fixed	X
Fixed	Span	X
Span	View
Fixed	View
View	Fixed
View	Span

String views should behave similarly to strings when it comes to casts.

Component(s)

C++

[felipecrv]

@llama90 FYI (I'm working on a PR).

[llama90]

Thank you for letting me know. I really appreciate it.

[felipecrv]

#43010 needs to be fixed before casts involving dictionary(_, utf8_view()|binary_view()) can be supported.

[felipecrv]

@llama90 FYI (I'm working on a PR).

I opened a draft PR to make the claim that I'm working on it more believable :)

• GH-42247: [C++] Support casting to and from utf8_view/binary_view #43302

[llama90]

@felipecrv Thank you. I will take a look!

[felipecrv]

@felipecrv Thank you. I will take a look!

I made the PR green.

[llama90]

I made the PR green.

Thanks!