feat: add row-based immutable data structure #181
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wgtmac
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Aug 16, 2025
wgtmac
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- Add StructLike, MapLike, and ArrayLike interfaces
- Add wrapper for ManifestFile and ArrowArray
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@dongxiao1198 @mapleFU @zhjwpku @lidavidm Could you please take a look? |
| std::string_view, // for non-owned string, binary and fixed | ||
| std::shared_ptr<StructLike>, // for struct |
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It's a bit confusing, if we want ownership, it might be:
Scalar = variant<Literal, std::shared_ptr<StructLike>, ...>If we don't want ownership, it would be:
<...
std::string_view,
const StructLike*,
const ArrayLike*,
...
>
Mixing string_view and sptr is so weird...
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And scalar seems re-invent some member in literal?
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These structures are all views. I don't want any ownership for string/binary/fixed/uuid, so use std::string_view and do not reuse Literal. But we need ownership for nested struct/map/list views, so sptr is used.
| /// Wrapper classes for manifest-related data structures that implement | ||
| /// StructLike, ArrayLike, and MapLike interfaces for unified data access. | ||
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| #include <functional> |
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Because std::reference_wrapper is used in the header file.
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| /// | ||
| /// Note that all string and binary values are stored as non-owned string_view | ||
| /// and their lifetime is managed by the wrapped object. | ||
| using Scalar = std::variant<std::monostate, // for null |
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Can Scalar be merged with Literal::Value?
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They are slightly different:
- scalar employs view-like semantics for var-length types but literal takes the ownership.
- scalar supports nested types but literal does not.
| double, // for double | ||
| std::string_view, // for non-owned string, binary and fixed | ||
| Decimal, // for decimal | ||
| std::shared_ptr<StructLike>, // for struct |
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In which case will a class except ArrowArrayStructLike inherit StructLike?
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Any object that might be evaluated against expression. I've provided implementation for ManifestFile and we may extend it for ManifestList, etc.
- Add StructLike, MapLike, and ArrayLike interfaces - Add wrapper for ManifestFile and ArrowArray
