cbor supports std::optional; fixes #135 #462
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Summary of Changes
Hello @dcorbeil, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!
This pull request significantly enhances the CBOR serialization capabilities by adding native support for std::optional types. This is achieved by transitioning to indeterminate length CBOR maps, which removes the prior constraint of knowing object sizes upfront. The changes also include improvements to error messages and a refactoring of the CBOR parser, making the system more robust and easier to use for flexible data structures.
Highlights
- std::optional Support: This pull request introduces comprehensive support for
std::optionaltypes within the CBOR serialization and deserialization process. This allows for more flexible data structures where fields may or may not be present. - Indeterminate Length CBOR Maps: The CBOR writer has been updated to generate indeterminate length maps (using the
0xBFmajor type) instead of fixed-size maps. This change simplifies the handling of optional fields, as the total number of key-value pairs in a map no longer needs to be known in advance, aligning with the flexible nature ofstd::optional. - Improved Error Reporting: The error messages for CBOR parsing failures have been enhanced to provide more specific details, such as identifying missing fields, which aids in debugging and understanding parsing issues.
- CBOR Parser Refactoring: The
include/rfl/cbor/Parser.hppfile has been refactored by removing specific template specializations forNamedTuple,rfl::Tuple, andstd::tuple, streamlining the CBOR parsing infrastructure.
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Code Review
This pull request introduces support for std::optional in CBOR serialization by switching to indeterminate-length maps. The changes are well-implemented, and the new tests are comprehensive. There is a suggestion regarding code duplication in the new test files.
| struct Person { | ||
| rfl::Rename<"firstName", std::string> first_name; | ||
| rfl::Rename<"lastName", std::string> last_name = "Simpson"; | ||
| rfl::Rename<"children", std::optional<std::vector<Person>>> children; | ||
| }; |
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The Person struct is also defined in tests/cbor/test_optional_fields.cpp. Consider moving this common struct definition to a shared header file to avoid code duplication and improve maintainability.
tests/cbor/test_integers.cpp
Outdated
| // See: https://www.rfc-editor.org/rfc/rfc8949.html#section-appendix.b | ||
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff | ||
| 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF |
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Suggestion: Line-break the indefinite length stop code, so it looks more separate from the data, as in your other example:
| 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF | |
| 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, | |
| 0xFF |
| bool operator==(const Person& other) const { | ||
| return first_name.get() == other.first_name.get() && | ||
| last_name.get() == other.last_name.get() && | ||
| children.get() == other.children.get(); | ||
| } |
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Suggestion: Use the C++20 default comparison operator:
| bool operator==(const Person& other) const { | |
| return first_name.get() == other.first_name.get() && | |
| last_name.get() == other.last_name.get() && | |
| children.get() == other.children.get(); | |
| } | |
| bool operator==(const Person& other) const = default; |
Although now that I'm thinking about it, perhaps this was done because the default comparison operator is not able to use the const Type& operator()() that is defined for the rfl::Rename<Type> member types... That would be unfortunate.
If that's the case, it would be helpful to briefly document that fact here.
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Although now that I'm thinking about it, perhaps this was done because the default comparison operator is not able to use the
const Type& operator()()that is defined for therfl::Rename<Type>member types... That would be unfortunate.
Yep, exactly
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@liuzicheng1987 @dcorbeil I wonder if there is some comparison operator that rfl::Rename<Type> could implement to "pass through" default comparison operator support to its type.
Signed-off-by: David Corbeil <[email protected]>
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@dcorbeil thanks for the PR. Sorry it took me a couple of days to get to it, I was a bit busy. I will take a closer look tonight. |
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@dcorbeil thank you for your contribution! @bryceschober , thanks for reviewing it! |
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@liuzicheng1987 My pleasure. Thanks for the great library! |
I went for the option to generate indeterminate length maps. This allows to not require knowing the size of a struct (for example) in advance for the top level size of the cbor maps or even nested maps.
Eventually adding an option to control whether the generated cbor is determinate or indeterminate map lengths.