Protocol Buffers - Google's data interchange format (grpc依赖)
https://developers.google.com/protocol-buffers/
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77 lines
2.3 KiB
77 lines
2.3 KiB
# C style guide |
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<!--* |
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# Document freshness: For more information, see go/fresh-source. |
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freshness: { owner: 'haberman' reviewed: '2024-02-05' } |
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*--> |
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Since upb is written in pure C, we supplement the |
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[Google C++ style guide](https://google.github.io/styleguide/cppguide.html) with |
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some C-specific guidance. |
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Everything written here is intended to follow the spirit of the C++ style guide. |
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upb is currently inconsistent about following these conventions. It is intended |
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that all code will be updated to match these guidelines. The priority is |
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converting public interfaces as these are more difficult to change later. |
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## Naming |
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### Functions and Types |
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C does not have namespaces. Anywhere you would normally use a namespace |
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separator (`::`) in C++, we use an underscore (`_`) in C: |
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```c++ |
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// C equivalent for upb::Arena::New() |
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upb_Arena* upb_Arena_New(); |
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``` |
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Since we rely on `_` to be our namespace separator, we never use it to merely |
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separate words in function or type names: |
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```c++ |
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// BAD: this would be interpreted as upb::FieldDef::has::default(). |
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bool upb_FieldDef_has_default(const upb_FieldDef* f); |
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// GOOD: this is equivalent to upb::FieldDef::HasDefault(). |
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bool upb_FieldDef_HasDefault(const upb_FieldDef* f); |
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``` |
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For multi-word namespaces, we use `PascalCase`: |
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```c++ |
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// `PyUpb` is the namespace. |
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PyObject* PyUpb_CMessage_GetAttr(PyObject* _self, PyObject* attr); |
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``` |
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### Private Functions and Members |
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Since we do not have `private` in C++, we use the `UPB_PRIVATE()` macro to mark |
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internal functions and variables that should only be accessed from upb: |
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```c++ |
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// Internal-only function. |
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int64_t UPB_PRIVATE(upb_Int64_FromLL)(); |
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// Internal-only members. Underscore prefixes are only necessary when the |
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// structure is defined in a header file. |
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typedef struct { |
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const int32_t* UPB_PRIVATE(values); |
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uint64_t UPB_PRIVATE(mask); |
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int UPB_PRIVATE(value_count); |
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} upb_MiniTableEnum; |
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// Using these members in an internal function. |
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int upb_SomeFunction(const upb_MiniTableEnum* e) { |
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return e->UPB_PRIVATE(value_count); |
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} |
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``` |
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This prevents users from accessing these symbols, because `UPB_PRIVATE()` |
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is defined in `port_def.inc` and undefined in `port_undef.inc`, and these |
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textual headers are not accessible by users. |
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It is only necessary to use `UPB_PRIVATE()` for things defined in headers. |
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For symbols in `.c` files, it is sufficient to mark private functions with |
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`static`.
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