Alexander Shabalin
314edd7066
Merge-request: KT-MR-7880 Merged-by: Alexander Shabalin <Alexander.Shabalin@jetbrains.com>
61 lines
3.7 KiB
Markdown
61 lines
3.7 KiB
Markdown
# Code style for C++
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**TODO**: Expand beyond naming and formatting
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## Headers
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* Headers should live in the same folder with it's implementation counterpart (if there's one) **TODO**: This does not work with multiple implementations of a single header.
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* Headers can use either `#pragma once` or header guards.
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* Headers that are designed to be included into both `.cpp`/`.mm` and `.c`/`.m` should have extension `.h`
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* Headers that are designed to be included into `.cpp`/`.mm` only should have extension `.hpp`
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## Namespace usage
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* Do not use namespace blocks inside implementation files (`*.c`, `*.cpp`, `*.m`, `*.mm`). Use fully qualified names for definitions.
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* Do not use `extern "C"` blocks inside implementation files.
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### Runtime-specific
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* Put main module inside `namespace kotlin`
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* Put other modules under `namespace kotlin` in a nested `namespace [module_name]`
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* Put implementation details inside `.h`/`.hpp` into a nested `namespace internal` (e.g. implementation details of module `mm` go into `namespace kotlin { namespace mm { namespace internal { ... } } }`)
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* Put implementation details inside `.cpp`/`.mm` into a global anonymous `namespace`
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* For `extern "C"` declarations emulate namespaces with `Kotlin_[module_name]_` prefixes.
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* To mark type as move-only, privately inherit from `kotlin::MoveOnly`
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* To mark type unmovable and uncopyable, privately inherit from `kotlin::Pinned`
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* Use `std_support::*` containers and smart pointers instead of `std::*` ones. The former ones default to runtime-specific allocator.
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* Use `new (std_support::kalloc) T(...)` (defined in `std_support/New.hpp` instead of `new T(...)` and `std_support::kdelete(ptr)` instead of `delete ptr`. The former ones use runtime-specific allocator.
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## Naming
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* Types should use `PascalCase`
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* Local variables and function parameters should use `camelCase`
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* Global variables should use `camelCase`
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* Constants should use `kPascalCase` (with prefix `k`)
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* Private functions (not visible outside a compilation unit) should use `camelCase`
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* Exported functions (declared in headers or shared with Kotlin) should use `PascalCase`
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* Member fields should use `camelCase`. Private member fields should add `_` suffix: `camelCase_`
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* Member functions should use `camelCase`
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* Macros should use `SCREAMING_SNAKE_CASE`
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* namespaces should use `snake_case`
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* `enum` and `enum class` members should use `kPascalCase`
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If API is designed to mimic C++ stdlib (e.g. stubbing `<atomic>` for platforms that do not support it), its allowed
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to follow stdlib naming conventions.
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## Formatting
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For automated formatting you can use [config for CLion](codestyle/cpp/CLionFormat.xml) or `clang-format` (see [config](.clang-format) at the repo's root). Note, that CLion uses `clang-format` by default; this can be turned off if you prefer to use rules from `CLionFormat.xml`.
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Since 1.8.20 there's also a `:kotlin-native:clangFormat` task that will effectively run `git-clang-format -f $(git merge-base origin/master HEAD) -- kotlin-native/`.
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The task accepts optional arguments `--parent` to specify base branch other than `origin/master`, and `--interactive` to run the tool with `-p` flag and interactively accept or reject formatted patches.
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Formatting rules are designed to closely mirror [Kotlin rules](https://kotlinlang.org/docs/reference/coding-conventions.html).
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* Use spaces instead of tabs. Indentation width is 4 spaces. Continuation width is 8 spaces
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* Do not indent namespaces
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* Visibility modifiers are placed without indentation
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* All operators should be wrapped with a space or a line break
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* In pointer and reference definitions `*` and `&` should be placed on a type instead of a variable
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* In pointer to functions prefer not to use `*` at all.
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* Add a space between `template` and `<`
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