Will Hawkins
124 lines
3.0 KiB
Markdown
124 lines
3.0 KiB
Markdown
## P4RSE: P4 Runtime In Swift Environment
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_P4RSE_ (yes, the acronym is a bit forced) is a P4 parser and runtime written in Swift. The project was started as a means to better learn Swift.
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### Status
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Very, very alpha:
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1. Limited parts of the language can be parsed.
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2. Limited programs can be evaluated.
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As an example of what can be parsed and evaluated, here is a fairly complex P4 program cobbled together from our unit tests:
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```P4
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control simple(bool x, bool y) {
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action a(int z) {
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z = false;
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}
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table t {
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key = {
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x: exact;
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y: exact;
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}
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}
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};
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struct Testing {
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bool yesno;
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int count;
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};
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parser main_parser() {
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state start {
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Testing ts;
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ts.count = 1;
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transition select (ts.count) {
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0: accept;
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_: reject;
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};
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}
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};
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```
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Please check back often!
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### Building
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#### Requirements And Basic Build
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This project uses [code item macros (`CodeItemMacros`)](https://github.com/swiftlang/swift-evolution/blob/main/proposals/0397-freestanding-declaration-macros.md#future-directions) which
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are an experimental feature in Swift and not [_available in production_](https://github.com/swiftlang/swift/blob/1ba5ae105876b15914688cdf8431fd390651296e/include/swift/Basic/Features.def).
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Therefore, to compile this project, you must be using a non-production version of the compiler.
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With that caveat noted, building can be done with `swift build`:
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```console
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$ swift build
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```
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### Contributing
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We would _love_ your help! Contributions are very welcome!
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#### Coding Style
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Here are the style guidelines that we are _trying_ to maintain:
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- variables are in `snake_case`.
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- types are in `CamelCase`.
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Of course, we want to follow the formatter, too: see [below](#checking-format).
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#### Commit Messages
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We will try to maintain the following headline format for commit messages:
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```
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<component>: <subcomponent>: <change>
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```
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where `<component>` is one of:
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1. `grammar`: For the tree-sitter-based grammar.
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2. `compiler`: For the Swift-based P4 compiler of tree-sitter-based-parser parsed programs into AST.
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3. `runtime`: For the Swift-based P4 interpreter.
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4. `common`: For any Swift-based components common to the entire project (and macros).
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5. `documentation`: For any documentation updates.
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6. `testing`: For Swift-based tests.
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where `<subcomponent>` can be more free-form and `<change>` is a pithy description of the changes in the commit.
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#### Testing
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To run the P4RSE tests:
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```console
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$ swift test
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```
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To run the parser tests, from the `tree-sitter-p4` directory:
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```console
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$ npx tree-sitter test
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```
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#### Generating Documentation
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To build the documentation:
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```console
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$ swift package generate-documentation
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```
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To preview the generated documentation:
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```console
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$ swift package swift package --disable-sandbox preview-documentation --target <some target>
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```
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For more information, see the [documentation for the Swift-DocC plugin](https://swiftlang.github.io/swift-docc-plugin/documentation/swiftdoccplugin/).
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#### Checking Format
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To check the format:
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```console
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$ swift-format --recursive -i Sources/
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``` |