tree-sitter-c-sharp
===========================

[![Build Status](https://github.com/tree-sitter/tree-sitter-c-sharp/workflows/build/badge.svg)](https://github.com/tree-sitter/tree-sitter-c-sharp/actions?query=workflow%3Abuild)

C# grammar for [tree-sitter](https://github.com/tree-sitter/tree-sitter) based on an export of the Roslyn grammar export with various changes in order to:

- Deal with differences between the parsing technologies
- Work around some bugs in that grammar
- Handle `#if`, `#else`, `#elif`, `#endif` blocks
- Support syntax highlighting/parsing of fragments
- Simplify the output tree

### Status

Comprehensive support for C# exists with the following exceptions:

- [ ] `async` and `await` cannot be used as identifiers

#### C# 7.0 (complete)

- [x] Tuples
- [x] Discards
- [x] Basic pattern matching
- [x] Recursive pattern matching
- [x] Ref locals and return
- [x] Local function statements
- [x] Expression bodied constructors
- [x] Expression bodied destructors/finalizers
- [x] Throw expressions
- [x] Binary and `_` literal support

#### C# 7.1 (complete)

- [x] `async` main method
- [x] Default literals (as `default_expression`)
- [x] Inferred tuple element names
- [x] Generic type pattern matching

#### C# 7.2 (complete)

- [x] `in` parameter modifiers
- [x] `ref readonly` method returns
- [x] `readonly struct`
- [x] `ref struct`
- [x] Non-named trailing arguments
- [x] `_` leading binary and hex literals
- [x] `private protected` modifier
- [x] Conditional `ref` expressions

#### C# 7.3 (complete)

- [x] `stackalloc` array initializers
- [x] `unmanaged` generic type parameter constraint
- [x] Attributes attached to auto property backing fields
- [x] `out` support for parameters on initializers, constructors etc.

#### C# 8.0 (complete)

- [x] `readonly` members
- [x] Default interface methods
- [x] `switch` expressions
- [x] `switch` property patterns
- [x] `switch` tuple patterns
- [x] `static` local functions
- [x] Nullable reference types
- [x] Null-forgiving operator
- [x] Null-coalescing assignment

#### C# 9.0 (complete)

- [x] Covariant returns
- [x] Extending partial methods
- [x] Extension GetEnumerator
- [x] Function pointers
- [x] Init properties
- [x] Lambda discard parameters
- [x] Local function attributes
- [x] Module initializers
- [x] Native integers
- [x] Patterns
  - [x] Simple type patterns
  - [x] Relational patterns
  - [x] Logical patterns
- [x] Records
- [x] Skip Locals Init
- [x] Static anonymous functions
- [x] Target-typed conditional expression
- [x] Target-typed new
- [x] Top-level statements

### References

* [Official C# 6 Language Spec](https://github.com/dotnet/csharplang/blob/master/spec/) provides chapters that formally define the language grammar.
* [Roslyn C# language grammar export](https://github.com/dotnet/roslyn/blob/master/src/Compilers/CSharp/Portable/Generated/CSharp.Generated.g4)
* [SharpLab](https://sharplab.io) (web-based syntax tree playground based on Roslyn)