oxc_ast_macros 0.50.0

use proc_macro::TokenStream;
use syn::{parse_macro_input, Item};

mod ast;
mod generated;

/// This attribute serves two purposes:
///
/// Firstly, it is a marker for `oxc_ast_tools`, to understand that a type is part of the AST.
///
/// Secondly, it adds the following code around the type:
///
/// ### `#[repr(C)]`
///
/// `#[repr]` attribute is added to the type, to make the memory layout of the type predictable:
///
/// * Structs: `#[repr(C)]`. e.g. `#[repr(C)] struct S { x: X, y: Y }`
/// * Fieldless enums: `#[repr(u8)]` e.g. `#[repr(u8)] enum E { X, Y, Z, }`.
/// * Fieldful enums: `#[repr(C, u8)]` e.g. `#[repr(C, u8)] enum E { X(X), Y(Y) }`
///
/// ### Derive `Ast` trait
///
/// `#[derive(oxc_ast_macros::Ast)]` is added to the type.
///
/// `Ast` derive macro is a no-op (see below) but allows custom attributes on AST types.
///
/// See `derives` and `generators` directories in `tasks/ast_tools` for details of the various
/// custom attributes, and how they're used.
///
/// ### Trait assertions
///
/// `oxc_ast_tools` generates code for trait impls where those traits are specified with
/// `#[generate_derive(SomeTrait)]`. This is similar to `#[derive(SomeTrait)]`, but the code is
/// generated ahead-of-time, rather than in a proc macro.
///
/// Add assertions that traits used in `#[generate_derive(...)]` are in scope.
#[proc_macro_attribute]
pub fn ast(_args: TokenStream, input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as Item);
    let expanded = ast::ast(&input);
    TokenStream::from(expanded)
}

/// Dummy derive macro for a non-existent trait `Ast`.
///
/// Does not generate any code.
/// Its only purpose is to allow the occurrence of helper attributes used in `tasks/ast_tools`.
///
/// See [`macro@ast`] for further details.
#[proc_macro_derive(
    Ast,
    attributes(clone_in, content_eq, estree, generate_derive, plural, scope, span, ts, visit)
)]
pub fn ast_derive(_input: TokenStream) -> TokenStream {
    TokenStream::new()
}