proc_macro for generating highly optimized V8 functions from Deno ops.

// Declare an op.
#[op(fast)]
pub fn op_add(_: &mut OpState, a: i32, b: i32) -> i32 {
  a + b
}

// Register with an extension.
Extension::builder()
  .ops(vec![op_add::decl()])
  .build();

The macro can optimize away code, short circuit fast paths and generate a Fast API impl.

Cases where code is optimized away:

• -> () skips serde_v8 and rv.set calls.
• -> Result<(), E> skips serde_v8 and rv.set calls for Ok() branch.
• -> ResourceId or -> [int] types will use specialized method like v8::ReturnValue::set_uint32. A fast path for SMI.
• -> Result<ResourceId, E> or -> Result<[int], E> types will be optimized like above for the Ok() branch.

The macro will infer and try to auto generate V8 fast API call trait impl for sync ops with:

• arguments: integers, bool, &mut OpState, &[u8], &mut [u8],&[u32],&mut [u32]`
• return_type: integers, bool

The #[op(fast)] attribute should be used to enforce fast call generation at compile time.

Trait gen for async ops & a ZeroCopyBuf equivalent type is planned and will be added soon.