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extern crate proc_macro;
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, DeriveInput};
#[proc_macro_derive(DeriveKnet)]
pub fn derive(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
let ienum = &ast.ident;
let ienum_string = ienum.to_string();
let variants = if let syn::Data::Enum(syn::DataEnum { variants, .. }) = &ast.data {
variants
} else {
unimplemented!("Derive Knet only support Enum")
};
let max_ident = variants
.iter()
.map(|v| v.ident.to_string().len())
.max_by(|v1, v2| v1.cmp(&v2));
let serialize_variants = variants.iter().map(|v| {
let name = &v.ident;
let sname = name.to_string();
let ty = inner_ty(&v.fields);
quote! {
#ienum::#name(data) => {
let size = ::std::mem::size_of::<#ty>();
let mut v = vec![0u8; #max_ident + size];
let src_ptr = ::std::boxed::Box::new(*data);
let dst_ptr = v.as_mut_ptr();
unsafe {
std::ptr::copy_nonoverlapping(#sname.as_ptr(), dst_ptr, #sname.len());
let dst_ptr = dst_ptr.offset(#max_ident as isize);
let src_ptr = ::std::boxed::Box::into_raw(src_ptr).cast::<u8>();
std::ptr::copy_nonoverlapping(src_ptr, dst_ptr, size);
};
let _ = ::std::boxed::Box::from_raw(src_ptr);
v
}
}
});
let serialize = quote! {
fn serialize(&self) -> ::std::vec::Vec<u8> {
match self {
#(#serialize_variants)*
}
}
};
let deserialize_variants = variants.iter().map(|v| {
let name = &v.ident;
let sname = name.to_string();
let ty = inner_ty(&v.fields).unwrap();
quote!{
#sname => {
let mut data = #ty::default();
let src_ptr = v[#max_ident..].as_ptr();
let dst_ptr = ::std::boxed::Box::into_raw(::std::boxed::Box::new(data)).cast::<u8>();
unsafe {
std::ptr::copy_nonoverlapping(src_ptr, dst_ptr, ::std::mem::size_of::<#ty>());
data = *dst_ptr.cast::<#ty>();
::std::boxed::Box::from_raw(dst_ptr);
};
*self = #ienum::#name(data);
}
}
});
let deserialize = quote! {
fn deserialize(&mut self, v: &[u8]) {
let name = std::string::String::from_utf8(v[0..#max_ident].to_vec())
.unwrap();
let name = name.trim_end_matches(|c| c as u8 == 0u8);
match name {
#(#deserialize_variants),*
_ => { panic!("`{}` is not a part of {}", name, #ienum_string) }
}
}
};
let from_raw_variants = variants.iter().map(|v| {
let name = &v.ident;
let sname = name.to_string();
let ty = inner_ty(&v.fields).unwrap();
quote! {
#sname => {
let mut data = #ty::default();
let src_ptr = v[#max_ident..].as_ptr();
let dst_ptr = ::std::boxed::Box::into_raw(::std::boxed::Box::new(data)).cast::<u8>();
unsafe {
std::ptr::copy_nonoverlapping(src_ptr, dst_ptr, ::std::mem::size_of::<#ty>());
data = *dst_ptr.cast::<#ty>();
::std::boxed::Box::from_raw(dst_ptr);
};
#ienum::#name(data)
}
}
});
let from_raw = quote! {
fn from_raw(v: &[u8]) -> Self {
let name = std::string::String::from_utf8(v[0..#max_ident].to_vec())
.unwrap();
let name = name.trim_end_matches(|c| c as u8 == 0u8);
match name {
#(#from_raw_variants),*
_ => { panic!("`{}` is not a part of {}", name, #ienum_string) }
}
}
};
let get_size_variants = variants.iter().map(|v| {
let name = &v.ident;
let sname = name.to_string();
let ty = inner_ty(&v.fields).unwrap();
quote! {
#sname => {
::std::mem::size_of::<#ty>()
}
}
});
let get_size_of_data = quote! {
fn get_size_of_data(v: &[u8]) -> usize {
let name = std::string::String::from_utf8(v.to_vec())
.unwrap();
let name = name.trim_end_matches(|c| c as u8 == 0u8);
match name {
#(#get_size_variants),*
_ => { panic!("`{}` is not a part of {}", name, #ienum_string) }
}
}
};
let get_size_of_payload = quote! {
fn get_size_of_payload() -> usize {
#max_ident
}
};
let expanded = quote! {
impl knet::KnetTransform for #ienum {
#serialize
#deserialize
#from_raw
#get_size_of_data
#get_size_of_payload
}
};
expanded.into()
}
fn inner_ty(field: &syn::Fields) -> Option<&syn::Ident> {
if let syn::Fields::Unnamed(syn::FieldsUnnamed { unnamed, .. }) = field {
if let Some(first) = unnamed.first() {
if let syn::Type::Path(syn::TypePath { path, .. }) = &first.into_value().ty {
if path.segments.len() == 1 {
return Some(&path.segments[0].ident);
}
}
}
}
None
}