/
desse.rs
116 lines (88 loc) · 3.4 KB
/
desse.rs
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use proc_macro2::TokenStream;
use quote::quote;
use syn::punctuated::Punctuated;
use syn::token::Comma;
use syn::Data::*;
use syn::Fields::*;
use syn::{DataEnum, DataStruct, DataUnion, DeriveInput, Field};
pub fn get_desse_impl(input: DeriveInput) -> TokenStream {
let name = input.ident;
let (serialize, deserialize) = match &input.data {
Struct(ref struct_data) => get_struct_expr(&struct_data),
Enum(ref enum_data) => get_enum_expr(&enum_data),
Union(ref union_data) => get_union_expr(&union_data),
};
quote! {
#[automatically_derived]
#[allow(unused_qualifications)]
impl Desse for #name {
type Output = [u8; Self::SIZE];
#[inline]
fn serialize(&self) -> Self::Output {
let mut bytes: Self::Output = [0; Self::SIZE];
#serialize
bytes
}
#[inline]
fn deserialize_from(bytes: &Self::Output) -> Self {
let mut object: Self = unsafe { std::mem::zeroed() };
#deserialize
object
}
}
}
}
fn get_enum_expr(_enum_data: &DataEnum) -> (TokenStream, TokenStream) {
panic!("This macro cannot be used on enums!")
}
fn get_union_expr(_union_data: &DataUnion) -> (TokenStream, TokenStream) {
panic!("This macro cannot be used on unions!")
}
fn get_struct_expr(struct_data: &DataStruct) -> (TokenStream, TokenStream) {
let punctuated = match &struct_data.fields {
Named(ref named_fields) => &named_fields.named,
Unnamed(ref unnamed_fields) => &unnamed_fields.unnamed,
Unit => panic!("Cannot implement serialize for unit struct"),
};
let serialize = get_serialize_expr_for_punctuated(&punctuated);
let deserialize = get_deserialize_expr_for_punctuated(&punctuated);
(serialize, deserialize)
}
fn get_serialize_expr_for_punctuated(punctuated: &Punctuated<Field, Comma>) -> TokenStream {
if punctuated.is_empty() {
panic!("Cannot implement serialize for struct with no fields");
}
let mut exprs = Vec::with_capacity(punctuated.len());
let mut counter = quote! { 0 };
for (i, field) in punctuated.iter().enumerate() {
let name = match &field.ident {
None => quote! { #i },
Some(ref ident) => quote! { #ident },
};
let ty = &field.ty;
exprs.push(
quote! { (&mut bytes[ (#counter)..( #counter + <#ty>::SIZE ) ]).copy_from_slice(&Desse::serialize(&self. #name)); },
);
counter = quote! { #counter + <#ty>::SIZE };
}
quote! { #(#exprs)* }
}
fn get_deserialize_expr_for_punctuated(punctuated: &Punctuated<Field, Comma>) -> TokenStream {
if punctuated.is_empty() {
panic!("Cannot implement serialize for struct with no fields");
}
let mut exprs = Vec::with_capacity(punctuated.len());
let mut counter = quote! { 0 };
for (i, field) in punctuated.iter().enumerate() {
let name = match &field.ident {
None => quote! { #i },
Some(ref ident) => quote! { #ident },
};
let ty = &field.ty;
exprs.push(
quote! { object. #name = <#ty>::deserialize_from(&*(bytes[ (#counter) .. ( #counter + <#ty>::SIZE ) ].as_ptr() as *const [u8; <#ty>::SIZE])); },
);
counter = quote! { #counter + <#ty>::SIZE };
}
quote! { unsafe { #(#exprs)* } }
}