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use proc_macro2::Group;
use crate::syn::parse::Parser;
use syn::punctuated::Punctuated;
use proc_macro2::TokenStream;
use quote::{quote, quote_spanned, format_ident};
use syn::spanned::Spanned;
use syn::*;
pub fn derive_root(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
// Parse the input tokens into a syntax tree.
let input = parse_macro_input!(input as DeriveInput);
let pools = pools(input.attrs);
// Used in the quasi-quotation below as `#name`.
let name = input.ident;
let mut expanded = vec![];
for p in &pools {
// Add a bound `T: RootObj` to every type parameter T.
let generics = add_trait_bounds(input.generics.clone(), &pools, &p);
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
// Generate an expression to sum up the heap size of each field.
let sum = root_all_fields(&name, &input.data);
expanded.push(quote! {
#[automatically_derived]
#[allow(unused_qualifications)]
impl#impl_generics corundum::RootObj<#p> for #name #ty_generics #where_clause {
#[inline]
fn init(j: &corundum::stm::Journal<#p>) -> Self {
#sum
}
}
});
}
let expanded = quote! { #(#expanded)* };
// Hand the output tokens back to the compiler.
proc_macro::TokenStream::from(expanded)
}
fn pools(attrs: Vec<Attribute>) -> Vec<TokenStream> {
let mut p = vec![];
for attr in &attrs {
for segment in attr.path.segments.iter() {
if segment.ident.to_string() == String::from("pools") {
if let Ok(g) = parse2::<Group>(attr.tokens.clone()) {
let parser = Punctuated::<Path, Token![,]>::parse_terminated;
if let Ok(pools) = parser.parse2(g.stream()) {
for pool in pools {
p.push(quote! { #pool });
}
}
}
};
}
}
if p.is_empty() {
vec![quote!{ corundum::default::BuddyAlloc }]
} else {
p
}
}
// Add a bound `T: RootObj` to every type parameter T.
fn add_trait_bounds(mut generics: Generics, pool: &Vec<TokenStream>, p: &TokenStream) -> Generics {
for param in &mut generics.params {
if let GenericParam::Type(ref mut type_param) = *param {
let ident = type_param.ident.clone();
let me = ident.to_string();
if !pool.iter().any(|p| p.to_string() == me) {
type_param.bounds.push(parse_quote!(corundum::RootObj<#p>));
}
}
}
generics
}
// Generate an expression to sum up the heap size of each field.
fn root_all_fields(ident: &Ident, data: &Data) -> TokenStream {
match *data {
Data::Struct(ref data) => {
match data.fields {
Fields::Named(ref fields) => {
let recurse = fields.named.iter().map(|f| {
let name = &f.ident;
quote_spanned! {f.span()=>
#name: corundum::RootObj::init(j)
}
});
quote! {
Self {
#(#recurse,)*
}
}
}
Fields::Unnamed(ref fields) => {
// Expands to an expression like
//
// 0 + self.0.heap_size() + self.1.heap_size() + self.2.heap_size()
let recurse = fields.unnamed.iter().enumerate().map(|(_, f)| {
quote_spanned! {f.span()=>
corundum::RootObj::init(j)
}
});
quote! {
Self(#(#recurse,)*)
}
}
Fields::Unit => {
// Unit structs cannot own more than 0 bytes of heap memory.
quote!(0)
}
}
}
Data::Enum(DataEnum { ref variants, .. }) => {
let res = variants.iter().map(|ref v| {
let variant = v.ident.clone();
match v.fields {
Fields::Unit => quote! {
#ident::#variant => #ident::#variant
},
Fields::Unnamed(ref fields) => {
let recurse = fields.unnamed.iter().enumerate().map(|(i, f)| {
let varname = format_ident!("__self_{}", i);
quote_spanned! {f.span()=>
#varname
}
});
let ints = recurse.clone();
quote! {
#ident::#variant(#(#recurse,)*) =>
#ident::#variant(#(corundum::RootObj::init(&#ints, j),)*)
}
},
Fields::Named(ref fields) => {
let recurse = fields.named.iter().enumerate().map(|(i,f)| {
let name = &f.ident;
let varname = format_ident!("__self_{}", i);
quote_spanned! {f.span()=>
#name: #varname
}
});
let clones = fields.named.iter().enumerate().map(|(_i,f)| {
let name = &f.ident;
quote_spanned! {f.span()=>
#name: corundum::RootObj::init(j)
}
});
quote! {
#ident::#variant{#(#recurse,)*} =>
#ident::#variant{#(#clones,)*}
}
}
}
});
quote! {
match self {
#(#res,)*
}
}
}
Data::Union(_) => panic!("Union types cannot derive RootObj"),
}
}