use proc_macro2::{Span, TokenStream};
use quote::quote;
use syn::{DeriveInput, Ident, Error};
use proc_macro_crate::crate_name;
const CRATE_NAME: &str = "sc-chain-spec";
const ATTRIBUTE_NAME: &str = "forks";
pub fn extension_derive(ast: &DeriveInput) -> proc_macro::TokenStream {
derive(ast, |crate_name, name, generics: &syn::Generics, field_names, field_types, fields| {
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let forks = fields.named.iter().find_map(|f| {
if f.attrs.iter().any(|attr| attr.path.is_ident(ATTRIBUTE_NAME)) {
let typ = &f.ty;
Some(quote! { #typ })
} else {
None
}
}).unwrap_or_else(|| quote! { #crate_name::NoExtension });
quote! {
impl #impl_generics #crate_name::Extension for #name #ty_generics #where_clause {
type Forks = #forks;
fn get<T: 'static>(&self) -> Option<&T> {
use std::any::{Any, TypeId};
match TypeId::of::<T>() {
#( x if x == TypeId::of::<#field_types>() => Any::downcast_ref(&self.#field_names) ),*,
_ => None,
}
}
fn get_any(&self, t: std::any::TypeId) -> &dyn std::any::Any {
use std::any::{Any, TypeId};
match t {
#( x if x == TypeId::of::<#field_types>() => &self.#field_names ),*,
_ => self,
}
}
}
}
})
}
pub fn group_derive(ast: &DeriveInput) -> proc_macro::TokenStream {
derive(ast, |crate_name, name, generics: &syn::Generics, field_names, field_types, _fields| {
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let fork_name = Ident::new(&format!("{}Fork", name), Span::call_site());
let fork_fields = generate_fork_fields(&crate_name, &field_names, &field_types);
let to_fork = generate_base_to_fork(&fork_name, &field_names);
let combine_with = generate_combine_with(&field_names);
let to_base = generate_fork_to_base(name, &field_names);
let serde_crate_name = match proc_macro_crate::crate_name("serde") {
Ok(name) => Ident::new(&name.replace("-", "_"), Span::call_site()),
Err(e) => {
let err = Error::new(
Span::call_site(),
&format!("Could not find `serde` crate: {}", e),
).to_compile_error();
return quote!( #err ).into();
}
};
quote! {
#[derive(
Debug,
Clone,
PartialEq,
#serde_crate_name::Serialize,
#serde_crate_name::Deserialize,
ChainSpecExtension,
)]
pub struct #fork_name #ty_generics #where_clause {
#fork_fields
}
impl #impl_generics #crate_name::Group for #name #ty_generics #where_clause {
type Fork = #fork_name #ty_generics;
fn to_fork(self) -> Self::Fork {
use #crate_name::Group;
#to_fork
}
}
impl #impl_generics #crate_name::Fork for #fork_name #ty_generics #where_clause {
type Base = #name #ty_generics;
fn combine_with(&mut self, other: Self) {
use #crate_name::Fork;
#combine_with
}
fn to_base(self) -> Option<Self::Base> {
use #crate_name::Fork;
#to_base
}
}
}
})
}
pub fn derive(
ast: &DeriveInput,
derive: impl Fn(
&Ident, &Ident, &syn::Generics, Vec<&Ident>, Vec<&syn::Type>, &syn::FieldsNamed,
) -> TokenStream,
) -> proc_macro::TokenStream {
let err = || {
let err = Error::new(
Span::call_site(),
"ChainSpecGroup is only available for structs with named fields."
).to_compile_error();
quote!( #err ).into()
};
let data = match &ast.data {
syn::Data::Struct(ref data) => data,
_ => return err(),
};
let fields = match &data.fields {
syn::Fields::Named(ref named) => named,
_ => return err(),
};
const PROOF: &str = "CARGO_PKG_NAME always defined when compiling; qed";
let name = &ast.ident;
let crate_name = match crate_name(CRATE_NAME) {
Ok(chain_spec_name) => chain_spec_name,
Err(e) => if std::env::var("CARGO_PKG_NAME").expect(PROOF) == CRATE_NAME {
CRATE_NAME.replace("-", "_")
} else {
let err = Error::new(Span::call_site(), &e).to_compile_error();
return quote!( #err ).into()
},
};
let crate_name = Ident::new(&crate_name, Span::call_site());
let field_names = fields.named.iter().flat_map(|x| x.ident.as_ref()).collect::<Vec<_>>();
let field_types = fields.named.iter().map(|x| &x.ty).collect::<Vec<_>>();
derive(&crate_name, name, &ast.generics, field_names, field_types, fields).into()
}
fn generate_fork_fields(
crate_name: &Ident,
names: &[&Ident],
types: &[&syn::Type],
) -> TokenStream {
let crate_name = std::iter::repeat(crate_name);
quote! {
#( pub #names: Option<<#types as #crate_name::Group>::Fork>, )*
}
}
fn generate_base_to_fork(
fork_name: &Ident,
names: &[&Ident],
) -> TokenStream {
let names2 = names.to_vec();
quote!{
#fork_name {
#( #names: Some(self.#names2.to_fork()), )*
}
}
}
fn generate_combine_with(
names: &[&Ident],
) -> TokenStream {
let names2 = names.to_vec();
quote!{
#( self.#names.combine_with(other.#names2); )*
}
}
fn generate_fork_to_base(
fork: &Ident,
names: &[&Ident],
) -> TokenStream {
let names2 = names.to_vec();
quote!{
Some(#fork {
#( #names: self.#names2?.to_base()?, )*
})
}
}