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#![recursion_limit = "256"]
extern crate proc_macro;
use quote::quote;
use proc_macro2::TokenStream;
#[proc_macro_derive(Schematic, attributes(schematic))]
pub fn derive_schematic(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input: TokenStream = input.into();
let result: TokenStream = {
let ast: syn::DeriveInput = syn::parse_str(&input.to_string()).unwrap();
let input_type = &ast.ident;
let mut base_name =
syn::LitStr::new(&ast.ident.to_string(), proc_macro2::Span::call_site());
let mut magic: Option<syn::Expr> = None;
for attr in &ast.attrs {
if let Ok(syn::Meta::List(syn::MetaList {
path: ref meta_path,
ref nested,
..
})) = attr.parse_meta()
{
if meta_path.is_ident("schematic") {
for inner in nested {
if let syn::NestedMeta::Meta(syn::Meta::NameValue(syn::MetaNameValue {
path: ref meta_path,
lit: syn::Lit::Str(ref lit),
..
})) = *inner
{
if meta_path.is_ident("rename") {
base_name = lit.clone();
} else if meta_path.is_ident("magic") {
magic = Some(syn::parse_str(&lit.value()).unwrap());
}
}
}
}
}
}
let magic = match magic {
Some(expr) => quote! { Some(#expr) },
None => quote! { None },
};
match ast.data {
syn::Data::Struct(syn::DataStruct { ref fields, .. }) => match fields {
syn::Fields::Named(_) => {
let field_tys: Vec<_> = fields.iter().map(|field| &field.ty).collect();
let field_tys = &field_tys;
let field_names: Vec<_> = fields
.iter()
.map(|field| field.ident.as_ref().unwrap())
.collect();
let field_names = &field_names;
let mut generics = ast.generics.clone();
let generic_params: Vec<_> = ast
.generics
.type_params()
.map(|param| ¶m.ident)
.collect();
let generic_params = &generic_params;
let extra_where_clauses = quote! {
where
#(#field_tys: trans_schema::Schematic + 'static,)*
#(#generic_params: trans_schema::Schematic,)*
};
let extra_where_clauses: syn::WhereClause =
syn::parse_str(&extra_where_clauses.to_string()).unwrap();
generics
.make_where_clause()
.predicates
.extend(extra_where_clauses.predicates);
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let expanded = quote! {
impl #impl_generics trans_schema::Schematic for #input_type #ty_generics #where_clause {
fn create_schema() -> trans_schema::Schema {
let mut name = #base_name.to_owned();
#(
name += &trans_schema::schema::<#generic_params>().full_name().raw();
)*
trans_schema::Schema::Struct(trans_schema::Struct {
name: trans_schema::Name::new(name),
magic: #magic,
fields: vec![
#(trans_schema::Field {
name: trans_schema::Name::new(stringify!(#field_names).to_owned()),
schema: trans_schema::schema::<#field_tys>(),
}),*
],
})
}
}
};
expanded.into()
}
syn::Fields::Unnamed(_) => {
if fields.iter().len() != 1 {
panic!("Tuple structs other than newtype not supported");
}
let inner_ty = fields.iter().next().unwrap();
let mut generics = ast.generics.clone();
let extra_where_clauses = quote! {
where #inner_ty: trans_schema::Schematic + 'static
};
let extra_where_clauses: syn::WhereClause =
syn::parse_str(&extra_where_clauses.to_string()).unwrap();
generics
.make_where_clause()
.predicates
.extend(extra_where_clauses.predicates);
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let expanded = quote! {
impl #impl_generics trans_schema::Schematic for #input_type #ty_generics #where_clause {
fn create_schema() -> trans_schema::Schema {
<#inner_ty as trans_schema::Schematic>::create_schema()
}
}
};
expanded.into()
}
syn::Fields::Unit => panic!("Unit structs not supported"),
},
syn::Data::Enum(syn::DataEnum { ref variants, .. }) => {
let mut generics = ast.generics.clone();
let generic_params: Vec<_> = ast
.generics
.type_params()
.map(|param| ¶m.ident)
.collect();
let generic_params = &generic_params;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
if variants.iter().all(|variant| {
if let syn::Fields::Unit = variant.fields {
true
} else {
false
}
}) {
let variants = variants.iter();
let expanded = quote! {
impl #impl_generics trans_schema::Schematic for #input_type #ty_generics #where_clause {
fn create_schema() -> trans_schema::Schema {
let mut base_name = #base_name.to_owned();
#(
base_name += &trans_schema::schema::<#generic_params>().full_name().raw();
)*
trans_schema::Schema::Enum {
base_name: trans_schema::Name::new(base_name),
variants: vec![#(trans_schema::Name::new(stringify!(#variants).to_owned())),*],
}
}
}
};
expanded.into()
} else {
let variants = variants.iter().map(|variant| {
let variant_name = &variant.ident;
let field_names = variant
.fields
.iter()
.map(|field| field.ident.as_ref().unwrap());
let field_tys = variant.fields.iter().map(|field| &field.ty);
quote! {
trans_schema::Struct {
name: trans_schema::Name::new(stringify!(#variant_name).to_owned()),
magic: None,
fields: vec![
#(trans_schema::Field {
name: trans_schema::Name::new(stringify!(#field_names).to_owned()),
schema: trans_schema::schema::<#field_tys>(),
}),*
],
}
}
});
let expanded = quote! {
impl #impl_generics trans_schema::Schematic for #input_type #ty_generics #where_clause {
fn create_schema() -> trans_schema::Schema {
let mut base_name = #base_name.to_owned();
#(
base_name += &trans_schema::schema::<#generic_params>().full_name().raw();
)*
trans_schema::Schema::OneOf {
base_name: trans_schema::Name::new(base_name),
variants: vec![#(#variants),*],
}
}
}
};
expanded.into()
}
}
syn::Data::Union(_) => panic!("Unions not supported"),
}
};
result.into()
}